Yeast: Not Just for Baking Bread

 A Q&A about the potential benefits to producers of using yeast as a feed additive.

Melissa Jolly-Breithaupt grew up on a cow-calf operation in northeast Kansas, a background that gave her a love for the cattle industry. After get ting her master’s and doctorate in feedyard nutrition at University of Nebraska–Lincoln, Jolly-Breithaupt eventually made her way back to Kansas and into her current role in beef technical services with Lallemand Animal Nutrition. In this discussion she provides insight to how rumen specific yeast probiotics can be used to increase feed efficiency and profit margin for beef cattle producers. Can you provide a Reader’s Digest version of how yeast additives can increase feed efficiency in cattle? A: Within the rumen, there are billions of microbes such as bacteria, yeast, protozoa and viruses that break down feed and forages, producing volatile fatty acids, gases and microbial protein — all essential for cattle to survive. It’s a dynamic, pH sensitive ecosystem that thrives on balance and microbial co operation to efficiently capture nutrients and maintain animal health and performance. Imagine plant fiber as a tough nut — the nutrients inside are valuable, but they’re locked behind a hard shell. The cow’s teeth and rumen microbes are like a team of workers trying to crack that nut open. They can do it, but it’s slow and inefficient. Especially with forages that are more mature or have more lignin. A live yeast probiotic acts like a specialized nutcracker — not cracking the nut itself, but helping the microbial team grip, drill and break through the shell more effectively. By supporting the microbes attached to the fiber surface, this specialized live yeast helps unlock more nutrients faster — improving digestion, energy availability, and animal performance and efficiency. What distinguishes yeast from other microbial feed additives in terms of performance outcomes? A: There are many different microbial varieties and strains and that leads to different products being available for producers to use in their mineral, feed  or supplements, so it can get a little confusing. Generally, the yeast products available for cattle producers fall into two different categories: prebiotics or probiotics. Prebiotics are products that feed microbes in the digestive tract. These can be plant-based or inactive, dead yeast or bacterial cell components. They are unable to elicit a response on their own, but producers may see improvements because they’ve done a better job feeding the existing microorganisms. A probiotic, which is what [yeast] is, is a live and active microorganism. So as soon as the cow consumes the mineral, those yeast cells are going to start positively changing the rumen environment — shifting the microbial populations, improving pH and fiber digestion. One common question I see from producers is, ‘Oh, I’ve got a prebiotic product; how is that different from your probiotic?’ To which I respond, one is a feed for the rumen microbes, and one is a live microorganism that is active and functioning and can change the function and efficiency of the rumen, for the better. From your research, what key productivity metrics consistently improve when feeding yeast products? A: We completed a cow calf project back in 2023. We provided Levucell® SC within a dry loose mineral 30 days prior to calving and fed through weaning. The only difference between the two cattle groups was that one received Levucell SC in their mineral mix, and the other did not. We saw the Levucell SC group had calves with higher weaning weights and average daily gain, and the cows were half a body condition score better than the control cows. With cows being in better body condition score than the control cows, that sets them up to be in a higher body condition score at time of calving that next spring, which then sets her up for that lactation cycle. On the calf side, the calves that were nursing the cows that were consuming a Levucell mineral had higher weaning weights that were an average of 22 pounds (lb.) heavier at weaning than the control calves. At face level, calves that are 22 lb. heavier at weaning means an extra $66 per head with market prices a few years ago. Also, the calves were weaned early due to drought. Then you add in the benefit to the cows — they were ready for breeding sooner and set up better for their next calving and lactation. How long does it typically take for producers to start seeing measurable results after integrating the additive? A: On the dairy side of the business, we can see results within a few days. Producers are milking the cows and can see eating behavior and production outcomes almost immediately. Due to how we raise and manage beef cattle our measurements might not be seen in that short of a time frame. For example, [since] we might only weigh calves on sale day or when we pull those cows off pasture, it might take a little longer to see those positive performance results. With the Kansas trial, we saw positive cow and calf performance outcomes and a strong return on investment (ROI) for the producer after weaning.