Written by: Louise Calderwood | May 18, 2020
Over the past two months as we have all hunkered down in our own ways to aid in public actions against the COVID-19 pandemic, many people have looked to the comfort of homemade bread as a way to ease the effects of changed work and social norms. The power of yeast, a single-celled fungus, to convert flour and sugar to fragrant, chewy, delicious bread, is amazing. Humans first used yeast to produce raised breads around 3,000 B.C. But what about the value of yeast in animal feeds? In the last few decades, the same class of organisms that provide delicious food for humans are being considered as important nutrients and immune enhancers for many different animals.
Historically, yeast cell walls, which are membranes comprised of sugars and proteins, were added to animal feed because of their nutrient content, but recent research points to the beneficial impact of yeast on animal health. In many animal species, yeast cell walls bind pathogenic bacteria, inhibiting their colonization of the gut and preventing infections or the release of toxins. Put simply, yeast cell walls reduce the number and effect of harmful bacteria while promoting a healthy digestive tract environment.
The most common yeast species used in the feed industry is Saccharomyces cerevisiae. It is typically fed in dairy cattle rations to alter rumen fermentation, leading to improved nutrient digestion, nitrogen use, animal performance and reduces the risk of digestive upsets. The single celled organism increases the efficiency and health of dairy cows while reducing the amount of ammonia the cows release into the environment.
The same variety of yeast is often added to poultry diets to enhance the health of the lining of the digestive tract and improve the digestibility of many nutrients. Thousands of studies have shown that chickens and turkeys fed diets supplemented with yeast have significantly improved their body weight gain and resulted in lower mortality rates than non-supplemented birds.
Multiple studies have shown that feeding nursery piglets yeast immediately after weaning improves their performance resulting in enhanced growth, feed intake and feed efficiency. The weeks following weaning are especially important for baby pigs and yeast can help ease them through the transition and improve feed efficiency. Feeding yeast to sows improves the quality and production of colostrum (i.e., the first milk fed to piglets) improves piglet growth in the first 24 hours of life and reduces the weaning to estrus period, meaning more litters can be born per year.
Yeast added to milk or milk replacers significantly reduces the pathogen counts in baby calves, suggesting the microorganism has beneficial impacts on gut health. Research has revealed that yeast also provides several benefits to calves’ performance, including increase in daily weight gain and faster transition to a grain diet.
As you bite into that next slice of homemade bread, or quaff a hoppy beer, pay homage to the humble yeast, for its transformative powers to human food and its life-saving measures in livestock diets.