Life without antibiotics

by George Looby

In the several decades since the introduction of antibiotics, the livestock industry has enjoyed a period during which animal losses due to susceptible diseases was greatly reduced. In addition to the treatment of active diseases, it was found that the addition of certain antibiotics to cattle diets acted as growth stimulants, increasing feed efficiency. However, consumer groups came to the realization that some of the antibiotics used in the feeding and treatment of some animals might be retained in their meat. These groups began to question the use of antibiotics in the rations of animals destined for human consumption, worried about the possible adverse effects of consuming such products.

For several years, consumers and livestock advocates defended their respective positions; consumer groups prevailed. Livestock groups were required to obtain veterinarian prescriptions to treat sick or exposed animals with antibiotics. The use of antibiotics as growth stimulants was no longer allowed. In 2017, the FDA decreed that commercial farmers could no longer add low levels of antibiotics to animal rations. Self treatment was no longer permitted. Those who labor in the labs were effectively given a new challenge – come up with one or more ways of treating animal disease without compromising human health.

One approach being explored is using probiotics in a variety of ways. Probiotics are microbes that live in the intestinal tracts of healthy, normal animals to help maintain normal microbial flora in the gut.

Probiotics are unlikely to replace antibiotics in the treatment of any diseases which domestic animals are prone to, but they offer some possibilities as an aid in prevention. If probiotics are to play a role in disease management and control it will be a supportive one – not the control of infectious bacteria. The possibilities seem endless, but continuing research is needed.

Bayer has developed a product named Zelnate, a non-antibiotic immunostimulant which received FDA approval. It protects cattle against bovine respiratory disease by stimulating the immune systems of cattle at the first sign of an infection.

Another approach to combating infectious agents is CRISPR, which uses unique technology to kill bacteria that carry a gene for antibiotic resistance by causing viruses (called phages) that destroy the bacteria.

Cattlemen have known for decades that excellent husbandry practices can do much to reduce the likelihood of infectious agents from gaining a foothold in a herd. Cleanliness is cheap, easy to do and requires no special skills or training. Workers at Colorado State have come up with a novel approach, developing “metal-organic frameworks.” The substance adheres to the surface of textiles or polymers and copper contained in it acts as an antibacterial, keeping bacteria from adhering to it. This technique seems to last a long time.

New technology will likely play an ever-increasing role in early disease detection. Systems are available that can detect the earliest signs of impending disease – far sooner than even the most astute herdsman. Robotic milking systems have the capability of recording even the slightest deviations in average daily milk production. Such fluctuations are carefully monitored to ensure they are not cause for concern. Monitors in swine facilities are capable of detecting variations and deviations in normal sounds which might be early signs of impending problems. Other monitors can detect levels of various volatile organic compounds that might be exhaled by an animal in the earliest stages of respiratory infection.

Some of the newer approaches to the management of diseases in livestock populations may not be quite as effective as antibiotics, but producers are adapting to the newer regulations.

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