Direct-fed microbials (DFM) are naturally occurring microorganisms that alter cattle ruminal fermentation and intestinal function and have been shown to improve growth performance and nutrient digestibility of cattle. The use of DFM in animal feed has continuously increased in feedlots as an alternative to traditional antibiotic additives, which have gained negative public perception and additional regulatory scrutiny. High-energy diets can induce physiological challenges to cattle, especially when based on high starch availability ingredients, which may negatively affect animal growth performance. Such physiological digestive challenges may be overcome by a target combination of DFM bacterial strains (Lactobacillus animalis, Propionibacterium freudenreichii, Bacillus subtilis, and Bacillus licheniformis). These microorganisms individually have shown to have positive effects on finishing cattle offered high-energy diets, which highlights the need for research to optimize DFM types and doses to enhance the use of bacterial strains that can positively affect cattle growth performance, carcass traits, nutrient digestibility, and other variables relevant to the physiology of digestion. In the current experiment, feedlot steers offered a specific bacterial DFM combination/dose had improved average daily gain and feed efficiency, which were reflected as a positive influence on hot carcass weight and digestibility of nutrients, while not effectcting feeding behavior and ruminal morphology.

Read the full article in the Journal of Animal Science.