Antibiotic use in swine production

Why new regulations are a double-edged sword.

The use of antibiotics and antimicrobials at sub-therapeutic levels has revolutionized agriculture for the last 65 years. Though initially introduced to treat disease, the beneficial effects of antibiotics delivered in-feed (or water) on performance, including the rate of gain and feed efficiency, became essential drivers for their expanded use in livestock, including pigs.

Additional value was attached to these performance benefits when using feed-grade antibiotics, which were also shown to reduce wasted nutrients, overall farm waste and farm labor requirements. However, as consumers became more informed and concerned about the quality of food products reaching their table, there has been an increased interest in on-farm antibiotic usage and its potential secondary effects on human health. This led the FDA (Food and Drug Administration) to conduct investigations in 2017 to evaluate the potential risk of antibiotic residues and antibiotic resistance. Based on their findings, new regulations 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 for in-feed or in-water applications of those antibiotics. Since its implementation in January 2017, sales of medically necessary antibiotics approved for use in livestock have declined by 43% from the peak use year of 2015.

The therapeutic effects of antibiotics on livestock animals are similar to their effects on humans in controlling pathogenic bacteria, but antibiotics can harm normal/beneficial microbiota, just as in humans. Antibiotics have the potential to indiscriminately remove large populations of bacteria, disrupting the delicate balance of bacterial populations that work together to promote digestive health and gut barrier protection against pathogens. This underscores the potential risks of antibiotic use in swine production, which is a critical consideration considering the new regulations.

Though most commercial swine producers have adopted the National Pork Board recommendations on the responsible use of antibiotics by using them only for prevention, treatment and disease control, some smaller producers have adopted antibiotic-free approaches to eliminate their use in pork production. However, complete elimination of antibiotics may not be the best solution. Raising pigs antibiotic-free leads to challenges, when compared to commercially raised pigs, in maintaining similar health, production/performance, and profitability. 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. Moreover, the pathogenic bacterial effects on lower gut integrity, associated with a lack of antibiotic support, can increase individual pig and barn population health risks. The best way to protect pigs in an antibiotic-free environment is through proactive management practices, including judicious use of vaccines, strict cleaning and biosecurity measures and a nutritional program to strengthen the animal’s natural immunity.

When considering raising pigs antibiotic-free or using fewer 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 before farrowing to allow delivery to the piglet via colostrum of leptospirosis, parvovirus, erysipelas and SIV. Other pre-farrowing vaccinations may include Rotavirus, Escherichia coli and Mycoplasma hypopneumoniae, depending on her health history. Following proper vaccination schedules, including boosters, is crucial to the overall disease resistance of your animals. Your farm veterinarian would recommend different vaccine schedules for boars, piglets, and grow finishers.

While water is often overlooked in daily pig operations, it is essential. Pigs consume 2-3 times more daily water than their feed intake. 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 can grow yeast, mold and bacteria, reducing the pig’s water consumption. Pipelines should be inspected and cleaned routinely to avoid this problem.

Mycotoxins can also become a severe problem when managing antibiotic-free herds. They are commonly found in corn and corn DDGS but can also be found in corn and soy vegetable oils. These toxic fungi can intensify enteric and respiratory infections at any stage of a pig’s growth. Proper management practices can prevent and reduce mycotoxins within feed; they include adequate storage, regular testing and monitoring and additives to bind and inactivate mycotoxins.

Weaning is a stressful event for a nursery pig, which potentially increases its susceptibility to harmful pathogens, yet it is crucial in a pig’s life. A nursery pig can remain disease-free and grow efficiently only if it has a healthy gastrointestinal tract 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 day 21. However, for an antibiotic-free environment, it is recommended that the weaning age be pushed back to 28 days or longer to benefit the pig’s health and decrease the risk of harmful bacteria disrupting the normal function of its gastrointestinal tract.

In conclusion, antibiotic resistance is a growing global One Health concern for agriculture and human medicine. Commercial pork producers in the U.S. have responded by adopting a strict policy to limit the use of medically necessary antibiotics for treating and preventing disease in pigs. The use of these drugs to promote growth or improve feed efficiency is no longer tolerated. Adherence to these new rules has brought unintended consequences, including higher rates of illness in young pigs and lower growth efficiencies. These negative consequences of limiting antibiotic use in pigs have emphasized the need for vigilant management practices regarding vaccine use, water quality, control of mycotoxins and weaning age adjustments. It has also heightened the importance of identifying greener alternatives to antibiotics.

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