Study showed cattle that received a yeast supplement, then infected with respiratory disease bacteria, had lower inflammation and lesions
MANHATTAN, Kansas — Bovine respiratory disease is a leading cause of sickness and death in feedlots, yet there are still limited treatments available.
Supplementing cattle with yeast offers an alternative to antibiotics, says a researcher from the United States Department of Agriculture.
“We have very little tools that we can actually use to combat respiratory disease outside the use of antibiotics. We are not real certain what the future holds for that and how we are going to be restricted on their use,” said researcher Jeff Carroll of Lubbock, Texas.
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As concerns over antibiotic resistance increase, alternative treatments are being sought.
“I think these yeast supplements may actually hold some promise,” Carroll said at the International Beef Welfare Symposium held at Kansas State University last month.
A group of 1,100 heifers at a commercial feedlot in Texas was fed a standard ration and also given a commercially available respiratory disease vaccine 35 days before being infected with mannheimia haemolytica, bacteria connected to respiratory disease.
A subgroup also received 2.5 grams of live yeast and 2.5 grams of a yeast cell wall product every day for 31 days.
Many got sick, but yeast-supplemented cattle tended to have fewer circulating white blood cells and less inflammation. They seemed to drink more and they had fewer severe nasal lesions.
“This information is very relevant. Just because they are vaccinated doesn’t mean they are going to be totally protected,” Carroll said.
Another test supplemented cattle with yeast to see if they could better handle heat stress. Those receiving yeast seemed to endure the heat better. They drank more and had lower body temperatures.
“Both of these studies are telling me that we are altering the metabolism……we appear to be making these animals a little more resistant or capable of handling stressors,” he said. “We may be able to do some supplementation that is actually working.”
Work is continuing on combinations of live yeast and yeast cell walls because the different supplements behave differently or may provide no benefit.
“Based on some preliminary findings, we know that live yeast and cells walls bind different bacteria. Some have more affinity for salmonella while others go after E. coli,” he said.
In the U.S., legislation governing the use of antibiotics in livestock is slated to come into effect next year. Growth promotion claims are no longer allowed and veterinary prescriptions are required to obtain antibiotics.
There is general agreement antimicrobials resistance problems are growing, said Mike Apley of Kansas State University. The university found 70 percent of mannheimia haemolytica isolates are resistant to every product available.
This may be linked to mass treatment of feedlot cattle with antibiotics as a preventive measure.
Apley said protecting cattle against disease is part of a good welfare plan. If non-antibiotic alternatives to prevent or treat disease are available, they should be considered.
“I believe we have to protect animal welfare by sticking to the science,” he said.
Also, selecting the proper antibiotic for a specific disease is important. Considerable research has examined which treatments are efficacious, but there has been less work on the balance between duration of therapy and treatment successes, failure and relapses.
Antibiotics can protect animals, and most in the cattle industry say they want these products available in the future to deal with tough diseases.
The possibility of antimicrobial resistance being passed on in meat products is being examined.
Also, there is a growing number of consumers who do not like the idea of antibiotic use in principle.
Some consumers argue that mass antibiotic treatments are used because animals are raised in confinement. However, Apley wonders how much the average consumer worries about this issue.
He also pointed out it is incorrect to say all meat is antibiotic free because there are withdrawal times. A product like tetracycline can be found at 10 parts per billion even after the withdrawal period.
“When we meet the withdrawal times, that is within a tolerance.”
