Gut feeling: Make sure your calves’ is a good one
Want stronger calves at birth? Healthier calves at weaning? More fertile cows at breeding time? Higher gains in the feedlot?
The beef industry has spent decades individually researching the best production methods to achieve maximum performance and optimal health; however, the answer to all may boil down to one common denominator — gut health.
In a recent study published by Nature Microbiology journal, researchers are looking at further understanding the work done by bacteria in the gut and how different stressors can impact the delicate balance of the microbiomes found within a ruminant animal’s intestinal tract.
“In previous studies, we have studied the communities that colonize digestive systems using cultures; however, this gave us a limited picture of what was actually happening in the rumen or intestine” said Wade Abbott, University of Lethbridge adjunct professor of Agriculture and Agri-Food Canada. “After the humane genome project that came out in the early 2000s, there started to be a real change in how scientists studied these communities. We can now see what DNA is present within the microbiomes and how it changes based on diet, sickness and stress. We can now study microorganisms that can’t be cultured to give us a better picture of what is there.”
Abbott’s team is currently working to put together a large data base of genes and bacteria to better understand the functions of the individual genes, how various feeds are metabolized and how nutrients and carbohydrates respond to the bacteria living in the rumen.
“We are trying to determine what happens to the microbiome when an animal is offered different nutrients,” he said. “The idea is if we can get an idea of how a ruminant digests different ingredients in a ration, we have a strong basis for making educated decisions on the feed ration in a feedlot setting to help the animal digest the feed more efficiently.”
Abbott said with this information, there is a potential for producers to not only rely on the indigenous flora already in the animal’s system, but producers could also offer enzymes through additives that could promote a healthy gut.
“We have discovered a number of enzymes that are currently being used in research studies,” Abbott said. “Some of these enzymes could eventually make their way to the producer, but first we must determine if it’s possible to make the enzyme in large enough quantities that is affordable to use. So there’s a big jump from getting it from the lab to the farmer.”
With the introduction of the Veterinary Feed Directive in early 2017, there is a greater focus on antibiotic use in the livestock industry. By optimizing gut health, cattle will naturally be able to ward off sickness easier and avoid needing antibiotics.
“There has been greater interest in the use of probiotics and prebiotics; the VFD is absolutely accelerating this,” said Chris Chase, DVM, veterinarian at South Dakota State University’s Department of Veterinary and Biomedical Sciences. “Currently, everybody has a magic bullet to sell, but not everyone knows if these products work. We will definitely see more of these products hitting the marketplace as more producers look for alternatives to antibiotics.”
Chase said producers are becoming increasingly aware that the gastrointestinal tract is the largest immune organ of the body.
“What goes on in the GI tract impacts the entire body,” Chase said. “With this knowledge, we want to better select tools that will help us during times of stress. When we were using low levels of antibiotics in our cattle, we weren’t necessarily sure of the long-term effects. It probably did help direct the microbiome to be more productive by getting rid of some of the bad guys in the gut.”
However, even with this feed-grade antibiotic use, the products can’t always overcome stressors.
“We’ve done some research on probiotics in the form of a live yeast product, and we’ve studied the microbiome of cattle when introducing certain stressors,” Chase said. “What we have found is the microbiome changes dramatically if they get off feed or water; it can put enough stress on the animal that you see a huge change in the bugs within just a few hours. Hydration is hugely important, and when we look at things like weaning time or other stressful events, we want to try to minimize the number of things that could stress the animal out.”
Changes in diet can greatly influence the microbiome, he said, along with the level and longevity of the immune response of the animal.
“When I was in practice, some of the worst cases of BRD I would see were in fat, over-conditioned calves,” Chase said. “These calves would be plenty fleshy at weaning and then if they experienced a diet change post-weaning, it was a huge stressor. Feeding and conditioning definitely play into gut health.”
Of course, optimal health starts in the fetus, so healthy cows are critical, and so is the need for calves to get colostrum in those first hours of life.
“Colostrum is composed of antibodies, cytokines and cells,” Chase said. “Antibody is the most important component of colostrum and provides an immediate source of antibody for the intestinal tract. Colostrum also contains high levels of anti-inflammatory cytokines that allow for gut microbial colonization.”
With additional research, mapping the pathways and understanding the roles of various nutrients in the forms of proteins and carbohydrates can help bring researchers closer to enhancing productivity through natural processes, Abbott said.
“It’s not enough to know what genes are present in the microbiome, we need to know what these genes do,” Abbott said. “We’re looking at how we can help animals digest feedstocks better, how we can improve their performance by using agricultural residues for growth promotion, and how we can improve food safety. It’s looking at ways to try to release more nutrition from complex glycans now that we know what bacteria and enzymes are required to do that.” ❖
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