Do Cattle Bacteria Contribute to Antibiotic Resistance in Human Medicine?

This article written by Dr. Reynold Bergen, BCRC Science Director, originally appeared in the November 2020 issue of Canadian Cattlemen magazine and is reprinted on the BCRC Blog with permission of the publisher.

E. coli live in the digestive tracts of warm-blooded animals and birds. Most are harmless, some are beneficial, and some (like E. coli O157:H7) can be very dangerous. E. coli are also involved in antibiotic resistance.

“Extended-spectrum beta-lactamase producing” (or ESBL) E. coli are a major concern in human medicine. These bacteria are resistant to many antibiotics used in both human and veterinary medicine. Ordinary E. coli can cause urinary tract or bloodstream infections in people. They’re usually quite easy to treat with antibiotics. But if ESBL E. coli are responsible, the infection can’t be easily treated with antibiotics, and the illness can be much worse or even fatal.

E. coli rarely causes disease in feedlot cattle. But ESBL E. coli are still a concern, because antibiotic resistance genes are often located on “mobile genetic elements” that bacteria can trade with each other, even with completely unrelated bacteria. So antibiotic resistant BRD bacteria like Mannheimia, Pasteurella or Histophilus can spread their antibiotic resistance genes to each other, or possibly to E. coli. That’s like a border collie developing horns after a day of herding Herefords. Continue reading

Spinning Straw Into Gold

This article written by Dr. Reynold Bergen, BCRC Science Director, originally appeared in the October 2019 issue of Canadian Cattlemen magazine and is reprinted on the BCRC Blog with permission of the publisher.

The rumen allows cattle to digest fiber that chickens, pigs and humans can’t, and produce high quality beef protein from feed and land that otherwise wouldn’t produce food. Understanding the rumen better is the key to improving feed efficiency and improving cattle’s ability to convert fiber to protein.

There’s as much energy in straw as grain – burning a ton of either straw or grain generates the same amount of heat. But cattle can’t access all the energy in straw.

Grain is mostly starch. Starch is a long chain of identical sugar (glucose) molecules connected by simple links that rumen microbes can easily break using a few enzymes. That’s why feedlot cattle digest and convert grain-based diets so rapidly and efficiently. In contrast, straw contains cellulose, hemicellulose, pectin and lignin fibers. These contain many different molecules (not just glucose) connected by complex links that are much tougher (and require many more enzymes) for microbes to break. That’s why cows can’t be wintered on straw alone.

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