Despite the use of conscientious health and biosecurity practices across the pork industry, pigs still get sick. That is why U.S. pork producers will continue to rely on antibiotics as a critical part of their herd health programs.
What may change, however, is the extent to which antibiotics are used and how they fit into herd health plans, according to swine health experts addressing the recent Pork Industry Conference on Antibiotic Use in Animal Agriculture, sponsored by the University of Illinois Department of Animal Sciences and the National Pork Board.
For years, the pork industry has felt increasing pressure from special interest and activist groups to reduce or even eliminate antibiotic use as a production practice. As negative media reports stir consumer interest, organizations and groups lobby Congress for legislation that restricts antibiotics in agriculture. The outcome of this hotly debated scientific and ethical issue could profoundly affect the pork industry.
“Health management is a dynamic, resource-constrained and technologically challenged enterprise,” says David Reeves, DVM, associate professor in the Food Animal Health and Management Program at the University of Georgia. “The industry needs a broad array of antibiotics to manage health. Further, we need to be able to treat large numbers of pigs through the feed and water.”
The industry has made significant advances in health management; however, disease still happens. Restrictive laws and regulations could have significant production and welfare consequences.
“The zero antibiotic option is not viable,” Reeves says. “There is simply a lack of effective technology that can replace antibiotics. There are many instances where we can improve the use of antibiotics, but there will always be a need. By the same token, however, indiscriminate use of antibiotics is not acceptable in today's climate.”
A major shortfall contributing to the need for antibiotics in health management is the lack of understanding about the complexity of disease pathogenesis and the epidemiology of disease, Reeves says. Emerging pathogens complicate the issue further.
Symptoms and the impact of disease can vary among pigs, and even more so across herds. It can be extremely difficult to ascertain if variations are caused by subtle changes in management practices, or if they can be attributed to variation within a particular pathogen.
Another shortfall is the lack of cost analysis attributable to various diseases. Although there are cost analyses for some of the major diseases, such as pseudorabies and foot-and-mouth disease, the industry hasn't done a good job of determining the costs of common chronic diseases or in terms of animal pain and suffering, says Reeves.
“From an industry perspective, we need to get a handle on what is happening, not just with disease that manifests as epidemics, but also with diseases that tend to be endemic within farms,” he asserts. “Some of these result in chronic and sustained morbidity and mortality. We need better economic analyses for making decisions, not only on individual farms, but also as an industry.”
Although the United States has one of the world's healthiest pig populations, there are instances where vaccines don't work.
Therefore, pharmaceuticals are critical in most current farm environments, says Rodney (Butch) Baker, DVM, clinical associate professor of swine health and production medicine at North Carolina State University. Mortality syndromes have been pervasive in the industry since the late 1980s when porcine reproductive and respiratory syndrome (PRRS) emerged, he says.
Vaccination programs often fall short of expectations, particularly the swine influenza, Haemophilus parasuis and PRRS vaccines. The mycoplasma vaccines have historically been very effective, but due to PRRS and porcine circovirus-associated disease (PCVAD), Mycoplasmal pneumonia and other co-infections often cause pigs to become sick.
Keeping a lid on health care costs becomes a major concern when reducing or eliminating antibiotics from a production system. Producers spend an additional 5-20% over conventional practices to produce no-antibiotic or low-antibiotics pigs, he says. Most of the extra costs are in added vaccines, poorer feed efficiency and nursery-finisher mortality.
Vaccine use in herds producing antibiotic-free pigs usually costs an additional $2-3/pig above the standard vaccine program, Baker says.
In recent years, producers have begun changing management practices, partly to prepare for possible government restrictions. The current trend is towards veterinarian-prescribed antibiotic use. In other words, focused therapeutic treatments vs. broad-spectrum, preventive use. Baker says, in his experience, there is a significant decrease in subtherapeutic use across the industry.
Other increasingly important practices used to prevent and manage disease include dedicated replacement sourcing, parity segregation, and weaning pigs at later ages — as late as 24 days. It is difficult to prevent disease in pigs weaned at 17 or 18 days without some reliance on antibiotics, he says.
Dedicated replacement sourcing refers to a single breeding stock supplier dedicated solely to supplying a customer at a single site. It can be an internal (company-owned) multiplier, which supplies gilts to a single breeding herd site, for example. This arrangement is becoming more common, particularly in larger production systems, Baker notes.
Swine veterinarians are also adopting a new way of thinking about antibiotic use. Baker says that disease is most often managed with diagnosis, precision therapy and reevaluation efforts. Therapeutic-level medications are used in place of routine preventive group treatments. In larger systems, veterinarians have been using postmortems and other diagnostic tools more aggressively to accurately identify diseases, and then implement interventions targeted to treat a specific disease occurrence.
Ultimately, producers have the responsibility for using antibiotics prudently. Reducing or eliminating antibiotics can be costly for producers who will likely reap no direct benefits, unless they choose to market their products as organic or antibiotic-free.
At the University of Guelph Veterinary College, Scott McEwen, DVM, has been asking producers for years to measure their antibiotic use as part of various research projects. Although producers seem willing to assist, few fully comply since it is not a high priority, nor do they derive an economic benefit. Getting producers to change how they manage antibiotics is a hard sell.
“It is asking a lot for producers to absorb the cost of this in order that someone else might benefit,” McEwen says. “So we have to find other ways to encourage and reward producers for making these kinds of sacrifices on behalf of the public.”