Yeast as a Source of Exogenous Enzymes in Ruminant Feeding

Worldwide, the livestock industry faces various challenges, which often differ greatly depending on the geographical regions and production systems. Therefore, research and information sharing are needed for innovations and/or implementation of specific solutions to these challenges. These challenges includes: poor fibre digestibility, acidosis and endotoxins production in high milk producing cows, poor animal performance due to mycotoxin ingestion, irregular growth pattern in the dry season in some tropical countries, greenhouse gases production (nitrous oxide and methane), gastrointestinal microbial instability in weaned animals and alternatives solutions due to the ban on the use of antibiotics at subtherapeutic levels. This paper presents convincing evidence that yeast is a potential candidate to address these challenges. For instances, Saccharomyces cerevisiae can improve fibre digestibility and red rice yeast (Monascus purpureus) can reduce methane output. Similarly, Saccharomyces cerevisiae can protect consumers and the animal from the effect of aflatoxin by reducing its (aflatoxin) concentration in milk and increasing its concentration in faecal output. It could also be used in feed cost modulation by replacing soybean without affecting health and productivity of animals. Kluyveromyces lactiscan could be used to improve the protein quality of crop residues by pre-treating low protein crop residues. Yeast could also be an additional source of energy for ruminants through the inclusion of oleaginous yeasts, Cystobasidium oligophagum and Cryptococcus sp. as they can produce lipids from crop residues and by-products and increase the quantity of unsaturated fatty acid escaping biohydrogenation in the rumen of ruminant. Addition of yeasts in ruminant feeding can have multifaceted benefits to the improvement of their productivity.