Microbial Feed Additives

Abstract

The recent global concerns associated with the use of antibiotics and other growth-promoting stimulants in the animal feeds have created a window of opportunities and responsibilities for livestock nutritionists to search for alternative safer feed additives, such as direct-fed microbials based on viable naturally occurring beneficial microorganisms. In the last decade, nutritionists and microbiologists have elucidated comprehensive details related to the normal intestinal microbiota of mammals and also the benefits it provides to the host. In this milieu, numerous species and strains of probiotic bacteria, yeast, and fungal cultures have been isolated and experimented, and a number of these microbes have been found to confer numerous benefits to the host animal when added to a diet. Some of the benefits associated with these microbial supplements are stimulation of beneficial microbial growth in the rumen, stabilization of the rumen pH, improved ruminal fermentation and end-product production, increased nutrient flow and digestibility, alleviated stress, enhanced immune response, reduced pathogens, reduced acidosis, improved weight gain, increased milk yield, etc. Although the research on the use of microbes as animal feed additives has been intensive as well as extensive in the last couple of decades, more investigations, nevertheless, are still needed to ascertain the species- and strain-specific effects associated with these microorganisms, to explicate the molecular mechanisms involved in the animal responses, and also to search for more efficient and steady formulations for maximum and consistent livestock productivity.