Abstract
This study evaluated the effects of a novel silage inoculant containing Saccharomyces cerevisiae strain 3 as a direct fed microbial (DFM) on the ensiling, aerobic stability, and nutrient digestibility of whole-crop corn silage and growth performance of beef cattle. Treatments included uninoculated corn silage (CON) or corn silage inoculated with a mixture of 1.1 × 105 cfu g-1 fresh forage Lactobacillus plantarum and Lactobacillus buchneri (INOC1) or 1.0 × 104 cfu g-1 fresh forage S. cerevisiae strain 3 (INOC2) or a mixture of INOC1 and INOC2 (INOC3). Silage in INOC1 had lower (P = 0.03) proportion of lactate, with acetate (Ac) proportion ranking as INOC1 > INOC3 > INOC2 (P < 0.01). In terminal silage, numbers of lactic acid bacteria were greater (P = 0.05) for INOC1 than CON and INOC2, while yeast counts tended (P = 0.08) to be greater for INOC2 than INOC3 on day 3 of aerobic exposure. Aerobic stability of corn silage was not impacted by inoculation with S. cerevisiae strain 3. Heifers fed INOC2 and INOC3 had lower (P < 0.01) ruminal Ac concentration than those fed CON. Apparent total tract digestibilities of DM, OM, ADF, and NDF were greater (P ≤ 0.03) for heifers fed INOC2 than those fed CON. Growth performance was similar across treatments, excepting DMI as percent of BW tended to be lower (P = 0.08) for INOC2 steers compared to CON steers. These results suggest that S. cerevisiae strain 3 has potential as a component in a fourth generation DFM silage inoculant.