Yeast culture (Saccharomyces cerevisiae) supplementation in growing animals in the dairy industry

Increasing the digestibility of ruminant diets and thereby improving nutrient efficiency is an important aspect of ruminant nutrition. This improvement in nutrient utilization must initially come from an improved rumen digestion and utilization. Yeast products have been added to the diets of monogastric as well as ruminant animals for many years to improve their productivity with a variety of results. In the dairy industry, yeast has been used since the early 1900s as an enhancer in milk production and in growing animals to improve their gains and efficiency. The mode of action of yeast products (live and dead) has not been able to be completely described, but many hypotheses are related to a change in rumen fermentation pattern with increases in volatile fatty acids (VFAs), neutral detergent fibre (NDF) digestibility and disappearance, organic matter digestibility, bacteria and protozoa population and decreases in lactic acid concentrations, lag time of dry matter (DM) degradation and stabilization of rumen pH, with an overall benefit in the rumen environment leading to improvement in the metabolic performance of the animal. The aim of this review is to survey the effects of yeast supplementation in growing ruminant animals and the effects that have been noted in the literature especially in the dairy industry.