Guest article: Why is routine antibiotic dosing still used when we have better livestock and aquaculture health solutions?

Dr. Melony Sellars is CEO and managing director and Dr. Jeremy Brawner is head of genetics solutions at Genics, a provider of animal health, pathogen management, and breeding program technology.

The views expressed in this article are the authors’ own and do not necessarily represent those of AgFunderNews.

Despite the lack of evidence for its efficacy, routine “preventative” livestock antibiotic dosing is still common in many countries. Meanwhile, the detrimental consequences of antibiotic overuse, such as eroded antibiotic effectiveness and the threat of antibiotic-resistant pathogens, are well established.

But, in this era of highly accurate early-detection pathogen testing, we now have effective, affordable alternatives to routine antibiotic dosing. For farmers, there are strong incentives to transition away from excessive antibiotic use and take advantage of modern pathogen testing technology. Not only is it easily accessible at this point in time, it’s also more cost-effective, safer, and a valuable investment in the future productivity of livestock breeding programs.

We’ve known about the problems with antibiotic overuse for decades

More than half a century ago, in 1969, a British government committee conducted a landmark investigation into the value of agricultural antibiotic dosing. The UK government commissioned the investigation following an outbreak of antibiotic-resistant salmonella that killed six people and which scientists suspected was caused by the overuse of antibiotics in farming.

The report of the Joint Committee on the Use of Antibiotics in Animal Husbandry and Veterinary Medicine, or ‘the Swann report’ as it became known, was designed to be a foundation for the legislative regulation of farm antibiotic use. It was strongly critical of contemporary veterinary practices, stating that “it is sometimes advocated that an antibiotic should be given to apparently healthy animals with the intention of preventing cases of a specific illness or illnesses which previous experience has suggested may be expected. It is hard to find any excuse in logic or in theory for this practice, and even harder to find any practical evidence that it does any good at all.”

Agricultural antibiotic reform is overdue

Despite the emphatic findings of the Swann committee in 1969, its authors chose to be conservative in their regulatory recommendations. They focused on discouraging antibiotic overuse for growth promotion, a common practice at the time, but made no proposals for ending other types of questionable routine use, including so-called “disease prevention.”

The Swann report did not make a significant impact on agricultural practices. In the twentieth century, most farmers couldn’t access viable, affordable disease prevention alternatives. New regulations in some countries meant they were forced to obtain livestock antibiotics via veterinary prescription, but despite this, farm antibiotic overuse and antibiotic resistance amongst livestock continued to increase.

Half a century after the Swann report, in April 2019, the Interagency Coordination Group on Antimicrobial Resistance (IACG) published another report on agricultural antibiotic use and resistant pathogens. Like the Swann authors 50 years earlier, the IACG stated that the use of antibiotics for growth promotion and routine “prevention” were both contributing to antibiotic resistance in livestock.

The IACG authors wrote that “the use of antimicrobials to promote growth and routinely prevent disease in healthy animals and crops without appropriate indication and in the absence of good agricultural practices to prevent infectious diseases on farms are further contributing to the development and spread of antimicrobial resistance.”

In other words, 50 years after the Swann report, farmers were still spending good money to dose their livestock with antibiotics, to little effect. In fact, rather than protecting them from disease, antibiotic overuse was perpetuating a spiral where animals became more susceptible to pathogens, generation by generation.

Modern commercial pathogen testing is a better alternative

In 2022, the EU introduced new rules on the use of antibiotics in agriculture. Designed to curb antibiotic overuse on European farms, one of the principal EU regulations decreed the cessation of “preventative group treatments.”

So, how is the EU able to take such uncompromising action without concern about disease outbreaks on farms? The answer is that EU regulators are following the science and know they can rely on more modern approaches to disease management utilizing genomic profiling and PCR pathogen testing technology.

Unlike routine antibiotic dosing of livestock, clinical PCR (polymerase chain reaction) pathogen testing doesn’t have collateral adverse outcomes for future livestock health. Rather than unnecessarily squandering antibiotics treating healthy animals, farmers can use pathogen lab testing services as a diagnostic screening system. It makes early pathogen detection possible so farmers can focus their efforts on the specific diseases that are a real and immediate threat.

Genetic profiling is also a powerful tool to increase disease resistance in animal populations. With consistent genetic monitoring, farmers can selectively breed animals that become more resistant to disease, generation by generation. This starkly contrasts with the routine antibiotic dosing paradigm, where animals are effectively incubators for increasingly virulent and destructive pathogens.

Although readily available commercial PCR lab testing for agriculture is relatively new, the concept of disease screening as an alternative to antibiotic dosing is well established. In their 1999 publication ‘Approaches to Minimizing Antibiotic Use in Food-Animal Production,’ the United States National Research Council Committee on Drug Use in Food Animals stated: “Molecular biology approaches can be applied to genetic strategies to enhance selection for advantageous traits, including resistance in livestock to disease.

“Traditionally, breeding strategies have not been designed to select for host resistance and desirable production traits at the same time. One alternative to the traditional approach is the use of genetic-marker-assisted selection, which offers an opportunity for simultaneous improvement in all the traits.”

“New tools of molecular biology make it possible to simultaneously improve production and disease resistance traits. Molecular genotyping techniques allow the detection of DNA polymorphisms. Such polymorphic marker loci can be used in marker-assisted selection. For example, selection for a disease resistance gene, for which there is no direct method of genotyping, can be affected by selection for the appropriate alleles at linked marker loci.”

The National Research Council determined that enhancing immunity via strategic breeding could be an alternative to agricultural antibiotic overuse. Although the implementation of those ideas was futuristic in the 1990s, these techniques are the foundation of today’s industry-leading breeding programs, which are underpinned by disease detection and management services.

With modern genetic profiling services, farmers can implement breeding program to increase the disease resistance of their animals generationally. While antibiotic dosing weakens disease resistance over time, the DNA-supported breeding approach produces livestock that are more resilient, as well as more productive.

In the current era, when routine PCR testing and genetic livestock monitoring are readily available and highly affordable, there’s no reason to perpetuate the unhealthy practice of antibiotic overuse. Certified laboratory testing and rapid disease screening protocols not only preserve the efficacy of antibiotics, they also offer far more precise and efficient disease control capabilities on farms.

The way forward for farm productivity and human health

More than ever before, overusing and misusing antibiotics in farming is widely seen as an unacceptable risk. The World Health Organization (WHO) has long been raising awareness about the dangers of antibiotic overuse in farming, which extend beyond livestock health issues into the domain of human health.

“WHO strongly recommends an overall reduction in the use of all classes of medically important antibiotics in food-producing animals, including complete restriction of these antibiotics for growth promotion and disease prevention without diagnosis. Healthy animals should only receive antibiotics to prevent disease if it has been diagnosed in other animals in the same flock, herd, or fish population.” World Health Organization 2017

Disease prevention techniques like PCR pathogen testing and genetic breeding programs offer a more secure pathway to sustainable agricultural outcomes. In addition to being an effective defense against epidemics, these modern approaches also lower the cost of health management. Genetically managed livestock populations with better disease resistance and lower exposure to antibiotics are ultimately more robust, which means lower overheads involved with disease mitigation.

Of course, improved animal husbandry, proper nutrition, and biosecurity are all crucial factors in overcoming agricultural antibiotic dependence. But the only way producers can ensure their livestock are protected is by regular testing with certified, laboratory-grade pathogen detection and a systematic, proactive approach to breeding for disease resistance.