Probiotics studied for feedlot cattle rations

Many Canadians eat yogurt to improve their gut health.

The health benefits of probiotics in yogurt are debatable, yet a growing body of research suggests that probiotics, in general, may help prevent and treat disease.

But what about cattle?

Could it be possible to give feedlot cattle a probiotic so they are less likely to get sick?

University of Saskatchewan researchers are studying a probiotic that could be added to the ration of feedlot cattle. The beneficial bacteria could ward off mycoplasma bovis infections, which can cause chronic pneumonia and polyarthritis syndrome (CPPS).

“M. bovis is involved in bovine respiratory disease complex (BRD), and also plays a role in CPPS in high-risk, fall-placed feedlot calves,” says the Beef Cattle Research Council. “This syndrome has emerged as a leading cause of mortality in feedlot calves in Western Canada.”

M. bovis is connected to pneumonia but it also causes some cattle to go lame when the infection moves from the lungs to the joints.

“If you have an animal that… becomes chronically ill and dies, we can almost always pull mycoplasma bovis out of the (corpse),” said Murray Jelinski, a professor at the Western College of Veterinary Medicine in Saskatoon. “It’s really a feedlot disease. It’s related to the stress and all these other pneumonias.”

Feedlot operators use antimicrobials to treat and prevent mycoplasma infections, but a reliance on antimicrobials can cause other problems.

“This has resulted in antimicrobial resistance, particularly to the macrolide drug class, which are used extensively in feedlots,” says a U of S summary describing research on mycoplasma bovis.

Jelinski is leading a project seeking a different way to control mycoplasma infections — probiotics. In the world of livestock, probiotics are basically bacteria that may improve the health and performance of animals.

While probiotics are featured in yogurt commercials and get a lot of media attention, scientists don’t fully understand how they work.

Some produce chemicals that kill off neighbouring bacteria, which could control the pathogens that cause infections. Or, once inside the body, they might steal the resources from the hazardous bacteria.

“Proteins and carbohydrates and animo acids. They kind of gobble up all those things and outcompete the other (bacteria),” Jelinksi said.

Jelinski and his colleagues identified a probiotic called bovirhinis, which might be effective against the pathogen. But when they tested it in the lab, it didn’t inhibit the growth of mycoplasma bovis.

Tony Ruzzini, a veterinary microbiologist at the WCVM who is working with Jelinski on the project, suggested they try a different species of bacteria: bacillus.

“If you went and swabbed your desk right now and took it to a microbiology lab, there is some strain of bacillus there. They are everywhere in the environment,” Jelinski said.

Ruzzini identified a promising type of bacillus and the researchers repeated the lab experiment. This time, the bacillus hindered the growth of mycoplasma bovis in a petri dish.

Ruzzini took it a step farther and discovered the bacillus was releasing a chemical that controlled the mycoplasma.

The probiotic worked in the lab, but the U of S scientists still needed to answer a couple of critical questions.

  • Could they get it into the noses of cattle through feed?
  • If they could get it in the nose, would it ward off mycoplasma bovis in the feedlot?

To answer the first question, researchers grew a larger batch of the probiotic and added it to the feed of a group of cattle at the U of S’s Livestock and Forage Centre of Excellence. That work began but COVID-19 halted the research in early 2020.

The scientists obtained swabs from the nostrils of cattle that were given the bacillus probiotic in feed and cattle that did not. Unfortunately, they found bacillus in the noses of both groups.

Now, they’re testing the strains to see if their bacteria made it into the noses of cattle or if it’s another bacillus that exists at the Livestock Forage Centre of Excellence.

If they find the probiotic in the nasal cavity, the next step is to repeat the experiment.

“But this time let’s (expose) them to mycoplasma bovis and see if we can inhibit (the pathogen),” Jelinski said.

However, that type of research is still on hold at the university because of COVID-19.

The work remains in the proof-of-concept stage, but if the probiotic does help control mycoplasma bovis in the U of S cattle, the scientists would then conduct a large, clinical field trial at multiple feedlots.

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