Water hygiene is essential for achieving antibiotic-free poultry production

Significant resources are spent on the correct nutrients in the diet and the correct additives for bird health. Water quality should be a priority, and a water quality monitoring program is essential for success in an ABF program. All things being equal, animals will perform better if they have access to high-quality water.

The variability of water quality in the grow-out region should determine how many water quality samples are taken. In highly variable areas, water quality should be measured at every season change on enough farms in every region to know if the solutes are changing. If the water quality is good and consistent, monitoring may be reduced significantly. Water quality should be a part of a “problem farm” work up or related to otherwise unexplained poor performance.

Water-soluble additives: Prevent biofilm

The use of water-soluble products is common in ABF production systems and their frequent use may provide a carbon source for bacteria. This, along with warm temperatures and slow water flow in enclosed water systems, makes the perfect environment for biofilm development.

It is important to frequently flush lines, give birds access to fresh water between additives, and sanitize water lines after using a product that can provide nutrients to bacteria in the line. The biofilm is a perfect location to harbor and protect pathogens from acids and mild or under-dosed disinfectants.

Designing a water quality program

Sample collection

The first step to building a water quality program is to understand the challenge on every farm. Correct sample collection is critical to achieving good results. Take a water sample from as close to the well as possible and submit for water quality analysis: pH, hardness, and minerals. This sample should also be submitted for bacterial load: total aerobic plate count (CFU) per mL and total coliforms per mL.

Monitor bacterial load

A drip sample should be collected from the end of the line for bacterial load analysis as well. This will help determine if the bacterial challenge begins at the source or is limited to the house. Additionally, a swab from the inside of the end of the water line should be taken to determine the level of biofilm. The total bacterial count should be less than 1,000 CFU/mL without fecal coliforms in a free-flowing sample, and total bacteria should be less than 10,000 CFU/mL on a biofilm swab.

Monitor water pH

Water should have a pH between 5 and 8. Water with a pH consistently lower than 5 can be damaging to equipment, while a pH over 8 reduces the efficacy of many disinfectants and can have a bitter taste to birds. Hard water can increase scaling of lines and equipment, leading to leaking seals. Scale also provides a matrix for biofilm formation, making cleaning and disinfection more difficult.

Clean and disinfect water lines

Cleaning water lines between flocks is the minimum program for ABF production. Stabilized hydrogen peroxide products are excellent for disinfecting water lines between flocks. The levels needed for proper disinfection of lines are generally too strong for birds, and the lines must be flushed prior to bird placement.

Water lines are often only cleaned in the house; it is important to periodically clean the lines that transport water from the well or water source to the poultry house as this may be a significant reservoir for bacteria. If the well is identified as a source of contamination, it is essential to seek the help of a qualified technician before adding any sanitizing product to a wellhead.

Continuous disinfection

Ideally, water should be continuously disinfected with a product that is approved for poultry consumption. One of the best products for continuous disinfection is chlorine dioxide, which is effective at reducing bacteria and also reducing the concentrations of some mineral components. High levels of iron in the water can create a favorable environment for E. coli and other bacteria such as C. perfringens.

In addition to disinfection, chlorine dioxide is an effective treatment to reduce soluble iron levels. High sodium and chloride levels can lead to flushing and promote the growth of some bacteria. If high levels of sodium and chloride are consistent across a grow-out region, it may be possible to decrease the levels in the feed to reduce flushing. If the levels of sodium and chloride are considerably high, reverse osmosis should be considered to improve water quality.

Bottom line: invest in high-quality water

Another effective product is stabilized hydrogen peroxide at an appropriate residual level for bird consumption. There are other options for water line sanitation that can be explored on a case-by-case basis.

There are excellent online resources [link] for poultry water quality. The important message remains, in any case, that investment in high-quality water is a critical step for success in ABF poultry production.

 

References

Austin, B.J., J. Payne, S.E. Watkins, M. Daniels, and B.E. Haggard. 2016. How to Collect Your Water Sample and Interpret the Results for the Poultry Analytical Package. Arkansas Water Resources Center, Fayetteville, AR, FS-2017-01: 8 pp.

Scantling, M. and Watkins, S. 2013. Identify Poultry Water System Contamination Challenges. FSA8011. University of Arkansas Division of Agriculture Research and Extension.

Watkins, S. 2008. Water: Identifying and correcting challenges. Avian Advice 10(3):10-15. University of Arkansas Cooperative Extension Service, Fayetteville, AR

There is no more efficient place to invest than in pullets. Pullets are the future of an integrated company. Successful pullet rearing is simply attention to detail, management, serology, biosecurity, vaccination, and worming. Decisions, both good and bad, made during rearing will follow that company for a year. This is especially true related to the introduction of pathogens such as mycoplasmas, Salmonella, and reoviruses, which are persistent and can be vertically transmitted. The importance of biosecurity in any pullet program cannot be overstated, but it is even more critical in an antibiotic-free (ABF) program.

The 4 pillars of rearing pullets without antibiotics

1. Effective management

It is imperative to properly manage flock uniformity, weight, and frame size. For details on how to manage and feed pullets, it is always advised to use the technical support of the primary breeder company because no one knows their bird better than them. Pullet uniformity is critical to the success of the flock in the breeder house. Uniform and healthy pullets are easier to manage to peak and easier to feed for persistency of lay.

Uniform and consistent feed distribution is crucial to managing pullets: people must monitor feeding on a regular and consistent basis. Simply because the feed disappears before the next feeding does not mean it was distributed in an effective way to all birds. Non-uniform feed distribution is not only bad for uniformity but may train other undesirable behaviors such as race tracking, foraging, and roosting on lines to feed. These behaviors increase the risk for trauma and picking up pathogens in the litter.

There are multiple stressful transition periods in the life of a pullet. It is advised to spread the stressors apart as much as possible. Do not make major management changes, such as turning birds out, changing their lighting or feed program, all at the same time. The more gradual the transitions are, the easier it will be on the birds, and the more likely they will perform as desired.

2. Heightened biosecurity

It is recommended to have dedicated inside and outside boots for all growers, service technicians, and regular visitors. A divided entrance (i.e., Danish entry) is ideal to further limit the risk of bringing pathogens in from the outside. Rodent and insect control is another important facet of pullet biosecurity and must be closely monitored. Vehicles entering the farm must be consistently cleaned and disinfected.

Managing the risk of pathogen introduction via feed is important and feed hygiene should not be ignored. Visitors are almost always the cause of biosecurity breaks and pullets receive a lot of visitors including vaccination crews that travel between farms with equipment. Ensure that vaccination equipment is properly sanitized between farms and crews always use appropriate personal protective equipment.

3. Focus on intestinal health

One of the most difficult challenges to raising pullets is conferring early and uniform immunity to coccidia. These parasites can be managed successfully with chemicals, ionophores, or vaccine programs, although every program has pros and cons. A fundamental problem with an ionophore program is accidentally feeding ionophores (technically considered antibiotics) to ABF flocks due to logistic errors at the feed mill.

Chemical programs can be very effective at managing Eimeria spp. cycling. Most of the time they work a little too well and birds do not develop adequate immunity; consequently, putting flocks at risk of breaking with Eimeria necatrix after chemicals are removed from the diets. A coccidiosis vaccine program is the most sustainable for rearing pullets.

The relative low density of birds, compared to broilers, and the lower feed consumption and thus lower consumption of water can result in dry litter early. The reduced density can also make it difficult for birds to pick up oocysts early in the coccidiosis cycle. Several techniques may be used to increase the chance of success. Birds can be spray-vaccinated at the hatchery and again when placed in the house. Brooding the birds in a portion (e.g., ¼) of the house for the first 7 to 8 days before turning them out to half house, and then to full house can improve early cycling.

Carefully using built-up litter may improve exposure to beneficial microflora; thereby, improving gut health. Managing intestinal health with the correct non-antibiotic feed additives such as saponins, essential oils, and pre and probiotics can significantly improve pullet health.

A well-designed deworming program is important for bird health and uniformity. It is also essential to help reduce the risk of Blackhead disease, which is caused by Histomonas meleagridis, while its intermediate host is Heterakis gallinarum (cecal worms).

4. Tailored vaccination program

Building a vaccination program for pullets has two critical functions: protect the health of the pullets/breeders and protect the health of the offspring by conferring maternal immunity. The exact constituents of the program depend heavily on regional disease challenges. Matching the program to disease pressure is best accomplished with a combination of a rigorous serology program for hens as well as periodically checking the blood of processing-age broilers.

Serology combined with open communication between the breeder and broiler departments about disease challenges can greatly improve the antigen choices of the vaccination program. Pullet rearing is attention to detail – managing the small details will help the long-term success of the poultry company.

The 3 must-haves for antibiotic-free necrotic enteritis control in poultry

1. Prevent mucosal damage

The most common cause of damage to intestinal mucosa in broilers is excessive cycling of Eimeria maxima. The ubiquitous nature of this parasite in poultry production makes it one of the most important contributors to NE. This species of coccidia is most relevant with respect to NE because its life cycle invades deeper into tissues than other species leading to more damage to the intestinal mucosa.

The life cycle of coccidiosis lasts roughly seven days, with each cycle producing exponentially higher numbers of the parasite. Three consecutive replication cycles are needed to produce immunity. The biology of E. maxima is a significant reason why NE commonly occurs around 18-21 days. However, many other things may damage the intestinal mucosa, including mycotoxins, worms, and rancid fat. Managing all sources of mucosal disruption are critical to preventing and controlling NE.

2. Support the microflora

The importance of the microbiome on health is well known; the ability to modify the microbiome to a more appropriate or healthy status is a more difficult challenge. There is a tremendous volume of research in all species about the impact and importance of intestinal microflora on immunity, health, and disease. The microflora is not static but rather a dynamic community of microorganisms that change with bird age, time of day, composition of the diet, and treatment with antibiotics or other additives. Management of intestinal microflora is a very difficult process because its development and manipulation are not fully understood.

Any significant feed formulation or feed form change is a stress event for intestinal microflora. Feed changes are thus high-risk periods for the development of NE. It is a best practice to avoid feed changes when birds are in the NE risk window. It is important to support the intestinal microflora with either in-feed or in-water products to improve intestinal health during feed changes.

It is important to avoid feed outages. After a feed outage, the disruption to the microflora and the increase in mucus production increases the likelihood of an NE outbreak in the following days. Preemptively adding a water additive to improve intestinal health directly after a feed outage can reduce the risk of NE in the flock.

When managing intestinal microflora: probiotics, prebiotics, plant extracts, enzymes, and organic acids are the most commonly used tools. Each of these product classes interacts with the bird and its flora in a different way and selecting additives with complimentary modes of action is critical to the success of the program. Direct colonizing organisms like Lactobacillus spp. can help to directly change the microflora, providing a more mature and healthier microbiome.

Prebiotics such as mannan- and fructo-oligosaccharides provide a food source for beneficial microorganisms and can interact directly with the immune system of the bird. Plant extracts can have antimicrobial or anti-inflammatory properties that can also modulate the microflora by impacting the growth and metabolism of different species of microorganisms in the intestine.

3. Limit Clostridium perfringens growth

It is not possible to eliminate toxin-producing C. perfringens from the environment. Clostridia are spore-forming microorganisms that are very resistant to disinfectants. However, it is possible to manage the abundance of these microorganisms in a system through proper litter management, sanitation, and disposal of mortality.

A house that has a history of NE should have the litter completely removed and the environment cleaned and disinfected as much as the facility will allow. New clean shavings should be brought into the house at a sufficient depth to limit access to the floor. Several non-antimicrobial feed and water additives have shown promise in reducing numbers of C. perfringens in feces of infected birds. Feed and water additives are an essential tool to reduce the impact of NE.

Conclusion: the more you prevent, the less you have to treat

Even with the best management practices, outbreaks of NE will happen. In order to successfully treat a flock with NE, it is critical to catch the mortality early. Once a flock is experiencing high mortality from NE, it is very difficult to treat because the sickest birds will not be drinking enough water to receive a significant amount of water additives. Treating or managing an outbreak is as much art as science, but it is a combination of reducing the inciting causes.

Manage microflora and clostridial growth with organic acids, copper sulfate, phytogenics, or probiotics. Reduce coccidiosis cycling with amprolium, saponins, or other phytogenics. With excellent husbandry, the impact of NE can be reduced drastically even without using antibiotics. Managing NE incidence in poultry is a mixture of animal husbandry, managing coccidiosis cycling, feed and water additive selection, and high-quality nutrition.

 

5 nutrition tips for antibiotic-free poultry production

1. Consider feed form and delivery

Feed form and delivery are nearly as important as the nutrient content of the formulation. If feed form or handling is improper and feed separates, is improperly mixed, or oxidized, the birds will not appreciate the effort that went to develop a balanced diet. A durable pellet or crumble is important to allow all birds to have equal access to a nutritionally complete diet with every bite.

Additionally, if the finished feed or individual ingredients are not stored properly, they may not have the same value that is attributed to them in the formulation process. Other than correct nutrient formulation, three parts of the diet that should be considered are feed additives, mycotoxin contamination, and lipid oxidation.

2. Prevent oxidative stress

The impact of oxidative stress on the intestinal mucosa, immune system, and performance is well-documented across species. Oxidized fat sources reduce the available energy, but equally significant to bird health is the reduction in vitamin availability, resulting in increased oxidative stress for the animal. Protecting the sources of fat and the finished feed is important to spare fat-soluble vitamins, specifically vitamin E.

Oxidized fat can also irritate the intestinal mucosa leading to decreased absorption of nutrients. The process of breaking down macromolecules during digestion and converting them to forms useful for further metabolism is a significant contributor to oxidative stress. The immune system is also a great contributor to oxidative stress. Immune cells use reactive oxygen species to kill pathogens that are phagocytosed.

A large portion of the immune system is located in the GI tract in order to protect the animal from pathogens crossing from the gut into the animal. In addition to being a contributor to oxidative stress, the immune system can be negatively impacted by oxidized feed (Liang et al., 2015). The combination of metabolic and immune activity in the intestines puts it at a high risk of damage from oxidative stress. It is vital to protect fat sources with synthetic or natural antioxidants; reducing the incoming stress from oxidized fat should be a priority to improve poultry health.

3. Mitigate mycotoxin risks

Another risk to bird health and mucosal integrity is mycotoxins. Diets containing mycotoxins may damage the mucosa of the GI tract directly or may damage other organs leading to significant health challenges and decreases in performance. Some mycotoxins or compounds created by fungi can disrupt the intestinal microflora by acting on bacterial cells, as many fungal metabolites are antimicrobial.

The best approach to managing mycotoxins is eliminating them from the system by purchasing high-quality grain and storing it appropriately. It is impossible to completely eliminate all risks of receiving ingredients contaminated with mycotoxins. An internal program should be developed to test the incoming ingredients and finished feed regularly for mycotoxins.

Knowing the challenging ingredient sources may help reduce the risk to highly susceptible birds like Breeders or chicks through dilution in formulation or the addition of toxin binders and/or enzymes. Several toxins may be found in a feed stuff and many of the mycotoxins are synergistic in their deleterious effects (Murugesan et al., 2015). Different binders have varying affinity for different mycotoxins; closely examining the product literature can help to choose the correct product to mitigate risk.

4. Choose optimal additives

Choosing the correct feed additive program for intestinal health, food safety, and growth performance depends on the specific challenges in the complex. When selecting a feed additive that is not FDA approved, it is important to base the decision as much as possible on scientific evidence through peer-reviewed research.

In addition to published data, internal testing within the production system is also helpful to ensure the product matches the local challenge. In a market saturated with “natural” products, it is essential to find a supplier that is trustworthy and is engaged in the success of the complex and health of the birds, not only in selling products. A partnership will be much more successful in the long term than only a buy/sell arrangement.

5. Manage expectations

When considering removing antibiotics from a program, the temptation is to expect natural products to completely replace the efficacy of antibiotics. This is an unreasonable expectation. The success of a transition to ABF production relies on modifying management practices as well. The vast majority of program success is related to attention to the details of husbandry, biosecurity, and sanitation. The remaining opportunity to improve health rests on the additive program.

References

Liang, Fangfang, Shouqun Jiang, Yi Mo, Guilian Zhou, and Lin Yang. “Consumption of Oxidized Soybean Oil Increased Intestinal Oxidative Stress and Affected Intestinal Immune Variables in Yellow-Feathered Broilers.” Asian-Australasian Journal of Animal Sciences 28, no. 8 (2015): 1194–1201. https://doi.org/10.5713/ajas.14.0924.

Murugesan, G.R., D.R. Ledoux, K. Naehrer, F. Berthiller, T.J. Applegate, B. Grenier, T.D. Phillips, and G. Schatzmayr. “Prevalence and Effects of Mycotoxins on Poultry Health and Performance, and Recent Development in Mycotoxin Counteracting Strategies.” Poultry Science 94, no. 6 (2015): 1298–1315. https://doi.org/10.3382/ps/pev075.

 

Coccidiosis is one of the most devastating enteric challenge in the poultry industry costing over over 14 billion US$ per year (Blake et al., 2020). In the early days of  intensive poultry production, outbreaks of Eimeria tenella, were most destructive. Eimeria tenella is a coccidia species that causes severe haemorrhages and hypovolemic shock, leading to a fatal outcome for the affected bird. 

Poultry producers need to control the performance and welfare issues caused by subclinical coccidiosis

Understanding and managing coccidiosis in poultry

However, today, subclinical coccidiosis accounts for even more of production losses due to intestinal cells injuries: lower body weights, higher feed conversion rates, lack of flock uniformity, failures on skin pigmentation and, at the end mortality. Variation in the supply and quality of animal feed exacerbates the issue and compromises farm profitability even more. To tackle this challenge, we need to understand the basics of coccidiosis control in poultry and what options producers have to manage coccidiosis risks.

From Eimeria infection to disease

Coccidiosis is a disease caused by protozoan parasites, mainly of the genus Eimeria, that are located in the small and large intestines. Being very resistant and highly contagious, these protozoa are easily transmitted by various routes (via feed, litter, water, soil, material, insects, and wild animals).

Coccidia are present in all livestock species. However, the infection is particularly severe in poultry. The health consequences can be significant: loss of appetite, reduction in feed intake, increased FCR, enteritis, hemorrhagic diarrhea, and mortality. The most common species of Eimeria in broilers are: E. acervulina, E. mitis, E. maxima, E. brunetti, E. necatrix, E. praecox, and E. tenella. They are widely found in broiler productions across the globe (McDougall & Reid, 1991).

Figure 1: Sporulated oocyst of Eimeria maxima and E. Acervulina (40 x)

The pathogenesis of infection varies from mild to severe and is largely dependent on the magnitude of infection. Coccidiosis outbreaks are related to multiple factors that, together, promote a severe infestation in the farm.

Within poultry, the highest economic impact is in broilers, where the most common species of Eimeria are E. acervulina, E. maxima, E. tenella and E. necatrix, which all show high virulence. However, pathogenicity is influenced by host genetics, nutritional factors, concurrent diseases, age of the host and the particular species of the Eimeria (Conway & McKenzie, 2007).

Figure 2: Interaction of factors that promote coccidia outbreaks

The Eimeria infection starts with the ingestion of protozoa that are at a sporulated stage. Once inside the gut, the protozoa liberate the sporozoites. This infective form can get into enterocytes and then begin a massive reproduction, killing thousands of intestinal cells. (Olabode et al., 2020; Shivaramaiah et al., 2014)

Figure 3: Eimeria spp. life cycle

The reproduction potential depends on the coccidia species. E. acervulina, E. mitis and E. praecox have the highest reproduction rate. This characteristic is closely related to their short life cycle.

In broilers, coccidiosis usually occurs after 21 days of age. The infection spreads gradually from day 1 already, depending on species of Eimeria and their virulence. A typical progression of coccidiosis in broilers is shown in Figure 4.Figure 4: Typical development of a coccidia infection in relation to broiler feed phases

Coccidiosis control in poultry: Strategy guidelines

The intrinsic characteristics of coccidiosis makes this parasite unique and many times frustrating to control. Resistance to available coccidiostats makes this task even harder.  Good farm management, litter hygiene, and the use of control coccidiosis programs such as shuttle and rotation are functional measures to prevent clinical coccidiosis. Successful control strategies specifically recognize the importance of monitoring, use anticoccidial drugs wisely, and include vaccines where applicable.

Monitoring

The first step is to establish a strict monitoring program in all stages of production, including the feed mill. It is important to verify that therapeutics are included in the feed in an adequate form and quantity, and that the follow-up in the field takes place.

Field monitoring should be frequent and in line with the operation’s coccidiosis management program. Field monitoring is a complementary work that collates clinical, necropsy, and faeces findings to closely track the disease situation.

Coccidiosis control in poultry operations needs to include rigorous monitoring

Anticoccidial drugs

Since the middle of the 20^th century, chemotherapeutic agents have offered the best way to control coccidia. However, unbridled use of anti-coccidial drugs and the emergence of the new resistant field strains of coccidia have made it increasingly challenging to control coccidiosis with commonly available coccidiostat drugs.

The coccidiostats have been classified in two groups: ionophores, molecules obtained from microbiological fermentation, and chemicals, synthetic compounds. The mode of action of ionophores is to interfere with the membrane ion exchange, killing the extracellular stages (sporozoites and or merozoites) as they expend energy to maintain the osmotic balance. Chemical compounds can have an anticoccidial effect even on extracellular and intracellular stages (Sumano López & Gutiérrez Olvera, 2005).

However, resistance development is limiting their effectiveness, and certain compounds cannot be used in older birds or in hot environments. Moreover, government regulations often include anti-coccidial drugs in bans on antibiotics use. This does not mean that these drugs are not crucial to controlling this disease, but it is important to use alternative tools: they help make a coccidiosis control program not only less dependent on anticoccidial drugs but also more robust.

Vaccines

There are two commercial kinds of coccidia vaccines; the first one uses natural strains. These Eimeria are selected from field outbreaks, show a medium pathogenicity, and allow for a controlled replication of a coccidia infection. The second kind of vaccines include attenuated strains; these are precocious strains and birds usually show low or no post-vaccinal reactions.

The management of coccidia vaccines is the principal challenge for using this tool to control coccidia. Special vaccination training is required at the hatchery, which then needs a follow-up on the farm. In the field, this follow-up and the alignment of all the protocols has proven challenging for many producers.

Managing coccidiosis in poultry: Next steps

The limitations chemotherapy and vaccines have led to a surge in the quest for effective  natural solutions. Recent research into plant-derived phytochemicals shows that these compounds have properties that make them an interesting tool against coccidiosis (cf. Cobaxin-Cárdenas, 2018). Knowledge, research, and technological developments are now ready to offer solutions that can be an effective part of coccidia control programs. These natural solutions create opportunities to make poultry production more sustainable by reducing dependency on harmful drugs.

References

Bafundo, K.W., L. Gomez, B. Lumpkins, G.F. Mathis, J.L. McNaughton, and I. Duerr. “Concurrent Use of Saponins and Live Coccidiosis Vaccines: The Influence of a Quillaja and Yucca Combination on Anticoccidial Effects and Performance Results of Coccidia-Vaccinated Broilers.” Poultry Science 100, no. 3 (2021): 100905. https://doi.org/10.1016/j.psj.2020.12.010.

Blake, Damer P., Jolene Knox, Ben Dehaeck, Ben Huntington, Thilak Rathinam, Venu Ravipati, Simeon Ayoade, et al. “Re-Calculating the Cost of Coccidiosis in Chickens.” Veterinary Research 51, no. 1 (September 14, 2020). https://doi.org/10.1186/s13567-020-00837-2.

Cobaxin-Cárdenas, Mayra E. “Natural Compounds as an Alternative to Control Farm Diseases: Avian Coccidiosis.” Farm Animals Diseases, Recent Omic Trends and New Strategies of Treatment, March 21, 2018. https://doi.org/10.5772/intechopen.72638.

Conway, Donal P., and M. Elizabeth McKenzie. Poultry Coccidiosis: Diagnostic and Testing Procedures. Ames, IA, IA: Blackwell Publishing, 2007.

McDougall, L. R., and W. M. Reid. “Coccidiosis.” Chapter. In Diseases of Poultry, edited by B. W. Calnek, H. W. Yoder, W. M. Reid, C. W. Beard, and H. J. Barnes. Ames, IA: Iowa State University Press, 1991.

Olabode, Victoria Bose, Dashe Yakubu Gunya, Umaru Mada Alsea, Tobias Peter Pwajok Choji, and Israel Joshua Barde. 2020. “Histopathological Lesions of Coccidiosis Natural Infestation in Chickens”. Asian Journal of Research in Animal and Veterinary Sciences 5 (2), 41-45. https://www.journalajravs.com/index.php/AJRAVS/article/view/30090.

Shivaramaiah, Chaitanya, John R. Barta, Xochitl Hernandez-Velasco, Guillermo Téllez, and Billy M. Hargis. “Coccidiosis: Recent Advancements in the Immunobiology of Eimeria Species, Preventive Measures, and the Importance of Vaccination as a Control Tool against These Apicomplexan Parasites.” Veterinary Medicine: Research and Reports 2014, no. 5 (April 28, 2014): 23–34. https://doi.org/10.2147/vmrr.s57839.

Sumano López, Héctor, and Gutiérrez Olvera Lilia. Farmacología Clínica En Aves Comerciales. México: UNAM, Departamento de Fisiología y Farmacología, 2005.

What makes up a successful coccidiosis control program for ABF systems?

When managing a poultry program without antibiotics in the U.S., where ionophores are classified as antibiotics, the only available tools for coccidiosis control are vaccines, chemical coccidiostats, and natural products supporting gut health during challenging times.

• The use of a chemical-only program is possible and often successful. Still, the choice of chemicals is limited, and the risk of building resistance must always be considered and managed through the appropriate rotation of active ingredients.
• A second option is a coccidiosis vaccine with or without chemical coccidiostats. This is an excellent long-term option but the most difficult to manage.
• A third effective option is a coccidiosis vaccine combined with the use of phytomolecule-based solutions contributing to the coccidiosis control program and delivering improved gut health.

What do most ABF newcomers do?

When making the transition from conventional to ABF production, broiler producers usually try:

1. A chemical coccidiostat program,
2. A bio-shuttle program: a coccidiosis vaccine, followed by a chemical coccidiostat, or
3. Phytomolecule-based feed additives; typically, in combination with a coccidiosis vaccine or chemical program.

When the operation can master managing the coccidiosis vaccine and other husbandry challenges, the optimal solution is the combination of vaccination and phytomolecule-based feed supplements.

Why a combination?

A coccidiosis control program based on vaccination begins in the hatchery and continues through live production. Its success relies on many moving parts working in sync to produce the desired result of early uniform immunity to coccidiosis. Phytomolecule-based products additionally can support the animals in terms of gut health, oxidative balance, and immunity.

Vaccination success depends on attention to detail

If one decides to use vaccination for coccidiosis control, the following points must be considered to achieve high effectiveness.

Vaccine storage – the right temperature is crucial

Proper storage is essential for all vaccines. In general, coccidiosis vaccines should be stored between 2° to 7°C (35° to 45°F), but optimally, one asks the vaccine manufacturer for product-specific directions. Coccidiosis vaccines must not freeze. Freezing will severely damage or kill the oocysts, thus significantly reducing efficacy. It is also important to ensure that there are no cold spots in the refrigerator. Hence, vaccines should be stored in the middle of a shelf with air space around or in a foam-insulated place inside the fridge.

For monitoring the temperature, an analog high/low thermometer should be placed by the vaccine. The temperature should be recorded, and the thermometer reset daily. To minimize the risk of administering a frozen vaccine, it is recommended to put freeze indicators outside the boxes. If, despite all these measures, vaccines are suspected to have frozen, segregate the suspect product and contact the supplier for assistance.

Vaccine administration – mind an even distribution for all steps

The goal of vaccination is to build early and uniform immunity in all chickens, which is achieved by exposure to repeated cycles of coccidia replication in the intestine.

1.      Even distribution of the oocysts in the vaccine

It is essential to ensure that all oocysts flow from the bottle into the distribution jug when mixing the vaccine. The oocysts should be well-mixed and then must be constantly agitated to remain suspended in solution. The most common way to suspend oocysts is to use a small air pump to bubble the vaccine, creating turbulence.

2.      Even spraying of the vaccine onto the chicks

The next important step is to ensure that the chicks are evenly covered with the vaccine. When in doubt, run a chick box through the spray cabinet, collect the nozzles’ output, and measure the volume sprayed. To check the spray pattern, set a piece of clear hard plastic on top of the pegs in the chick basket and run the box through the spray cabinet. Evaluate the spray pattern on the plastic sheet and adjust as needed to ensure an even spraying. The spray pattern should be checked every time a new batch of vaccines is mixed.

Even spraying of coccidiosis vaccine can be easily tested using a clear plastic sheet.

3.      A similar amount of vaccine intake for all chicks

Coccidiosis vaccines must be preened and consumed to be effective. Adding a dye to the spray compatible with the vaccine will help stimulate the birds to preen. A well-lit and temperature-controlled processing and holding area will promote preening behavior. Tongues should be checked regularly to ensure that chicks consume the vaccine. At a minimum, check ten birds per basket and ten baskets per lot. More than 98% of birds should have evidence of vaccine consumption within 10-15 minutes post-vaccination.

Chick vitality is a critical success factor in an ABF program. Healthy chicks perform better in the field. In the context of a coccidiosis vaccine, they are more apt to preen, more likely to consume food and water quickly, and less likely to excessively pick at the litter.

A dye helps to evaluate if the coccidiosis vaccine was evenly sprayed across all chicks.

Uniform immunity through effective farm management

A successful coccidiosis vaccination program achieves uniform immunity against coccidia, which slowly develops from the hatchery. For this purpose, birds must be evenly spread throughout all stages of growth to seed the litter evenly with oocysts and to have even coccidiosis pressure in all parts of the house.

Time management allows even immunization

Birds should be turned out from half to full house between 9 and 11 days. This schedule allows the birds to excrete the first round of oocysts and for the oocysts to sporulate and be consumed by the birds.

The birds need to be moved to full house before they secrete the second round of oocysts. This will allow the oocysts to be spread uniformly in the house. Coccidia reproduce exponentially and the second round of oocyst production is significantly more numerous than the first.

It is possible to brood birds in the full house while on coccidiosis vaccine. Still, it is complicated to manage the coccidiosis cycling because bird density is generally too low to ensure that birds effectively cycle the vaccine strain oocysts.

Litter consistency is decisive

Litter management is essential to control the cycling of coccidiosis because one stage of the life cycle of coccidia occurs in the litter. Litter moisture of 25% is ideal. When litter is squeezed in a fist, it should briefly form and immediately break apart. If it stays formed, it is too wet. If the litter is free-flowing and dusty, it is too dry for adequate sporulation.

Non-antibiotic supplements support coccidiosis management

Managing coccidiosis cycling requires attention to detail and is probably the most challenging part of adequately managing an ABF program. All farms are not equal and need to be supervised according to their specific needs. The use of non-antibiotic feed and water additives can help control coccidiosis and other enteric diseases.

Some non-antibiotic supplements have anticoccidial (e.g. amprolium, saponins, tannins) or antibacterial (e.g., plant extracts) activity. When used correctly, these may improve the performance of birds in a vaccination or chemical-based coccidiosis control program. Other non-antibiotic alternatives such as probiotics, prebiotics, organic acids, and yeast cell wall extracts have been shown to improve gastrointestinal health. The combination of excellent animal husbandry and the correct feed/water additive program is the key to success.

References

Noack, Sandra, H. David Chapman, and Paul M. Selzer. “Anticoccidial Drugs of the Livestock Industry.” Parasitology Research 118, no. 7 (2019): 2009–26. https://doi.org/10.1007/s00436-019-06343-5.

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.

 

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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 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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Murugesan, G.R., Ledoux, D.R., Naehrer, K., Berthiller, F., Applegate, T.J., Grenier, B., Phillips, T.D. and Schatzmayr, G., 2015. Prevalence and effects of mycotoxins on poultry health and performance, and recent development in mycotoxin counteracting strategies. Poultry science, 94(6), pp.1298-1315.

O’Bryan, C.A., Pendleton, S.J., Crandall, P.G. and Ricke, S.C., 2015. Potential of plant essential oils and their components in animal agriculture–in vitro studies on antibacterial mode of action. Frontiers in veterinary science, 2, p.35.

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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

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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.

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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

 

by Inge Heinzl, Marisabel Caballero, Ajay Bhoyar, EW Nutrition

Necrotic enteritis is a profit killer in poultry production

Necrotic enteritis is the cause of USD 6 billion losses every year in global poultry production, corresponding to USD 0.0625 per bird (Wade and Keyburn, 2015). This controllable disease is on the rise. One reason is the voluntary or legally required reduction of antibiotics in animal production due to the increasing occurrence of antimicrobial resistance but also consumer demand. Another reason is the administration of live Coccidiosis vaccines and partial reduction of ionophores, which also show efficacy against Gram-positive bacteria (Williams, 2005).

Necrotic enteritis and coccidiosis are the most significant health problem in broilers (Hofacre et al., 2018).

The disease generally occurs in broiler chickens of 2-6 weeks of age. It is caused by an overgrowth of Clostridium perfringens type A and, to a lesser extent, type C in the small intestine. The toxins produced by C. perfringens also damage the intestinal wall.

Clinical and subclinical forms of NE – which one causes more significant losses?

The clinical form is obvious

…is characterized by acute, dark diarrhea resulting in wet litter and suddenly increasing flock mortality of up to 1% per day after the first clinical signs appear (Ducatelle and Van Immerseel, 2010), sometimes summing up to mortality rates of 50% (Van der Sluis, 2013). The birds have ruffled feathers, lethargy, and inappetence.

Necropsy typically shows ballooned small intestines with a roughened appearing mucosal surface, lesions, and brownish (diphtheritic) pseudomembranes. There is a lot of watery brown, blood-tinged fluid and a foul odor during post-mortem examination. The liver is dark, swollen, and firm, and the gall bladder is distended (Hofacre et al., 2018).

In the case of peracute Necrotic Enteritis, birds may die without showing any preliminary signs.

The subclinical form often only can be noticed at the end of the cycle

When birds suffer from the subclinical form, chronic damage to the intestinal mucosa and an increased quantity of mucus in the small intestine lead to impaired digestion and absorption of nutrients resulting in poor growth performance. The deteriorated feed conversion and the resulting decreased performance become noticeable around day 35 of age. As feed contributes approximately 65-75% of the input cost to produce a broiler chicken, poor feed conversion increases production costs and significantly influences profitability. Often, due to a lack of clear symptoms, this subclinical disease remains untreated and permanently impacts the efficiency of production.

The pathogen causing NE – a ubiquitous bacterium

Responsible for Necrotic Enteritis are Gram-positive, anaerobic bacteria, specific strains of Clostridium perfringens type A and, to a lesser extent, type C (Keyburn et al., 2008).

Clostridia primarily occur in the soil where organic substances are degraded, in sewage, and in the gastrointestinal tract of animals and humans. These bacteria produce spores, which are extremely resistant to environmental impact (heat, irradiation, exsiccation), some disinfectants, and can survive for several years. Under suitable conditions, C. perfringens spores can even proliferate in feed or litter.

Clostridium perfringens is a “natural inhabitant” of the intestine of chickens. In healthy birds, it occurs in a mixture of diverse strains at 10²-10⁴ CFU/g of digesta (McDevitt et al., 2006). The disease starts when C. perfringens proliferates in the small intestine, usually due to a combination of factors such as high amount protein, low immunity, and an imbalance in the gut flora. Then, the number rises to 10⁷-10⁹ CFU/g of digesta (Dahiya et al., 2005).

Highly important: NetB, a pore-forming toxin is a key virulence factor for NE

To establish in the host, Clostridium Spp. and other pathogens depend on virulence factors (see infobox). These virulence factors include for example “tools” for attachment, evasion or suppression of the host’s immune system, “tools” for getting nutrients, and “tools” for entry into intestinal cells. Over the years, the α-toxin produced by C. perfringens was assumed to be involved in the development of the disease and a key virulence factor. In 2008, Keyburn and coworkers found another key virulence factor by using a C. perfringens mutant unable to produce α-toxin, while still causing Necrotic Enteritis.

Thus, another toxin was identified occurring only in chickens suffering from Necrotic Enteritis: C. perfringens necrotic enteritis B-like toxin (NetB). NetB is a pore-forming toxin. Pore-forming toxins are exotoxins usually produced by pathogenic bacteria but may also be produced by other microorganisms. These toxins destroy the integrity of gut wall cell membranes. The leaking cell contents serve as nutrients for the bacteria. If immune cells are destroyed, an immune reaction might be partially imparted.

Additionally, pathogenic strains of C. perfringens produce bacteriocins – the most important is Perfrin (Timbermont et al., 2014) – to inhibit the proliferation of harmless Clostridium Spp. strains and to replace the normal intestinal flora of chickens (Riaz et al., 2017).

Predisposing factors favor the development of NE

A chicken with optimal gut health may be less susceptible to NE. Additional predisposing factors are necessary to allocate nutrients and make the gut environment suitable for the proliferation of these pathogens,  enabling them to cause disease (Van Immerseel et al., 2008; Williams, 2005).

1.   FEED: composition and particle size are critical

Feed plays a role in the development of Necrotic Enteritis that should not be underestimated. Here, substances creating an intestinal environment favorable for C. perfringens must be mentioned.

2.   Mycotoxins create ideal conditions for NE

Mycotoxins harm gut integrity and create ideal conditions for the proliferation of Clostridium perfringens:

Mycotoxins do not have a direct effect on C. perfringens proliferation, toxin production, or NetB transcription. However, mycotoxins disrupt gut health integrity, creating a favorable environment for the pathogen. For example:

• DON provides good conditions for proliferation of perfringens by disrupting the intestinal barrier and damaging the epithelium. The possibly resulting permeability of the epithelium and a decreased absorption of dietary proteins can lead to a higher amount of proteins in the small intestine. These proteins may serve as nutrients for the pathogen (Antonissen et al., 2014).
• DON and other mycotoxins decrease the number of lactic acid producing bacteria indicating a shift in the microbial balance (Antonissen et al., 2016.)

3.   Eimeria spp.: forming a perfect team with Clostridium perfringens

An intact intestinal epithelium is the best defense against potential pathogens such as C. perfringens. Here, coccidiosis comes into play. Moore (2016) showed that by damaging the gut epithelium, Eimeria species give C. perfringens access to the intestinal basal domains of the mucosal epithelium. Then, the first phase of the pathological process takes place and from there, C. perfringens invades the lamina propria. Damage to the epithelium follows (Olkowski et al., 2008). The plasma proteins leaking to the gut and the mucus produced are rich nutrient sources (Van Immerseel et al., 2004; Collier et al., 2008). A further impact of coccidiosis is shifting the microbial balance in the gut by decreasing the number of e.g., Candidatus savagella which activates the innate immune defense.

 

Figure 1

Figure 1:

1. Eimeria induce leakage of plasma proteins by killing epithelial cells
2. They enhance mucus production in the intestine

A+B lead to an increase in available nutrients and create an environment favorable for the proliferation of perfringens

Not only Eimeria Spp., also other pathogens (e.g. Salmonella Spp., Ascarid larvae, viruses) and agents, such as mycotoxins damaging the intestinal mucosa can pave the way for a C. perfringens infection. Predisposing factors like wet litter, the moisture of which is essential for the sporulation of Eimeria Spp. oocysts, must also be considered as promoting factors for Necrotic Enteritis (Williams, 2005).

4. Immunosuppressive Factors: Bacteria, viruses…, and stress

Any factor which induces stress in the animals disrupts the balance of the intestinal flora. The resulting suppression of the immune system contributes to the risk of Necrotic Enteritis (Tsiouris, 2016).

Bacteria

Shivaramaiah and coworkers (2011) investigated a neonatal Salmonella typhimurium infection as a predisposing factor for NE. The early infection causes significant damage to the gut (Porter et al., 1998) Additionally, Hassan et al. (1994) showed that the challenge with Salmonella typhimurium negatively impacted the development of lymphocytes which might also promote a colonization of Clostridium perfringens.

Viruses

Infectious Bursal Disease is known to increase the severity of infections with salmonella, staphylococci, but also clostridia. Another clostridia-promoting viral disease is Marek’s Disease.

Stress:

The intestinal tract is particularly sensitive to any type of stress. This stress can be caused by e.g. too high temperatures, high stocking densities, an abrupt change of feed.

Figure 2: Predisposing factors weakening the birds and enabling Clostridium to attack

Treatment is necessary in the case of acute disease

In this instance, the farmer is obligated to consult a veterinarian and treat his birds.

It must be mentioned that, as the treatment takes place via feed or water, only birds which still consume water or feed may be treated.

 Antibiotics are effective but also take a risk

Antibioitics targeting Gram-positive bacteria are commonly used for the treatment of acute NE. The antibiotic choice shall be addressed by a veterinarian, taking into account the mode of action and the presence of resistance genes in the farm/flock.

The profilactic use of antibiotics is not recommened and many countries have already banned it in order to reduce antimicrobial resistance (AMR).

Bacteriophages would be possible but are still disputed

Experimental use of phage treatments has shown to be effective in reducing disease progression and symptoms of Necrotic Enteritis (Miller et al., 2010). By oral application of a bacteriophage cocktail, Miller and coworkers could reduce mortality by 92% in C. perfringens-challenged broilers compared to the untreated control.

Mode of action: the endolysins, highly evolved enzymes produced by bacteriophages, are able to digest the bacterial cell wall for phage progeny release (Fischetti, 2010). However, phages are still not approved by the EFSA.

Excurs:

Figure 3: Possibilities of a bacterial cell to defend itself against antibiotics

Figure 4: Possibilities to transfer resistance to other bacterial cells

Preventing a disease is always better than its treatment!

But how to do it? Preventing the conditions that favor the proliferation of Clostridium perfringens and strengthening the host’s immune response lowers the probability of disease. Besides eliminating the predisposing factors, the main targets are:

• Balance of the gut flora
• Optimization of gut function and integrity
• Maintenance of immunity

1. Biosecurity is of the highest importance!

There is evidence that most Clostridium strains isolated from birds suffering from Necrotic Enteritis could induce the disease experimentally, while strains isolated from healthy birds cannot. This confirms that only specific strains are problematic (Ducatelle and Van Immerseel, 2010).
So, it’s of highest importance to avoid introducing these pathogenic strains to the farm.

 Strict biosecurity measures!

2. Specific measures against coccidiosis

1. Vaccination

According to parasitologists, 7 to 9 Eimeria species are found in chickens, and they do not cross-protect against each other. An effective vaccination must contain sporulated oocysts of the most critical pathogenic Eimeria species (E. acervulina, E. maxima, E. tenella, E. necatrix, and E. brunetti). The more species contained in the vaccine, the better. However, if not applied the correct way, vaccines can be ineffective or cause reactions in the birds that might lead to NE (Mitchell, 2017).

2. Anticoccidials

Alternate use of chemicals (synthetic compounds) and ionophores (polyether antibiotics) with different modes of action is important to avoid development of resistance.

Ionophores have a specific mode of action and kill oocysts before they are able to infect birds. Being very small, ionophore molecules can be taken up and diffused into the outer membrane of the sporozoite. There, it decreases the concentration gradient leading to an accumulation of water within the sporozoite causing its bursting.

3. Diet – favorable for the birds but not for clostridium!

Minimizing non-starch polysaccharides (NSPs) in cereals

To prevent a “feeding” of Clostridium perfringens, high content of water-soluble but indigestible NSPs such as wheat, wheat by-products, and barley should be avoided or at least minimized. Additionally, xylanases should be included in the feed formulation to reduce the deleterious effects of NSPs and improve feed energy utilization. Instead of these cereals, maize could be included in the diet. It is considered a perfect ingredient in broiler diets due to its high energy content and high nutrient availability.

Formulating low protein diets/diets with highly digestible amino acids

Feeding low-protein diets supplemented with crystalline amino acids might be beneficial to reduce the risk of Necrotic Enteritis (Dahiya et al., 2007). To improve protein digestibility and therefore reduce the proliferation of C. perfringens, proteases may be added to the feed.

Avoiding/Minimizing animal fats in the diet

Animal fats tend to increase the counts of Clostridium perfringens; thus, they should be replaced by vegetable fat sources.

Feed form is decisive

In terms of feed form, Engberg et al. (2002) found that birds fed pellets showed a reduced number of Clostridium perfringens in the caeca and the rectum than mash-fed birds. Branton and coworkers (1987) reported a lower mortality by feeding roller-milled (coarsely ground) than hammer-milled feed.

4. Additives

Additives can be used either to prevent the proliferation of Clostridium perfringens or to change the environmental conditions in a way that  proliferation of C. perfringens is prevented.

1. Probiotics directly support the balance of the microbiome

These live microbial supplements can be used to help to establish, maintain or re-establish the intestinal microflora.

Mode of action:

They compete with pathogenic bacteria for substrates and attachment sites and produce antimicrobial substances inhibiting the growth of pathogenic bacteria (Gillor et al., 2008). They bind and neutralize enterotoxins (Mathipa and Thantsha, 2017) andpromote immune function of the host (Yang et al., 2012)

2. Prebiotics indirectly promote the microbiome

These feed ingredients serve as substrates to promote beneficial bacteria in the intestine.

Mode of action:

D-mannose or fructose, starches non-digestible by birds, selectively stimulate the growth and the activity of the “good” gut flora. Fructooligosaccharides decrease C. perfringens and E. coli in the gut and increase the diversity of Lactobacillus Spp. (Kim et al., 2011). Galactooligosaccharides, in combination with a B. lactis-based probiotic, have been reported to selectively promote the proliferation of Bifidobacterium Spp. (Jung et al., 2008).

3. Organic acids support gut health

Organic acids are often used in animal diets to improve intestinal health.

Mode of action:

A decreased pH promotes beneficial bacteria. Caprylic acid suppresses C. perfringens but also Salmonella spp. by inhibiting their utilization of glucose (Skrivanova et al., 2006). Lauric, citric, oleic, and linoleic acid, as well as medium-chain fatty acids (C8-C14), impede the growth of C. perfringens.

A trial with different organic acid products showed high efficacy for Acidomix AFG and Acidomix AFL against Clostridium perfringens as well as against Salmonella enterica. For the test, 50 µl solution containing different microorganisms (reference strains of S. enterica and C. perfringens; conc. 10⁵ CFU/ml) together with 50 µl of increasing concentrations of various organic acids/organic acid products (Acidomix) were pipetted into microdilution plates. After the respective incubation, the MICs of every organic acid/organic acid product were calculated.

Figure 5 shows the minimum inhibiting concentrations (MIC). For Acidomix AFL and AFG, lower concentrations than for fumaric, lactic, and propionic acid were needed to inhibit the growth of Salmonella enterica and Clostridium perfringens.

Figure 5: Minimal inhibiting concentrations of Acidomix AFL and Acidomix AFG against Salmonella enterica and Clostridium perfringens

Phytomolecules : different types are available against NE

Phytomolecules, also known as secondary plant compounds, have been used against pathogens for centuries. In general, two subgroups of these substances are known as effective against Clostridium perfringens: Tannins and Essential Oils.

Tannins

Many studies have shown the efficacy of tannins against different pathogens such as helminths, Eimeria spp., viruses, and bacteria. Extracts from the chestnut and quebracho trees are effective not only against C. perfringens but also its toxins (Elizando et al., 2010). Tannins act against Eimeria spp. (Cejas et al., 2011) and Salmonella Sp., two predisposing factors for NE.

A trial was conducted with Pretect D, a product based on tannins and saponins, to show its efficacy against coccidia, one of the predisposing factors of NE. For the 35-day study conducted at a commercial research facility in the US, 1800 one-day-old Cobb 500 broilers were divided into four groups of 450 birds each (with 9 replicates & 50 birds per replicate). They all received the standard feed of the farm (Starter D0-D21, Grower D22-D35).

The challenge was given in the form of a freshly prepared mixed inoculum with E. acervulina (100,000 oocysts/ bird), E. maxima (50,000 oocysts/ bird), and E. tenella (75,000 oocysts/ bird). The inoculum was mixed into the feed in the base of each pen’s tube feeder.

The oocyst count per gram of feces (OPG) was done on D21, D27 & D35. The cocci lesion scoring (CLS) was done on D27 following Johnson and Reid (1970) with 0=normal; 4=most

Group	Challenge	Additive
Non-challenged Control (NC)	No	No
Challenged Control (CC)	Yes	No
CC + Ionophore	Yes	Ionophore@60ppm
CC + Pretect D	Yes	Pretect D@500ppm

The trial showed that, due to Pretect D, the lesion score showed a lower value indicating that lesions could be reduced or were less severe, which can be seen in figure 6:

Figure 6: Average lesion score

Essential Oils

Their hydrophobic characteristic enables them to interact with the lipids of the membrane of C. perfringens. They can incorporate into the bacterial membrane and disrupt its integrity, increasing the permeability of the cell membrane for ions and other small molecules such as ATP and leading to the decrease of the electrochemical gradient above the cell membrane and the loss of the cell’s energy equivalents. Besides their direct effect on Clostridium spp., many phytomolecules improve gut health and help prevent the proliferation of Clostridium spp. And, therefore, Necrotic Enteritis.

An In vitro-trial shows Ventar D reducing Clostridia and sparing the beneficial lactobacilli. In this trial, the bacteria (Clostridium perfringens, Lactobacillus agilis S73, and Lactobacillus plantarum) were cultured under favorable conditions (RCM, 37°C, anaerobe for Clostridium perfringens, and MRS, 37°C, 5 % CO₂ for Lactobacilli) and exposed to different concentrations of Ventar D (0 µg/ml – control, 500 µg/ml, 750 µg/ml, and 1000 µg/ml).

The results of the trial with Clostridium perfringens are shown in figure 7.

Figure 7: Different concentrations of Ventar D added to Clostridium perfringens cultures

Here, a significant reduction of colonies could already be observed at a concentration of 500 µg/ml of Ventar D. With 750 µg/ml, only a few colonies remained, and at a Ventar D concentration of 1000 µg/ml, Clostridium perfringens didn’t grow anymore.

In contrast, the Lactobacilli showed a different picture: only at the higher concentration (1250 µg/ml of Ventar D) did Lactobacillus plantarum and Lactobacillus agilis S73 show a slight growth reduction (figure 8).

Figure 8: Lactobacillus plantarum exposed to 0 (left) and 1250 µg/ml (right) of Ventar D

1. In vivo-trial in poultry shows that phytomolecules reduce gut lesions

The study was conducted at Southern Poultry Feed & Research, Athens, GA (USA), over 42 days. It included in total 880 Cobb 500 broilers across 2 trial groups, with 11 repetitions per trial set-up and 40 animals per replicate floor pen. All animals received routine vaccinations at the hatchery and were healthy when starting the trial.

Control group	Built-up litter (no additive)
Ventar D group	Built-up litter + Ventar D, 100 g/MT of feed

All birds received standard feed, fed as crumbles/pellets ad libitum. Feed intake by pen was recorded per feeding phase for starter (D21), grower (D35), and finisher feed (D42). Bird weights were recorded at study initiation, on D21, D35, and D42. On D21 and D35, three birds per pen were sacrificed. The GIT was scored for necrotic enteritis lesions; figures 9 and 10 show the results.

Figures 9 and 10: Lesion score on days 21 and 35

Already on day 21, the birds of the Ventar D group showed a less impacted gut mucosa, indicated by a lower lesion score. Lesions were reduced in both groups until day 35; however, the value of the Ventar D group was still better.

A less impacted gut has a higher digestion and absorption capacity, which results in better performance (FCR and weight gain) and lower mortality (figures 11-14).

Figures 11-14: Performance data of a control group compared with birds supplemented with Ventar D

The two trials show that Ventar D allows the poultry producer to proactively strengthen broilers’ gut health by controlling Clostridia perfringens and promoting/saving beneficial bacteria such as lactobacilli. The effects of the reduction of Clostridia can be seen in vivo in a lower lesion score and better performance.

Toxin binders adsorb bacterial and mycotoxins

These binders have two modes of action:

They bind mycotoxins and, therefore, reduce or prevent damage to the intestinal wall so that the preconditions for Clostridium spp. proliferation are not generated.

Additionally, binding toxins produced by Clostridium perfringens can reduce the occurrence or severity of lesions: Alpha-toxin, phospholipase C, hydrolyses membrane phospholipids and damages erythrocytes, leucocytes, myocytes, and endothelial cells and causes their lipolysis (Songer, 1996), leading to necrosis and tissue damage.

Binding NetB toxin, the key virulence factor, could reduce the severity of Necrotic Enteritis.

A trial was conducted in a laboratory in Valladolid/Spain to show the high binding capacity of Solis Plus 2.0. All tests were carried out as duplicates and using a standard liquid chromatography/mass spectrometry (LC/MS/MS) quantification. Interpretation and data analysis were carried out with the corresponding software. Toxin concentrations, anti-mycotoxin agent application rates, and pH levels were set as follows:

Mycotoxin	Challenge Level	Challenge (ppb)	Solis Plus 2.0 inclusion rate	Assay time
Aflatoxin	Low	150	0.2%	30 min.
	High	1500
Fumonisin	Low	500
	High	5000
Ochratoxin	Low	150
	High	1500

The results are shown in figure 15:

Figure 15: Adsorption capacity of Solis Plus for relevant mycotoxins

Under acidic conditions (pH 3), Solis Plus 2.0 effectively adsorbs the three tested mycotoxins at low and high contamination levels:

• Aflatoxin: 150 ppb -100 %; 1500 ppb – 98 %
• Fumonisin: 500 ppb – 87%; 5000 ppb – 86 %
• Ochratoxin: 150 ppb – more than 43 %; 1500 ppb – 52 %.

By binding harmful toxins and preventing their negative impact on the gut, toxin binders can also be a tool to reduce necrotic enteritis.

NE can be controlled – even in an antibiotic-free era

The ever-growing trend of reduced antibiotic and ionophore use increases the incidence of Necrotic Enteritis in poultry production. Especially the subclinical form, which generally goes unnoticed, results in poor feed efficiency and is a major cause of financial losses to poultry producers.

Maintaining optimum gut health is key to preventing the occurrence of Necrotic Enteritis. In the era of antibiotic-free poultry production, alternatives acting against the pathogenic bacterium and also against its predisposing factors must be considered to control this devastating disease. The industry already provides solutions like phytomolecules-based products or toxin binders to support the animals.

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