PSVI-13 Effects of Saccharomyces cerevisiae and Aspergillus-based enzyme extracts on rumen fermentation, fiber digestibility, and plasma metabolome of beef steers fed red clover/orchard hay

Abstract

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.