Direct Fed Microbial and Fungal Additives in Ruminants

Introduction Before birth, developing animals are sterile in the womb of their mothers. Upon birth, the digestive tracts of all animals are naturally colonized by a variety of microorganisms. Under healthy and non-stressful conditions, “beneficial” microflora colonizes the rumen and lower gut in a symbiotic relationship with the host. Beneficial rumen and gut microorganisms supply nutrients to the host, aid in digestion of dietary nutrients, and compete with potential pathogens. There is good evidence that the bacterial and fungal probiotics are effective in the manipulation of rumen development and function. More recently, growing concern over the use of antibiotics and other growth stimulants in animal feeds, the potential risk of antibiotic residues appearing in meat and milk, and the need for a food supply that is perceived as safe by consumers, has prompted many livestock producers to explore alternative strategies to enhance the overall health and performance of their herd or flock. Direct-fed microbials (DFM), or probiotics as they traditionally have been called, is one such naturally occurring product that has been incorporated into livestock diets in an attempt to accomplish this objective. DFM, particularly yeast cultures, stimulate growth of rumen bacteria in contrast to ionophores and antibiotics, which are toxic to selective bacteria. Although the total microbial population is increased with DFM supplementation, the cellulolytic and lactic acid utilizing bacteria are stimulated preferentially. Other yeasts and yeast cultures, such as brewers yeast, have been used as supplements in animal feeds for years, primarily due to their high protein and vitamin content. Direct Fed Microbial Term direct-fed microbial to describe microbial-based feed additives to fed animals and multitude of claims have been made for various DFM products and combinations. International Journal of Science, Environment ISSN 2278-3687 (O) and Technology, Vol. 4, No 3, 2015, 716 – 72