Resumen:
To keep the concept of a safe food supply to the consumers, animal feed industries world over are showing an increasing
interest in the direct-fed microbials (DFM) for improved animal performance in terms of growth or productivity. This becomes
all the more essential in a situation, where a number of the residues of antibiotics and/or other growth stimulants reach in
milk and meat with a number of associated potential risks for the consumers. Hence, in the absence of growth stimulants,
a positive manipulation of the rumen microbial ecosystem to enhance the feedstuff utilization for improved production efficiency
by ruminants has become of much interest to the researchers and entrepreneurs. A few genera of live microbes
(i.e., bacteria, fungi and yeasts in different types of formulations from paste to powder) are infrequently used as DFM for the
domestic ruminants. These DFM products are live microbial feed supplements containing naturally occurring microbes in
the rumen. Among different DFM possibilities, anaerobic rumen fungi (ARF) based additives have been found to improve
ruminant productivity consistently during feeding trials. Administration of ARF during the few trials conducted, led to the
increased weight gain, milk production, and total tract digestibility of feed components in ruminants. Anaerobic fungi in the
rumen display very strong cell-wall degrading cellulolytic and xylanolytic activities through rhizoid development, resulting in
the physical disruption of feed structure paving the way for bacterial action. Significant improvements in the fiber digestibility
were found to coincide with increases in ARF in the rumen indicating their role. Most of the researches based on DFM
have indicated a positive response in nutrient digestion and methane reducing potential during in vivo and/or in vitro supplementation
of ARF as DFM. Therefore, DFM especially ARF will gain popularity but it is necessary that all the strains