Abstract We examined the effects of two direct-fed microbials (DFM) containing multiple microbial species and their fermentation products on ruminal fermentation, bacterial community and metabolome of beef steers. Nine rumen-cannulated Holstein steers were assigned to 3 treatments arranged in a 3 × 3 Latin square design with three 21-d periods. Dietary treatments were (1) CON (basal diet without additive), (2) PROB (basal diet plus 19 g/d of Commence), and (3) SYNB (basal diet plus 28 g/d of RX3). Commence is a blend of active S. cerevisiae, Enterococcus lactis, Bacillus subtilis, Enterococcus faecium, and L. casei, and their fermentation products. RX3 is a blend of active S. cerevisiae and the fermentation products of S. cerevisiae, Enterococcus lactis, Bacillus licheniformis, and Bacillus subtilis. Daily dry matter intake was calculated. On d 21 of each period, ruminal contents were sampled at 3, 6, 12, and 18 h after feeding for analysis of VFA, bacterial community via 16S rRNA sequencing, and metabolome via chemical isotope labeling liquid chromatography mass spectrometry. There was no effect on DMI. Compared to CON, supplementation of either PROB or SYNB increased or tended to increase (P ≤ 0.10) total VFA, propionate, and valerate concentrations. Compared to CON, PROB reduced (P ≤ 0.05) the relative abundance of Prevotella 1 and Prevotellaceae UCG-001, but increased those of Rikenellaceae RC9, Succinivibrionaceae UCG-001, Succiniclasticum, Ruminococcaceae UCG-014, and Ruminococcaceae UCG-002, whereas SYNB decreased (P ≤ 0.05) the relative abundance of Prevotella 1 and Prevotellaceae UCG-001, and increased those of Prevotella 7, Succinivibrio, Succiniclasticum, and Ruminococcaceae UCG-014. Metabolome analysis revealed that 8 ruminal metabolites, including some amino acids, were increased (P ≤ 0.05) by PROB, whereas no differences were found for SYNB. This study demonstrated that supplemental PROB or SYNB altered the ruminal bacterial community and metabolome differently to achieve a similar ruminal fermentation pattern.

Abstract This study evaluated the effects of two different multi-strain direct-fed microbial products on energy status, nutrient digestibility, and ruminal metatranscriptome of beef steers. Nine rumen-cannulated Holstein steers were assigned to 3 treatments arranged in a 3 × 3 Latin square design with three 21-d periods. Dietary treatments were (1) CON (basal diet without additive), (2) PROB (basal diet plus 19 g/d of Commence), and (3) SYNB (basal diet plus 28 g/d of RX3). Commence is a blend of S. cerevisiae, Enterococcus lactis, Bacillus subtilis, Enterococcus faecium, and L. casei. RX3 is a blend of S. cerevisiae and the fermentation products of S. cerevisiae, Enterococcus lactis, Bacillus licheniformis, and Bacillus subtilis. Rumen fluid (for metatranscriptomics analysis) and blood samples (for analysis of plasma glucose and non-esterified fatty acid) were collected on d 21 of each period. From d 16 – 20, TMR and fecal samples were collected daily to determine apparent total tract digestibility of nutrients using indigestible neutral detergent fiber (iNDF) method. The data were analyzed using the GLIMMIX procedure of SAS. The model included the effects of treatment, period, and random effects of cow and square. There were no effects on DMI and non-esterified fatty acid. Compared with CON, steers fed either additives had greater (P = 0.02) plasma glucose concentrations. Results of metatranscriptome analysis revealed no differentially expressed functional genes among the treatments. Apparent total-tract digestibility of nutrients were also similar among treatments. These results demonstrated that supplemental PROB and SYNB improved the plasma glucose concentration, but had no effects on the functional capacity of the ruminal microbiome and apparent digestibility of nutrients in beef steers.

Abstract Saccharomyces cerevisiae (SC) and Aspergillus-based enzyme extracts (ABE) are respectively fed to improve gut health and forage digestibility in ruminants. Also, cells of SC contain polyamines which can regulate the immune function. This study evaluated the synergistic effects of SC and ABE on rumen fermentation, plasma polyamine concentrations, and in vitro fiber digestibility of beef steers fed red clover/orchard hay. Eight rumen-cannulated Holstein steers were assigned to 4 treatments arranged in a 4 × 4 Latin square design with four 21-d periods. Dietary treatments were (1) CON (basal diet without additive), (2) SC (CON + 15 g/d of live SC; PMI, Arden Hills, MN, (3) ABE (5 g of ABE; PMI, Arden Hills, MN, USA) and (4) SC+ABE (15 g/d of live SC + 5 g of ABE). On d 21, blood samples were collected before morning feeding for analysis of plasma polyamines (spermines, spermidine, and putrescine). Rumen fluid samples were collected 3, 6, and 9 hours after feeding for analysis of VFA and in vitro dry matter and fiber digestibility. The model included the effects of treatment, period, and random effects of cow and square. Compared with CON, neither SC nor ABE had effects (P > 0.10) on ruminal VFA profile. In contrast, SC+ABE increased (P ≤ 0.05) the ruminal concentrations of acetate, butyrate, valerate and total VFA concentrations. In vitro dry matter and fiber digestibilities were increased (P < 0.05) by SC+ABE, but not by SC or ABE alone. Both SC and SC+ABE increased (P < 0.05) plasma concentrations of spermidine and spermine. These results suggest that SC supplementation with or without ABE increased plasma concentrations of polyamines; however, SC and ABE synergistically improved the rumen fermentation and in vitro fiber and DM digestibility.

We examined the effects of dietary supplementation of a Saccharomyces cerevisiae-based direct-fed microbial on the performance, whole-blood immune gene expression, and plasma metabolome of beef steers during a 42-d receiving period. Forty newly weaned Angus crossbred steers (7 d post-weaning; 210 ± 12 kg of BW) were stratified by BW and randomly assigned to 1 of 2 treatments: basal diet with no additive (CON; n = 20) or a basal diet top-dressed with 19 g of the DFM (PROB; n = 20). PROB (PMI, Arden Hills, MN) is an optimized blend of 6.2 × 1011 cfu/g of S. cerevisiae, 3.5 × 1010 cfu/g of a mixture of Enterococcus lactis, Bacillus subtilis, Enterococcus faecium, and L. casei. Daily DMI and weekly body weights were measured to calculate average daily gain (ADG) and feed efficiency (FE). Expression of 84 immune-related genes was analyzed on whole blood samples collected on days 21 and 42. Plasma metabolome was analyzed on day 42. The data were analyzed using the GLIMMIX procedure of SAS with treatment as a fixed effect and BW as a random effect. Compared with CON, PROB increased or tended to increase final body weight (P = 0.01), ADG (P = 0.04), and FE (P = 0.10). Compared with CON, PROB increased (P ≤ 0.05) the expression of seven immune-related genes involved in detecting pathogen-associated molecular patterns and T-cell differentiation. Plasma metabolome analysis revealed an increase (P ≤ 0.05) in concentrations of ten metabolites involved in protecting the animals against inflammation in steers fed PROB diet. This study demonstrated that supplementation of PROB improved the performance and health of newly weaned beef steers during a 42-d receiving period.