Use of antibiotics at sub-therapeutic levels revolutionized agriculture for the last 65 years. Though originally introduced to treat disease, the beneficial effects of antibiotics delivered in-feed (or water) on performance, including rate of gain and feed efficiency, became important drivers for their expanded use in livestock, including pigs (Dibner and Richards, 2005). Additional value was attached to these performance benefits later when use of feed-grade antibiotics was also shown to reduce wasted nutrients, overall farm waste, and farm labor requirements. However, as consumers became more informed about the quality of food products reaching their table, there was been an increased level of interest in antibiotic use in agriculture and its potential secondary effects on human health as it pertains to antibiotic residues and antibiotic resistance. In 2017, investigations into this area led the FDA to implement new new regulations that eliminated over-the-counter status for in-feed antibiotics that are medically important in human medicine, and required additional veterinary oversight for on-farm applications by requiring a Veterinary Feed Directive or in-feed or in-water applications of those antibiotics. Since it's implementation in January, 2017, sales of medically important antibiotics approved for use in livestock has declined by 43 percent from peak use in 2015.
The therapeutic effects of antibiotics on livestock animals are similar to their effects on people in terms of controlling pathogenic bacteria. However, as also observed in humans, the consumption of antibiotics can have detrimental effects on normal and beneficial microbiota. Antibiotics have the potential to indiscriminately remove large populations of bacteria, and consequently disrupt the intertwined relationships between bacterial populations that are working together to promote digestive health and gut barrier protection against pathogens (REF).
Though most commercial swine producers have adopted National Pork Board recommendations on responsible use of antibiotics (Responsible Use Antibiotics), using them only for prevention, treatment and control of disease, some smaller producers have adopted antibiotic-free approaches to completely eliminate their use in pork production. However, complete elimination of antibiotics may not be the best solution. Raising pigs antibiotic-free leads to challenges in maintaining similar health, production, performance and profitability as compared to conventionally-raised pigs. Specifically, antibiotic-free challenges include, but are not limited to: increased risk of exposure to bacterial and viral pathogens within facilities, increased disease stress, increased body condition variability and days to market, increased mortality, reduced water intake and feed consumption and higher costs for alternative treatments for disease (Gilliam, 2016). Moreover, pathogenic bacterial effects on lower gut integrity, associated with lack of antibiotic support, can lead to increased individual pig and barn population risks (Gilliam, 2016). The best way to protect pigs in an antibiotic-free environment is through proactive management practices that include judicious use of vaccines, strict cleaning and biosecurity measures and implementation of a nutritional program designed to strengthen the animal's natural immunity.
When considering raising pigs antibiotic-free or using less antibiotics in compliance with the new responsible use guidelines, vaccines become an even more vital part of the management strategy for herd health. Vaccines offer a cost-effective, non-antibiotic approach to prevent disease in pigs. Although vaccines are available for numerous diseases contracted by pigs, a minimalist schedule for use in Michigan, for example, would include vaccination of the sow (prior to farrowing, to allow delivery to the piglet via colostrum) for leptospirosis parvovirus, erysipelas and SIV. Depending on herd health history, other pre-farrowing vaccinations may include rotavirus, Escherichia coli and Mycoplasma hyopneumoniae. Different vaccine schedule would be recommended by your farm veterinarian for boars, piglets and grow finishers.
While water is often overlooked in daily pig operations, it's essential. Pigs consume two to three times more water per day compared to their feed intake. (Boimin, 2017). The quality of water available is as important as the quantity. Dirty or contaminated water can instigate disease and reduce growth within a population. Water pipelines have the potential to grow yeast, mold and/or bacteria, which will ultimately reduce the pig's water consumption. Pipelines should be inspected and cleaned routinely to avoid this problem.
Mycotoxins can also become a serious problem when managing antibiotic-free herds. They're commonly found in corn and soy vegetable oils. These toxic fungi can intensify enteric and respiratory infections at any stage of a pigs growth. Proper management practices can prevent and reduce mycotoxins within feed; they include proper storage, regular testing and monitoring, and additives to bind and inactivate mycotoxins (Zangaro, 2019).
Weening age is vital in a pig's life. A nursery pig has a good change to remain disease-free and grow efficiently only if it has a healthy gastrointestinal tract that's capable of absorbing nutrients while minimizing the entry of pathogens. In conventionally-raised barns, the pig's gut is mature enough to handle the stress of environmental and nutritional changes by d 21 (Biomin, 2017). However, for an antibiotic-free environment, it's recommended that the weaning age be pushed back to 28 days or longer (Colson et al., 2006) to benefit the pig's health and and decrease the risk of harmful bacteria disrupting the normal function of its gastrointestinal tract.
In conclusion, antibiotic resistance is a growing global public health concern for both agriculture and human medicine. Commercial pork producers in the U.S. have responded by adopting a strict policy designed to limit use of medically important antibiotics for the treatment and prevention of disease in pigs. use of these drugs to promote growth or improve feed efficiency is no longer tolerated. Adherence to these new rules has brought some unintended consequences, including higher rates of illness in young pigs and lower growth efficiencies. These negative consequences of limiting antibiotic use in pigs has increased the need for vigilant management practices with regard to vaccine use, water quality, control of mycotoxins and weaning age adjustments. It's also heightened the importance of identifying greener alternatives to antibiotics.
“5 Factors to Consider in an Antibiotic-Free Pig Program.” Mycotoxins Will Pose Greater Threat to Feed Safety, Hindering Industry Productivity and Su - Biomin.net, 23 Aug. 2017, www.biomin.net/en/articles/5-factors-to-consider-in-an-antibiotic-free-pig-program/.
Colson, Violaine, et al. "Consequences of weaning piglets at 21 and 28 days on growth, behaviour and hormonal responses." Applied Animal Behaviour Science 98.1-2 (2006): 70-88
Dibner, J. J., and J. D. Richards. "Antibiotic growth promoters in agriculture: history and mode of action." Poultry science84.4 (2005): 634-643.
Gilliam, Russell. “Transitioning to Antibiotic-Free Pig Production: Change Your Expectations.” National Hog Farmer, 19 Aug. 2016, www.nationalhogfarmer.com/animal-well-being/transitioning-antibiotic-free-pig-production-change-your-expectations.
Responsible Use of Antibiotics, National Pork Board, www.pork.org/public-health/responsible-use-antibiotics/
Zangaro, Casey. “Part 3 of mycotoxins in swine feed: Alleviation tactics of mycotoxins.” Michigan State University Extension, 6 Mar. 2019, https://www.canr.msu.edu/news/part-3-of-mycotoxins-in-swine-feed-alleviation-tactics-of-mycotoxins.
FDA 2017 Report Summary Report On Antimicrobials Sold or Distributed for Use in Food-Producing Animals, https://www.fda.gov/media/119332/download
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