Implication and challenges of direct-fed microbial supplementation to improve ruminant production and health

Abstract

Direct-fed microbials (DFMs) are feed additives containing live naturally existing microbes that can benefit animals’ health and production performance. Due to the banned or strictly limited prophylactic and growth promoting usage of antibiotics, DFMs have been considered as one of antimicrobial alternatives in livestock industry. Microorganisms used as DFMs for ruminants usually consist of bacteria including lactic acid producing bacteria, lactic acid utilizing bacteria and other bacterial groups, and fungi containing Saccharomyces and Aspergillus. To date, the available DFMs for ruminants have been largely based on their effects on improving the feed efficiency and ruminant productivity through enhancing the rumen function such as stabilizing ruminal pH, promoting ruminal fermentation and feed digestion. Recent research has shown emerging evidence that the DFMs may improve performance and health in young ruminants, however, these positive outcomes were not consistent among studies and the modes of action have not been clearly defined. This review summarizes the DFM studies conducted in ruminants in the last decade, aiming to provide the new knowledge on DFM supplementation strategies for various ruminant production stages, and to identify what are the potential barriers and challenges for current ruminant industry to adopt the DFMs. Overall literature research indicates that DFMs have the potential to mitigate ruminal acidosis, improve immune response and gut health, increase productivity (growth and milk production), and reduce methane emissions or fecal shedding of pathogens. More research is needed to explore the mode of action of specific DFMs in the gut of ruminants, and the optimal supplementation strategies to promote the development and efficiency of DFM products for ruminants.

Active dry yeast supplementation benefits ruminal fermentation, bacterial community, blood immunoglobulins, and growth performance in young dairy goats, but not for intermittent supplementation

“…After antibiotic additives were banned in animal feed, researchers and farmers extensively sought alternative, environmentally-friendly additives. Probiotics, which can influence gastrointestinal fermentation and microbiota, have emerged as a popular alternative for maintaining and improving livestock health and performance ( Amin and Mao, 2021 ; Ban and Guan, 2021 ). As a functional and cost-effective probiotic, studies suggest that active dry yeast (ADY; Saccharomyces cerevisiae CNCM I-4407 or proprietary strains; 5.7 × 10 7 or 4.0 × 10 10 or 5.0 × 10 10 cfu/d per cow) alters ruminal fermentation and volatile fatty acid (VFA) production, stimulates ruminal microbial growth, and increases fiber degradation in the parturient and lactating ruminants ( Jiang et al., 2017 ; Kumprechtova et al., 2019 ; Li et al., 2021 ).…”

Effects of Bovine Pichia kudriavzevii T7, Candida glabrata B14, and Lactobacillus plantarum Y9 on Milk Production, Quality and Digestive Tract Microbiome in Dairy Cows

“…As a dominant member of the gut microbial community, diverse LAB is present in the digestive tract of ruminants, such as Lactobacillus , Streptococcus, and Enterococcus [ 11 , 12 ]. The bacteriocins and hydrogen peroxide produced by LAB could inhibit the growth of the E. coli and other pathogens in the rumen [ 13 ]. Another mechanism of LAB was to enhance the mucosal and systemic immune response for improving body health [ 11 ].…”

The Effect of Direct-Fed Lactobacillus Species on Milk Production and Methane Emissions of Dairy Cows

“…There are several possible explanations for the small numerical effect observed. Lactobacillus has been reported to have the potential to boost ruminal microbes adapting to high lactic acid environments during sub-acute ruminal acidosis [ 42 ], but our cows had high ruminal pH of 6.6—an environment where there is no need for adaptation and hence no benefit from the presence of Lactobacillus . It is also possible that the dose of Lactobacillus used was too low.…”