By Dr. Inge Heinzl, Editor, EW Nutrition

Salmonellosis is third among foodborne diseases leading to death (Ferrari, 2019). More than 91,000 human cases of Salmonellosis are reported by the EU each year, generating overall costs of up to €3 billion a year (EFSA, 2023), 10-20% of which are attributed to pork consumption (Soumet, 2022). The annual costs arising from the resulting human health losses in 2010 were about €90 million (FCC Consortium, 2010). Take the example of Ireland, where a high prevalence of Salmonella in lymph nodes still shows a severe issue pre-slaughter and a big challenge for slaughterhouses to stick to the process hygiene requirements (Deane, 2022).

Several governments already have monitoring programs in place, and the farms are categorized according to the salmonella contamination of their pigs. In some countries, e.g., Denmark, an economic penalty of 2% of the carcass value must be paid if the farm has level 2 (intermediate seroprevalence) and 4-8% if the level is 3. Other countries, e.g., Germany, the UK, Ireland, or the Netherlands, use quality assurance schemes. The farmers can only sell their carcasses under this label if their farm has a certain level.

Let’s take a quick look at the genus of Salmonella

Salmonellas are rod-shaped gram-negative bacteria of the family of enterobacteria that use flagella for their movement. They were named after the American vet Daniel Elmer Salmon. The genus of Salmonella consists of two species (S. bongori and S. enterica with seven subspecies) with in total more than 2500 serovars (see Figure 1). The effects of the different serovars can range from asymptomatic carriage to severe invasive systemic disease (Gal-Mor, 2014). All Salmonella serovars generally can cause disease in humans; the rosa-marked ones already showed infections.

Figure 1: the genus of Salmonella with Salmonella serovars relevant for pigs (according to Bonardi, 2017: Salmonella in the pork production chain and its impact on human health in the European Union)

Within the group of Salmonella, some serovars can only reside in one or few species, e.g., S. enterica spp. enterica Serovar Dublin (S. Dublin) in bovines (Waldron, 2018) or S. Cholerasuis in pigs (Chiu, 2004). An infection in humans with these pathogens is often invasive and life-threatening (WHO, 2018). On the contrary, serovars like S. Typhimurium and S. Enteritidis are not host-specific and can cause disease in various species.

The serotypes S. Typhi and S. Paratyphi A, B, or C are highly adapted to humans and only for them pathogenic; they are responsible for the occurrence of typhus.

Serovars occurring in pigs and relevant for humans are, for example, S. Typhimurium (Hendriksen, 2004), S. Serotype 4,[5],12:I (Hauser et al., 2010), S. Cholerasuis (Chiu, 2004), S. Derby (Gonzalez-Santamarina, 2021), S. Agona (Brenner Michael, 2006) and S. Rissen (Elbediwi, 2021).

Transmission of Salmonella mostly happens via contaminated food

The way of transmission to humans depends on the serovar:
Human-specific and, therefore, only in humans and higher primates residing serovars S. Typhi and Paratyphi A, B, or C (typhoidal) are excreted via feces or urine. Therefore, any food or water contaminated with the feces or urine of infected people can transmit this disease (Government of South Australia, 2023). Typhoid and paratyphoid Salmonellosis occur endemic in developing countries with the lack of clean water and, therefore, inadequate hygiene (Gal-Mor, 2014).

Serovars which can cause disease in humans and animals (non-typhoidal), can be transmitted by
– animal products such as milk, eggs, meat
– contact with infected persons/animals (pigs, cows, pets, reptiles…) or
– other feces- or urine-contaminated products such as sprouts, vegetables, fruits….

Farm animals take salmonellas from their fellows, contaminated feed or water, rodents, or pests.

Symptoms of Salmonellosis can be severe

In the case of typhoid or paratyphoid Salmonellosis, the onset of illness is gradual. People can suffer from sustained high fever, unwellness, severe headache, and decreased appetite, but also from an enlarged spleen irritating the abdomen and dry cough.

A study conducted in Thailand with children suffering from enteric fever caused by the typhoid serovars S. Typhi and Paratyphi showed a sudden onset of fever and gastrointestinal issues (diarrhea), rose spots, bronchitis, and pneumonia (Thisyakorn et al., 1987)

The non-typhoid Salmonellosis is typically characterized by an acute onset of fever, nausea, abdominal pain with diarrhea, and sometimes vomiting (WHO, 2018). However, 5% of the persons – children with underlying conditions, e.g., babies, or people who have AIDS, malignancies, inflammatory bowel disease, gastrointestinal illness caused by non-typhoid serovars, and hemolytic anemia, or receiving an immunosuppressive therapy can be susceptible to bacteremia. Additionally, serovars like S. Cholerasuis or S. Dublin are apt to develop bacteremia by entering the bloodstream with little or no involvement of the gut (Chiu, 1999). In these cases, consequences can be septic arthritis, pneumonia, peritonitis, cutaneous abscess, mycotic aneurysm, and sometimes death (Chen et al., 2007; Chiu, 2004, Wang et al., 1996).

In pigs, S. Cholerasuis causes high fever, purple discolorations of the skin, and thereinafter diarrhea. The mortality rate in pigs suffering from this type of Salmonellosis is high. Barrows orally challenged with S. Typhimurium showed elevated rectal temperature by 12h, remaining elevated until the end of the study. Feed intake decreased with a peak at 48h after the challenge and remained up to 120h after the challenge. Daily gain reduced during the following two weeks after infection. A higher plasma cortisol level and a lower IGF-I level could also be noticed. All these effects indicate significant changes in the endocrine stress and the somatotropic axis, also without significant alterations in the systemic pro-inflammatory mediators (Balaji et al., 2000)

To protect humans, Salmonella in pork must be restraint

There are three main steps to keep the contamination of pork as low as possible:

1. Keeping Salmonella out of the pig farm
2. Minimizing spreading if Salmonella is already on the farm
3. Minimizing contamination in the slaughterhouse

1. How to keep Salmonella out of the pig farm?

To answer this question, we must look at how the pathogen can be transported to the farm. According to the Code of Practice for the Prevention and Control of Salmonella on Pig Farms (Ministry of Agriculture, Fisheries and Food and the Scottish Executive Rural Affairs Department), there are several possibilities to infiltrate the pathogen into the farm:

• Diseased pigs or pigs which are ill but don’t show any symptoms
• Feeding stuff or bedding contaminated with dung
• Pets, rodents, wild birds, or animals
• Farm personnel or visitors
• Equipment or vehicles

Caution with purchased animals!

To minimize/prevent the entry of Salmonella into the livestock, bought-in animals must come from reputable breeding farms with a salmonella monitoring system in place. As possible carrier animals are more likely to excrete Salmonella when stressed; they should be kept in isolation after purchasing. Additionally, the animals must go through a disinfectant foot bath before entering the farm.

Keep rodents, wild animals, and vermin in check!

Generally, the production site must be kept clean and as unattractive as possible for all these animals. Rests of feed must be removed, and dead animals and afterbirths must be promptly and carefully disposed of. A well-planned baiting and trapping policy should be in place to effectively control rodents.

Only selected people should enter the hog houses

In any case, the number of persons entering the hog house must be kept as low as possible. Farmworkers should be trained in the principles of hygiene. They should wear adequate clothing (waterproof boots and protective overalls) that can be easily cleaned/laundered and disinfected. The clothes/shoes should always be used only at this site. Thorough hand washing and the disinfection of the boots when entering and leaving the pig unit are a must.

If visits are necessary, the visitors should take the same measures as the farm workers. And, of course, they should not have had contact with another pig farm during the last 48 hours.

Keep pens, farm equipment, and vehicles clean!

Farm equipment should not be shared with other farms. If this cannot be avoided, it must be cleaned and disinfected before re-entering the farm. Also, the vehicles for the transport of the animals must be cleaned and disinfected as soon as possible after usage, as contaminated transporters always pose the risk of infection.

Feed should be Salmonella-free!

To get high feed quality, the feed should be purchased from feed mills/sources with a well-functioning bacterial control to guarantee the absence of Salmonella. It is essential that birds, domestic and wild animals cannot enter the feed stores.
It is also advised to keep dry feed dry as possibly contaminating Salmonella can multiply in such humid conditions. Additionally, all feed bins and delivery pipes for dry and wet feed must be consciously cleaned, and the damp feed pipes also disinfected.
The change from pellets to mash could be helpful as the pellets facilitate Salmonella colonization by stimulating the secretion of mucins (Hedemann et al., 2005).

For sanitation of the feed, we offer organic acids (Acidomix product range) or mixtures of organic acids and formaldehyde in countries where formaldehyde products are allowed (Formycine) to decrease the pathogenic load of the feed materials. In vitro trials show the effectiveness of the products:

For the in vitro trial with Formycine, autoclaved feed samples were inoculated with Salmonella enteritidis serovar Typhimurium DSM 19587 strain to reach a Salmonella contamination of 10⁶ CFU/g of feed. After incubating at room temperature for three hours, Formycine Liquido was added to the contaminated feed samples at 0, 500, 1000, and 2000 ppm. The control and inoculated feed samples were further incubated at room temperature, and Salmonella counts (CFU/g) were carried out at 24, 48, 72 hours and on day 15. The limit of Salmonella detection was set at 100 CFU/g (10²). Results are shown in figure 2.

Fig. 2: Effect of treatment time and different inclusion levels of Formycine Liquido on the Salmonella count in feed

As important as uncontaminated feed is clean water for drinking. It can be achieved by taking the water from a main or a bacteriologically controlled water borehole. Regular cleaning/disinfection of the tanks, pipes, and drinkers is essential.

Bedding should be Salmonella-free

Straw material containing feces of other animals (rodents, pets) always carries the risk of Salmonella contamination. Also, wet or moldy bedding is not recommended because it is an additional challenge for the animal. To optimize the quality of bedding, the straw should be bought from reliable and as few as possible sources. The material must be stored dry and as far as practicable from the pig buildings (Ministry of Agriculture, Fisheries and Food & Scottish Executive Rural Affairs Department, 2000).

Vaccination is a beneficial measure

For the control of Salmonella in swine herds, vaccination is an effective tool. De Ridder et al. (2013) showed that an attenuated vaccine reduced the transmission of Salmonella Typhimurium in pigs. The vaccination with an attenuated S. Typhimurium strain, followed by a booster vaccination with inactivated S. Cholerasuis, showed better effects than an inactivated S. Cholerasuis vaccine alone (Alborali et al., 2017). Bearson et al. (2017) could delimitate transmission through less shedding and protect the animals against systemic disease.
To achieve the best effects, the producer must understand the diversity of Salmonella serovars to choose the most promising vaccination strategy (FSIS, 2023).

2. How to minimize the spreading of Salmonella on the farm?

If there are already cases of Salmonella on the farm, infected animals must be separated from the rest of the herd. Small batch sizes are beneficial, as well as not mixing different litters after weaning. If feasible, separate units for different production phases with an all-in/all-out system could break the reinfection cycle and help reduce Salmonella contamination on the farm. And also in this case, vaccination is helpful.

Salmonella doesn’t like acid conditions

An effective tool is acidifying the feed with organic acids, as Salmonella doesn’t like acid conditions. A trial was conducted with Acidomix AFG and Acidomix AFL to show their effects against Salmonella. For the test, 10⁵ CFU/g of Salmonella enterica ser. Typhimurium was added to feed containing 1000 ppm, 2000 ppm, and 3000 ppm of Acidomix AFG or AFL. The stomach and intestine were simulated in vitro by adjusting the pH with HCl and NaHCO3 as follows:
Stomach              2.8
Intestine              6.8-7.0

After the respective incubation, the microorganisms were recovered from feed and plated on an appropriate medium for CFU counting. The results are shown in figures 3 and 4.

Figures 3 + 4: Effects of different concentrations of Acidomix AFG and Acidomix AFL against Salmonella enterica ser. Typhimurium in feed

Phytomolecules can support pigs against Salmonella

Plant compounds or phytomolecules can also be used against Salmonella in pigs. Some examples of phytomolecules to be used are Piperine, Allicin, Eugenol, and Carvacrol. Eugenol, e.g., increases the permeability of the Salmonella membrane, disrupts the cytoplasmic membrane, and inhibits the production of bacterial virulence factors (Keita et al., 2022; Mak et al., 2019). Thymol and Carvacrol interact with the cell membrane by H bonding, also resulting in a higher permeability.

An already published in vitro trial conducted with our product Ventar D also showed excellent effects against Salmonella while sparing the beneficial gut flora. A further trial once more demonstrated the susceptibility of Salmonella to Ventar D. It showed that Ventar D controls Salmonella by suppressing their motility and, at higher concentrations, inactivating the cells (see figures 5 + 6):

Figure 5: S. enterica motility test: on the left side – control; on the right side – motility medium containing.750 µg/mL of Ventar

Fig 6 . Disk diffusion assay employing S. enterica. upper left side – disk containing 10 µL of Ventar; upper right – 5 µL; lower left – control; lower right – 1µL.

In addition to the direct Salmonella-reducing effect, essential oils / secondary plant compounds / phytomolecules improve digestive enzyme activity and digestion, leading to increased nutrient absorption and better feed conversion (Windisch et al., 2008).

3. How can the farmer keep Salmonella contamination low in the slaughterhouse?

In general, the slaughterhouse personnel is responsible for adequate hygiene management to prevent contamination of carcasses and meat. However, also the farmer can make his contribution to maintain the risk of contamination in the slaughterhouse as low as possible. A study by Vieira-Pinto (2006) revealed that one Salmonella-positive pig can contaminate several other carcasses.

According to a trial conducted by Hurd et al. (2002), infection and, therefore, “contamination” of other pigs can rapidly occur, meaning that cross-contamination is a topic during transport to the slaughterhouse and in the lairages when the pigs come together with animals from other farms. The stress to which the pigs are exposed influences physiological and biochemical processes. The microbiome and animal’s immunity are affected, leading to higher excretion of Salmonella during transport and in the lairages. So, the animals should not be stressed during loading and unloading or transportation. The trailer poses a further risk of infection if it was not cleaned and disinfected before. So, reliable people who treat the animals well and keep their trailers clean should be chosen for transportation.

Pig producers are obliged to keep Salmonella in check – phytomolecules can help

At least in the EU, pig producers have the big duty to keep Salmonella low in their herds; otherwise, they will have financial losses. They are not only responsible for their farm, but also the slaughterhouses count on them. Besides the standard strict hygiene management and vaccination, farmers can use products provided by the industry to sanitize feed but also to support their animals directly with phytomolecules acting against pathogens and supporting gut health.

All these measures together should be a solution to the immense challenge of Salmonella, to protect people and prevent economic losses.

References:

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By Dr Merideth Parke BVSc, Regional Technical Manager Swine, EW Nutrition

We care for our animals, and antibiotics are a crucial component in the management of disease due to susceptible pathogens, supporting animal health and welfare.  However, the administration of antibiotics in pig farming has become a common practice to prevent bacterial infections, reduce economic losses, and increase productivity.

All antibiotic applications have collateral consequences of significance, bringing a deeper consideration to their non-essential application. This article aims to challenge the choice to administer antibiotics by exploring the broader impact that antibiotics have on animal and human health, economies, and the environment.

Antibiotics disrupt microbial communities

Antibiotics do not specifically target pathogenic bacteria. By impacting beneficial microorganisms, they disrupt the natural balance of microbial communities within animals. They reduce the microbiota diversity and abundance of all susceptible bacteria – beneficial and pathogenic ones… many of which play crucial roles in digestion, brain function, the immune system, and respiratory and overall health. Resulting microbiota imbalances may present themselves in animals showing health performance changes associated with non-target systems, including the nasal, respiratory, or gut microbiome^{10, 9, 16}. The gut-respiratory microbiome axis is well-established in mammals. Gut microbiota health, diversity, and nutrient supply directly impact respiratory health and function¹⁵. In pigs specifically, the modulation of the gut microbiome is being considered as an additional tool in the control of respiratory diseases such as PRRS due to the link between the digestion of nutrients, systemic immunity, and response to pulmonary infections¹².

The collateral effect of antibiotic administration disrupting not only the microbial communities throughout the animal but also linked body systems needs to be considered significant in the context of optimal animal health, welfare, and productivity.

Antibiotic use can lead to the release of toxins

The consideration of the pathogenesis of individual bacteria is critical to mitigate potential for direct collateral effects associated with antibiotic administration. For example, in cases of toxin producing bacteria, when animals are medicated either orally or parenterally, mortality may increase due to the associated release of toxins when large numbers of toxin producing bacteria are killed quickly³.

Modulation of the brain function can be critical

Numerous animal studies have investigated the modulatory role of intestinal microbes on the gut-brain axis. One identified mechanism seen with antibiotic-induced changes in fecal microbiota is the decreased concentrations of hypothalamic neurotransmitter precursors, 5-hydroxytryptamine (serotonin), and dopamine⁶. Neurotransmitters are essential for communication between the nerve cells. Animals with oral antibiotic-induced microbiota depletion have been shown to experience changes in brain function, such as spatial memory deficits and depressive-like behaviors.

Processing of waste materials can be impacted

Anaerobic treatment technology is well accepted as a feasible management process for swine farm wastewater due to its relatively low cost with the benefit of bioenergy production. Additionally, the much smaller volume of sludge remaining after anaerobic processing further eases the safe disposal and decreases the risk associated with the disposal of swine waste containing residual antibiotics⁵.

The excretion of antibiotics in animal waste, and the resulting presence of antibiotics in wastewater, can impact the success of anaerobic treatment technologies, which already could be demonstrated by several studies^{8, 13}. The degree to which antibiotics affect this process will vary by type, combination, and concentration. Furthermore, the presence of antibiotics within the anaerobic system may result in a population shift towards less sensitive microbes or the development of strains with antibiotic-resistant genes^{1, 14}.

Antibiotics can be transferred to the human food chain

Regulatory authorities specify detailed withdrawal periods after antibiotic treatment. However, residues of antibiotics and their metabolites may persist in animal tissues, such as meat and milk, even after this period. These residues can enter the human food chain if not adequately monitored and controlled.

Prolonged exposure to low levels of antibiotics through the consumption of animal products may contribute to the emergence of antibiotic-resistant bacteria in humans, posing a significant public health risk.

Contamination of the environment

As already mentioned before, the administration of antibiotics to livestock can result in the release of these compounds into the environment. Antibiotics can enter the soil, waterways, and surrounding ecosystems through excretions from treated animals, inappropriate disposal of manure, and runoff from agricultural fields. Once in the environment, antibiotics can contribute to the selection and spread of antibiotic-resistant bacteria in natural bacterial communities. This contamination poses a potential risk to wildlife, including birds, fish, and other aquatic organisms, as well as the broader ecological balance of affected ecosystems.

Every use of antibiotics can create resistance

One of the widely researched concerns associated with antibiotic use in livestock is the development of antibiotic resistance. The development of AMR does not require prolonged antibiotic use and, along with other collateral effects, also occurs when antibiotics are used within recommended therapeutic or preventive applications.

Gene mutations can supply bacteria with abilities that make them resistant to certain antibiotics (e.g., a mechanism to destroy or discharge the antibiotic). This resistance can be transferred to other microorganisms, as seen with the effect of carbadox on Escherichia coli⁷ and Salmonella enterica² and the carbadox and metronidazole effect on Brachyspira hyodysenteriae¹⁶. Additionally, there is an indication that the zinc resistance of Staphylococcus of animal origin is associated with the methicillin resistance coming from humans⁴.

Consequently, the effectiveness of antibiotics in treating infections in target animals becomes compromised, and the risk of exposure to resistant pathogens for in-contact animals and across species increases, including humans.

Alternative solutions are available

To successfully minimize the collateral effects of antibiotic administration in livestock, a unified strategy with support from all stakeholders in the production system is essential. The European Innovation Partnership – Agriculture¹¹ concisely summarizes such a process as requiring…

1. Changing human mindsets and habits: this is the first and defining step to successful antimicrobial reduction
2. Improving pig health and welfare: Prevention of disease with optimal husbandry, hygiene, biosecurity, vaccination programs, and nutritional support.
3. Effective antibiotic alternatives: for this purpose, phytomolecules, pro/pre-biotics, organic acids, and immunoglobulins are considerations.

In general, implementing responsible antibiotic stewardship practices is paramount. This includes limiting antibiotic use to the treatment of diagnosed infections with an effective antibiotic, and eliminating their use as growth promotors or for prophylactic purposes.

Keeping the balance is of crucial importance

While antibiotics play a crucial role in ensuring the health and welfare of livestock, their extensive administration in the agricultural industry has collateral effects that cannot be ignored. The development of antibiotic resistance, environmental contamination, disruption of microbial communities, and the potential transfer of antibiotic residues to food pose significant challenges.

Adopting responsible antibiotic stewardship practices, including veterinary oversight, disease prevention programs, optimal animal husbandry practices, and alternatives to antibiotics, can strike a balance between animal health, efficient productive performance, and environmental and human health concerns.

The collaboration of stakeholders, including farmers, veterinarians, policymakers, industry and consumers, is essential in implementing and supporting these measures to create a sustainable and resilient livestock industry.

References

1. Angenent, Largus T., Margit Mau, Usha George, James A. Zahn, and Lutgarde Raskin. “Effect of the Presence of the Antimicrobial Tylosin in Swine Waste on Anaerobic Treatment.” Water Research 42, no. 10–11 (2008): 2377–84. https://doi.org/10.1016/j.watres.2008.01.005.
2. Bearson, Bradley L., Heather K. Allen, Brian W. Brunelle, In Soo Lee, Sherwood R. Casjens, and Thaddeus B. Stanton. “The Agricultural Antibiotic Carbadox Induces Phage-Mediated Gene Transfer in Salmonella.” Frontiers in Microbiology 5 (2014). https://doi.org/10.3389/fmicb.2014.00052.
3. Castillofollow, Manuel Toledo, Rocío García Espejofollow, Alejandro Martínez Molinafollow, María Elena  Goyena Salgadofollow, José Manuel Pintofollow, Ángela Gallardo Marínfollow, M. Toledo, et al. “Clinical Case: Edema Disease – the More I Medicate, the More Pigs Die!” $this->url_servidor, October 15, 2021. https://www.pig333.com/articles/edema-disease-the-more-i-medicate-the-more-pigs-die_17660/.
4. Cavaco, Lina M., Henrik Hasman, Frank M. Aarestrup, Members of MRSA-CG:, Jaap A. Wagenaar, Haitske Graveland, Kees Veldman, et al. “Zinc Resistance of Staphylococcus Aureus of Animal Origin Is Strongly Associated with Methicillin Resistance.” Veterinary Microbiology 150, no. 3–4 (2011): 344–48. https://doi.org/10.1016/j.vetmic.2011.02.014.
5. Cheng, D.L., H.H. Ngo, W.S. Guo, S.W. Chang, D.D. Nguyen, S. Mathava Kumar, B. Du, Q. Wei, and D. Wei. “Problematic Effects of Antibiotics on Anaerobic Treatment of Swine Wastewater.” Bioresource Technology 263 (2018): 642–53. https://doi.org/10.1016/j.biortech.2018.05.010.
6. Köhler, Bernd, Helge Karch, and Herbert Schmidt. “Antibacterials That Are Used as Growth Promoters in Animal Husbandry Can Affect the Release of Shiga-Toxin-2-Converting Bacteriophages and Shiga Toxin 2 from Escherichia Coli Strains.” Microbiology 146, no. 5 (2000): 1085–90. https://doi.org/10.1099/00221287-146-5-1085.
7. Loftin, Keith A., Cynthia Henny, Craig D. Adams, Rao Surampali, and Melanie R. Mormile. “Inhibition of Microbial Metabolism in Anaerobic Lagoons by Selected Sulfonamides, Tetracyclines, Lincomycin, and Tylosin Tartrate.” Environmental Toxicology and Chemistry 24, no. 4 (2005): 782–88. https://doi.org/10.1897/04-093r.1.
8. Looft, Torey, Heather K Allen, Brandi L Cantarel, Uri Y Levine, Darrell O Bayles, David P Alt, Bernard Henrissat, and Thaddeus B Stanton. “Bacteria, Phages and Pigs: The Effects of in-Feed Antibiotics on the Microbiome at Different Gut Locations.” The ISME Journal 8, no. 8 (2014a): 1566–76. https://doi.org/10.1038/ismej.2014.12.
9. Looft, Torey, Heather K. Allen, Thomas A. Casey, David P. Alt, and Thaddeus B. Stanton. “Carbadox Has Both Temporary and Lasting Effects on the Swine Gut Microbiota.” Frontiers in Microbiology 5 (2014b). https://doi.org/10.3389/fmicb.2014.00276.
10. Nasralla, Meisoon. “EIP-Agri Concept.” EIP-AGRI – European Commission, September 11, 2017. https://ec.europa.eu/eip/agriculture/en/eip-agri-concept.html.
11. Niederwerder, Megan C. “Role of the Microbiome in Swine Respiratory Disease.” Veterinary Microbiology 209 (2017): 97–106. https://doi.org/10.1016/j.vetmic.2017.02.017.
12. Poels, J., P. Van Assche, and W. Verstraete. “Effects of Disinfectants and Antibiotics on the Anaerobic Digestion of Piggery Waste.” Agricultural Wastes 9, no. 4 (1984): 239–47. https://doi.org/10.1016/0141-4607(84)90083-0.
13. Shimada, Toshio, Julie L. Zilles, Eberhard Morgenroth, and Lutgarde Raskin. “Inhibitory Effects of the Macrolide Antimicrobial Tylosin on Anaerobic Treatment.” Biotechnology and Bioengineering 101, no. 1 (2008): 73–82. https://doi.org/10.1002/bit.21864.
14. Sikder, Md. Al, Ridwan B. Rashid, Tufael Ahmed, Ismail Sebina, Daniel R. Howard, Md. Ashik Ullah, Muhammed Mahfuzur Rahman, et al. “Maternal Diet Modulates the Infant Microbiome and Intestinal Flt3l Necessary for Dendritic Cell Development and Immunity to Respiratory Infection.” Immunity 56, no. 5 (May 9, 2023): 1098–1114. https://doi.org/10.1016/j.immuni.2023.03.002.
15. Slifierz, Mackenzie Jonathan. “The Effects of Zinc Therapy on the Co-Selection of Methicillin-Resistance in Livestock-Associated Staphylococcus Aureus and the Bacterial Ecology of the Porcine Microbiota,” 2016.
16. Stanton, Thaddeus B., Samuel B. Humphrey, Vijay K. Sharma, and Richard L. Zuerner. “Collateral Effects of Antibiotics: Carbadox and Metronidazole Induce VSH-1 and Facilitate Gene Transfer among Brachyspira Hyodysenteriae” Applied and Environmental Microbiology 74, no. 10 (2008): 2950–56. https://doi.org/10.1128/aem.00189-08.

By Lea Poppe, Regional Technical Manager On-Farm Solutions Europe, and Dr. Inge Heinzl, Editor

One of the ten global public health threats is antimicrobial resistance (AMR). Jim O’Neill predicted 10 million people dying from AMR annually by 2050 (O’Neill, 2016). The following article will show the causes of antimicrobial resistance and how antibodies from the egg could help mitigate the problem of AMR.

Global problem of AMR results from the incorrect use of antimicrobials

Antimicrobial substances are used to prevent and cure diseases in humans, animals, and plants and include antibiotics, antivirals, antiparasitics, and antifungals. The use of these medicines does not always happen consciously, partially due to ignorance and partially for economic reasons.

There are various possibilities for the wrong therapy

1. The use of antibiotics against diseases that household remedies could cure. A recently published German study (Merle et al., 2023) confirmed the linear relationship between treatment frequency and resistant scores in calves younger than eight months.
2. The use of antibiotics against viral diseases: antibiotics only act against bacteria and not against viruses. Flu, e.g., is caused by a virus, but doctors often prescribe an antibiotic.
3. Using broad-spectrum antibiotics instead of determining an antibiogram and applying a specific antibiotic.
4. A too-long treatment with antimicrobials so that the microorganisms have the time to adapt. For a long time, the only mistake you could make was to stop the antibiotic therapy too early. Today, the motto is “as short as possible”.

Let’s take the example of neonatal calf diarrhea, one of the most common diseases with a high economic impact. Calf diarrhea can be caused by a wide range of bacteria, viruses, or parasites. This infectious form can be a complication of non-infectious diarrhea caused by dietary, psychological, and environmental stress (Uetake, 2012). The pathogens causing diarrhea in calves can vary with the region. In Switzerland and the UK, e.g., rotaviruses and cryptosporidia are the most common pathogens, whereas, in Germany, E. coli is also one of the leading causes. To minimize the occurrence of AMR, it is always crucial to know which pathogen is behind the disease.

Prophylactic use of antibiotics is still a problem

1. The use of low doses of antibiotics to promote growth. This use has been banned in the EU now for 17 years now, but in other parts of the world, it is still common practice. Especially in countries with low hygienic standards, antibiotics show high efficacy.
2. The preventive use of antibiotics to help, e.g., piglets overcome the critical step of weaning or to support purchased animals for the first time in their new environment. Antibiotics reduce pathogenic pressure, decrease the incidence of diarrhea, and ensure the maintenance of growth.
3. Within the scope of prophylactic use of antimicrobials, also group treatment must be mentioned. In veal calves, group treatments are far more common than individual treatments (97.9% of all treatments), as reported in a study documenting medication in veal calf production in Belgium and the Netherlands. Treatment indications were respiratory diseases (53%), arrival prophylaxis (13%), and diarrhea (12%). On top, the study found that nearly half of the antimicrobial group treatment was underdosed (43.7%), and a large part (37.1%) was overdosed.

However, in several countries, consumers request reduced or even no usage of antibiotics (“No Antibiotics Ever” – NAE), and animal producers must react.

Today’s mobility enables the spreading of AMR worldwide

Bacteria, viruses, parasites, and fungi that no longer respond to antimicrobial therapy are classified as resistant. The drugs become ineffective and, therefore, the treatment of disease inefficient or even impossible. All the different usages mentioned before offer the possibility that resistant bacteria/microorganisms will occur and proliferate. Due to global trade and the mobility of people, drug-resistant pathogens are spreading rapidly throughout the world, and common diseases cannot be treated anymore with existing antimicrobial medicines like antibiotics. Standard surgeries can become a risk, and, in the worst case, humans die from diseases once considered treatable. If new antibiotics are developed, their long-term efficacy again depends on their correct and limited use.

Different approaches are taken to fight AMR

There have already been different approaches to fighting AMR. As examples, the annually published MARAN Report compiled in the Netherlands, the EU ban on antibiotic growth promoters in 2006, “No antibiotics ever (NAE) programs” in the US, or the annually published “Antimicrobial resistance surveillance in Europe” can be mentioned. One of the latest approaches is an advisory “One Health High-Level Expert Panel” (OHHLEP) founded by the Food and Agriculture Organization of the United Nations (FAO), the World Organization for Animal Health (OIE), the United Nations Environment Program (UNEP), and the World Health Organization (WHO) in May 2021. As AMR has many causes and, consequently, many players are involved in its reduction, the OHHLEP wants to improve communication and collaboration between all sectors and stakeholders. The goal is to design and implement programs, policies, legislations, and research to improve human, animal, and environmental health, which are closely linked. Approaches like those mentioned help reduce the spread of resistant pathogens and, with this, remain able to treat diseases in humans, animals, and plants.

On top of the pure health benefits, reducing AMR improves food security and safety and contributes to achieving the Sustainable Development Goals (e.g., zero hunger, good health and well-being, and clean water).

Prevention is better than treatment

Young animals like calves, lambs, and piglets do not receive immunological equipment in the womb and need a passive immune transfer by maternal colostrum. Accordingly, optimal colostrum management is the first way to protect newborn animals from infection, confirmed by the general discussion on the Failure of Passive Transfer: various studies suggest that calves with poor immunoglobulin supply suffer from diarrhea more frequently than calves with adequate supply.

Especially during the immunological gap when the maternal immunoglobulins are decreasing and the own immunocompetence is still not fully developed, it is crucial to have a look at housing, stress triggers, biosecurity, and the diet to reduce the risk of infectious diseases and the need for treatments.

Immunoglobulins from eggs additionally support young animals

Also, if newborn animals receive enough colostrum in time and if everything goes optimally, the animals suffer from two immunity gaps: the first one occurs just after birth before the first intake of colostrum, and the second one occurs when the maternal antibodies decrease, and the immune system of the young animal is still not developed completely. These immunity gaps raise the question of whether something else can be done to support newborns during their first days of life.

The answer was provided by Felix Klemperer (1893), a German internist researching immunity. He found that hens coming in contact with pathogens produce antibodies against these agents and transfer them to the egg. It is unimportant if the pathogens are relevant for chickens or other animals. In the egg, the immunoglobulins usually serve as an immune starter kit for the chick.

Technology enables us today to produce a high-value product based on egg powder containing natural egg immunoglobulins (IgY – immunoglobulins from the yolk). These egg antibodies mainly act in the gut. There, they recognize and tie up, for example, diarrhea-causing pathogens and, in this way, render them ineffective.

The efficacy of egg antibodies was demonstrated in different studies (Kellner et al., 1994; Erhard et al., 1996; Ikemori et al., 1997; Yokoyama et al., 1992; Marquart, 1999; Yokoyama et al., 1997) for piglets and calves.

Trial proves high efficacy of egg immunoglobulins in piglets

One trial conducted in Germany showed promising results concerning the reduction of mortality in the farrowing unit. For the trial, 96 sows and their litters were divided into three groups with 32 sows each. Two of the groups orally received a product containing egg immunoglobulins, the EP -1 + 3 group on days 1 and 3 and the EP – 1 + 2 + 3 group on the first three days. The third group served as a control. Regardless of the frequency of application, the egg powder product was very supportive and significantly reduced mortality compared to the control group. The measure resulted in 2 additionally weaned piglets than in the control group.

Egg immunoglobulins support young dairy calves

IgY-based products were also tested in calves to demonstrate their efficacy. In a field trial conducted on a Portuguese dairy farm with 12 calves per group, an IgY-containing oral application was compared to a control group without supplementation. The test product was applied on the day of birth and the two consecutive days. Key observation parameters during a two-week observation period were diarrhea incidence, onset, duration, and antibiotic treatments, the standard procedure on the trial farm in case of diarrhea. On-farm tests to check for the pathogenic cause of diarrhea were not part of the farm’s standards.

In this trial, 10 of 12 calves in the control group suffered from diarrhea, but in the trial group, only 5 calves. Total diarrhea and antibiotic treatment duration in the control group was 37 days (average 3.08 days/animal), and in the trial group, only 7 days (average 0.58 days/animal). Additionally, diarrhea in calves of the Globigen Calf Paste group started later, so the animals already had the chance to develop an at least minimally working immune system.

The supplement served as an effective tool to support calves during their first days of life and to reduce antibiotic treatments dramatically.

Conclusion

Antimicrobial reduction is one of the biggest tasks for global animal production. It must be done without impacting animal health and parameters like growth performance and general cost-efficacy. This overall demand can be supported with a holistic approach considering biosecurity, stress reduction, and nutritional support. Feed supplements such as egg immunoglobulins are commercial options showing great results and benefits in the field and making global animal production take the right direction in the future.

References upon request.

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

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

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

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

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

How to measure the feed conversion rate

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

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

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

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

Many factors influence the FCR

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

1. Species

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

Table 1: FCRs of different species

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

2. Sex, age, and growth phase

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

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

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

3. Health and gut health

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

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

4. Environment

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

5. Feed quantity, composition, and quality

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

Better FCR by increasing nutrient density and digestibility

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

Feed form and particle size play an important role

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

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

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

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

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

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

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

Molds and mycotoxins impair feed quality, but also animal health

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

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

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

Oxidation of fats also affects feed quality

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

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

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

Use adequate supplements to enhance FCR

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

1. Boost your animals’ gut health

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

Phytomolecules help stabilize the balance of the microbiome

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

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

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

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

Figure 2: FCR improvements for animals receiving Activo

Products mitigating the adverse effects of toxins

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

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

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

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

2. Improve nutrient utilization

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

Phytomolecules support the animal’s digestive system

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

Enzymes release more nutrients from feed

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

3. Be proactive about preserving feed quality

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

Antioxidants prevent feed oxidation

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

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

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

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

Inhibiting molds and keeping feed moisture

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

Conclusion

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

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

References

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

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

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

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

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

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

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

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

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

By Dr. Inge Heinzl, Editor, EW Nutrition

Nowadays, intensive livestock farming with high stocking densities causes stress in the animals and affects the immune system^{9, 13}. The increase in respiratory diseases with associated losses and costs is only one of the consequences. Due to antimicrobial resistance, antibiotics should only be used in critical cases, so effective alternatives are requested to support the animals.

Respiratory problems are a conjunction of several factors

It already has a name: PRDC or the Porcine Respiratory Disease Complex describes the cooperation of viruses, bacteria, and non-infectious factors such as environmental conditions (e.g., insufficient ventilation), stocking density, management (e.g., all-in-all-out only by pens and not for the whole house) and pig-specific factors such as age and genetics, altogether causing respiratory issues in pigs. Non-infectious factors such as high ammonia levels weaken the immune system and lay the foundation for, e.g., mycoplasmas which damage the ciliated epithelial cells in the upper respiratory tract, the first line of defense, and pave the way for PRRS viruses. They, on their part, enter the respiratory tract embedded in inhaled dust. There, they harm the macrophages and breach a further barrier of defense. Another pathfinder is the Porcine Circovirus 2 (PCV2), which destroys specific immune cells and leads to a generally higher susceptibility to infectious agents. Bacteria such as Pasteurella multocida or Streptococcus suis further on can cause secondary infections^{7, 20, 22}. Also, the combination of mycoplasma hyopneumoniae and porcine circovirus, both typically low pathogenic organisms, leads to severe respiratory disease¹⁵.

Restricted respiratory function impacts growth

The main tasks of the respiratory tract are to take in oxygen from the air and to pump out the CO₂ entailed by the catabolism of the tissue. In pigs, however, the respiratory tract is also responsible for thermoregulation, as pigs don’t have perspiration glands. The animals must get rid of excessive heat by rapid breathing. If the respiratory function is affected due to disease, thermoregulatory capacity is reduced. The resulting lower feed intake leads to decreased growth performance and less economic profit¹⁷. One of the first studies concerning this topic was conducted by Straw et al. (1989)²¹. They asserted that, with every 10 % more affected lung tissue, daily gain decreased by about 37g. This negative correlation between affected lung tissue and weight gain could be confirmed by Paz-Sánchez et al. (2021)¹⁸. They saw that animals with >10% lung parenchyma impacted by cranioventral bronchopneumonia needed a longer time to market (208.8 days vs. 200.8 days in the control), showed a lower carcass weight (74.1 kg vs. 77.7 kg in the control group) and, therefore, also a lower daily gain (500.8 g/day compared to 567.2 g/d). In another study, Pagot and co-workers (2007)¹⁶ observed 7000 pigs from 14 French farms. They saw a significant negative correlation (p<0.001) between the prevalence of pneumonia and growth and a weight gain loss of about 0.7 for each point of pneumonia increase.

Plant extracts support pigs with different modes of action

People have always used herbal substances to cure illnesses, be it willow bark for pain, chamomile for anti-inflammation or an upset stomach. Ribwort and thyme are used as cough suppressants, and eucalyptus and menthol help you breathe better. What is good for humans can also be used for pigs. To use plant extracts efficiently, it is crucial to know their specific modes of action. Due to their volatile nature, essential oils can directly reach the target site, the respiratory tract, via inhalation¹.

1.   Plant extracts can act as an antimicrobial

Many essential oils show some degree of antimicrobial activity. So, the oils of, e. g., oregano, tea tree, lemongrass, lemon myrtle, and clove are effective against a wide range of gram-positive and gram-negative bacteria. LeBel et al. (2019)¹² tested nine different oils against microorganisms causing respiratory issues in pigs. They found the oils of cinnamon, thyme, and winter savory the most effective against Streptococcus suis, Actinobacillus pleuropneumoniae, Actinobacillus suis, Bordetella bronchiseptica, Haemophilus parasuis, and Pasteurella multocida, with MICs and MBCs from 0.01 to 0.156%.

Not only the direct bactericidal effect is important. 1,8 cineol, e.g., although often considered to have only marginal or no antimicrobial activity¹⁰, effectively causes leakage of bacterial membranes² and allows other harmful substances to enter the bacterial cell. However, cineol possesses noted antiviral properties.

2.  Plant extracts can have mucolytic, spasmolytic, and antitussive effects

In the case of respiratory disease, mucolytic and spasmolytic characteristics of phytomolecules are decisive in allowing efficient respiration. Mucolytic substances dissolve the mucus, make it more liquid and facilitate the removal from the respiratory tract by the ciliated epithelium. As liquifying the mucus with essential oils or phytomolecules is related to local irritation, dosage and application form are of the highest importance⁵.

The “cleanup” is called mucociliary clearance. There are also substances that do not dissolve the mucus but stimulate the mucociliary apparatus itself and increase mucociliary transport velocity¹.

Spasmolytic activity on airway smooth muscle is shown, for example, by menthol⁸ or the essential oil of eucalyptus tereticornis⁴. Menthol showed antitussive effects¹¹.

3.   Plant extracts can have immune-modulatory and anti-inflammatory effects

If animals are suffering from a respiratory disease or are in danger of catching one, a supportive influence on the immune system is helpful. One thing is to make vaccination more effective. Mieres-Castro et al. (2021)¹⁴ figured out that the combined application of influenza vaccine and cineol to mice resulted in a longer survival time, less inflammation, less weight loss, a lower mortality rate, less pulmonary edema, and lower viral titers after a challenge with the virus seven days after the vaccination than the mice without cineol.

On the other hand, if the animals are already ill, strengthening their immune defense is essential. Li et al. (2012)¹³ showed that interleukin-6 concentration was lower (p<0.05) and the tumor necrosis factor-α level was higher (p<0.05) in the plasma of pigs fed a diet with 0.18% thymol and cinnamaldehyde than in the negative control group. Also, the lymphocyte proliferation for pigs fed the diet with thymol and cinnamaldehyde increased significantly compared with the negative control (p<0.05).

4.   Plant extracts can act as an antioxidant

There are respiratory diseases in which reactive oxygen species (ROS) play an important role. In these cases, the antioxidant activity of phytomolecules is of interest. Here again, Li et al. (2012)¹³ asserted that a diet with 0.18% thymol and cinnamaldehyde increased the total antioxidant capacity level (p<0.05) in pigs compared to a negative control group.

Can Baser & Buchbauer (2010) described eucalyptus oil containing 1,8-cineole, the monoterpene hydrocarbons α-pinene (10–12%), p-cymene, and α-terpinene, and the monoterpene alcohol linalool, is used to treat diseases of the respiratory tract in which ROS play an important role.

5.   Plant extracts reduce the production of ammonia

High concentration of ammonia in the pig house stresses the pigs’ respiratory tract and makes them susceptible to disease. Ammonia develops when feces and urine merge and the enzyme urease degrades them. Yucca extract, containing a high percentage of saponins, can reduce ammonia emissions in animal houses. Ehrlinger (2007)⁵ supposes that the glyco-components of the saponins bind ammonia and other harmful gases. Another explanation can be the decreased activity of urease shown in a trial with rats¹⁹ or the reduction of total nitrogen, urea nitrogen, and ammonia nitrogen in sow manure³.

6.   Plant extracts often show diverse modes of useful action against respiratory issues

Due to their natural task – protecting the plant – essential oils typically do not show only one beneficial activity for us. Camphene, for example, in Thymus vulgaris, shows expectorant, spasmolytic, and antimicrobial properties and is used in treating respiratory tract infections. Menthol can be effectively used in cases of asthma due to its bronchodilatory activity on smooth muscle, its interaction with cold receptors, and the respiratory drive. Menthol acts antitussive in low concentration, gives the impression of decongestion and reduces respiratory discomfort and sensations of dyspnea.

Cineol, on its part, acts antimicrobial, antitussive, bronchodilatory, mucolytic, and anti-inflammatory. It promotes ciliary transport and improves lung function^{1, 6}. Mucolytic, antioxidant, antiviral, and antibacterial activity is ascribed to thymol⁵.

Trial shows: phytomolecules help to keep respiratory diseases in check

A field study was conducted on a Philippine piglet farm with a history of chronic respiratory issues during the growing phase, with a morbidity of about 10-15%. In this study, a supplement for water containing phytomolecules that support animals against respiratory diseases (Grippozon) was tested. For the trial, 360 randomly selected 28-day-old pigs (average weight: 6.64±0.44 kg) were divided into two groups with 6 replications per group and 30 piglets per replication. All piglets came from sows raised antibiotic-free, and the piglets received antibiotics neither upon weaning except in case of symptoms (scouring: Baytril-1 mL/pig;  respiratory disease: Excede – 1mL/pig). All piglets received the same feed and a regular water therapy regimen:

Control group: no additional supplements
Grippozon group:  Addition of 250 mL of Grippozon per 1000 L of water

As parameters, the incidence of respiratory disease, final weight, daily gain, FCR, and antibiotic cost, were recorded.

The phytomolecules-containing product reduced the incidence of respiratory diseases by 52 %, leading to a 53% lower cost for antibiotic treatment. The animals showed better growth performance (600 g higher average weight and 13 g higher average daily gain), altogether resulting in an extra cost-benefit of 1.76 US$ per pig.

Reduction in disease and medication ensures healthier pigs in the Grippozon-supplemented group, reflected by better performance.

We have means at hand to reduce the use of antibiotics

Respiratory disease is a big problem in pigs. Due to the still high occurrence of antimicrobial resistance, it is essential to reduce antibiotic use as much as possible. Phytomolecules offer the possibility to strengthen the animals’ health so that they are less susceptible to disease or support them when they are already infected. With the help of phytomolecules, we can reduce antibiotic treatments and help keep antibiotics effective when their use is indispensable.

References

1. Can Baser , K. Hüsnü, and Gerhard Buchbauer. Handbook of Essential Oils: Science, Technology, and Applications. Boca Raton, FL: Taylor & Francis distributor, 2010.
2. Carson, Christine F., Brian J. Mee, and Thomas V. Riley. “Mechanism of Action of Melaleuca Alternifolia (Tea Tree) Oil on Staphylococcus Aureus Determined by Time-Kill, Lysis, Leakage, and Salt Tolerance Assays and Electron Microscopy.” Antimicrobial Agents and Chemotherapy 46, no. 6 (2002): 1914–20. https://doi.org/10.1128/aac.46.6.1914-1920.2002.
3. Chen, Fang, Yantao Lv, Pengwei Zhu, Chang Cui, Caichi Wu, Jun Chen, Shihai Zhang, and Wutai Guan. “Dietary Yucca Schidigera Extract Supplementation during Late Gestating and Lactating Sows Improves Animal Performance, Nutrient Digestibility, and Manure Ammonia Emission.” Frontiers in Veterinary Science 8 (2021). https://doi.org/10.3389/fvets.2021.676324.
4. Coelho-de-Souza, Lívia Noronha, José Henrique Leal-Cardoso, Francisco José de Abreu Matos, Saad Lahlou, and Pedro Jorge Magalhães. “Relaxant Effects of the Essential Oil of Eucalyptus Tereticornisand Its Main Constituent 1,8-Cineole on Guinea-Pig Tracheal Smooth Muscle.” Planta Medica 71, no. 12 (2005): 1173–75. https://doi.org/10.1055/s-2005-873173.
5. Ehrlinger, Miriam. “Phytogene Zusatzstoffe in der Tierernährung.” Dissertation, Tierärztliche Fakultät LMU, 2007.
6. Gelbe Liste Online. “Gelbe Liste Pharmindex Online.” Gelbe Liste. Accessed January 20, 2023. https://www.gelbe-liste.de/.
7. Hennig-Pauka, Isabell. “Atemwegserkrankungen: Schutz fängt schon bei Ferkeln an.” Der Hoftierarzt, January 13, 2021. https://derhoftierarzt.de/2021/01/atemwegserkrankungen-schutz-faengt-schon-bei-ferkeln-an/.
8. Ito, Satoru, Hiroaki Kume, Akira Shiraki, Masashi Kondo, Yasushi Makino, Kaichiro Kamiya, and Yoshinori Hasegawa. “Inhibition by the Cold Receptor Agonists Menthol and ICILIN of Airway Smooth Muscle Contraction.” Pulmonary Pharmacology & Therapeutics 21, no. 5 (2008): 812–17. https://doi.org/10.1016/j.pupt.2008.07.001.
9. Kim, K.H., E.S. Cho, K.S. Kim, J.E. Kim, K.H. Seol, S.J. Sa, Y.M. Kim, and Y.H. Kim. “Effects of Stocking Density on Growth Performance, Carcass Grade and Immunity of Pigs Housed in Sawdust Fermentative Pigsties.” South African Journal of Animal Science 46, no. 3 (2016): 294–301. https://doi.org/10.4314/sajas.v46i3.9.
10. Kotan, Recep, Saban Kordali, and Ahmet Cakir. “Screening of Antibacterial Activities of Twenty-One Oxygenated Monoterpenes.” Zeitschrift für Naturforschung C 62, no. 7-8 (2007): 507–13. https://doi.org/10.1515/znc-2007-7-808.
11. Laude, E.A., A.H. Morice, and T.J. Grattan. “The Antitussive Effects of Menthol, Camphor, and Cineole in Conscious Guinea-Pigs.” Pulmonary Pharmacology 7, no. 3 (1994): 179–84. https://doi.org/10.1006/pulp.1994.1021.
12. LeBel, Geneviève, Katy Vaillancourt, Philippe Bercier, and Daniel Grenier. “Antibacterial Activity against Porcine Respiratory Bacterial Pathogens and in Vitro Biocompatibility of Essential Oils.” Archives of Microbiology 201, no. 6 (2019): 833–40. https://doi.org/10.1007/s00203-019-01655-7.
13. Li, Xue, Xia Xiong, Xin Wu, Gang Liu, Kai Zhou, and Yulong Yin. “Effects of Stocking Density on Growth Performance, Blood Parameters and Immunity of Growing Pigs.” Animal Nutrition 6, no. 4 (2020): 529–34. https://doi.org/10.1016/j.aninu.2020.04.001.
14. Mieres-Castro, Daniel, Sunny Ahmar, Rubab Shabbir, and Freddy Mora-Poblete. “Antiviral Activities of Eucalyptus Essential Oils: Their Effectiveness as Therapeutic Targets against Human Viruses.” Pharmaceuticals 14, no. 12 (2021): 1210. https://doi.org/10.3390/ph14121210.
15. Opriessnig, T., L. G. Giménez-Lirola, and P. G. Halbur. “Polymicrobial Respiratory Disease in Pigs.” Animal Health Research Reviews 12, no. 2 (2011): 133–48. https://doi.org/10.1017/s1466252311000120.
16. Pagot, E., P. Keita, and A. Pommier. “Relationship between Growth during the Fattening Period and Lung Lesions at Slaughter in Swine.” Revue Méd. Vét., , , 5, 253-259 158, no. 5 (2007): 253–59.
17. Pallarés Martínez, Francisco José, Jaime Gómez Laguna, Inés Ruedas Torres, José María Sánchez Carvajal, Fernanda Isabel Larenas Muñoz, Irene Magdalena Rodríguez-Gómez, and Librado Carrasco Otero. “The Economic Impact of Pneumonia Processes in Pigs.” https://www.pig333.com. Pig333.com Professional Pig Community, December 14, 2020. https://www.pig333.com/articles/the-economic-impact-of-pneumonia-processes-in-pigs_16470/.
18. Paz-Sánchez, Yania, Pedro Herráez, Óscar Quesada-Canales, Carlos G. Poveda, Josué Díaz-Delgado, María del Quintana-Montesdeoca, Elena Plamenova Stefanova, and Marisa Andrada. “Assessment of Lung Disease in Finishing Pigs at Slaughter: Pulmonary Lesions and Implications on Productivity Parameters.” Animals 11, no. 12 (2021): 3604. https://doi.org/10.3390/ani11123604.
19. Preston, R. L., S. J. Bartle, T. May, and S. R. Goodall. “Influence of Sarsaponin on Growth, Feed and Nitrogen Utilization in Growing Male Rats Fed Diets with Added Urea or Protein.” Journal of Animal Science 65, no. 2 (1987): 481–87. https://doi.org/10.2527/jas1987.652481x.
20. Ruggeri, Jessica, Cristian Salogni, Stefano Giovannini, Nicoletta Vitale, Maria Beatrice Boniotti, Attilio Corradi, Paolo Pozzi, Paolo Pasquali, and Giovanni Loris Alborali. “Association between Infectious Agents and Lesions in Post-Weaned Piglets and Fattening Heavy Pigs with Porcine Respiratory Disease Complex (PRDC).” Frontiers in Veterinary Science 7 (2020). https://doi.org/10.3389/fvets.2020.00636.
21. Straw , B. E., V. K. Tuovinen, and M. Bigras-Poulin. “Estimation of the Cost of Pneumonia in Swine Herds.” J Am Vet Med Assoc. 1989 Dec 15;195(12):1702-6. 195, no. 12 (December 15, 1989): 1702–6.
22. White, Mark. “Porcine Respiratory Disease Complex (PRDC).” Livestock 16, no. 2 (2011): 40–42. https://doi.org/10.1111/j.2044-3870.2010.00025.x.

By Technical Team, EW Nutrition

A variety of stressors simultaneously occur at weaning, making this probably the most challenging period in pig production. During weaning, we commonly see altered gut development and gut microbiome, which increases piglets’ vulnerability to diseases. The most classic clinical symptom resulting from these stressors is the occurrence of post-weaning diarrhea. It is a sign that something went wrong, and piglet development and overall performance may be compromised (Guevarra et al. 2019).

Besides weaning, an unavoidable practice in pig production, the swine industry has been facing other changes. Among them, the increased pressure to reduce the use of antimicrobials stands out. Antimicrobials are often associated with improved piglet performance and health. Their usage has been reduced worldwide, however, due to the threat of antimicrobial resistance that affects not just animal health but also human health (Cardinal et al., 2019).

Reduce antimicrobials and post-weaning diarrhea: can piglet nutrition achieve both?

With these drastic changes for the piglets and the global swine industry, producers must find solutions to keep their farms profitable — especially from a nutritional perspective. Our last article presented two feed additives that can be part of an antibiotic-free concept for post-weaning piglets. This article will highlight a few essential nutritional strategies that swine producers and nutritionists must consider when formulating post-weaning feed without or with reduced amounts of antimicrobials.

What makes weaning so stressful for piglets?

Producers, nutritionists, and veterinarians all agree that weaning is a tough time for piglets (Yu et al., 2019) and, therefore, a challenge to all those involved in the pig production chain. Although there is a global trend towards increasing weaning age, generally speaking, animals are still immature when going through the weaning process. They face several physiological, nutritional, and environmental changes (figure 1).

Figure 1. Factors associated with weaning can compromise piglet well-being and performance

Most of these changes become “stressors” that trigger a cascade of reactions affecting the balance and morphology of the intestinal microbiome (figure 2). The outcome is a decrease in the piglets’ well-being and, in most cases, performance. We need to clearly understand how these stressors affect pigs to develop effective strategies against post-weaning growth impairments, especially when no antimicrobials are allowed.

Figure 2. Schematic diagram illustrating the effects of stress in weaned piglets (adapted from Jayaraman and Nyachoti, 2017)

Weaning support starts before weaning

The use of creep feed has been evaluated and even criticized for many years. Some operations are still reluctant to use such a feed due to its high cost and amount of labor on the farm, with manually providing feed and cleaning feeding trays. In addition, some questions have been raised regarding the ideal composition of the creep feed – how much complexity should we add to this special diet?

Therefore, the benefits of creep feed are under re-evaluation, not only considering piglet physiology per se, but also feed characteristics and different feeding programs. Recent studies have questioned highly complex creep feed formulations. Creep feed is being called “transition feed” (Molist, 2021) – i.e., that meal which is complementary to sows’ milk and not a replicate of it, helping piglets during the period of changing its main source of nutrients. We must, therefore, look at it as a way of making piglets familiar with solid feed, as highlighted by Mike Tokach during the 2020 KSU Swine Day. Dr. Tokach also mentioned that the presence of feeders in the lactation pen could stimulate the exploratory behaviors of the piglets. Combined, these practices can lead to a higher feed intake and performance during the nursery phase.

Towards a pragmatic stance on creep feed

Heo et al. (2018) evaluated three different creep feed types: a highly digestible creep feed, weaning feed as creep feed, and sow feed as creep feed until weaning. Piglets receiving the highly digestible creep had higher feed intake during the second to the last week pre-weaning (14 to 21 days of age) and higher ADG during the last week pre-weaning (21 to 28 days of age). This resulted in a trend for higher weaning weight. However, these benefits did not persist after weaning when all piglets received the weaning feed.

Guevarra et al. (2019) also suggested that the abrupt transition in piglet nutrition to a more complex nutrient source can influence shifts in the gut microbiota, impacting the absorptive capacity of the small intestine. Yang et al. (2016) evaluated 40 piglets from eight litters during the first week after weaning. They found that the change in diet during weaning reduced the proliferation of intestinal epithelial cells. This indicates that this period affects cellular macromolecule organization and localization, in addition to energy and protein metabolism. These results suggest that “similarity” in feed pre- and post-weaning may contribute more to the continuity of nutrient intake post-weaning than a highly complex-nutrient dense creep feed.

Nutritional strategies without antibiotics: focus on pig physiology

As mentioned, it is crucial to avoid a drastic drop in feed/nutrient intake after weaning compared to pre-weaning levels. In a classic study, Pluske et al. (1996) showed the importance of high intake levels on villus weight (used as a reference for gut health, cf. graph 1). Although not desirable, the reduction should be considered “normal” behavior.

Imagine these recently weaned piglets, facing all these stressors, having to figure out within this new group of peers when it is time to eat, where to find food, why water and food now come from two distinct sources… Therefore, management, feeding, water quality, and other aspects play important roles in post-weaning feed intake (figure 3).

Graph 1. Villus height following different levels of feed intake (M = maintenance) post-weaning (a.b.c bars with unlike superscript letters are different at P<0.05). (From Pluske et al., 1996.)

From a nutritional perspective, piglets at weaning experience a transition from milk (a high-fat, low-carbohydrate liquid) to a plant-based diet (a solid, low-fat, and high-carbohydrate diet) (Guevarra et al., 2019). Even when previously introduced to solid feed, it is still difficult for their enzymatic system to cope with grains and beans.

One of the consequences of the lower digestibility capacity is an increase of undigested nutrients. Harmful bacteria thrive and cause diarrhea, reducing even further an already compromised feed intake. This cycle must be broken with the support of formulations based on piglet physiology.

Post-weaning feed must support digestion and nutrient absorption, including the largest possible share possible of high-quality, digestible ingredients, with low anti-nutritional factors. High-performing feed also integrates functional amino acids, functional carbohydrates, and additives to support the intestinal mucosa and gut microbiome.

Figure 3. Supporting piglets with effective solutions

Crude protein – more of the same?

Levels of crude protein in piglet feed have been in the spotlight for quite some time. The topic can be very controversial where the exact percentage of crude protein in the final feed is concerned. Some nutritionists pragmatically recommend maximal levels of 20% in the weaner feed. Others go a bit lower, with some formulations reaching 17 to 18% total crude protein. Levels above 20% will incur high costs and may accentuate the growth of pathogenic bacteria due to a higher amount of undigested protein in the distal part of the small intestine (figure 4).

Figure 4. The dynamics of crude protein levels in piglet feed

What is not open for discussion, however, is the quality of the protein used, in terms of:

• digestibility,
• the total amount of anti-nutritional factors, and
• the correct supply of essential and non-essential amino acids (particularly lysine, methionine, threonine, tryptophane, isoleucine and valine).

The critical role of digestibility

High-digestibility ingredients for piglets need to deliver minimum 85% digestibility. In most cases, to reach high biological values (correlating to high digestibility), these ingredients typically undergo different processing steps, including heat, physical, and chemical treatments. Animal by-products (such as hydrolyzed mucosa, fish meal, spray-dried plasma) and processed vegetable sources (soy protein concentrate, extruded grains, potato protein) can be used in high amounts during this phase. They will notably reduce the total amount of undigested protein reaching the distal part of the intestine, with 2 main benefits:

• Less substrate for pathogenic bacteria proliferation (and therefore lower incidence of diarrhea)
• Lower nitrogen excretion to the environment

It is common knowledge that certain storage proteins from soybean meal (for instance, glycinin and B-conglycinin) can cause damage to piglets’ intestinal morphology and trigger the activation of the immune system. However, it is normal practice to introduce this ingredient to piglets around weaning so that the animals can develop a certain level of tolerance to such compounds (Tokach et al., 2003). In Europe, where most diets are wheat-barley based, soybean meal is included in levels varying from 3 to 9% in the first 2 diets, with gradual increases during the nursery phase.

Amino acids and protein: manage the balance

When the supply and balance between essential and non-essential amino acids is concerned, reducing total crude protein brings indeed complexity to the formulations. The concept of ideal amino acid should be expanded, ideally, to all 9 essential amino acids (lysine, methionine, tryptophan, threonine, valine, isoleucine, leucine, histidine, and phenylalanine). In most cases, formulations go up to the 5^th or 6^th limiting amino acid. Lawor et al. (2020) suggest 2 practical approaches to avoid deficiencies when formulating low-protein piglet feed:

• Maintain a maximum total lysine to crude protein ratio in the diet of 7.1 to 7.4%
• Do not exceed the SID lysine to crude protein ratio of 6.4%

Some conditionally essential amino acids (e.g. arginine, proline, and glutamine) also play critical roles in diets with reduced crude protein levels. Glutamine is especially interesting. When supplemented in the feed, it can be used as a source of energy by the intestinal epithelium and, therefore, prevent atrophy and support nutrient absorption, resulting in better growth post-weaning (Hanczakowska and Niwińska, 2013; Watford et al., 2015)

The importance of the buffer capacity of the feed – supporting the enzymatic system

Given the move towards antibiotic reduction, this topic is more relevant than ever to nutritionists worldwide. The acid-binding capacity (also known as buffering capacity) of the feed directly affects the capacity of the stomach to digest protein. Hence, buffer capacity is of utmost importance in antimicrobial-free diets as it influences the growth of pathogenic bacteria (Lawlor et al., 2005).

In short, the acid-binding capacity is the resistance of an ingredient or complete feed to pH change. For piglet feed/feed ingredients, it is normally measured by the acid-binding capacity at pH4 (ABC-4). A higher ABC-4 equates to a higher buffering capacity. Feed with a high ABC-4 would require large amounts of gastric acid for the pH of the stomach to reach 4 and below. As the post-weaned piglet has limitations on producing and secreting acid, the stomach pH would stay high and, thus, less favorable for protein digestion.

The recommendation is to have a complete feed based on single ingredients with low ABC-4 values and to use additives that further reduce the ABC-4 value (such as organic acids). According to Molist (2020), post-weaning feed must have an ABC-4 that is lower than 250-300 meq/kg.

Talking about fiber

Dietary fibers are also known for regulating intestinal health in both humans and animals. Chen et al. (2020), for example, examined the effects of dietary soluble fibers (inulin) and insoluble fibers (lignocellulose) in weaned piglet diets for four weeks. Results showed that combining those fibers can positively influence nutrient digestibility, gut microbiota composition, intestinal barrier functions, and growth performance (table 1 ).

Table 1. Effects of dietary fiber supplementation on piglet growth performance (adapted from Chen et al., 2020)

How to reduce antimicrobials? Understand the roles of piglet physiology and nutrition

Swine producers might think that “How can I reduce antimicrobial use on my farm?” and “How can I improve the performance of piglets at weaning?” are two separate questions. However, that is not always the case. Answers based on a deep understanding of physiology and nutrition dynamics help piglets overcome the challenges encountered during weaning – and, thus, lessen the need for antimicrobial interventions.

In this article, we have explored the basic principles that are the basis for ensuring the performance and health of the post-weaning piglet. Although we do not have a singular solution for eliminating antimicrobials on our pig farms, we can count on a group of robust and integrated nutritional strategies. By integrating factors ranging from management to feed additives, these solutions can improve piglet health and performance throughout their lives.

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Piglet weaning is a critical period. When not properly managed, it leads to decreased performance, diarrhea, and sometimes mortality. 

The six areas of intervention in our infographic will help pig producers manage these stressors, avoid diarrhea, and maintain piglet health and performance. 

In June 2017, the European Commission decided to ban the use of veterinary drugs containing high doses of zinc oxide (3000mg/kg) from 2022. The use of zinc oxide in pig production must then be limited to a maximum level of 150ppm. Companies have been on the lookout for effective alternative strategies to maintain high profitability.

Modern pig production is characterised by its high intensity. In many European countries, piglets are weaned after 3-4 weeks, before their physiological systems are fully developed (e.g. immune and enzyme system). Weaning and thus separation from the mother, as well as a new environment with new germs, means stress for the piglets. Besides, the highly digestible sow’s milk, for which the piglets are wholly adapted, is replaced by solid starter feed.

This, associated with the above-mentioned stressors, can result in reduced feed intake during the first week after weaning and therefore in a delayed adaptation of the intestinal flora to the feed. Since the immune system of animals is not yet fully functional, pathogens such as enterotoxic E. coli can colonize the intestinal mucosa. This can possibly develop into a dangerous dysbiosis, leading to an increased incidence of diarrhea. Inadequate absorption results in suboptimal growth with worse feed conversion. The consequences are economic losses due to higher treatment costs, lower yields, and animal losses.

Diarrhea is one of the most common causes of economic losses in pig production. In the past, this was the reason antibiotics were prophylactically used as growth promoters. Antibiotics reduce antimicrobial pressure and have an anti-inflammatory effect. In addition to reducing the incidence of disease, they eliminate competitors for nutrients in the gut and thus improve feed conversion.

However, the use of antibiotics as growth promoters has been banned in the EU since 2006 due to increased antimicrobial resistance. As a result, zinc oxide (ZnO) appeared on the scene. A study carried out in Spain in 2012 (Moreno, 2012) showed that 57% of piglets received ZnO before weaning and 73% during the growth phase (27-75 days).

Zinc oxide: the disadvantages outweigh the advantages

What made the use of zinc oxide so attractive? Zinc oxide is inexpensive, available in many EU countries, and as a trace element it can be used in high doses through premixing. In some countries, however, a veterinary prescription is needed; in others, the use is already banned.

Zinc is a trace element involved in cell division and differentiation, and it influences the efficacy of enzymes. Since defence cells also need zinc, a supplementation that covers the demand for zinc strengthens the body’s defences. Through a positive effect on the structure of the gut mucosa membrane, zinc protects the body against the penetration of pathogenic germs.

If ZnO is used in pharmacological doses, it has a bactericidal effect against e.g. staphylococci (Ann et al., 2014) and various types of E. coli (Vahjen et al., 2016). Thus, prophylactic use prevents the incidence of diarrhea and the consequent decrease in performance. But the use of zinc oxide also has “side effects”.

Accumulation in the environment

Zinc belongs to the chemical group of heavy metals. For the use as a performance enhancer, it has to be administered in relatively high doses (2000–4000ppm). These high amounts are far above the physiological needs of the animals. With relatively low absorption rates (the bioavailability amounts to approximately 20% (European Commission, 2003)) and subsequent accumulation in manure, zinc can cause substantial contamination of the environment.

Encouraging the development of antibiotic resistance

In addition to the accumulation of zinc in the environment, another aspect also plays an important role: according to Vahjen et al. (2015), a dose of ≥2500mg/kg of food increases the presence of tetracycline and sulfonamide resistance genes in bacteria. In the case of Staphylococcus aureus, the development of resistance to zinc is combined with the development of resistance to methicillin (MRSA; Cavaco et al., 2011; Slifierz et al., 2015). A similar effect can be observed in the development of multiresistant E. coli (Bednorz et al., 2013; Ciesinski et al., 2018).  The reason for this is that the genes that encode antibiotic resistance, i.e. the ones that are “responsible” for the resistance, are found in the same plasmid (a DNA molecule that is small and independent of the bacterial chromosome).

Consequence: no more zinc oxide in the production of piglets from 2022 onwards

The negative effects on the environment and the promotion of antibiotic resistance led to the European Commission’s decision in 2017 to completely ban zinc oxide as a therapeutic agent and as a growth promoter in piglets within five years.

There are effective alternatives to zinc oxide

By the 2022 deadline, the EU pig industry must find a solution to replace ZnO. It must develop strategies that make future pig production efficient, even without substances such as antibiotics and zinc oxide. To this end, measures should be taken at different levels, such as farm management and biosecurity (e.g. effective hygiene management). The promotion of intestinal health for high animal performance is most important, however.

Promotion of gut health through stable gut microbiota

The term eubiosis denotes the balance of microorganisms living in a healthy intestine, which must be maintained to prevent diarrhea and ensure performance. However, weaning, food switching, and other external stressors can endanger this balance. As a result, potentially pathogenic germs can “overgrow” the commensal microbiome and develop dysbiosis. Through the use of functional supplements, intestinal health can be improved.

Phytomolecules – potent compounds created by nature

Phytomolecules, or secondary plant compounds, are substances formed by plants with a wide variety of properties. The best-known groups are probably essential oils, but there are also bitter substances, spicy substances, and other groups.

In animal nutrition, phytomolecules such as carvacrol, cinnamon aldehyde, and capsaicin can help improve intestinal health and digestion. They stabilize the intestinal flora by slowing or stopping the growth of pathogens that can cause disease. How? Phytomolecules, for example, make the cell walls of several bacteria permeable so that cell contents can leak. They also partially interfere with the enzymatic metabolism of the cell or intervene with the transport of ions, reducing the proton motive force. These effects depend on the dose: all these actions can destroy bacteria or at least prevent their proliferation.

Another point of attack for phytomolecules is the communication between microorganisms (quorum sensing). Phytomolecules can prevent microorganisms from releasing substances known as autoinducers, which they need to coordinate joint actions such as the formation of biofilms or the expression of virulence factors.

Medium-chain triglycerides and fatty acids

Medium-chain triglycerides (MCT) and fatty acids (MCFA) are characterised by a length of six to twelve carbon atoms. Thanks to their efficient absorption and metabolism, they can be optimally used as an energy source in piglet feeding. MCTs can be completely absorbed by the epithelial cells of the intestinal mucosa and hydrolysed with microsomal lipases. Hence they serve as an immediately available energy source and can improve the epithelial structure of the intestinal mucosa (Hanczakowska, 2017).

In addition, these supplements have a positive influence on the composition of the intestinal flora. Their ability to penetrate bacteria through semi-permeable membranes and destroy bacterial structures inhibits the development of pathogens such as salmonella and coliforms (Boyen et al., 2008; Hanczakowska, 2017; Zentek et al., 2011). MCFAs and MCTs can also be used very effectively against gram-positive bacteria such as streptococci, staphylococci, and clostridia (Shilling et al., 2013; Zentek et al., 2011).

Prebiotics

Prebiotics are short-chain carbohydrates that are indigestible for the host animal. However, certain beneficial microorganisms such as lactobacilli and bifidobacteria can use these substances as substrates. By selectively stimulating the growth of these bacteria, eubiosis is promoted (Ehrlinger, 2007). In pigs, mannan-oligosaccharides (MOS), fructooligosaccharides (FOS), inulin and lignocellulose are mainly used.

Another element of prebiotics’ positive effect on intestinal health is their ability to agglutinate pathogens. Pathogenic bacteria and MOS can bind to each other through lectin. This agglutination prevents pathogenic bacteria from adhering to the wall of the intestinal mucosa and thus from colonizing the intestine (Oyofo et al., 1989).

Probiotics

Probiotics can be used to regenerate an unbalanced gut flora. To do this, useful bacteria such as bifido or lactic acid bacteria are added to the food. They must settle in the gut and compete with the harmful bacteria.

There are also probiotics which target the communication between pathogens. In an experiment, Kim et al. (2017) found that the addition of probiotics that interfere with quorum sensing can significantly improve the microflora in weaned piglets and thus their intestinal health.

Organic acids

Organic acids show strong antibacterial activity in animals. In their undissociated form, the acids can penetrate bacteria. Inside, the acid molecule breaks down into a proton (H+) and an anion (HCOO-). The proton reduces the pH value in the bacterial cell and the anion interferes with the bacteria’s protein metabolism. As a result, bacterial growth and virulence are inhibited.

Conclusion

Today there are several possibilities in piglet nutrition to effectively support the young animals after weaning. The main objective is to maintain a balanced intestinal flora and therefore to sustain intestinal health – its deterioration often leads to diarrhea and hence to reduced returns. Intestinal health is promoted by stimulating beneficial bacteria and by inhibiting pathogenic ones. This can be achieved through feed additives that have an antibacterial effect and/or support the intestinal mucosa, such as phytomolecules, prebiotics, and medium-chain fatty acids. Through a combination of these possibilities, additive effects can be achieved. Piglets receive optimal support and the use of zinc oxide can be reduced.

References

Ann, Ling Chuo, Shahrom Mahmud, Siti Khadijah Mohd Bakhori, Amna Sirelkhatim, Dasmawati Mohamad, Habsah Hasan, Azman Seeni, and Rosliza Abdul Rahman. “Antibacterial Responses of Zinc Oxide Structures against Staphylococcus Aureus, Pseudomonas Aeruginosa and Streptococcus Pyogenes.” Ceramics International 40, no. 2 (March 2014): 2993–3001. https://doi.org/10.1016/j.ceramint.2013.10.008.

Bednorz, Carmen, Kathrin Oelgeschläger, Bianca Kinnemann, Susanne Hartmann, Konrad Neumann, Robert Pieper, Astrid Bethe, et al. “The Broader Context of Antibiotic Resistance: Zinc Feed Supplementation of Piglets Increases the Proportion of Multi-Resistant Escherichia Coli in Vivo.” International Journal of Medical Microbiology 303, no. 6-7 (August 2013): 396–403. https://doi.org/10.1016/j.ijmm.2013.06.004.

Boyen, F., F. Haesebrouck, A. Vanparys, J. Volf, M. Mahu, F. Van Immerseel, I. Rychlik, J. Dewulf, R. Ducatelle, and F. Pasmans. “Coated Fatty Acids Alter Virulence Properties of Salmonella Typhimurium and Decrease Intestinal Colonization of Pigs.” Veterinary Microbiology 132, no. 3-4 (December 10, 2008): 319–27. https://doi.org/10.1016/j.vetmic.2008.05.008.

Cavaco, Lina M., Henrik Hasman, Frank M. Aarestrup, Members Of Mrsa-Cg: Jaap A. Wagenaar, Haitske Graveland, Kees Veldman, et al. “Zinc Resistance of Staphylococcus Aureus of Animal Origin Is Strongly Associated with Methicillin Resistance.” Veterinary Microbiology 150, no. 3-4 (June 2, 2011): 344–48. https://doi.org/10.1016/j.vetmic.2011.02.014.

Ciesinski, Lisa, Sebastian Guenther, Robert Pieper, Martin Kalisch, Carmen Bednorz, and Lothar H. Wieler. “High Dietary Zinc Feeding Promotes Persistence of Multi-Resistant E. Coli in the Swine Gut.” Plos One 13, no. 1 (January 26, 2018). https://doi.org/10.1371/journal.pone.0191660.

Crespo-Piazuelo, Daniel, Jordi Estellé, Manuel Revilla, Lourdes Criado-Mesas, Yuliaxis Ramayo-Caldas, Cristina Óvilo, Ana I. Fernández, Maria Ballester, and Josep M. Folch. “Characterization of Bacterial Microbiota Compositions along the Intestinal Tract in Pigs and Their Interactions and Functions.” Scientific Reports 8, no. 1 (August 24, 2018). https://doi.org/10.1038/s41598-018-30932-6.

Ehrlinger, Miriam. 2007. “Phytogene Zusatzstoffe in der Tierernährung.“ PhD Diss., LMU München. URN: urn:nbn:de:bvb:19-68242.

European Commission. 2003. “Opinion of the Scientific Committee for Animal Nutrition on the use of zinc in feedingstuffs.”  https://ec.europa.eu/food/sites/food/files/safety/docs/animal-feed_additives_rules_scan-old_report_out120.pdf

Hanczakowska, Ewa. ”The use of medium chain fatty acids in piglet feeding – a review.” Annals of Animal Science 17, no. 4 (October 27, 2017): 967-977. https://doi.org/10.1515/aoas-2016-0099.

Hansche, Bianca Franziska. 2014. „Untersuchung der Effekte von Enterococcus faecium (probiotischer Stamm NCIMB 10415) und Zink auf die angeborene Immunantwort im Schwein. Dr. rer. Nat. Diss., Freie Universität Berlin. https://doi.org/10.17169/refubium-8548

Kim, Jonggun, Jaepil Kim, Younghoon Kim, Sangnam Oh, Minho Song, Jee Hwan Choe, Kwang-Youn Whang, Kwang Hyun Kim, and Sejong Oh. “Influences of Quorum-Quenching Probiotic Bacteria on the Gut Microbial Community and Immune Function in Weaning Pigs.” Animal Science Journal 89, no. 2 (November 20, 2017): 412–22. https://doi.org/10.1111/asj.12954.

Oyofo, Buhari A., John R. Deloach, Donald E. Corrier, James O. Norman, Richard L. Ziprin, and Hilton H. Mollenhauer. “Effect of Carbohydrates on Salmonella Typhimurium Colonization in Broiler Chickens.” Avian Diseases 33, no. 3 (1989): 531–34. https://doi.org/10.2307/1591117.

Shilling, Michael, Laurie Matt, Evelyn Rubin, Mark Paul Visitacion, Nairmeen A. Haller, Scott F. Grey, and Christopher J. Woolverton. “Antimicrobial Effects of Virgin Coconut Oil and Its Medium-Chain Fatty Acids On Clostridium Difficile.” Journal of Medicinal Food 16, no. 12 (December 2013): 1079–85. https://doi.org/10.1089/jmf.2012.0303.

Slifierz, M. J., R. Friendship, and J. S. Weese. “Zinc Oxide Therapy Increases Prevalence and Persistence of Methicillin-Resistant Staphylococcus Aureus in Pigs: A Randomized Controlled Trial.” Zoonoses and Public Health 62, no. 4 (September 11, 2014): 301–8. https://doi.org/10.1111/zph.12150.

Vahjen, Wilfried, Dominika Pietruszyńska, Ingo C. Starke, and Jürgen Zentek. “High dietary zinc supplementation increases the occurrence of tetracycline and sulfonamide resistance genes in the intestine of weaned pigs.” Gut Pathogens 7, article number 23 (August 26, 2015). https://doi.org/10.1186/s13099-015-0071-3.

Vahjen, Wilfried, Agathe Roméo, and Jürgen Zentek. “Impact of zinc oxide on the immediate postweaning colonization of enterobacteria in pigs.” Journal of Animal Science 94, supplement 3 (September 1, 2016): 359-363. https://doi.org/10.2527/jas.2015-9795.

Zentek, J., S. Buchheit-Renko, F. Ferrara, W. Vahjen, A.G. Van Kessel, and R. Pieper. “Nutritional and physiological role of medium-chain triglycerides and medium-chain fatty acids in piglets” Animal Health Research Reviews 12, no. 1 (June 2011): 83-93. https://doi.org/10.1017/s1466252311000089.

Antimicrobial resistance is a natural process but this is accelerated by inappropriate prescribing of antimicrobials, poor infection control practices and the unnecessary use of antimicrobials in agriculture (Barber and Sutherland, 2017).

Antimicrobial resistance – a threat to humanity

Resistance to specific antibiotics occurs through mutations that enable the bacteria to withstand an antibiotic treatment. One mechanism is the production of enzymes degrading or altering the antibiotic, rendering them harmless. The elimination of entrances for antibiotics or the development of pumps discharging them is another possibility. A further option is the elimination of the targets the antibiotic would attack.

So-called “resistance genes” are responsible for resistance. These genes can be transferred from one bacterium to another and also from beneficial bacteria to harmful ones. When antibiotics are used, “normal” bacteria are killed; the resistant ones survive and have all possibilities to proliferate. The Dutch Government has been tracking resistant bacteria in poultry flocks for the last two decades. A clear correlation between antibiotic use and the percentage of resistance could be observed. The good thing: according to the 2020 MARAN report (De Greeff et al., 2020), by reducing the use of antibiotics, the occurrence of resistances can be pushed back.

Figure 1. Sales of antibiotics from 1999 to 2016 and the development of resistances (MARAN report, 2018)

Antibiotic use in animal production

In pig production, antibiotics are often used in stressful situations such as weaning or moving. Antibiotics decrease the pathogenic pressure in animals and help them overcome these critical periods. Disadvantage: Antibiotics do not differentiate between good and bad but between susceptible and resistant. Therefore, also the beneficial gut flora gets destroyed through antibiotic treatment, and resistance is spread.

After the ban of antibiotic growth promoters in Europe in 2006, the US has also made considerable efforts to reduce the use of antibiotics.

Is performance at risk without antibiotics?

When antibiotics are taken out of livestock production, measures in different areas must be implemented to keep performance and profitability high. Without supporting the animals by other means, they will get sick and even die in acute cases. Subclinical disease forms reduce their feed intake, and growth performance consequently decreases. According to literature, losses due to decreased average weight gain can be up to $40 per pig (Hao et al., 2014).

Goal: reducing antibiotics while maintaining performance

To support pigs, especially during the afore-mentioned critical periods, alternatives focusing on the maintenance of gut health and, therefore, also overall health must be chosen. This goal can only be achieved by balancing the intestinal flora with reducing pathogenic bacteria occurrence.

Phytomolecules are an effective solution

Phytomolecules are produced by plants to defend themselves against predators or pathogens. Farmers use the substances in animal feeds to support digestion, improve palatability, but also to reduce pathogenic pressure (Baser and Buchbauer, 2010).

In animal feeding, different application forms are available:

• As premixes containing microencapsulated phytomolecules with a slow release. This version is mixed into the feed in the feed mill and constitutes continuous long-term support for the animals. Due to microencapsulation, the active substances are released where they are needed – in the gut.
• As liquid complementary feeds for the application via the waterline. The application of the liquid form to the animals can be decided from one day to the other. It is an optimal additional tool to support the pigs in challenging situations such as weaning.

Scientific trials show: In-feed phytomolecules support performance

A trial conducted at the Federal University of Lavras (Brazil) evaluated if phytomolecules as a regular diet component can deliver the same effects on growth performance as AGPs in pig production.

For the trial, 108 castrated newborn male pigs were allocated to 3 groups (control, AGP (antibiotic growth promoters), and Activo). Pigs were weaned at 23 days of age with an average weight of 6.3 kg. They were fed a 3-phase diet (nursery, growing, and finishing). The inclusion rates of the additives (antibiotics and phytomolecules-based product – Activo) are shown in table 1.

On days 0, 1, and 2 of the experiment, the animals were challenged by applying a solution containing 10⁷ CFU of E. coli K88, producing the toxins LT, Sta, and bST. Additionally, during the two last days before the growing phase, the animals were exposed to 5h of heat stress, using infrared lamps and closed windows. The parameters weight gain, final weight, FCR, and gut flora composition in the cecum were evaluated.

Table 1. Inclusion rate of the additives in the feed
AGP: Antibiotic growth promoter; Activo: product based on phytomolecules, microencapsulated (EW Nutrition)

Results

The results of this trial are shown in figure 2.

Concerning growth performance, the group fed the phytomolecules-based product Activo showed a 4.36 kg higher final weight after 126 days than the group provided AGPs (p=0.11), resulting in a 3.28 kg higher weight gain (p=0.21) and a 13 points better feed conversion.

Figure 2. Data of growth performance including final weight, weight gain and FCR adjusted to 100kg

The evaluation of some bacteria naturally occurring in the gut flora showed that, in contrast to the antibiotic prophylaxes, Activo has no negative impact on E. coli, Lactobacillus and Bifidobacterium. However, the antibiotic group showed a slight decrease in the population of Lactobacilli (Figure 3).

Figure 3. Impact of antibiotics and phytomolecules (Activo) on the composition of the gut flora

This trial shows Activo increasing growth performance and feed conversion without any negative impact on gut flora. The addition of phytomolecules (Activo) to the feed is documented as optimal long-term support instead of antibiotic growth promoters.

Trial shows: Phytomolecules support animals in critical situations like weaning

In a trial conducted in the USA, a product containing phytomolecules and organic acids (Activo Liquid, EW Nutrition) was compared to an antibiotic for controlling bacterial diseases in US pig production (Mecadox). For the trial, a total of 360 weanling pigs, about 19 days old and weighing 5.70 kg, were divided into four groups. Each group consists of 9 pens with 10 animals per pen. All groups were fed a 3-phase diet.

To the different trial groups, the following products were added (table 2):

These performance parameters were evaluated: live weight, daily gain, daily feed intake, feed:gain ratios, and mortality.

Table 2. Feeding and inclusion of the additives

Results

The results of the trial are shown in figure 4. Concerning growth, no significant differences could be seen between the groups, only numerical differences. Live weight in the antibiotic group was 25.95 kg, and in the Activo Liquid groups, it ranges from 25.77 kg (shortest period of application) to 26.20 kg (see below). This resulted in calculated values for an average daily gain of 473 g in the Mecadox fed animals and 463 to 487g in the Activo Liquid groups. Due to a lower feed intake per kg of weight gain, all groups fed Activo Liquid showed a significantly (p=0.05) better feed conversion than the Mecadox group.

Figure 4. Live weight in the groups fed the antibiotic Mecadox and the phytomolecules-based product Activo Liquid for different periods
Average daily gain in the different trial groups
Average daily feed intake in the different trial groups (P=0.05)

Concerning mortality, the group fed Activo Liquid for 5 days showed the lowest mortality rate of 1.1% (figure 5).

Figure 5. Feed:gain ratio in the different trial groups (P=0.05) & Mortality rates

Considering all parameters, the group fed Activo Liquid for five days provided the best results: numerically the lowest mortality rate, highest daily gain, and one of the two lowest feed:gain ratios. This trial concludes that Activo Liquid with an application period of five days can safely replace antibiotic growth promoters in the diet. Therefore, Activo Liquid is an interesting tool to additionally support pigs during critical periods of life.

Phytomolecules help keep health and performance together

The trials conducted with two types of phytomolecules-based products show that phytomolecules efficiently support pigs to achieve their genetic potential. A basic supply of these substances within the feed yields results similar to those of animals receiving antibiotic growth promoters (AGPs). In challenging situations like weaning, additional short-term supply is recommended, which can be done with liquid products via the waterline.

With this strategy, the use of antibiotic growth promoters and, therefore, antibiotics in general can be drastically reduced. This approach can help decrease antimicrobial resistance and, not to be forgotten, accommodates final customers’ requests for the lower usage of antibiotics in livestock.

References

Barber, Sarah, and Nikki Sutherland. “O’Neill Review into Antibiotic Resistance.” House of Commons Library, March 6, 2017. https://commonslibrary.parliament.uk/research-briefings/cdp-2017-0074/.

Baser, Kemal Hüsnü Can, and Gerhard Buchbauer. Handbook of Essential Oils: Science, Technology, and Applications. Boca Raton, FL: Taylor & Francis distributor, 2010.

Davies, Dame Sally. “Antibiotic Resistance ‘Big Threat to Health’.” BBC News. BBC, November 16, 2012. https://www.bbc.co.uk/news/health-20354536.

De Greeff, S.C., A.F. Schoffelen, and C.M. Verduin. “MARAN Reports.” WUR. National Institute for Public Health and the Environment – Ministery of Health, Welfare and Sport, June 2020. https://www.wur.nl/en/Research-Results/Research-Institutes/Bioveterinary-Research/In-the-spotlight/Antibiotic-resistance/MARAN-reports.htm.

Hao, Haihong, Guyue Cheng, Zahid Iqbal, Xiaohui Ai, Hafiz I. Hussain, Lingli Huang, Menghong Dai, Yulian Wang, Zhenli Liu, and Zonghui Yuan. “Benefits and Risks of Antimicrobial Use in Food-Producing Animals.” Frontiers in Microbiology 5, no. Art. 288 (2014): 1–11. https://doi.org/10.3389/fmicb.2014.00288.

Marquardt, Ronald R, and Suzhen Li. “Antimicrobial Resistance in Livestock: Advances and Alternatives to Antibiotics.” Animal Frontiers 8, no. 2 (2018): 30–37. https://doi.org/10.1093/af/vfy001.

O’Neill, J. “Tackling Drug-Resistant Infections Globally.” Review on Antimicrobial Resistance. Wellcome Trust / HM Government, May 19, 2016. https://amr-review.org/sites/default/files/160518_Final%20paper_with%20cover.pdf.