by Ruturaj Patil, Product Manager Phytogenic Liquids, EW Nutrition

Commercial poultry operations have undergone enormous changes in production practices over the last 50 years. Genetic selection for high production rates, along with upgraded management techniques and dietary measures, have led to increased performance standards in all poultry operations (Kogut et al., 2017). However, it is sensible to now look into whether poultry performance may soon reach a ceiling due to genetic and/or physiological limits. So, aiming at further performance optimization, poultry researchers and producers are now focusing on gut health.

Gut health management is key to sustainably improve poultry performance

The caveat, of course, is that, due to concerns about antimicrobial resistance, antimicrobial growth promoters (AGPs) no longer offer the easy answer to gut health issues they once were. To preserve antibiotics’ efficacy for cases where they are indispensable, gut health-oriented performance enhancement needs to come from other sources. This article reviews the principles of gut health management in poultry and shows how Activo liquid, a phytomolecules-based in-water solution, strengthens poultry performance by targeting gut health.

Gut health: the cradle of poultry performance

Gastrointestinal health in poultry birds encompasses three dimensions: microflora balance, gut structural integrity, and immune system status. The gut plays a vital and diverse role as it hosts most microorganisms in the body, contains more than twenty different hormones, digests and absorbs the nutrients, and accounts for 20% of body energy expenditure (Choct, 2021). When gut health is compromised, digestion and nutrient absorption are affected, with likely detrimental effects on feed conversion, followed by economic loss and greater disease susceptibility.  Disease resistance and nutrient utilization largely depend on maintaining a beneficial gut antioxidant status, improving gut integrity, and modulating the gut microbiota (Oviedo-Rondón, 2019).

In birds, the gut is separated into five distinct regions (Figure 1): crop, proventriculus, gizzard, small intestine (duodenum, jejunum, and ileum), and large intestine (ceca, cloaca, and vent). Each of these regions has a specific role in the secretion of digestive juices and enzymes, the grinding of feed particles and then the digestion and absorption of nutrients (Bailey 2019).

Figure 1: Schematic overview of poultry gastrointestinal tract

Factors affecting gut health

Gut health is influenced by the balance between the physiological health status of host, the gut microbiota, and a range of specific factors, all of which producers need to consider. From a management perspective, key factors encompass deprived gut health, biosecurity, and production stress, which is elevated during certain critical stages (see table 1). Environmental factors include humidity, temperature, and ventilation. Dietary factors, such as feed and water quality, feed composition, and mycotoxin contamination, also impact the development and ongoing state of poultry birds’ intestinal microbiota.

Table 1: Critical stages for gut health issues in poultry birds

The future is here: antibiotic reduction through improved gut health

There is a strong trend towards antibiotic-free (ABF) poultry production, fueled by AGP bans in certain regions (such as the European Union) and increasing consumer interest in avoiding products containing traces of AGPs. ABF systems can be profitable as long as the prices for the final ABF products can cover the investment costs necessary to produce these products. Larger-scale, sustainable ABF production will depend on developing a more profound understanding of intestinal health alongside the development of practical applications that foster gut health throughout each step of the production system.

Feed additive solutions to support birds during challenging situations

Feed additive manufacturers are looking into accessible alternatives to mitigate the need for antibiotics in ABF systems, requiring enormous research and development efforts. At EW Nutrition, our approach is to offer a holistic antibiotic reduction program for gut health management in poultry. The program comprises feed- and water-based solutions to support gut health during high-challenge periods. Activo liquid, an in-water solution containing standardized amounts of selected phytomolecules, is a key component of our program. Based on its three-fold mode of action, Activo liquid provides gut health support that improves livability and feed efficiency:

• Antimicrobial activity hinders the growth of potential pathogens
• Better gut integrity and positive microbiota optimize feed efficiency and gut health
• Antioxidant activity at the gut level prevent free radical formation and oxidative stress

As a water-based solution, Activo liquid provides a quick and flexible option for gut health control on poultry farms. The benefits of Activo liquid supplementation have been demonstrated through several scientific and field studies globally.

Activo liquid reduces mortality and improves feed conversion in broilers

Numerous field studies for antibiotic-free broilers across different countries and breeds show: on average, the inclusion of Activo liquid reduces mortality by 0.6% and improves FCR by 5%, compared to non-supplemented control groups (Figure 2).

Figure 2: Changes in livability and feed conversion rate in Activo liquid-supplemented broilers

Activo Liquid supports broiler breeders from start of lay to pre-peak production

Broiler breeders are prone to gut-related issues from the start of lay to pre-peak production (age 24 to 32 weeks). This period is characterized by sudden changes in feed consumption and high production stress. Field studies from Thailand show that Activo liquid supplementation in this phase leads to improved livability and higher laying rates.

A of 34,000 female broiler breeders during the first 9 weeks of production found that for the group receiving Activo Liquid  (200 ml / 1000 L, 5 days per week, 6 hours per day):

• The average laying rate/HH increased by 7.2 % during the trial period,
• Nearly 3  more  hatching  eggs  per  hen  housed  and  about  5  more  hatching  eggs  than  the  genetic standard were produced, and
• Mortality decreased by 0.2 % points compared to the control.

Another study, again evaluating the first 9 weeks of production using 20,000 birds, also found that broiler breeders supplemented with  Activo  Liquid show reduced mortality, a higher laying rate, and more hatching eggs per hen housed (Figure 3).

Figure 3: Performance results from Cobb broiler breeders, Activo liquid supplementation vs. control

Activo program improves layer productivity

Commercial layers often becomes challenged due to stress originating from management issues, gut pathogens, and an improper assimilation of nutrients. The negative impact on gut health can result in poor uniformity, low livability, and impaired body weight gain. The Activo program (a combination of Activo powder and liquid) has been found to improve layer performance, likely because its phytogenic components foster better intestinal integrity and microbiome diversity.

A study of 8 replicates with 36 Hy-line brown laying hens was conducted in China, for instance, testing the inclusion of both Activo (100 g / MT of feed) and Activo Liquid (250 ml / 1000 L for 4 days, every 2 weeks, from week 15 to week 25). It found that the Activo program  can effectively support the animals in coping with NSP-rich diets (Figure 4). Supplemented layers showed 3.36% higher egg production, representing more than 3.5 eggs and more than 150 grams of additional egg mass per hen housed during the period.  Better  gut  health  in  the  Activo  Program  gut  was evidenced  by  a  better  hen  body  weight ,  as  well  as  higher  yolk  color, lower  FCR, and improved  intestinal morphology parameters.

Figure 4: Performance results from Hy-line layers, Activo program vs. control

Conclusion: future improvements in poultry performance will come from the gut

As the trend towards ABF poultry production gains momentum, a concerted focus on supporting birds’ gut health is key to achieving optimal performance. Multiple field studies of Activo liquid application demonstrate that, due to their antimicrobial and antioxidant properties, the phytomolecules present in Activo liquid effectively support birds’ intestinal health during challenging periods.

In combination with good dietary, hygiene and management practices, phytomolecules offer a potent tool for reducing the use of antibiotics. The inclusion of Activo liquid in their birds’ diets allows poultry producers to achieve better gut health and, thus, stronger performance results in a sustainable way.

References

Bailey, Richard A. “Gut Health in Poultry: the World within – Update.” The Poultry Site, July 6, 2021. https://www.thepoultrysite.com/articles/gut-health-in-poultry-the-world-within-1.

Choct, Mingan. “The Importance of Managing Gut Health in Poultry.” Poultry Hub Australia, November 26, 2014. https://www.poultryhub.org/importance-managing-gut-health-poultry.

Kogut, Michael H., Xiaonan Yin, Jianmin Yuan, and Leon Bloom. “Gut Health in Poultry.” CAB Reviews: Perspectives in Agriculture, Veterinary Science, Nutrition and Natural Resources 12, no. 031 (October 1, 2017): 1–7. https://doi.org/10.1079/pavsnnr201712031.

Oviedo-Rondón, Edgar O. “Holistic View of Intestinal Health in Poultry.” Animal Feed Science and Technology 250 (2019): 1–8. https://doi.org/10.1016/j.anifeedsci.2019.01.009.

by Inge Heinzl, Editor, and Marisabel Caballero, Global Technical Manager Poultry, EW Nutrition

What is your most crucial key feed performance indicator? We posted this question on an online professional platform and got more than 330 answers from professionals in the industry:

• 55 % of the respondents considered feed efficiency or feed conversion rate (FCR) the key indicator, and
• 35 % listed feed cost / kg produced as their most important indicator.

As feed represents 60-70 % of the total production costs, feed efficiency has a high impact on farm profitability – especially in times of high feed prices. Furthermore, for the meat industry, an optimal FCR is essential for competitiveness against other protein sources. Finally, for food economists, feed efficiency is connected to the optimal use of natural resources (Patience et al., 2015).

In this article, we explain the factors that influence feed efficiency and show options to support animals in optimally utilizing the feed – directly improving the profitability of your operation.

How to measure the feed conversion rate

The FCR shows how efficiently animals utilize their diet for maintenance and net production. In the case of fattening animals, it is meat production; for dairy cows, it is milk, and for layers, it is egg mass (kg) or a specific egg quantity.

The feed conversion rate is the mathematical relation obtained by dividing the amount of feed the animal consumed by the production it provided. The FCR is an index for the degree of feed utilization and shows the amount of feed needed by the animal to produce one kg of meat or egg mass, or, e.g., 10 eggs.

When comparing the FCRs of different groups of animals (e.g., from different houses or farms), some considerations are important:

• Feed consumed is not feed disappeared: Due to differences in feeder design and feeder adjustment, these two values can differ by 10-30 %. If FCR is calculated for economic purposes, the wasted feed must be included, as it causes costs and must be paid by the farmer. However, if FCR is calculated for scientific purposes (e.g., a performance trial), only the feed consumed should be included.
• Even if they are same-aged animals, individuals or groups differ in weight. Hence, they have different requirements for maintenance and also diverging quantity left for production. To avoid mistakes, weight-corrected FCR can be used.
• Nutrient utilization also depends on genotype and sex; thus, comparisons should consider these factors as they also influence weight gain and body composition (Patience et al., 2015).

Many factors influence the FCR

There are internal and external factors that influence feed efficiency. Internal factors originate in the animal and include genetics, age, body composition, and health status. In contrast, external factors include feed composition, processing, and quality, as well as the environment, welfare enrichment, and social aspects.

1. Species

Different species have different body sizes and physiology and, therefore, vary in their growth and maintenance requirements, impacting their efficiency in converting the feed.

Table 1: FCRs of different species

Compared to terrestrial animals, for example, fish and other aquatic animals have a low FCR. Being poikilothermic (animals whose body temperature ranges widely), they don’t spend energy on maintaining their body temperature if the surrounding water is within their optimal range. As they are physically supported by water, they also need less energy to work against gravity. Furthermore, carnivorous fish are offered highly digestible, nutrient-dense feed, which lowers their requirements in quantity. Omnivorous fish, on the other hand, also consume feedstuffs not provided by the producer (e.g., algae and krill), which is not considered in the calculation. Broilers are the only farm animals achieving a similar FCR.

2. Sex, age, and growth phase

Sex determines gene expression related to the regulation of feed intake and nutrient utilization. Males have a better feed conversion and put on more lean meat than females and castrates, which grow slower and easier run to fat.

Young animals have a fast growth rate and are offered nutritionally dense feed; hence, their FCR is lower. When the animal grows and gains weight, its energy requirement for maintenance increases and its growth rate and the feed nutrient density diminish.

Table 2: FCR during different life phases of pigs (based on Adam and Bütfering, 2009)

3. Health and gut health

Health decisively impacts feed conversion. An animal that is challenged by pathogens reduces its feed intake and, thus, decreases growth. Additionally, the body needs energy for the immune defense, the replacement of damaged or lost tissue, and heat production, in case of fever. As many immune components are rich in protein, this is the first nutrient to become limited.

An imbalance in the gut microbiome also impacts feed conversion: pathogenic microorganisms damage tissues, impair nutrient digestion and absorption, and their metabolic products are harmful. Furthermore, pathogens consume nutrients intended for the host and continue to proliferate at its expense.

4. Environment

The environment influences the way the animals spend their maintenance energy. According to Patience (2012), when a 70 kg pig is offered feed ad libitum, 34 % of the daily energy is used for maintenance. For each °C below the thermoneutral zone, an additional 1.5% of feed is needed for maintenance. In heat stress, each °C above the optimum range decreases feed intake by 2%. Therefore, the feed needs to be denser to fulfill the requirement, or the animal will lose weight. Social stress also influences animal performance, especially chronic stress situations. Keeping the animals in their thermoneutral zone and mitigating the impact of stressors means more energy can go towards performance.

5. Feed quantity, composition, and quality

The feed is the source of nutrients animals convert into production. So, it’s natural that its quality and composition, and the availability of nutrients affect feed efficiency.

Better FCR by increasing nutrient density and digestibility

Higher energy content in the diet and better protein digestibility improve FCR. Saldaña et al. (2015) assert that increasing the energy content of a diet led to a linear decrease of the average daily feed intake but improved FCR quadratically. The energy intake by itself remained equal. However, these diet improvements also increase costs, and a cost-benefit analysis should be conducted.

Feed form and particle size play an important role

Feed processing can improve nutrient utilization. Particle size, moisture content, and whether the feed is offered as pellets or mash influence feed efficiency. Reducing the particle size leads to a higher contact surface for digestive enzymes and higher digestibility. Chewning et al. (2012) tested the effect of particle size and feed form on FCR in broilers. They found that pellet diets enable better FCRs than mash diets – one reason is the lower feed waste, another one the smaller feed particle size in the pelleted feed. Comparing the different tested mash diets, the birds receiving feed with a particle size of 300 µm performed better than the birds getting a diet with 600 µm particles.

Richert and DeRouchey (2015) show that pigs’ feed efficiency improved by 1.3 % for every 100 µm when the particle size was reduced from 1000 µm to 400 µm , as the contact surface for the digestible enzymes increased. In weaning piglets of 28-42 days, the increase of particle size from 394 µm to 695 µm worsened FCR from 1.213 to 1.245 (Almeida et al., 2020). There is a flipside to smaller particle size as well, however: high quantities of fines in the diet can lead to stomach ulceration in pigs (Vukmirović et al., 2021).

Non-starch polysaccharide (NSP)-rich cereals worsen FCR

The carbohydrates in feedstuffs such as wheat, rye, and barley are not only energy suppliers, and if not managed well, the inclusion of these raw materials can deteriorate feed conversion. Vegetable structural substances such as cellulose, hemicellulose, or lignin (e.g., in bran), are difficult or even impossible to utilize as they lack the necessary enzymes.

Figure 1: Contents of arabinoxylan and ß-glucan in grain (according to Bach Knudsen, 1997)

Additionally, water-soluble NSPs (e.g., pectins, but also ß-glucans and pentosans) have a high water absorption capacity. These gel-forming properties increase the viscosity of the digesta. High viscosity reduces the passage rate and makes it more difficult for digestive enzymes and bile acids to come into contact with the feed components. Also, nutrients’ contact with the resorptive surface is reduced.

Another disadvantage of NSPs is their “cage effect.” The water-insoluble NSPs cellulose and hemicellulose trap nutrients such as proteins and digestible carbohydrates. Consequently, again, digestive enzymes cannot reach them, and they are not available to the organism.

Molds and mycotoxins impair feed quality, but also animal health

Molds reduce the nutrient and energy content of the feed and negatively impact feed efficiency. They are dependent on active water in the feed and feed ingredients. Compared to bacteria, which need about 0.9-0.97 Aw (active water), most molds require only 0.86 Aw.

Table 3: Comparison of 28-day-old chicks performance fed not-infested and molded corn

Besides spoiling raw materials and feed and reducing their nutritional value, molds also produce mycotoxins which negatively impact animal health, including gut health. They damage the intestinal villi and tight junctions, reducing the surface for nutrient absorption. In a trial with broiler chickens, Kolawole et al. (2020) showed a strong positive correlation between the FCR and the exposure to different mycotoxins. The increase in levels of toxin mixtures resulted in poor FCR. Williams and Blaney (1994) found similar results with growing pigs. The animals received diets containing 50 % and 75 % of corn with 11.5 mg nivalenol and 3 mg zearalenone per kg. The inclusion of contaminated corn led to a deterioration of feed efficiency from 2.45 (control) to 3.49 and 3.23.

Oxidation of fats also affects feed quality

DDGS (distiller’s dried grains with solubles), by-products of corn distillation processes, are often used as animal feed, especially for pigs. The starch content is depleted in the distillation process and thus removed. The fat, however, is concentrated, and DDGS reach a similar energy content as corn.

Pigs also receive fats from different sources (e.g., soybean or corn oil, restaurant grease, animal-vegetable blends), especially in summer. Due to heat, the animals eat less, so increasing energy density in the feed is a possibility to maintain the energy intake.  The high fat content, however, makes these feeds susceptible to oxidation at high temperatures.

The oxidation of feedstuffs manifests in the rancidity of fats, destruction of the fat-soluble vitamins A, D, and E, carotenoids (pigments), and amino acids, leading to a lower nutritional value of the feed.

Use adequate supplements to enhance FCR

The feed industry offers many solutions to improve the FCR for different species. They usually target the animal’s digestive health or maintain/enhance feed quality, including increasing nutrient availability.

1. Boost your animals’ gut health

Producers can improve gut health by preventing the overgrowth of harmful microorganisms and by mitigating the effects of harmful substances. For this purpose, two kinds of feed additives are particularly suitable: phytomolecules and products mitigating the impact of toxins and mycotoxins.

Phytomolecules help stabilize the balance of the microbiome

By preventing the proliferation of pathogens, phytomolecules help the animal in three ways:

1. They prevent pathogens from damaging the gut wall
2. They deter and mitigate inflammation
3. By inhibiting the overgrowth of pathogens, they promote better nutrient utilization by the animal

Only a healthy gut can optimally digest feed and absorb nutrients.

In trials testing the phytogenic Activo product range, supplemented animals showed the following FCR improvements compared to non-supplemented control groups (Figure 2).  Note that phy­tomolecules also have a digestive effect that contributes to the FCR improvements:

Figure 2: FCR improvements for animals receiving Activo

Products mitigating the adverse effects of toxins

Both mycotoxins and bacterial toxins negatively impact gut health. Mycotoxins are ingested with the feed; bacterial toxins appear when certain bacteria proliferate in the gut, e.g., gram-negative bacteria releasing LPS or Clostridium perfringens producing NetB and Alpha-toxin.

Products that mitigate the harmful effects of toxins help to protect gut health and maintain an optimal feed efficiency, as shown with a trial conducted with Mastersorb Gold:

Table 4: Trial design, the impact of Mastersorb Gold on broilers challenged with zearalenone and DON-contaminated feed

Figure 3: Average FCR for broilers, with or without zearalenone and DON challenge, with or without Mastersorb Gold supplementation

2. Improve nutrient utilization

Maximum use of the nutrients contained in the feed can be obtained with the help of feed additives that promote digestion. Targeting the animal, selected phytomolecules are used for their digestive properties. Focusing on the feed, specific enzymes can unlock nutrients and thus improve feed efficiency.

Phytomolecules support the animal’s digestive system

Phytomolecules promote optimal digestion and absorption of nutrients by stimulating the secretion of digestive juices, such as saliva or bile, enhancing enzyme activity, and favoring good GIT motility (Platel and Srinivasan, 2004). FCR improvements thanks to the use of a phy­tomolecules-based product (Activo) are shown in figure 2.

Enzymes release more nutrients from feed

Enzymes can degrade arabinoxylans, for example. Arabinoxylans are the most common NSP fraction in all cereals – and are undigestible for monogastric animals. Enzymes can make these substances available for animals, allowing for complete nutrient utilization.  Additionally, nutrients trapped due to the cage effect are released, altogether increasing the energy content of the diet and improving FCR.

3. Be proactive about preserving feed quality

The quality of feed can deteriorate, for instance, when nutrients oxidize, or mold infestation occurs. Oxidation by-products promote oxidative stress in the intestine and may lead to tissue damage. Molds, in turn, take advantage of the nutrients contained in the feed and produce mycotoxins. Both cases illustrate the importance of preventing feed quality issues. Feed additives such as antioxidants and mold inhibitors mitigate these risks.

Antioxidants prevent feed oxidation

Antioxidants scavenge free radicals and protect the feed from spoilage. In animals, they mitigate the adverse effects of oxidative stress. Antioxidants in pig nutrition can stabilize DDGS and other fatty ingredients in the feed, maintaining nutrient integrity and availability. Figure 4 shows the FCR improvement that a producer in the US obtained when using the antioxidant product Santoquin in pork finisher diets containing 30% DDGS.

Figure 4: FCR improvement in pigs receiving Santoquin (trial with a Midwest pork producer)

In DDGS-free diets, which are more common in poultry production, antioxidants also help optimize FCR, as shown by the results of a comprehensive broiler field study in 2015 (figure 5).

Figure 5: FCR in broilers receiving Santoquin, compared to a non-supplemented control group

Inhibiting molds and keeping feed moisture

To round off the topic of feed quality preservation, one should consider mold inhibitors, which also play an essential role. Used at the feed mill, these products blend two types of ingredients with their different modes of action: surfactants and organic acids. Surfactants bind active water so that the moisture of the feed persists, but fungi cannot survive. Organic acids, on the other hand, have anti-fungal properties, directly acting against molds. Both actions together prevent the reduction of energy in the feed, keeping feed efficiency at optimal levels.

Conclusion

The improvement of feed efficiency ranks as one of the most, if not the most, critical measures to cope with rising feed costs. By achieving optimal nutrient utilization, producers can make the most out of the available raw materials.

The feed industry offers diverse solutions to support animal producers in optimizing feed efficiency. Improving gut health, mitigating the negative impact of harmful substances, and maintaining feed quality are crucial steps to achieving the best possible FCR and, hence, cost-effective animal production.

References

Adam, F., and L. Bütfering. “Wann Müssen Meine Schweine an Den Haken?” top agrar. top agrar online, October 1, 2009. https://www.topagrar.com/schwein/aus-dem-heft/wann-muessen-meineschweine-an-den-haken-9685161.html.

Almeida, Leopoldo Malcorra, Vitor Augusto Zavelinski, Katiucia Cristine Sonálio, Kariny Fonseca da Silva, Keysuke Muramatsu, and Alex Maiorka. “Effect of Feed Particle Size in Pelleted Diets on Growth Performance and Digestibility of Weaning Piglets.” Livestock Science 244 (2021). https://doi.org/10.1016/j.livsci.2020.104364.

Chewning, C.G., C.R. Stark, and J. Brake. “Effects of Particle Size and Feed Form on Broiler Performance.” Journal of Applied Poultry Research 21, no. 4 (2012): 830–37. https://doi.org/10.3382/japr.2012-00553.

Gaines, A. M., B. A. Peerson, and O. F. Mendoza. “Herd Management Factors That Influence Whole Feed Efficiency.” Essay. In Feed Efficiency in Swine, edited by J. Patience, 15–39. Wageningen Academic, 2012.

Kolawole, Oluwatobi, Abigail Graham, Caroline Donaldson, Bronagh Owens, Wilfred A. Abia, Julie Meneely, Michael J. Alcorn, Lisa Connolly, and Christopher T. Elliott. “Low Doses of Mycotoxin Mixtures below EU Regulatory Limits Can Negatively Affect the Performance of Broiler Chickens: A Longitudinal Study.” Toxins 12, no. 7 (2020): 433. https://doi.org/10.3390/toxins12070433.

Patience, J. F. “The Influence of Dietary Energy on Feed Efficiency in Grow-Finish Swine.” Essay. In In Feed Efficiency in Swine, edited by J. Patience, 15–39. Wageningen Academic, 2012.

Patience, John F., Mariana C. Rossoni-Serão, and Néstor A. Gutiérrez. “A Review of Feed Efficiency in Swine: Biology and Application.” Journal of Animal Science and Biotechnology 6, no. 1 (2015). https://doi.org/10.1186/s40104-015-0031-2.

Platel, K., and K. Srinivasan. “Digestive Stimulant Action of Spices: A Myth or Reality?” Indian J Med Res, pp 167-179 119 (May 2004): 167–79. http://www.ncbi.nlm.nih.gov/pubmed/15218978

Richert, B. T., and J. M. DeRouchey. “Swine Feed Processing and Manufacturing.” Pork Information Gateway, September 14, 2015. https://porkgateway.org/resource/swine-feed-processing-and-manufacturing/.

Saldaña, B., P. Guzmán, L. Cámara, J. García, and G.G. Mateos. “Feed Form and Energy Concentration of the Diet Affect Growth Performance and Digestive Tract Traits of Brown-Egg Laying Pullets from Hatching to 17 Weeks of Age.” Poultry Science 94, no. 8 (2015): 1879–93. https://doi.org/10.3382/ps/pev145.

Vukmirović, Đuro, Radmilo Čolović, Slađana Rakita, Tea Brlek, Olivera Đuragić, and David Solà-Oriol. “Importance of Feed Structure (Particle Size) and Feed Form (Mash vs. Pellets) in Pig Nutrition – A Review.” Animal Feed Science and Technology 233 (2017): 133–44. https://doi.org/10.1016/j.anifeedsci.2017.06.016.

by Dr. Ajay Bhoyar, Global Technical Manager – Poultry, EW Nutrition

Necessity, goes the saying, is the mother of invention. No wonder, then, that necessity is driving innovation in the poultry industry.  A few distinct such drivers of change stand out:

Genetic improvements: Significant genetic improvements have consistently increased the production performance of breeders, as well as commercial broilers and layers. The genetically improved breeds demand improved nutrition and management practices.

Feed ingredient prices/availability: Corn and soybean meal are the main feed ingredients in poultry feed. Consequently any fluctuations in their prices have a high impact on the cost of production of eggs and meat. During the short span of the last 5 years, US corn and soybean meal prices have increased by around 54% and 68%, respectively. The optimum utilization of available feed ingredients and improvements in nutrient availability continue to be the key areas of interest for the poultry industry.

Consumer preference and regulatory changes: In certain geographies, these changes have resulted into 3 major trends in the poultry industry: antibiotics reduction (ABR), cage-free rearing, and food safety. The trend in the production and consumption of antibiotic-free meat products is growing faster than ever across the globe.

Antibiotics reduction (ABR): a key global trend

Apart from veterinary use, antibiotics are used as feed additives —antibiotic growth promoters (AGP) in animal production. Alarming levels of resistance to antibiotics have been reported in countries of all income levels, with the result that common diseases are becoming untreatable, and life-saving medical procedures riskier to perform.  Misuse and overuse of antimicrobials are the main drivers in the development of drug-resistant pathogens. (WHO/ https://www.who.int/news-room/fact-sheets/detail/antimicrobial-resistance )

Antibiotic-free chicken production has gained a lot of momentum in the recent past. Over the past years, consumer preferences in the US resulted in a significant increase in the production of antibiotics-free (ABF) broiler chicken meat. In effect, the number of birds produced in “no antibiotics ever” (NAE) programs in the U.S. today is now at more than 50 percent (Poultry Health Today, 2019).

The reduction of antibiotic use poses some challenges to poultry producers. Apart from increased capital investment for modifications in feed mills and farms, increase in feed additive cost, the main challenge due to the removal of AGPs from feed can be the reduced production performance of poultry, mainly due to increased gut health issues.

Good gut health is a must for profitable production

“The intestinal health of poultry has broad implications for the systemic health of birds, animal welfare, the production efficiency of flocks, food safety, and environmental impact,” state Oviedo-Rondón (2019). The main challenges for ABF chicken or turkey production fall under the same heading of gut health, in particular the prevention and control of coccidiosis and necrotic enteritis (Cervantes, 2015).

What are the most effective ways to mitigate gut health challenges?

Depending on specific production needs and challenges, various technologies are used by the poultry producers to address gut health issues. Some of the most commonly used innovative technologies include:

Dietary Fibers (DF)

Scientists have found that DF have an enormous impact on the gastrointestinal tract (GIT) development, digestive physiology, including nutrient digestion, fermentation, and absorption processes of poultry (Jha & Mishra, 2021).

The water-insoluble fibers are seen as functional nutrients, as they can escape digestion and modulate nutrient digestion: “A moderate level of insoluble fiber in poultry diets may increase chyme retention time in the upper part of the GIT, stimulating gizzard development and endogenous enzyme production, improving the digestibility of starch, lipids, and other dietary components” (Mateos et.al. 2012). The insoluble DF, when used in amounts between 3–5% in the diet, could have significant effects on intestinal development and nutrient digestibility.

Dietary fibers influence the development of the gizzard in poultry birds.  A well-developed gizzard is a must for good gut health. Jiménez-Moreno & Mateos (2012) noted that the coarse fiber particles are selectively retained in the gizzard, that ensures a complete grinding and a well-regulated feed flow and secretion of digestive juices, and regulates GIT motility & feed intake. The inclusion of insoluble fibers in adequate amounts improves the gizzard function and stimulates HCl production in the proventriculus. Thus it can help in the control of gut pathogens.

Probiotics and prebiotics

Probiotics and prebiotics have drawn considerable attention as alternatives to antibiotics in animal feeds. Supplementing diets with probiotics and prebiotics is a significant factor contributing to modified intestinal microflora, which, in turn, may effectively influence the birds’ growth performance and health (Yang et al. 2009).

Probiotics introduce desirable microorganisms into the intestinal tract through the diet (feed or water). They consist of live bacteria, fungi, or yeasts that positively contribute to the gastrointestinal flora. As such, they are important for a well-formed and well-maintained digestive system, and are indirectly essential to growth performance and to the overall health of animals in general. Probiotic supplementation could have the following effects, as stated by Jha et al:

• modification of the intestinal microbiota
• stimulation of the immune system
• reduction in inflammatory reactions
• prevention of pathogen colonization
• enhancement of growth performance
• alteration of the ileal digestibility and total tract apparent digestibility coefficient
• decrease in ammonia and urea excretion (Jha et.al., 2020)

Probiotics can be used not just in feed and drinking water, but also in spray solutions applied to day-old chicks either in the hatchery or immediately after placement in the brooding house. This way, the beneficial microorganisms can enter the intestine earlier than through other methods (known as early seeding).

Prebiotics are also a means of increasing the beneficial bacteria in the poultry gut microbiota. Prebiotics like mannan-oligosaccharides (MOS), inulin and its hydrolysate (fructooligosaccharides: FOS), as well as other prebiotics are important contributors to the modulation of the intestinal microflora and stimulating a potential immune response, as well as stimulating the development of beneficial microorganisms. Prebiotics can also help reduce pathogen colonization in the GIT.

Feed enzymes

The role of feed enzymes in promoting the efficiency of nutrient utilization is well recognized. Recent estimates (Adeola & Cowieson, 2011) indicate that feed enzymes saved the global feed market an estimated US $3–5 billion per year. Feed Enzymes can also have a positive impact on gut health.

Among the beneficial effects of feed enzymes are:

• Inactivating anti-nutrients in the feed ingredients
• Unlocking nutrients otherwise unavailable to birds (e.g. Phosphorus from phytic acid)
• Reducing harmful microbial proliferation, depriving detrimental microorganisms of nutrients
• Reducing the undigestible components of feed, the viscosity of digesta, or the irritation to the gut mucosa that causes inflammation.

Enzymes also generate metabolites that promote microbial diversity, which helps to maintain gut ecosystems that are more stable and more likely to inhibit pathogen proliferation (Bedford, 1995; Kiarie et al., 2013). Feed enzymes are heat-sensitive and tend to lose their activity potential during pelleted feed manufacturing. There has been a significant interest in the application of intrinsically heat stable enzymes for more efficient action. Apart from coated feed enzymes, the post pellet liquid application (PPLA) of feed enzymes has increased in the recent past.

Toxin binders & antioxidants

Intestinal health problems can often be preempted, especially in poultry companies with ABF production programs, by mitigating the danger of mycotoxins in feedstuffs and rancid fats (Murugesan et al., 2015; Grenier and Applegate, 2013). Mycotoxins can compromise several key functions of GIT. This often results in decreased nutrient absorption (by decreasing the available surface area), modulation of nutrient transporters, and loss of barrier function (Grenier and Applegate, 2013). Some mycotoxins “encourage” the persistence of intestinal pathogens and thus enhance the possibility of intestinal inflammation.

Rancid fats and oils have been linked to the pathogenesis of enteric diseases (Hoerr, 1998; Butcher and Miles, 2000; Collet, 2005). The oxidation of oils and fats negatively impacts the energy content of these ingredients. The addition of feed antioxidants during the rendering process/ blending of fats and oils, and proper storage and transport before final use in feed can control rancidity in oils and fats. Proper fat storage conditions in tanks and transportation lines should be constantly monitored to prevent the development of rancidity in the feed mill. Antioxidants and mycotoxin binders can reduce the effects of mycotoxins and peroxide, especially, but not only, in ABF programs (Yegani and Korver, 2008).

Organic acids

Organic acids are compounds with acidic properties that occur naturally and include carbon. As the digestive process includes microbial fermentation, beneficial bacteria which naturally reside in the crop, intestines, and ceca produce such organic acids (Huyghebaert et.al. 2010). The inclusion of organic acids in poultry diets can improve gut health, increase endogenous digestive enzyme secretion and activity, and improve nutrient digestibility. Thus they generally contribute to the overall gut health of the animal.

The inclusion of organic acids in feed can help not only decontaminate feed but also have the potential to reduce enteric pathogens in poultry. The acids can cross the bacterial cell wall and disrupt the normal actions of certain types of bacteria, including Salmonella spp, E. coli, Clostridia spp, Listeria spp. and some coliforms.

Organic acids are also used in drinking water to help lower the microbial count. This can be achieved by lowering the pH of water and by the prevention/removal of biofilms in the water lines.

However, organic acids should be included in the feed or water with caution. The limitations for use of organic acids in animal production can be:

• Bacterial resistance to organic acids over long-term use
• Adverse effect on feed palatability, leading to feed refusal
• Organic acids are corrosive in nature and can damage poultry equipment
• Buffering capacity of dietary ingredients can impact efficacy

Essential oils/Phytomolecules

Essential oils (EOs) are raw extracts from plants (herbs, flowers, leaves, roots, fruit etc.). The beneficial effects of EOs include appetite stimulation, improvement of enzyme secretion related to food digestion, and immune response activation (Krishan and Narang, 2014)

EOs are an unpurified mix of different phytomolecules. The raw extract from oregano is a mix of various phytomolecules (terpenoids) like carvacrol, thymol, and p-cymene. Carvacrol, for instance, is a monoterpinoid found in various plants such as oregano or thyme. A phytomolecule is one active compound.

These botanicals have received increased attention as possible growth performance enhancers for animals in the last decade because of their beneficial influence on lipid metabolism, as well as their antimicrobial and antioxidant properties (Botsoglou et al., 2002), their ability to stimulate digestion (Hernandez et al., 2004), their immune-enhancing activity, and anti-inflammatory potential (Acamovic and Brooker, 2005). Many studies have reported on the supplementation of poultry diets with essential oils that enhanced weight gain, improved carcass quality, and reduced mortality rates (Williams and Losa, 2001). The use of specific EO blends can be effective in reducing the colonization and proliferation of Clostridium perfringens and controlling coccidia infections. Consequently, it may also help reduce necrotic enteritis (Guo et al., 2004; Mitsch et al., 2004; Oviedo-Rondón et al., 2005, 2006a, 2010).

Mode of action of phytomolecules

The gut health optimizing mode of action of phytomolecule-based preparations like Activo® (EW Nutrition) can be described as follows:

Digestive

The digestive properties increase the secretion of digestive enzymes and enhance gut motility. A “significant increase in pancreatic trypsin, amylase, and maltase activities in broilers fed different blends of commercial essential oils” has been reported as well (Jang et al., 2007). The essential oils in carvacrol, for instance, have positive effects on growth performance and the intestinal barrier function of broilers. They were also able to support repairing the intestinal damage caused by lipopolysaccharides (Liu et al. 2020).

Antimicrobial

The antimicrobial properties of phytomolecules can impede the growth of potential pathogens. Thymol, eugenol, and carvacrol have been shown to have “synergistic or additive antimicrobial effects when combined at lower concentrations” (Bassolé and Juliani, 2012). In in vivo studies, essential oils used either individually or in combination “have shown clear growth inhibition of Clostridium perfringens and E. coli in the hindgut and ameliorated intestinal lesions and weight loss than the challenged control birds” (Jamroz et al., 2006, Jerzsele et al., 2012, Mitsch et al., 2004).

One well-known mechanism of antibacterial activity is linked to the phytomolecules’  hydrophobic nature. This characteristic helps disrupt the permeability of cell membranes and cell homeostasis. The consequence of this disruption is the loss of cellular components, influx of other substances, or even cell death (Brenes and Roura, 2010, Solórzano-Santos and Miranda-Novales, 2012, Windisch et al., 2008, O’Bryan et al., 2015).

Antioxidant

The antioxidant properties at the gut level prevent free radical formation and oxidative stress. Thymol and carvacrol have been shown to inhibit lipid peroxidation (Hashemipour et.al. 2013), a mechanism leading to the oxidative destruction of cellular membranes (Rhee et al., 1996). This destruction can ultimately lead to cell death and to the production of toxic and reactive aldehyde metabolites, known as free radicals. Among these free radicals, malondialdehyde (MDA) as a final product of lipid peroxidation has often been used for determining oxidative damage (Jensen et al., 1997).  Thymol and carvacrol both have strong antioxidant activity (Yanishlieva et al., 1999). Oregano “added in doses of 50 to 100 mg/kg to the diet of chickens exerted an antioxidant effect in the broiler tissues” (Botsoglou et al., 2002).

It has also been suggested that chicken body oxidative balance can benefit from essential oils. Karadas et al. (2014) fed a blend of carvacrol, cinnamaldehyde, and capsicum oleoresin to Ross 308 broilers, and found a significant increase in the hepatic concentration of carotenoids and coenzyme Q10 at d 21 of age.

Essential oils, or phytomolecules, are highly volatile substances and are susceptible to changes caused by external factors such as light, oxygen, and temperature, in addition to being prone to evaporating. They need to be protected/micro-encapsulated during the process of feed manufacturing. The advantages of matrix encapsulation include

• a slow and gradual release of active ingredients in the digestive tract
• protection of phytomolecules from oxidation and other harsh conditions during feed processing
• prevention of any negative effects on palatability of feed

Above: Micro-encapsulation protecting phytomolecules in feed processing

Apart from use in feed, the liquid phytomolecules preparations for drinking water use can prove to be beneficial in preventing and controling losses during challenging periods of the birds’ life (feed change, handling, environmental stress, etc.).  The liquid preparations have the potential to reduce morbidity and mortality in poultry houses and thus the use therapeutic antibiotics. Barrios et al. (2021) suggested that Activo and Activo Liquid may ameliorate the impact of Necrotic Enteritis on broilers and further hypothesized that the effects of Activo Liquid were particularly important in improving overall mortality.

Conclusion

The prevailing driving forces of the market will continue to challenge the dynamic poultry industry. Still, gut health challenges in ABF poultry production can be alleviated with multifactorial approaches, including changes in nutrition and improved management practices. Innovative feed additive technologies have contributed to reducing production losses triggered by the removal of AGPs in poultry production.

Essential oils/phytomolecules are one such promising technology, with proven benefits in terms of the production performance of poultry. Phytomolecules are generally recognized as safe and are commonly used in the food industry. Some of the phytomolecules combinations have multiple modes of action, supporting an efficient and sustainable reduction in antibiotics use in poultry production.

To make ABF programs successful, however, more attention needs to be given to the whole production system, not only to feed, feed additives or control of a few enteric pathogens. Housing, management, water quality and biosecurity at both breeder and grow-out levels are critical in ABF production.

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by EW Nutrition USA, Inc.

In the poultry industry, Necrotic Enteritis is of great interest due to the potential detrimental growth effects it may have in a flock, even at subclinical levels⁵⁰. Coccidiostats and antibiotics have been used for a long time to get the disease-causing bacterium Clostridium perfringens under control, but with increasing antimicrobial resistance, alternative approaches are required. This article aims to give an overview of the disease and the measures against it.

Clostridium perfringens – a ubiquitous, highly resilient bacterium

Clostridium perfringens is a Gram-positive, spore-forming, anaerobic, rod-shaped bacterium⁵⁰. This encapsulated, non-motile microorganism is fastidious in growth requirements⁵⁹. Most often, complex media like cooked meat or thioglycolate broth are used as enrichment³⁰.

It was Welch and Nuttall who first identified C. perfringens in 1892 as Bacillus aerogenes capsulatus¹⁸. In Great Britain, the bacterium was commonly known as C. welchii and sometimes called Frankel’s bacillus in Germany until designated C. perfringens by Bergey¹³.

Clostridium perfringens is the causal microorganism for Necrotic Enteritis (NE)¹⁴. In humans, it is one of the most common causes of foodborne illness²⁰. The Centers for Disease Control and Prevention (CDC, 2012) estimates that nearly one million people are affected every year, making C. perfringens the third most frequent source of domestically acquired foodborne illness after Norovirus and Salmonella.

Clostridium perfringens can be found everywhere

Clostridium perfringens is found in soil, water, and other organic materials. As far as poultry facilities, C. perfringens has been isolated from litter, dust, walls, floors, fans, transportation coops, feeders, and feed⁸⁹.

Additionally, C. perfringens is found in the GI tract of broiler chickens, humans, and other mammals⁴⁷. When intestinal samples of broiler chickens were analyzed for C. perfringens, 75-95 % tested positive²⁴. Drew and co-workers¹⁰ determined that C. perfringens is usually found at ~10⁴ colony-forming units (CFU)/g of broiler digesta. These results agree with Jia et al.²⁶, who stated that C. perfringens is present at low levels in healthy poultry. In humans, investigations in different parts of the world showed a prevalence of Clostridium perfringens between 57-94%³².

Different types of Clostridium perfringens with different toxins

There are five types (A-E) of C. perfringens, which can be identified through their toxin production (see table 1). All strains produce alpha-toxin. Furthermore, Clostridium perfringens has been described to produce eight other toxins, three (delta, theta, kappa) can be lethal, but these are seldom involved in disease origin³⁷.

Table 1. Different types of Clostridium perfringens

High resilience gives an advantage against competitors

Since Clostridium perfringens is a spore-forming bacterium, it is very resilient to high temperatures, slight pH variations, and toxic chemicals^{43, 7}.

Labbe et al.³⁰ established that C. perfringens can reproduce at temperatures between 15-50 °C. Hence, proper refrigeration temperatures (below 10 °C) can be an effective means of control. The optimum range is between 37-47 °C, and at these temperatures, the mean generation time – the time required for the bacterial count to double – is approximately 10-12 minutes⁴¹. These short generation times allow the bacteria to outcompete other microorganisms that may need similar resources in a certain environment.

The optimum pH range of Clostridium perfringens is between 5.5-7.0²². However, it can grow at a pH as low as 5 and as high as 9. In live broiler chickens, the pH in the small intestine has been determined to be between 6.00-7.78.

Necrotic enteritis in poultry

The disease necrotic enteritis was first described by Parish^{45, 46} in cockerels in England. Some of the symptoms include depression, reluctance to move, ruffled feathers, somnolence, diarrhea, loss of appetite, and anorexia²¹. Mortality ranges from 0-50% ⁶ have been reported in infected flocks. Since then, virtually every area that raises poultry has reported signs of necrotic enteritis.

Clostridium perfringens – How NE unravels

As already mentioned, 10⁴ colony-forming units (CFU)/g of broiler digesta¹⁰ are normal and can be found in healthy birds. C. perfringens becomes problematic when counts reach 10⁷-10⁸ CFU/g⁶.

Necrotic enteritis is caused by types A and C of Clostridium perfringens, but normally, predisposing factors “set the stage”^{24, 48}. This could be seen in an investigation where they wanted to create a model to reproduce NE in a laboratory setting. Researchers realized that inoculation of C. perfringens alone did not cause the disease found in the field⁴⁸. Therefore, it was assessed that certain cofactors must play a significant role in the pathogenicity of C. perfringens. Williams⁵⁷ reviewed concurrent infections of coccidiosis and necrotic enteritis in chickens (Figure 1). The copious interactions of these diseases with predisposing factors, control methods, sources of infection, and disease form is a testament to the complexity of this poultry industry matter.

Coccidiosis creates access

Shane et al.⁵³ noted that several authors had considered coccidiosis to be a predisposing factor for NE. They proceeded to describe the pathogenesis of Eimeria acervulina, one of the protozoa responsible for coccidiosis in poultry. When the oocysts are ingested, they quickly attach to the intestinal wall causing lesions where the protozoa reproduce numerous times. These are the lesions to which C. perfringens attaches.

What happens in the animal?

Long et al.³³ proposed the pathogenesis for NE: First, epithelial cells are vacuolated, and the epithelium lifts off the lamina propria, which is congested and edematous. These lesions can be caused by a combination of factors like toxin production and/or, as just mentioned, coccidiosis. Clostridium perfringens cells attach to the lamina propria, where they thrive. The tissue becomes necrotic as large numbers of heterophils, a type of phagocyte, flood the foci (sites of lesions).

A combination of disease-inducing factors such as bacteria proliferation, heterophil lysis, and villus’ necrosis seem to develop quickly. The inflammation zone then becomes riddled with mononuclear cells, cells containing lymphocytes, antigen-presenting cells, and eosinophilic-staining (proteinaceous) amorphous material. This necrotizing process moves from the tip of the villi to the crypt.

Chronic version

In chronic cases, villi may be found to have multiple cysts from recurrent necrosis. In birds that overcome the disease, injured epithelial cells are replaced by newly formed reticular structures. These new cells travel from the crypt to the tip of the villi and replace the old, damaged cells. The result is a short, flat villus with a reduced surface area for nutrient absorption^{44, 45, 34}. These morphologically altered villi are the necrotic lesions found in the field and some C. perfringens challenge trials (Figure 2).

Acute form

The acute form of NE results in enlarged lesions along the gut wall, and the epithelium becomes eroded and detached; consequently, a diphtheritic membrane is formed. This yellow, green, or brownish pseudo-membrane is called the “Turkish towel,” which describes the appearance of the friable, gas-filled, foul-smelling GI tract⁵⁷.

Subclinical form

Poultry producers are not only concerned with the acute form of NE. Recent studies have shown that the disease’s subclinical form can be as detrimental as the acute illness¹⁹. Lovland and co-workers³⁵ stated that this symptomless disease is often overlooked at the farm, and the effects are only noticed at the processing facility.

Subclinical NE (SNE) can cause cholangiohepatitis, a condition where the liver is enlarged with pale reticular patterns and sometimes small, pale foci. In the United Kingdom, it was estimated that 4% of broiler carcasses and 12% of livers are condemned at processing plants due to clostridial infection; thereby, reducing profit³⁶. Moreover, sparse lesions that may be found in a case of SNE may be enough to hinder growth performance; thus, resulting in an underproductive flock³⁹.

Feeding Against Necrotic Enteritis

It has been reported that diet formulation has the greatest impact on the prevalence of C. perfringens in chicken GI tracts⁶¹. The poultry industry formulates diets on a least-cost basis, which may become problematic if nutritionists do not take into consideration the pathological consequences that some ingredients may have in the GI tracts of chickens. Every feed ingredient has a specific purpose in the diet. For instance, cereal grains are fed for their energy concentration as well as fiber. Also, some grain and animal/plant meals are used for their protein content. Since these ingredients are obtained from different sources, they are highly variable in macro and micronutrients¹.

The diet provides the conditions for proliferation

There are multiple elements that affect the proliferation of C. perfringens in chicken intestines, one of the most critical factors being diet formulation^{5, 36}. Some feed ingredients have been found to exacerbate the numbers of C. perfringens in chickens’ gastrointestinal tract. Diets formulated with wheat increased NE intestinal lesion scores compared to broiler chickens fed a corn-based diet⁴. In another study, Drew et al.¹⁰ investigated the effects of different protein sources on the intestinal populations of C. perfringens in broiler chickens. Diets were formulated to contain 230, 315, and 400 g/kg of fishmeal or soy protein concentrate (SPC). The numbers of C. perfringens in the ileum and ceca increased when the amount of protein increased from 230 to 400 g/kg.

Type of grain influences the occurrence of Clostridium perfringens

Authors have studied the effects of grain inclusion on gut microbiota, and it is well established that small cereal grains such as barley, rye, and wheat tend to increase the prevalence of C. perfringens in the GI tract. Shakouri et al.⁵² investigated the influence of barley, sorghum, wheat, and corn on counts of C. perfringens in the different intestinal segments. Corn and wheat had the lowest C. perfringens counts, followed by sorghum, while barley yielded the highest counts. These findings agree with Riddell and Kong⁵¹.

Other researchers have concluded that the increase in gut viscosity and increased chyme transit time elicit the overgrowth of C. perfringens in the intestines²⁸. Grains like wheat and barley contain high amounts of non-starch polysaccharides (NSP), which increase viscosity²⁶. Furthermore, it has been alleged that, since these grains are high in NSP, the bird cannot absorb nutrients as efficiently, thereby leaving them for microbes like C. perfringens to consume³¹.

Enzymes improve nutrient availability in the presence of C. perfringens

Shakori et al.⁵² and Jia et al.²⁶ also studied the impact of several diets with the inclusion of a blend of carbohydrases such as glucanase and xylanase. Their findings suggested that enzyme addition did not affect counts of C. perfringens in the different intestinal sections. However, they did find an improvement in growth performance. They stated that enzymes improved chyme viscosity by degrading the encapsulation of nutrients in diets.

For this reason, researchers have investigated the use of enzymes in wheat and barley-based diets on the incidence of C. perfringens in chicken intestines. Jackson et al.²⁵ studied the effect of beta-mannanase addition on flocks infected with Eimeria spp. and C. perfringens. They found that feeding this enzyme significantly reduced the impact of C. perfringens on the performance of infected flocks as well as intestinal lesion scores. Moreover, the authors explained that this might be due to beta-mannanase crossing the intestinal wall to provoke an immune response. They determined that this enzyme tended to ameliorate the symptoms of necrotic enteritis, but not significantly.

MOS may have a positive impact on immunity

Hofacre et al. ²³ found similar results when birds were fed mannan-oligosaccharides. A marked effect was only found when mannan-oligosaccharides were included along with lactic acid-producing, competitive exclusion products (probiotics).

The feed form is decisive

Feed form has also been investigated on the incidence of C. perfringens. When birds were fed whole wheat compared to ground, researchers found reduced counts of C. perfringens in the gut². These results can be extrapolated to the findings of Engberg et al.¹¹. They found that when birds were fed coarse versus fine mash or pellets, C. perfringens counts were consistently higher in flocks fed mash diets. These authors concluded that feeding pellets or whole grains increases gizzard activity, which consequently triggers hydrochloric acid production and decreases pH in the GI tract. This drop in pH of approximately 0.5 units may be responsible for decreased C. perfringens counts.

Mind the protein source

Another well-established fact is that the C. perfringens population can be affected by the type of the protein source and the inclusion rates.

Potato is worse than fish

Palliyeguru et al. ⁴² studied the inclusion of protein concentrates (potato, fish, and soy) on subclinical NE. They determined that the potato-containing diet resulted in the highest incidence of C. perfringens in the gut, followed by fish and soy. Also, the potato-containing diet had the highest activity of trypsin inhibitors and lowest lipid content. Increased trypsin inhibition does not allow for the inactivation of alpha and beta toxins produced by C. perfringens, resulting in increased intestinal wall lesions.

Fish is worse than soy due to the amino acid composition

Drew et al.¹⁰ formulated diets containing fishmeal or a soy protein concentrate at different levels. Feeding dietary fishmeal resulted in a higher incidence of C. perfringens as compared to the soy protein diet. Furthermore, with increasing levels of soy and fishmeal diets, counts of C. perfringens increased as well. A notable difference in fishmeal protein concentrate compared to the soy protein concentrate was the amino acid ratio in this experiment; the methionine and glycine ratios were 1.3 times greater in fishmeal diets. Muhammed et al.⁴⁰ determined that methionine was required for C. perfringens sporulation. This may be of interest to nutritionists since some authors have estimated that 10-20 % of synthetic amino acids are not absorbed and reach the lower intestinal tract, i.e., ceca; thereby, aiding in the proliferation of C. perfringens.

Fat source – animal fat is critical

The effects of fat sources on C. perfringens population remain largely unknown. Knarreborg et al.²⁹ studied the bacterial microflora in chicken intestines after feeding different dietary fats (soy oil and a tallow and lard mix) in rations containing antibiotic growth promoters (AGP). When soy oil was fed, C. perfringens counts were significantly lower than diets containing animal fats. The authors stated that, since plant oils contain higher amounts of unsaturated fatty acids, the chyme in birds fed oil diets would have decreased viscosity, decreasing transit time. Furthermore, an additive effect was found when soy oil was provided along with AGP, which may be due to facilitated antibiotic dispersion caused by the oil’s lipophilic properties. Knarreborg et al. (2002) investigated the effects of fat sources on C. perfringens. They found that total anaerobic counts increased with animal fat addition. However, zinc bacitracin was included in their diets, specifically targeting Gram-positive microorganisms like C. perfringens; thus, potentially biasing their results.

Antibiotics and coccidiostats in the diet – helpful, but finite

Antibiotics and coccidiostats have been commonly included in poultry diets since the mid-1940s and 1950s^{61, 58}.

Prescott et al.⁴⁹ studied the inclusion of zinc bacitracin to prevent necrotic enteritis and concluded that it successfully controlled the C. perfringens challenge. Flocks in the antibiotic treatments were able to overcome disease and perform similarly to unchallenged birds. Multiple authors have replicated these results using different antibiotics such as virginiamycin and salinomycin^{17, 3, 11}.

Improvements in flock performance with the inclusion of antibiotics and coccidiostats are well understood and omnipresent in the literature. However, the potential loss of subtherapeutic antibiotic usage in livestock in the United States due to increasing concerns over antimicrobial resistance and consumer demands makes research of viable alternatives to these compounds paramount.

So, what are your alternatives?

A lot of different approaches are possible. In general, these measures should act against Clostridium perfringens while supporting gut health.

Tested substances without the desired effects

Lastly, multiple options have been studied to control C. perfringens in poultry. Some researchers have studied the inclusion of complex carbohydrates and fibers like pine shavings, guar gum, and pectin with limited success^{4, 31}. Another popular alternative is the use of competitive exclusion-based products such as prebiotics and probiotics^{27, 16}. Still, these products failed to yield consistent results.

Other options that have been investigated are the addition of lactose and organic acids^{54, 38}. Potassium diformate did not produce lowered counts of C. perfringens. Lactose reduced C. perfringens counts but resulted in undesirable ceca characteristics including, enlargement and increased fermentation⁵⁴.

Essential oils alone or in combination may be a solution

Mitsch and coworkers³⁹ investigated the efficacy of two blends of essential oils with positive effects on the reduction of C. perfringens from the gut and feces of broilers. Gaucher and coworkers¹⁵ compared growth performance and gut health of broilers fed a conventional (anticoccidials and AGPs) vs. ABF (Coccidiosis vaccine and essential oil blends) diet. They established that livability, age at slaughter, and percentage of condemnation did not change with diet type. However, average daily weight gain and FCR were negatively affected. Furthermore, NE was more prevalent in ABF flocks.  Still, many authors agree that a multifactorial approach is necessary if antibiotics should be completely replaced by these strategies³⁶.

A contemporary study by Wati et al.⁵⁶ aimed to compare AGPs to a commercial blend of essential oils fed to broilers. Authors found that chickens fed essential oils had body weights and FCRs that were statistically similar to the AGP treatment. Moreover, both AGP and essential oil treatments had statistically lower counts of Salmonella and E. coli after an oral challenge than the control group.

Conclusion

C. perfringens is a potential pathogen found in every place poultry is raised. Therefore, we must continue to identify strategies to control the development of Necrotic Enteritis. Since antibiotics alone may not always successfully control C. perfringens and have the potential for subtherapeutic use loss in the US, a multifactorial approach must be considered and investigated. Grain size, enzymes, feed form, animal protein source, fats, and feed supplements such as essential oils can affect the proliferation of C. perfringens. Nutritionists, veterinarians, and live production personnel must come together to develop the best approach for their specific complex circumstances.

Figure 1. Interaction between coccidiosis and NE with environmental factors

Solid-line arrows are beneficial in controlling disease. Dashed-line arrows impart high disease risk factors. Double-line arrows depict major disease-risk factors. AGP, antibiotic growth promoter; CIA, chick infectious anemia; CEP, competitive exclusion product; Cp, Clostridium perfringens; IBD, infectious bursal disease; MD, Marek’s disease; NE, necrotic enteritis. (Williams, R.B. 2005)

 Figure 2. Necrotic Enteritis lesions in chicken intestines

Yellowish necrotic lesions in three intestinal samples. Intestines A and C show a few marked lesions. Intestine B shows clusters of lesions typical of the “Turkish towel” syndrome. (Source: http://www.mdpi.com/2072-6651/2/7/1913/htm. Accessed: January 14, 2021).

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Older laying birds are still a valuable asset, as long as they are managed for performance and productivity. Eggshell quality is one of the elements that, without proper management, can quickly deteriorate. It is therefore essential that the egg producer takes into account all the necessary elements for the formation of high-quality eggs.

The eggshell, in a nutshell

The eggshell represents ten percent of the entire egg, by weight[i]. For instance, a 60-gram egg contains approximately 6 g of shell. Out of this particular shell, approximately 95% is CaCO₃[ii], with a total of 2.3 g of Calcium (Ca).

But where does the calcium in the eggshell come from?

The Ca required for the eggshell is obtained, in variable proportions, directly from the feed or water additives (absorbed from the gut and transported via the blood to the shell gland), or from the bone (resorbed by osteoclasts and the Ca transported to the blood to the shell gland).

Maintaining eggshell quality and bone calcium: Mission Impossible?

Eggshell quality is often negatively correlated to bone strength[iii], most probably because body calcium is redirected to the shell to the detriment of the bones and the other way around. This impacts the long-term health of the skeleton; however, modern laying hens can maintain shell quality while preserving bone mineralization[iv].

60 to 75% of shell Ca is derived from the diet on shell-forming days

Approximately 60 to 75% of shell Ca is derived directly from the diet on shell-forming days[v]. This means that the greater the proportion of Ca coming directly from the feed or water additives, the better the eggshell quality can be. Therefore, the factors that can improve shell quality will also reduce the need to mobilize bone Ca and can also help to maintain skeletal health.

In old laying birds, generally after peak production, the ability to deposit Ca onto the shell remains relatively constant[vi], so an increase in egg size after peak production will tend to result in reduced shell quality. Dietary requirements for Ca tend to increase and those for phosphorus (P) tend to decrease as hens age.

Also, as hens age, the efficiency of Ca metabolism decreases[vii]. Increases in dietary Ca and a widening of the Ca:available P ratio are intended to counter this issue. Excess dietary P can also reduce shell quality[viii].

Because of its importance in Ca and P absorption from the gut, adequate dietary vitamin D activity must also be provided[ix]. Feeding of the vitamin D metabolite 25-OH vitamin D3 can help to maintain skeletal and shell quality in high-producing laying hens[x].

Ca metabolism is a complex game

Ca metabolism is regulated by various hormones such as calcitonin, 1,25-dihydroxyvitamin D3 (calcitriol), and parathyroid hormone. Estrogen, androgens, and prostaglandins also appear to have an important role in avian Ca metabolism.

Source: Ricardo (2008)

Egg formation and Ca requirements

Source

A hen ovulates approximately 15 to 75 minutes following oviposition[xi], and the ovum takes approximately 4.25 hours to reach the shell gland[xii], at which point calcification takes approximately 17 hours[xiii]. Hens generally lay eggs in the morning and early in the afternoon[xiv]. The hen can use the Ca and P made available through diet to recover medullary bone losses during the next 5 hours after oviposition.

Once the ovum reaches the shell gland, the demand for calcium naturally increases greatly as eggshell formation progresses. The highest eggshell mineral accretion takes place 5 – 15 hours after the egg enters the shell gland[xv], which normally happens later in the afternoon and during the night preceding egg laying.

Hourly Ca requirements for eggshell calcification

Ca dietary requirements vary with species, age, breeding status, and dietary levels of vitamin D. Egg-laying birds and growing birds require more Ca than adult non-breeding birds.

Common eggshell quality problems and causes

In many cases, the source of eggshell problems can be detected by recognizing the specific markers. For instance, cracked, soft-shelled or corrugated eggs can be caused by saline water, or the impact of mycotoxins; shell-les eggs can be caused by improper amounts of Ca, P, Mn or vitamin D3, as well as by infectious bronchitis or Newcastle disease IB. However, among the main causes of eggshell quality issues is heat stress.

In hot temperatures, increased respiration rates can cause an increase in CO₂ loss. The reduction of the pool of bicarbonate ions can result in respiratory alkalosis and an increase in blood pH[xvi]. A reduction in bicarbonate ions in the shell gland reduces the formation of CaCO₃ and decreases shell quality.

Under heat stress, birds will also tend to decrease their feed intake during the day to reduce diet-induced thermogenesis. Calcium intake is therefore also reduced, and shell quality decreases as a consequence.

3 solutions for eggshell quality in older layers

Midnight feeding in hot climates

At midnight, when temperatures are typically cooler, the addition of one to two hours of light can help the birds increase feed consumption[xvii]. Midnight feeding can also have the benefit of providing a dietary source of Ca to support eggshell formation during the night and reduce reliance on bone reserves[xviii].

Nutrition supplements

Along with Calcium, some micro-minerals can also influence eggshell quality. Zinc, Manganese and Copper act as cofactors of enzymes involved in the mineralization process during eggshell formation. Although European Union legislation restricts the use of high levels of these minerals, several studies in layers indicate increased egg shell resistance by increasing the dietary concentrations of microminerals. Using organic forms of Zinc, Manganese and Copper appears to be an alternative way to increase the absorption of these minerals, as organic forms appear to be more digestible than inorganic forms. Considering the high cost of organic minerals, a mix of organic and inorganic forms of critical minerals could be a better option.

Liquid Ca supplements

If a hen is fed a diet containing only a small-particle Ca sources, such as finely ground limestone, the intestine will be deprived of a source of Ca during the night, when demand for Ca is highest. At that point, the hen will be entirely reliant on bone Ca to support eggshell formation. A combination of Ca supplementation through water additives can be a good alternative as readily available Ca to the hen to support high Ca requirements during the late afternoon and through the night. Liquid Ca additives also offer further precise and user-friendly    application.

Stimuvital IP: a liquid solution from EW Nutrition

Stimuvital IP (formerly Shellimprover) is a liquid nutritional additive for laying hens, supporting the quality of eggshells and bone health. It contains a cocktail of Ca and vitamins whose benefits in laying birds are well proven through field studies, existing literature, and years of market experience.

Benefits proven in Australia field trial

22,500 layer birds were split into two equal-size groups, one of which (11250 birds) was supplemented with Stimuvital IP for 3 days every two weeks, starting from age 53^rd to 63^rd week. Improvements in eggshell thickness and strength could be noticed after the application of Shellimprover. Egg weight was consistent in Stimuvital IP -supplemented birds.3 days every fortnight by using the Easy@ system. In total, the 11250 birds received (2 (feed lines) x 3 (times per days) x 265ml x 3 (days) x 6 (week 53, 55, 57, 59, 61, 63) 28620mll of Stimuvital IP.

Benefits proven in China field trial

The field trial was carried out on a commercial layer farm. A control group and Stimuvital IP (Shellimprover) group had 50,000 birds each. Stimuvital IP was supplemented for 3 days every two weeks, starting from age 57^th to 62^nd week. The Stimuvital IP supplementation improved eggshell quality, including eggshell thickness, laying rate, and number of saleable eggs during the trial period.

Optimizing quantity, quality, and overall profitability for layer producers

Ca concentration in the blood is controlled by many interacting feedback loops that involve Ca, phosphate, PTH, vitamin D₃, and calcitonin. Supplementation of Vitamin D₃ can help maintain skeletal and shell quality in high-producing laying hens[xxiv].

Stimuvital IP offers an essential cocktail that caters to the additional requirements of Ca and vitamins in older laying birds. It thus supports Ca metabolism and eggshell quality. And, in the end, better eggshell quality reduces broken egg percentage and optimizes the number of salable eggs and profitability for layer producers.

Notes

[i] Pelicia et al., 2009; Bello and Korver, 2019

[ii] Nys et al., 2004

[iii] Orban and Roland Sr, 1990

[iv] Bello and Korver, 2019

[v] Driggers and Comar, 1949

[vi] Roland Sr et al., 1975

[vii] Wistedt et al., 2019

[viii] Miles et al., 1983

[ix] Wen et al., 2019

[x] Silva, 2017; Akbari Moghaddam Kakhki et al., 2019

[xi] Beuving and Vonder, 1981

[xii] Roberts, 2004

[xiii] Hincke et al., 2012

[xiv] Samiullah et al., 2016; Hunniford et al., 2017

[xv] Hincke et al., 2012

[xvi] Franco-Jimenez et al., 2007

[xvii] van Staaveren et al., 2018

[xviii] Harms et al., 1996

[xix] Chowdhury, 1990

[xx] Leach and Gross, 1983

[xxi] Zhang et al., 2017

[xxii] Atteh and Leeson, 1983

[xxiii] Atteh and Leeson, 1985

[xxiv] Silva, 2017; Akbari Moghaddam Kakhki et al., 2019

Full references are available upon request.

What is dysbacteriosis?

Dysbacteriosis has been defined as the presence of a qualitatively and/or quantitatively abnormal microbiota in the proximal parts of the small intestine. This abnormal microbiota produces a cascade of reactions in the gastrointestinal tract, including reduced nutrient digestibility and impaired intestinal barrier function, increasing the risk of bacterial translocation and inflammatory responses (Panneman, 2000; Van der Klis, 2000 and Lensing, 2007).  Dysbacteriosis is not a specific disease but a secondary syndrome. Along the entire GI tract, there is a diverse microbial community comprised of bacteria, yeasts, archaea, ciliate protozoa, anaerobic fungi, and bacteriophages, commonly referred to as the intestinal microbiota.

Dysbacteriosis is an imbalance in the gut microbiota as a consequence of an intestinal disruption. The impact of dysbacteriosis can be separated into economic and welfare issues (Bailey, 2010). Dysbacteriosis can lead to very wet litter and caking issues. The prolonged contact of broilers with the caked litter can result in painful ulceration of the feet and hocks (pododermatitis and hock-burn), leading to a serious welfare issue and degradation of the carcass.

Apart from these issues, a major economic impact comes from reduced growth rates, FCR, and increased veterinary treatment costs (Kizerwetter-Świda and Binek, 2008).

Causes of dysbacteriosis

It is believed that both non-infectious and infectious factors can play a role in dysbacteriosis (DeGussem, 2007).

Non-infectious causes are:

• Diet
• Brooding
• Biosecurity
• Risk periods
• Environmental conditions

Diet

Intestinal bacteria derive most of their energy from dietary compounds. Thus, diet has a major influence over the bacterial populations (Apajalahti et al., 2004). Any change in feed and feed raw materials, as well as the physical quality of feed, influence the balance of the gut microbiota. Processing significantly affects the characteristics of the feed as a substrate for the bacterial community. Perhaps the temperature and pressure of the conditioning process give its characteristic signature to the bacterial community structure.

Inappropriate brooding conditions

The provision of optimal brooding conditions is essential for ensuring optimal gut microbiota development. Birds receiving appropriate brooding develop a gut that performs well and has a greater capacity to cope with the challenges of the broiler shed. Early access to feed and water is crucial. One of the most critical factors for the occurrence of dysbacteriosis is the lack of digesta. The microbiota can change in a period of hours when nutrients are not present. The quality of water is also essential to maintain normal intestinal function and digesta pH.

Faulty biosecurity

If clean-out and disinfection procedures are improperly conducted, pathogens will be introduced into the poultry shed, and exposure to these pathogens will influence gut health and development. It has been proven that litter management regimes affect chicken gastrointestinal tract (GIT) and microbiota (Wang et al., 2016)

Risk periods

There are times during poultry production when the bird will be challenged, for example, during feed changeovers, vaccination handling and transportation, overcrowding, or placement in new housing. During these periods, the gut microbiota can fluctuate and, in some cases, if management is sub-optimal, dysbacteriosis can occur.

Environmental conditions

Achieving optimal environmental conditions will promote good gut health. Any perturbation in gastroenteric physiology or immunity of the bird, caused by temperature stress or other environmental discomforts, can cause dysbacteriosis and/or enteritis. These are associated with lower absorption of nutrients by the host. Suzuki et al. 1983 demonstrated that overcrowding and heat stress, very commonly seen in intensive poultry farming, has a significant impact on the microbiota of chickens.

Infectious agents that potentially play a role in dysbacteriosis

• Mycotoxins
• Eimeria spp.
• Clostridium perfringens
• Other bacteria producing toxic metabolites

Mycotoxins

Many mycotoxins can stimulate the secretion of several antimicrobial molecules, which have positive effects on the maintenance of intestinal homeostasis. Fumonisins inhibit the growth of fungi, Fusarium toxins exhibit different antimicrobial defensive mechanisms, and aflatoxins exhibit a moderate antimicrobial activity against Escherichia coli, Bacillus subtilis, and Enterobacter aerogenes [Bevins et al. 1999 and Wan et al.2013]. Mycotoxins such as aflatoxins, trichothecenes, zearalenone, fumonisin, and ochratoxin can alter the normal intestinal functions, such as the barrier function and nutrient absorption. Some mycotoxins, like trichothecenes and ochratoxin, affect the histomorphology of the intestine (Winnie et al., 2018). Mycotoxicosis changes the population equilibrium, which can lead to dysbacteriosis.

Eimeria spp.

Coccidiosis caused by Eimeria spp. in chickens appears to be one of the principal destabilizing agents, causing the destruction of enterocytes and affecting the integrity of the intestinal mucosa and wall. The lesions that it causes, the inflammatory process, the reduced absorption and consequent excess of nutrients in the lumen all contribute to the proliferation of certain groups of bacteria. This situation clearly predisposes birds to intestinal dysbacteriosis and/or bacterial enteritis, and in particular to necrotic enteritis.

Clostridium perfringens

Clostridium perfringens is a natural part of the habitat in the hindgut that is not dangerous under normal circumstances. If it multiplies, the bacterium produces toxic substances that damage the intestinal mucosa and cause a condition called necrotic enteritis.  The disease is characterized by necrosis and inflammation of the GIT. Without treatment, this can escalate to perforation of the intestines, hemorrhages, and eventual death from septic shock.

Signs and consequences of dysbacteriosis

Dysbacteriosis can have profound effects on the host. Dysbacteriosis alters the GIT environment and favors the growth of pathogenic bacteria. Pathogenic bacteria produce toxins that increase intestinal motility or cause alterations in the amounts of mucus produced or in its composition. They also result in modifications of gastric acidity, reduction in the production of bacteriostatic peptides in the pancreas, and reduced immunoglobulin (IgA) secretion.

Toxins released by entero-pathogens damage intestinal villi, resulting in focal ulcerations of the mucosa, tissue necrosis, and shifts in gut microorganism numbers and metabolism. The costliest condition for animal production is the chronic inflammatory response of the animal to constant minor dysbacteriosis. These chronic responses can reduce weight gain and cause low feed conversion efficiency. Coccidiosis infections and any other enteric disease can be aggravated when dysbacteriosis is prevalent. Generally, animals with dysbacteriosis have high concentrations of Clostridium that generate more toxins, leading to necrotic enteritis.

In broilers, the syndrome is generally seen between 20 and 30 days of age (Wilson et al., 2005). Clinically, the main signs are:

• pale, glistening or orange droppings with undigested food particles
• wet and greasy droppings and hence dirty feathers
• sometimes foamy caecal droppings
• reduced physical activity
• increased water intake
• decrease in feed intake with a check in weight or reduced gain rates
• increased feed conversion

(Wilson et al., 2005; De Gussem, 2007)

Wet litter is also a general outcome of dysbacteriosis that may affect the air quality of the house, leading to a higher incidence of respiratory problems.

Additionally, foodborne pathogens such as Salmonella spp. and E.coli proliferate more in the dysbiotic intestine and can become persistent residents of the hindgut.

At necropsy, the main observations are

• a thin, fragile, often translucent intestinal wall
• watery or foamy intestinal contents
• frequent orange mucus and undigested particles in the intestines
• ballooning of the gut
• intestinal inflammation

(Pattison, 2002; De Gussem,2007)

Prevention of dysbacteriosis

The most important factors to prevent dysbacteriosis are

• Minimizing environmental stress
• Maintaining good water quality
• Improving feed digestibility
• Avoiding antinutritional factors, mycotoxins, and rancidity
• Feed additives that could modulate microbial component and avoid dysbacteriosis

Growth-promoting antibiotics are well known for the inhibition of undesired microbiota and the negative effects of their metabolites, and selection for beneficial bacteria. However, the adverse result is that they diminish the natural diversity of the gut microbiota. Antibiotics can also result in animals developing bacterial resistance.

Other products have been proposed as alternatives to growth promotion, taking into consideration the increasing bacterial resistance to some antibiotic categories.

Alternate feed additive technologies that have a promising role in controlling dysbacteriosis are:

• Probiotics
• Prebiotics
• Enzymes
• Organic acids
• Essential oils and phytomolecules

Probiotics

The post-hatch period is very critical for the chicks’ intestine development. Exposure to the environment in hatchery and farm affects microbial colonization in the intestine tract. The use of selective probiotics in day-old chicks at the hatchery and on the farm immediately after placement in broiler house reduces the risk of dysbacteriosis. Probiotics work by competitive exclusion, thereby prevent the colonization of potentially pathogenic bacteria. Probiotics prevent enteric diseases, improves intestine development and digestion process.

The benefits include enhanced growth and laying performance, improved gut histomorphology, immunity, and an increase in beneficial microbiota (Rajesh Jha et al., 2020)

Prebiotics: Mannan Oligosaccharide

(MOS) mimics the properties of the cells on the gut wall to attract and bind with harmful bacteria. Rather than allowing the bad bacteria to attach to the gut wall, the MOS acts as a sticky sponge, clearing up the harmful bacteria and removing them from the digestive system. MOS play an important role in gut functionality and health, through enhanced nutrient digestibility and improved gut barrier function and local defenses. MOS is also related to long villi and shallow crypts in the intestine, so a larger surface area helped with the absorption of nutrients and improved animal performance (Chand et al., 2016b)

Enzymes

Careful choice of feed enzymes will reduce nutrients available for pathogenic bacterial growth and improve gut health. Bacterial Xylanase is showing promise by digesting both soluble and insoluble arabinoxylans and reducing the viscosity of intestinal content. It maintains gut motility, improves nutrients digestibility, and impairs the growth of pathogenic bacteria in the hindgut.

Organic acids

Organic acids ameliorate the conditions of the GIT through the reduction of GIT pH, promoting proteolytic enzyme activity, intensifying pancreatic secretions. They encourage digestive enzyme activity and nutrient digestibility. Organic acids are creating stability of the microbial population by stimulating the growth of beneficial bacteriaPapatisiros et al., 2013).

Phytomolecules

Multiple scientific studies have proven the positive effects of phytomolecules (also known as phytogenics or secondary plant compounds) on the gut health of livestock animals. These substances support digestion and improve the utilization of nutrients. This results in higher daily weight gain and better feed conversion. In addition, phytomolecules have a proven antimicrobial effect, based on different biological modes of action.

EW Nutrition offers standardized phytomolecule-based solutions (Activo and Activo Liquid) that positively influence gut health and subsequent performance parameters in poultry. In scientific studies, the Activo product line has shown a positive effect on gut pathogenic bacteria, reducing necrotic enteritis (Fig 1) and improving production performance.

Conclusion

Dysbacteriosis can have profound effects on the host. Acute dysbacteriosis can result in the proliferation of pathogenic microorganisms that become enteropathogenic. Pathogenic bacteria can produce toxins and metabolites that increase gut motility, increase fermentation with gas production, change gut pH, irritate the mucosa, cause inflammation, and increase mucous secretion. This process reduces the digestibility and absorption of nutrients.

Maintaining the equilibrium of the gut ecosystem is key to avoiding dysbacteriosis. Improving feed digestibility and using feed additives that modulate gut microflora help to maintain more stable gut ecosystems, even during periods of intestinal stress preventing dysbacteriosis. Effective prevention and control of dysbacteriosis help increase poultry operations’ economic profitability by way of improved performance, health, and welfare, and reduce foodborne pathogens and environmental impact of poultry production.

References

Apajalahti, J., Kettunen, A., and H. Graham. 2004. Characteristics of the gastrointestinal microbial communities, with special reference to the chicken. World Poultry Sci J 60:223- 232.

Bailey, Richard A. 2010. Intestinal microbiota and the pathogenesis of dysbacteriosis in broiler chickens. PhD thesis submitted to the University of East Anglia. Institute of Food Research, United Kingdom.

Bevins, C. L.; Martin-Porter, E.; Ganz, T. Defensins and innate host defence of the gastrointestinal tract. Gut, 1999, 45, 911–915.

De Gussem , M. 2007. Coccidiosis in poultry: review on diagnosis, control, prevention and interaction with overall gut health . In Proceedings of the XVI European  Symposium on Poultry Nutrition (pp. 160 169 . Strasbourg , France.

Gurrre, Philippe. 2020. Review Mycotoxin and Gut Microbiota Interactions. Toxins, 12, 769.

Jha, Rajesh, Razib Das, Sophia Oak, and Pravin Mishra, 2020. Probiotics (Direct-Fed Microbials) in Poultry Nutrition and Their Effects on Nutrient Utilization, Growth and Laying Performance, and Gut Health: A Systematic Review. Animals (Basel). 10(10): 1863.

Kizerwetter-Świda, M., and M. Binek. 2008. Bacterial microflora of the chicken embryos and newly hatched chicken. Journal of Animal and Feed Sciences 17:224-232

Panneman, H. 2000 . Clostridial enteritis/dysbacteriosis, fast diagnosis by T-RFLP, a novel diagnostic tool. In Proceedings of the Elanco Global Enteritis Symposium. Cork Ireland.

Papatisiros VG, Katsoulos PD, Koutoulis KC, Karatzia M, Dedousi A, Christodoulopoulos G. Alternatives to antibiotics for farm animals. CAB Rev Ag Vet Sci Nutr Res. (2013) 8:1–15. doi: 10.1079/PAVSNNR20138032.

Pui-Pui, Winnie, and Sabran Mohd-Redzwan. 2018. Mycotoxin: Its Impact on Gut Health and Microbiota. Frontiers in Cellular and Infection Microbiology, 8:60.

Rebel, J.M.J., Balk, F.R.M., Post, J., Van Hemert, S., Zekarias, B. and Stockhofe, N. 2006. Malabsorption syndrome in broilers. World’s Poultry Science Journal, 62: 17–29.

Saeed, Mohammad, Fawwad Ahmad, Mohammad Asif Arain, Mohamed E Abd El-Hack, Mohamed Emam, Zohaib Ahmed Bhutto and Arman Moshaven, 2017. Use of Mannen – Oligosaccharides (MOS) As a Feed Additive in Poultry Nutrition. J. World Poult. Res. 7(3): 94-103.

Suzuki, K., R. Harasawa, Y. Yoshitake, and T. Mitsuoka. 1983. Effects of crowding and heat stress on intestinal flora, body weight gain, and feed efficiency of growing rats and chicks. Nippon Juigaku Zasshi 45:331-8.

Van der Klis, J.D. and Lensing, M. 2007. Wet litter problems relate to host–microbiota interactions. World Poultry, 23: 20–22.

Wan, M. L.; Woo, C. S.; Allen, K. J.; Turner, P. C.; El-Nezami, H. Modulation of porcine-defensins 1 and 2 upon individual and combined fusarium toxin exposure in a swine jejunal epithelial cell line. App. l. Environ. Microbiol., 2013, 79(7), 2225-2232

Wang L, Lilburn M, Zhongtang Y. 2016. Intestinal microbiota of broiler chickens as affected by litter management regimens Front. Microbiol (2016).

Wilson, J., Tice, G., Brash, M.L. and St Hilaire, S. 2005. Manifestations of Clostridium perfringens and related bacterial enteritides in broiler chickens. Worlds Poultry Science Journal, 61: 435–449.

Lutein belongs to the group of carotenoids, which is divided into carotenes and xanthophylls. Lutein, chemically expressed as “3,3’-dihydroxy-α-carotene”, is a xanthophyll always accompanied by its isomer zeaxanthin. It is synthesized out of two α-carotenes through hydroxylation.

Lutein provides benefits for animals and humans

Lutein has antioxidant protective properties

Under normal conditions, the cells in the animal and human organism control ROS (reactive oxygen species) levels. Usually, there is a balance between the generation of ROS and their elimination by scavenging systems. However, the high performance levels in modern animal production can easily lead to high ROS levels, translated into oxidative stress and leading to cell damage. Cell damage contributes to the generation of cancer and early aging in humans. In animals, the negative impact of oxidative stress can be responsible for lower performance and inferiority of meat and eggs.

Antioxidants stop ROS by taking up their energy

Through the uptake of energy, molecules can get into an excited state. One example is singlet excited oxygen, a highly reactive form of oxygen able to destroy proteins, lipids, and DNA. Carotenoids can intervene in this process: by exchanging electrons, the singlet excited oxygen gets neutralized, and the carotenoid gets into this excited state with higher energy. Once able to release this energy as heat into the environment, the carotenoid gets back to its normal state and can once again start acting as an antioxidant.

In this way, carotenoids, including lutein, ‘quench’ the energy of excited molecules and prevent the adverse effects of ROS (reactive oxidative substances).

Antioxidant properties profitably used

The antioxidant character of lutein plays an important role in the treatment or prophylaxis of macular degeneration in humans (Landrum & Bone, 2001). There is also evidence that lutein can be used to improve the visual and retinal function in dogs (Wang et al., 2016). In the eye, lutein and zeaxanthin, occurring in the retina and the macula, neutralize free radicals produced due to the ultraviolet light and thereby prevent damage to the macula.

Further possible applications are against cardiovascular diseases (Dwyer et al., 2001)  and various types of cancer (e.g., breast cancer, Gong et al., 2018).

Lutein is important in infant nutrition

Lutein and its isomer zeaxanthin are the two primary carotenoids found in human milk (Giordano and Quadro, 2018). Stringham and co-workers (2019) postulate that lutein plays an important role in children’s visual and cognitive development/optimization. They report that a lutein supplementation of the mother can lead to a higher concentration of this substance in the milk and, consequently, in the child’s plasma (Sherry et al., 2014). In dairy cows, an increased level of lutein in the milk can also be observed (Xu et al., 2014), suggesting that lutein could also be essential in calf development.

Lutein stimulates the immune system

Another benefit of lutein is its positive influence on the immune system.

On the one hand, lutein stimulates the production of antibodies. In dogs, Guimarães Alarça et al. (2016) could show an increase of CD4+ and CD8+ T-lymphocyte subtypes. Kim et al. (2000) demonstrated the increase of lymphocytes and cells expressing CD5, CD4, CD8, and major histocompatibility complex class II (MHC II) molecules. Bédécarrats and Leeson (2006) provoked a higher secondary antibody response to infectious bronchitis vaccination in laying hens.

Besides, lutein acts as an anti-inflammatory agent, as shown in vitro by Chao et al. (2015) and in broiler chickens by Moraes and team (2016).

Lutein improves the attractivity of poultry products

In the marketing of poultry products, appearance and color are of central importance for evaluating quality. Egg yolk coloration is to a large extent a matter of regional preferences, however it is clear that an egg with a yolk that does not have the typical color is classified as inferior by the consumer. In areas with traditional corn growing, a white-skinned chicken is not commercially viable. Even when pullets are bought, the shanks and beaks should be yellow.

The use of xanthophylls like lutein and zeaxanthin enables producers to safely control the color of the egg yolk and of the broiler skin. It also leads to a healthy color of the shanks and beaks of the birds.

Lutein in a nutshell

Lutein is a true all-rounder: a substance that delivers benefits across the board. In plants, it helps fruits and petals become attractive for insects and other animals. It positively influences the animal, acting as an antioxidant, promoting infant development, and stimulating the immune system. As a pigment, it makes poultry and poultry products look more attractive to the consumer. Through its presence in eggs and milk, lutein provides clear and clean benefits to both animals and humans.

References

Bédécarrats, G.Y. and S. Leeson. “Dietary lutein influences immune response in laying hens.”  J. Appl. Poult. Res. 15 (2006): 183–189.

https://doi.org/10.1093/japr/15.2.183

Chao, Shih-Chun, Tommaso Vagaggini, Chan-Wei Nien, Sheng-Chieh Huang, and Hung-Yu Lin. “Effects of Lutein and Zeaxanthin on LPS-Induced Secretion of IL-8 by Uveal Melanocytes and Relevant Signal Pathways.” Journal of Ophtalmology, vol. 2015 Article ID 152854 (2015): 7 pages. https://doi.org/10.1155/2015/152854

Dwyer, James H., Mohamad Navab, Kathleen M. Dwyer, Kholood Hassan, Ping Sun, Anne Shircore, Susan Hama-Levy, Greg Hough, Xuping Wang, Thomas Drake, C. Noel Bairey Merz, and Alan M. Fogelman. “Oxygenated Carotenoid Lutein and Progression of Early Atherosclerosis.” Circulation (American Heart Association) 103, no. 24 (2001): 2922-2927.

https://doi.org/10.1161/01.CIR.103.24.2922

Gong, Xiaoming, Joshua R. Smith, Haley M. Swanson, and Lewis P. Rubin. “Carotenoid Lutein Selectively Inhibits Breast Cancer Cell Growth and Potentiates the Effect of Chemotherapeutic Agents through ROS-Mediated Mechanisms.” Molecules 23 no. 4(2018): 905.

http://dx.doi.org/10.3390/molecules23040905

Guimarães Alarça, Laís, Fabiane Yukiko Murakami, Ananda Portella Félix, Everton Luis Krabbe, Simone Gisele de Oliveira, Sebastião Aparecido Borges da Silva. “Dietary lutein supplementation on diet digestibility and blood parameters of dogs.” Cienc. Rural 46 no.12 (2016)

http://dx.doi.org/10.1590/0103-8478cr20151493

Kim, Hong Wook, Boon Chew, Teri Ann S Wong, Jean Soon Park, Bor-Chun Weng, Katherine M Byrne, Michael G Hayek, and Gregory A. Reinhart. “Dietary lutein stimulates immune response in the canine.” Veterinary Immunology and Immunopathology 74 no. 3-4 (2000): 315-327.

https://doi.org/10.1016/S0165-2427(00)00180-X

Landrum, J. T. and R.A. Bone. “Lutein, zeaxanthin, and the macular pigment.” Archives of Biochemistry and Biophysics 385 no. 1 (2001): 28–40.

https://doi.org/10.1006/abbi.2000.2171.

Moraes, M. L., A. M. L. Ribeiro, E. Santin, and K. C. Klasing. “Immunology, health, and disease: effects of conjugated linoleic acid and lutein on the growth performance and immune response of broiler chickens.” Poultry Science 95 (2016): 237–246.

http://dx.doi.org/10.3382/ps/pev325

Ochoa Becerra, Mario, Luis Mojica Contrerasa, Ming Hsieh Loa, Juan Mateos Díaz, Gustavo Castillo Herrera. “Lutein as a functional food ingredient: Stability and bioavailability.” Journal of Functional Foods 66 (2020): 103771.

https://doi.org/10.1016/j.jff.2019.103771

Sherry, Christina L.,  Jeffery S. Oliver, Lisa M. Renzi, and Barbara J. Marriage. “Lutein supplementation increases breast milk and plasma lutein concentrations in lactating women and infant plasma  concentrations but does not affect other carotenoids.” J. Nutr. 144 (2014): 1256–1263.

http://dx.doi.org/10.3945/jn.114.192914

Stringham, James M., Elizabeth J Johnson, and B Randy Hammond. “Lutein across the lifespan: From childhood cognitive performance to the aging eye and brain.” Curr Dev Nutr 3 (2019): nzz066.

http://dx.doi.org/10.1093/cdn/nzz066

Wang, Wei, Jerome Hernandez, Cecil Moore, Janet Jackson, and Kristina Narfström. “Antioxidant supplementation increases retinal responses and decreases refractive error changes in dogs.” J. Nutr. Sci. 5 e18 (2016): 7 pages

http://dx.doi.org/10.1017/jns.2016.5

Xu, C.Z., H. F. Wang, J. Y. Yang, J. H. Wang, Z. Y. Duan, C. Wang, J. X. Liu , and Y. Lao. “ Effects of feeding lutein on production performance, antioxidative status, and milk quality of high-yielding dairy cows.” J. Dairy Sci. 97;  American Dairy Science Association (2014):7144–7150

http://dx.doi.org/10.3168/jds.2014-8276

How lipopolysaccharides cause disease

LPS are rather large and structured chemical molecules with a weight of over 100,000 D. They are highly thermostable; boiling in water at 100°C for 30 minutes does not destabilize their structure. LPS consist of three chemically distinct sections: a) the innermost part, lipid A, consisting mostly of fatty acids; b) the core, which contains an oligosaccharide; and c) the outer section, a chain of polysaccharides called O-antigen (Figure 1).

Figure 1: Structure of an LPS

The toxicity of LPS is mainly caused by lipid A; however, both lipid A and O-antigen stimulate the immune system. This happens when the LPS pass the mucosa and enter the bloodstream or when they attack the leukocytes.

The intestinal mucosa is the physical immune barrier that protects the microvilli from external agents (bacteria, free LPS viruses, etc.). Despite its strength (the thickness, for example, amounts to ≈830 µm in the colon and ≈123 µm in the jejunum), vulnerable points exist (cf. Zachary 2017).

LPS can easily come into contact with the cells of the lamina propria (a layer of connective tissue underneath the epithelium) through the microfold (M) cells of the Peyer’s patches (which consist of gut-associated lymphoid tissue). The M cells are not covered by mucus and thus exposed.

Secondly, LPS can also pass through the mucosa, where they become entangled in this gelatinous structure. There, they come into contact with the lymphocytes or can reach the regional lymph nodes through the afferent lymphatic vessels.

Thirdly, LPS might affect the tight junctions, the multiprotein complexes that keep the enterocytes (cells that form the intestinal villi) cohesive. By destabilizing the protein structures and triggering enzymatic reactions that chemically degrade them, LPS can break the tight junctions, reaching the first capillaries and, consequently, the bloodstream.

The presence of endotoxins in the blood, endotoxemia, can trigger problematic immune responses in animals. An innate immune stimulation leads to an increase in the concentration of pro-inflammatory cytokines in the blood and, consequently, to an induced febrile response in the animal: heat production increases, while the available metabolic energy decreases.  As a result, performance suffers, and in the worst-case scenario, septic shock sets in. Furthermore, when LPS compromise intestinal integrity, the risk of secondary infections increases, and production performance may decline.

LPS’ modes of action

How does all of this happen? The physiological consequences of endotoxemia are quite complex. Simplified, the immune system response to LPS in the blood takes three forms:

• The stimulation of TLR4 (toll-like receptor 4) induces monocytes and macrophages to secrete critical pro-inflammatory cytokines, primarily interleukin (IL) IL-1β, IL-6, IL-8, and tumor necrotic factor (TNF) α and β. TLR4 is a structure on the cell membrane of mainly macrophages and leukocytes, which is activated by the LPS-binding protein (LBP).
• The complement cascade constitutes about 10% of plasma proteins and determines the chemotaxis and activation of leukocytes. It can form a membrane attack complex (MAC), which perforates the membranes of pathogenic cells, enabling lysis.
• The Hagemann factor, also known as coagulation factor XII: once stimulated by LPS, it initiates the formation of fibrin (through the intrinsic coagulation pathway), which might lead to thrombosis. The Hagemann factor directly stimulates the transformation of prekallikrein to kallikrein (enzymes involved in regulating blood pressure).

Figure 2: How LPS leads to endotoxemia – 3 modes of action

These three modes of action of inflammatory stimulation lead to important physiological reactions:

• Pro-inflammatory cytokines (see above) modulate the functional expression of other immune cell types during the inflammatory response;
• Metabolites of arachidonic acid (prostaglandins, leukotrienes, and lipoxins), intra- and extracellular messengers that influence the coagulation cascade;
• Synthesis in the blood of bradykinin, a peptide responsible for the typical symptoms of inflammation, such as swelling, redness, heat and pain;
• PAF (platelet-activating factor), which creates inflammatory effects through narrowing of the blood vessels and constriction of the airways, but also through the degranulation of leukocytes.

The symptoms of endotoxemia are:  hypotension, metabolic acidosis, hemoconcentration, intestinal hemorrhage, fever, activations of neutrophils and endothelial cells, and predisposition to thrombosis.

In case of a progression to septic shock, the following sequence takes place:

1) Reduction in blood pressure and increased heart rate (hemodynamic alterations)

2) Abnormalities in body temperature

3) Progressive hypoperfusion at the level of the microvascular system

4) Hypoxic damage to susceptible cells

Up to here, symptoms follow a (severe) endotoxemia pathogenesis. A septic shock furthermore entails:

5) Quantitative changes in blood levels of leukocytes and platelets

6) Disseminated intravascular coagulation (see Hageman factor)

7) Multi-organ failure

8) Death of animal

If an animal is continously challenged with endotoxins, experiences septic shock, or comes close to it, it risks developing LPS tolerance, also known as CARS (compensatory anti-inflammatory response syndrome). This syndrome essentially depresses the immune system to control its activity. The anti-inflammatory prerogative of CARS is not to interfere directly with the elimination of pathogens but to regulate the “excessive” inflammatory reaction in a hemostatic way. However, this regulation can be extremely dangerous as the syndrome involves a lack of homeostasis control, and an excessive depression of the immune system leaves the organism exposed to the actual pathogens.

Farm animal research on endotoxemia pathogenesis

Lipopolysaccharides are difficult to quantify in the intestine of a live animal. One way to evaluate a possible endotoxemia is to analyze biomarkers present in the bloodstream. The most important one is the LPS themselves, which can be detected in a blood sample taken from the animal via ELISA. Other biomarkers include pro-inflammatory interleukins, such as TNF α and β, IL-6 or IL-8, and fibrin and fibrinogen (though they are not specific to endotoxemia). It is vital to carry out a blood sample analysis to deduce a possible endotoxemia from symptoms and performance losses in the animal.

How the metabolic effects of endotoxemia depress performance

One of the biggest issues caused by endotoxemia is that animals reduce their feed intake and show a poor feed conversion rate (FCR). Why does this happen? The productive performance of farm animals (producing milk, eggs, or meat) requires energy. An animal also requires a certain baseline amount of energy for maintenance, that is, for all activities related to its survival. As a result of inflammation and all those physiological reactions mentioned above, endotoxemia leads to a feverish state. Maintenance needs to continue; hence, the energy required for producing heat will be diverted from the energy usually spent on producing milk, egg, meat, etc., and performance suffers.

The inflammation response can result in mitochondrial injury to the intestinal cells, which alter the cellular energy metabolism. This is reflected in changes to the levels in adenosine triphosphate (ATP), the energy “currency” of living cells. A study by Li et al. (2015) observed a respective reduction of 15% and 55% in the ATP levels of the jejunum and ileum of LPS-challenged broilers, compared to the unchallenged control group. This illustrates the extent to which animals lose energy while they experience (more or less severe) endotoxemia.

Figure 3: Reduction in ATP level in Jejunum and Ileum in broilers (adapted from Li et al., 2015)

A piglet study by Huntley, Nyachoti, and Patience (2017) took this idea further (Figure 4):  3 groups of 10 Yorkshire x Landrace pigs, weighing between 11 and 25 kg, were studied in metabolic cages and in respiratory chambers. This methodology allows for simultaneous measurement of oxygen consumption, CO₂ production, energy expenditure, physical activity, and feed/water intake. The study found that LPS-challenged pigs retained 15% less of the available metabolizable energy and showed 25% less nutrient deposition. These results show concrete metabolic consequences caused by the febrile response to endotoxemia we discussed above.

Figure 4: Retained Energy as % of ME intake and nutrient deposition of pigs in metabolic cages (adapted from Huntley, Nyachoti, and Patience, 2017)

Control treatment (CON) = Pigs fed by a basal diet
Immune system stimulation treatment (ISS) = Pigs given LPS (E. coli serotype 055:B5) injection

A loss of energy retained due to a reduction in available metabolizable energy leads to losses in performance as the amount of energy available for muscle production and fat storage will be lower. Furthermore, the decrease in feed intake creates a further energy deficit concerning production needs.

A trial carried out at the University of Illinois examined the effects of repeated injections of 400 μg E. coli LPS on chick performance from 11 to 22 days after hatching. The chicks were fed casein-based diets with graded levels of arginine. LPS administration reduced weight gain (P<0.05) and feed intake, and these effects tended to be worse at higher levels of arginine supplementation (Figure 5). The researchers hypothesize that, in response to endotoxin and elevated cytokine levels, macrophages use more arginine to produce nitric oxide, diverting it from protein production for muscle development.

Figure 5: Effects of LPS on feed intake and body weight gain in chicks fed graded level of arginine (based on Webel, Johnson, and Baker, 1998)

NC = negative control

This data on poultry complements the results for swine, again showing that endotoxin-induced energy losses quantifiably depress animal performance even in milder disease cases.

The way forward: Endotoxin mitigation

Animals suffering from endotoxemia are subject to severe metabolic dysfunctions. If they do not perish from septic shock, they are still likely to show performance losses. Moreover, they at great risk of immunosuppression caused by the immune system “overdrive.” Effective endotoxin mitigating agents can help to prevent these scenarios.

EW Nutrition’s Mastersorb Gold is not only a leading anti-mycotoxin agent; thanks to its specific components, it effectively binds bacterial toxins. An in vitro study conducted at the Hogeschool Utrecht laboratory (part of Utrecht University) evaluated the binding capacity of Mastersorb Gold on LPS compared to three different competitor products. All products were tested at two different inclusion rates. At an inclusion rate of 0.25%, only Mastersorb Gold reduced the toxin load on the solution by 37%. At 1% inclusion, Mastersorb Gold bound 75% of the toxin, while only one competitor product demonstrated any binding (10%).

Figure 6: LPS adsorption capacity (%) – Mastersorb Gold clearly outperforms other anti-endotoxin products

Lipopolysaccharides are a constant challenge for animal production. The quantity of Gram-negative bacteria in an animal intestine is considerable; therefore, the danger of immune system over-stimulation through endotoxins cannot be taken lightly. Producers need to prioritize the maintenance of intestinal eubiosis in production animals proactively; for instance, through targeted gut health-enhancing additives based on phytomolecules and, possibly, organic acids.

Most importantly, the detrimental impact of LPS can be mitigated by using a high-performance agent such as Mastersorb Gold. To limit losses from an energy point of view yields positive results in terms of production levels and the prevention of secondary infections, preserving animal health and farms’ economic viability.

References

Adib-Conquy, Minou, and Jean-Marc Cavaillon. “Compensatory Anti-Inflammatory Response Syndrome.” Thrombosis and Haemostasis 101, no. 01 (2009): 36–47. https://doi.org/10.1160/th08-07-0421.

Huntley, Nichole F., C. Martin Nyachoti, and John F. Patience. “Immune System Stimulation Increases Nursery Pig Maintenance Energy Requirements.” Iowa State University Animal Industry Report 14, no. 1 (2017). https://doi.org/10.31274/ans_air-180814-344.

Li, Jiaolong, Yongqing Hou, Dan Yi, Jun Zhang, Lei Wang, Hongyi Qiu, Binying Ding, and Joshua Gong. “Effects of Tributyrin on Intestinal Energy Status, Antioxidative Capacity and Immune Response to Lipopolysaccharide Challenge in Broilers.” Asian-Australasian Journal of Animal Sciences 28, no. 12 (2015): 1784–93. https://doi.org/10.5713/ajas.15.0286.

Mani, Venkatesh, James H Hollis, and Nicholas K Gabler. “Dietary Oil Composition Differentially Modulates Intestinal Endotoxin Transport and Postprandial Endotoxemia.” Nutrition & Metabolism 10, no. 1 (2013): 6. https://doi.org/10.1186/1743-7075-10-6.

Webel, D.M., R.W. Johnson, and D.H. Baker. “Lipopolysaccharide-Induced Reductions in Body Weight Gain and Feed Intake Do Not Reduce the Efficiency of Arginine Utilization for Whole-Body Protein Accretion in the Chick.” Poultry Science 77, no. 12 (1998): 1893–98. https://doi.org/10.1093/ps/77.12.1893.

Zachary, James F. “Chapter 4 – Mechanisms of Microbial Infections.” Essay. In Pathologic Basis of Veterinary Disease, 132–241. St Louis, MO: Mosby, 2017. https://doi.org/10.1016/B978-0-323-35775-3.00004-7.

As people across the globe are re-discovering home cooking, grocery items such as milk, flour, and eggs are in higher demand than ever. Legendary chef Michel Roux once said that “Eggs are more than an element of cooking… The little egg is life.” Let us look at the complex system that allows us to enjoy this superfood – and how egg producers tackle the supply chain disruptions caused by the pandemic.

The coronavirus pandemic has led to increased demand for eggs and, therefore, to temporary shortages

Eggs: from farm to table

The story of our breakfast eggs starts with another set of eggs. The hens and cocks on so-called parent stock or layer breeder farms produce fertilized eggs (1). These “hatching eggs” are transferred to specialized hatcheries where the chicks hatch after 21 days (2). The female chicks, who will go on to become the hens that lay our eggs, are sent to so-called rearing or pullet farms, where they grow up (3). The young hens are then transferred to the layer farms (4).

When they are about 20 weeks old, the hens start to lay – and join the 7 billion chickens that produce more than 1.3 trillion eggs for us every year. During their 14-month laying period, hens will lay 360+ eggs.

Newly laid eggs need to be collected, and checked for quality (grading). About 50-65% of the hens’ output can be sold as “shell eggs,” i.e. whole eggs, to outlets servicing the hospitality industry and end consumers (5). These eggs need to be stamped and then packaged in the egg cartons we all know. “Breaker eggs,” i.e. irregularly sized or broken eggs, do not go to waste: they are moved to processing plants that produce liquid egg and egg powder products for food industry clients such as industrial bakeries and ice cream manufacturers (6).

How many steps it ultimately takes to get eggs from the farm to your plate depends on the complexity of the marketing channel. Farms might do their branding on-site; others work with specialized companies for packaging and branding. Some farms have direct relationships with retailers; others sell to wholesale outlets and distributors. The logistics for getting eggs quickly and safely from A to B involve dedicated egg distribution centers and fleets of refrigerated trucks.

Did you know?

An egg’s color depends on the layer hen’s breed. In the beginning, all eggs are white; those that end up being brown (or, in the case of certain chicken breeds, green or blue) have pigments deposited on them as the eggs pass through the hen’s oviduct.
The reason brown eggs are usually more expensive than white ones is that brown egg layer breeds tend to be heavier and consumer more feed. The eggshell color does not influence the egg’s taste or nutritional value.

Infographic: The egg supply chain, from farm to table

Coronavirus and food: disruptive effects on supply

The impact of the COVID-19 pandemic is felt along each step of this complex process. Disruptions in the supply chain for feed ingredients that mostly come from China, such as amino acids and vitamins, has led to increased price volatility of these ingredients, affecting farmers’ production costs.

Labor availability is a significant concern, for example with respect to the numerous transitions between locations. According to a recent Rabobank report on the situation in Europe, even though food transportation services are exempted from lockdown measures, the high incidence of COVID-19 cases are contributing to driver shortages and higher transport costs. Importantly, everyone working on the “front line” of food supply chains – drivers, as well as farmers, processors, distributors, or retail employees – are doing so at considerable personal risk.

… and effects on demand

Despite these disruptions, animal producers are under pressure to increase production as food consumption patterns are changing in light of COVID-19. In Argentina, for example, the national egg producers association just reported that household consumption of eggs rose by 40% since the country went into lockdown on March 20.

In the US, egg orders from some retailers have increased by up to six times their normal levels, according to market research firm Urner Barry, while wholesale egg prices have risen 180% throughout March. Yet, hens can’t lay more than they already do; to increase flocks takes time and significant investment in additional facilities.

To ease egg supply shortages, the US Food and Drug Administration has temporarily relaxed certain packaging and labeling requirements for shell eggs sold in retail markets. In Canada, egg supplies usually destined for restaurants are being re-directed to meet increased consumer demand.

Egg producers are finding solutions

This would not work in Germany, where, according to egg and poultry analyst Margit Beck, many of the eggs used in the ailing foodservice sector are cage eggs*, for which there is little end consumer demand. Cage egg prices are effectively in free fall, while crisis-induced consumer reflections on purchasing behaviors appear to strengthen demand for free-range and organic eggs. Smaller farmers in Germany and Austria report that they capitalize on this trend through increased direct sales to customers at farm shops and markets.

The sight of (temporarily) empty supermarket shelves might be disconcerting – but, positively, it ought to inspire us to appreciate the incredible work that goes into putting eggs on our tables. Clapping for health care workers has become a new tradition during this pandemic. It would only be fitting to also give a hand for the numerous people along food supply chains whose commitment keeps us all going.

* Note: Conventional battery cages have been banned in Germany since 2010; eggs classified as cage eggs come from laying hens kept in small-group housing systems or in so-called “enriched cages”.

By Technical Team, EW Nutrition

Sub-therapeutic doses of antibiotic growth promoters (AGPs) were used for more than 50 years in poultry production to achieve performance targets – until growing concerns arose regarding antibiotic resistance (Kabir, 2009) and decreasing efficacy of antibiotics for medical purposes (Dibner & Richards, 2005).

Isolates of ESBL-producing E.coli from animals, farmworkers, and the environment were found to have identical multidrug resistance patterns (A. Nuangmek et al., 2018). There is also evidence that AMR strains of microorganisms spread from farm animal to animal workers and beyond. Global AMR fatalities are increasing and might reach 10 million by 2050 (Mulders et al., 2010, Trung et al., 2017, Huijbers et al., 2014).

In light of this, certain AGPs have already been banned, and there is a strong possibility of future restrictions on their use worldwide. Bans are effective: the MARAN report 2018 shows that lower antibiotics usage following the EU ban on AGPs has reduced resistant E.coli in broilers. Another positive consideration is the market opportunities that exist for antibiotic residue-free food.

However, the key element that poultry producers need to get right for antibiotic reduction to be successful is respiratory health management. This article looks at why respiratory health is a particular challenge – and how phytogenic solutions can help.

A closer look at the chickens’ respiratory system

The respiratory tract is equipped with a functional mucociliary apparatus consisting of a protective mucous layer, airway surface liquid layer, and cilia on the surface of the ciliated cells. This apparatus produces mucus, which traps the inhaled particles and pathogens and propels them out of the airways. This mechanism, called the mucociliary clearance, is the primary innate defense mechanism of the respiratory system.

High stocking density combined with stressful environmental factors can negatively influence birds’ immune systems (Heckert et al., 2002; Muniz et al., 2006), making them more susceptible to respiratory disease. When a bird suffers from respiratory disease, which is nowadays usually complicated by a co-infection or secondary bacterial infection, there is an excess production of mucus that results in ciliostasis and, therefore, in an impaired mucociliary clearance. The excess mucus in the tract obstructs the airways by forming plagues and plugs, resulting in dyspnea (hypoxia) and allowing the invasive bacteria to adhere and colonize the respiratory system.

The build-up of mucus in the respiratory tract severely reduces oxygen intake, causing breathlessness, reduced feed intake, and a drop in the birds’ energy levels, which negatively impacts weight gain and egg production. Respiratory problems can result from infection with bacteria, viruses, and fungi, or exposure to allergens. The resultant irritation and inflammation of the respiratory tract leads to sneezing, wheezing, and coughing – and, therefore, the infection rapidly spreads within the flock.

Relatively high stocking density is the norm in poultry production

Low or no antibiotics: how to manage respiratory disease?

Unsurprisingly, respiratory diseases in poultry are a major cause of mortality and economic loss in the poultry industry. For Complicated Chronic Respiratory Disease (CCRD), for instance, although the clinical manifestations are usually slow to develop, Mycoplasma gallisepticum (MG), in combination with E. coli, can cause severe airsacculitis. Beside feed and egg production reduction, these problems are of high economic significance since respiratory tract lesions can cause high morbidity, high mortality, and significant carcass condemnation and downgrading.

Producers need to pre-empt the spread of respiratory pathogens, react quickly to alleviate respiratory distress and maintain the mucociliary apparatus’ functionality. Traditionally, treatment options are based on antiviral, anti-inflammatory, and antibiotic drugs. Can the poultry industry limit losses from respiratory infections without excessive recourse to antibiotics?

Indeed, a sudden reduction in antibiotic usage comes with a risk of impaired performance, increased mortality, and impaired animal health and welfare. The impact has been quantified as a 5% loss in broiler meat production per sq. meter (Gaucher et al., 2015). Effective antibiotics reduction requires a combination of innovative products and suitable consultancy services to manage poultry gut health, nutrition, flock management, biosecurity, and, particularly, respiratory health.

Non-antibiotic alternatives to control diseases and promote broiler growth, such as organic acids (Vieira et al., 2008), probiotics (Mountzouris et al., 2010), prebiotics (Patterson & Burkholder, 2003), and essential oils (Basmacioğlu Malayoğlu et al., 2010) have been the subject of much research in recent years.

Phytogenic solutions: proven efficacy

Essential oils, which are extracted from plant parts, such as flowers, buds, seeds, leaves, twigs, bark, wood, fruits, and roots, have a particularly well-established track record of medicinal applications. Efforts have centered on phytomolecules, the biologically active secondary metabolites that account for the properties of essential oils (Hernández et al., 2004; Jafari et al., 2011).

Studying these properties is challenging: essential oils are very complex natural mixtures of compounds whose chemical compositions and concentrations are variable. For example, the concentrations of the two predominant phytogenic components of thyme essential oils, thymol and carvacrol, have been reported to range from as low as 3% to 60% of the whole essential oil (Lawrence and Reynolds, 1984).

Another well-researched example is eucalyptus oil. The essential oils of eucalyptus species show antibacterial, anti-inflammatory, diaphoretic, antiseptic, analgesic effects (Cimanga et al., 2002) and antioxidant properties (Lee and Shibamoto, 2001; Damjanović Vratnica et al., 2011). The oils are mainly composed of terpenes and terpene derivatives in addition to some other non-terpene components (Edris, 2007). The principal constituent found in eucalyptus is 1,8-cineole (eucalyptol); however, other chemotypes such as α-phellandrene, ρ-cymene, γ-terpinene, ethanone, and spathulenol, among others, have been documented (Akin et al., 2010).

Close-up of eucalyptus leaf oil glands and
the molecular structure of eucalyptol C₁₀H₁₈O (red = oxygen; dark grey = carbon; light grey = hydrogen)

Antimicrobial activity

In modern intensive broiler production, bacterial diseases such as salmonellosis, colibacillosis, mycoplasmosis, or clostridia pose serious problems for the respiratory system and other areas. Analyses of the antibacterial properties of essential oils have been carried out by multiple research units (Ouwehand et al., 2010; Pilau et al., 2011; Solorzano- Santos and Miranda-Novales, 2012; Mahboubi et al., 2013; Nazzaro et al., 2013; Petrova et al., 2013).

Phenols, alcohols, ketones, and aldehydes are clearly associated with antibacterial activity; the exact mechanisms of action, however, are not yet fully understood (Nazzaro et al., 2013). Essential oils’ antimicrobial activity is not attributable to a unique mechanism but instead results from a cascade of reactions involving the entire bacterial cell (Nazzaro et al., 2013). However, it is accepted that antimicrobial activity depends on the lipophilic character of the components.

The components permeate the cell membranes and mitochondria of the microorganisms and inhibit, among others, the membrane-bound electron flow and thus the energy metabolism. This leads to a collapse of the proton pump and draining of the ATP (adenosine triphosphate) pool. High concentrations may also lead to lysis of the cell membranes and denaturation of cytoplasmic proteins (Nazzaro et al., 2013; Gopi et al., 2014).

According to current knowledge, lavender, thyme, and eucalyptus oil, as well as the phytomolecules they contain, show enhanced effects when combined with other essential oils or synthetic antibiotics (Sadlon and Lamson, 2010; Bassole and Juliani, 2012; Sienkiewicz, 2012; de Rapper et al., 2013; Zengin and Baysal, 2014).

Minimum inhibitory concentration (MIC) of some essential oil components against microorganisms in vitro

Immune system boost I: improved production of antibodies

Some essential oils were found to influence the avian immune system positively, since they promote the production of immunoglobulins, enhance the lymphocytic activity, and boost interferon-γ release (Awaad et al., 2010; Faramarzi et al., 2013; Gopi et al., 2014; Krishan and Narang, 2014). Placha et al. (2014) showed that the addition of 0.5g of thyme oil per kg of feed significantly increased IgA levels.

Awaad et al. (2010) experimented on birds vaccinated with the inactivated H5N2 avian influenza vaccine. The experiment revealed that adding eucalyptus and peppermint essential oils to the water at a rate of 0.25 ml per liter resulted in an enhanced cell-mediated and humoral immune response.

Saleh et al. (2014), who applied thyme and ginger oils in quantities of 100mg and 200mg per kg of feed, respectively, observed an improvement in chickens’ immunological blood profile through increased antibody production. Rehman et al. (2013) stated that the use of herbal products containing eucalyptus oil and menthol in broilers showed consistently higher antibody titers against NDV (Newcastle disease virus), compared to untreated broilers.

Immune system boost II: better vaccine responses and anti-inflammatory effects

Essential oils are also used as immunomodulators during periods when birds are exposed to stress, acting protectively and regeneratively. Importantly, the oils alleviate the stress caused by vaccination (Barbour et al., 2011; Faramarzi et al., 2013; Gopi et al., 2014). The study by Kongkathip et al. (2010) confirmed the antiviral activity of turmeric essential oil.

In recent years studies have been carried out on the use of essential oils in conjunction with vaccination programs, including those against infectious bronchitis (IB), Newcastle disease, and Gumboro disease. The results of the experiments show that essential oils promote the production of antibodies, thus enhancing the efficacy of vaccination (Awaad et al., 2010; Barbour et al., 2010; Barbour et al., 2011; Faramarzi et al., 2013).

Essential oils contain compounds that are known to possess strong anti-inflammatory properties, mainly terpenoids, and flavonoids, which suppress the metabolism of inflammatory prostaglandins (Krishan and Narang, 2014). Also, other compounds found in essential oils have anti-inflammatory, pain-relieving, or edema-reducing properties, for example, linalool from lavender oil, or 1,8-cineole, the main component of eucalyptus oil (Peana et al., 2003).

Immune system boost III: antioxidant effects and radical scavenging

An imbalance in the rate of production of free radicals or removal by the antioxidant defense mechanisms leads to a phenomenon referred to as oxidative stress. A mixture of Oregano (carvacrol, cinnamaldehyde, and capsicum oleoresin) was found to beneficially affect the intestinal microflora, absorption, digestion, weight gain and also to have an antioxidant effect on chickens (Bassett, 2000).

Zeng et al. (2015) indicated the positive effect of essential oils on the production of digestive secretions and nutrient absorption. They reduce pathogenic stress in the gut, exert antioxidant properties, and reinforce the animal’s immune status.

Inside the cell, essential oils can serve as powerful scavenger preventing mutations and oxidation (Bakkali et al., 2008). Studies have demonstrated the concentration-dependent free radical scavenging ability of oils from eucalyptus species (Kaur et al., 2010; Marzoug et al., 2011; Olayinka et al., 2012). Some authors attribute the strong antioxidant capacity of essential oils to their phenolic constituents and synergistic effect between tannins, rutin, thymol, and carvacrol, and probably 1, 8-cineole. Moderate DPPH radical scavenging activity reported by Edris(2007), El-Moein et al. (2012), and Kaur et al. (2011).

Vázquez et al. (2012) have demonstrated the potential of the phenolic compounds in eucalyptus bark as a source of antioxidant compounds. The study showed that eucalyptus had ferric reducing antioxidant power in the ranges 0.91 to 2.58 g gallic acid equivalent (GAE) per 100 g oven-dried bark and 4.70 to 11.96 mmol ascorbic acid equivalent (AAE) per 100 g oven-dried bark, respectively (see also Shahwar et al., 2012). Moreover, Eyles et al. (2004) were able to show superoxide dismutase (SOD)-like activity for different compounds and fractions isolated from wood extracts.

Last but not least: positive effects on the respiratory system

In poultry production houses, especially in summer, high temperatures and low humidity increase the amount of air dust. Under such conditions, respiratory tract disorders in broiler chickens, including the deposition of particulates, become more frequent and more severe.

Clinical signs of respiratory disease in chickens include coughing, sneezing, and rales

Thyme oil, thanks to the phytomolecules thymol and carvacrol, supports the treatment of respiratory disorders. These substances smooth tightened muscles and stimulate the respiratory system. An additional advantage lies in their expectorant and spasmolytic properties (Edris, 2007).

These properties are also seen in essential oils such as eucalyptus and peppermint, which contain eucalyptol and menthol. They thin out the mucus and facilitate its removal from the airways. As a result, the airways are cleared and breathing during inflammation becomes easier (Durmic and Blache, 2012).

Another positive effect of the terpenoid compounds used in commercial preparations for poultry is that they disinfect the bronchi, preventing respiratory infections (Awaad et al., 2010; Barbour et al., 2011; Mahboubi et al., 2013). Barbour and Danker (2005) reported that the essential oils of eucalyptus and peppermint improved the homogeneity of immune responses and performance in MG/H9N2-infected broilers.

Grippozon: the phytogenic solution for respiratory health

Grippozon is a liquid composition with a high content of essential oils, which are combined to systematically prevent and ease respiratory diseases. The formulation is derived from the research on essential oils’ effectiveness against respiratory pathogens that are common in animal farming. Grippozon exhibits a synergistic action of all its components to optimally support animal health. It contains a high concentration of active components; both their quantity and quality are guaranteed to deliver results.

Application of Grippozon

Grippozon application can be flexibly adapted to most common housing systems. It is fully water-soluble for use in the drinking line and it is also possible to nebulize a diluted solution in air.

The dose recommendation in drinking water usually amounts to 100ml to 200ml per 1000 liters of drinking water (Grippozon administration has not been reported to affect water consumption). The active substances in Grippozon adhere to mouth mucosa and become volatile in the breathing air later on. Therefore Grippozon can enter the respiratory system indirectly as well. The volatile compounds also spread into the whole barn air and, thus, indirectly via breathing into the respiratory system (and farmers notice the smell of essential oils when Grippozon is applied through in the waterline)

Grippozon can also be used as a spray at a rate of 200ml/10 liters of water for 2000 birds, twice daily on 2-3 days a week. This produces a very effective nebulization effect and offers faster respiratory relief to birds.

Grippozon is an impactful tool for managing respiratory problems. Thanks to its effective mucolytic and relaxant activity, Grippozon gives symptomatic relief to the birds during high-stress periods of respiratory diseases. Mucus in the trachea works as media for the proliferation of bacteria and viruses, so by thinning the mucus, Grippozon slows down the proliferation of bacteria and the spread of disease. Grippozon helps in improving air quality and air intake. It can also be used to stimulate the immune response during vaccination.

Authors:
Ruturaj Patil – Product Manager Phytogenic Liquids
Kowsigaraj Palanisamy – Global Validation Trial Manager

References available on request