The use of bacterial probiotics and direct-fed microbials as dietary supplements in dairy cow nutrition

Abstract

Direct-fed microbials (DFM), or probiotics, overall can improve feed digestion and/or fermentation, reduce the risk of rumen acidosis, increase milk production, enhance immunity and gut health, especially reducing calf diarrhea, and reduce mastitis in dairy cattle. The commonly used DFM include species of lactic acid bacteria (e.g., Lactobacillus spp.), lactate-utilizing bacteria (e.g., Megasphaera spp.), propionate-producing bacteria (e.g., Propionibacterium spp.), Bacillus species, etc. Multispecies DFM can be more effective than single-species DFM. The modes of action differ between DFM intended to function in the rumen and those functioning in the intestines. However, the responses to DFM are inconsistent, owing to variations in bacterial species and strains, dose, diet, and animal factors. Future research is needed to elucidate the mechanism of particular DFM and their interactions with diet and the rumen and/or intestinal microbes, and other animal factors, and to optimize the dose, timing, and duration of DFM supplementation.