Beef Cows Grazing Fescue Respond to Yeast Culture Supplementation During the Latter Stages of Lactation and Grazing Season

Abstract

Angus and Angus-Hereford cows were used to evaluate the effect of yeast (Saccharomyces cerevisiae) culture (YC) provided in a free-choice mineral mix on fescue-based pasture. Organic matter intake was similar in June but higher in August (P = 0.01) in the YC group (0.19 oz/lb Body Weight) in relation to the control group (0.14 oz/lb Body Weight). August organic matter digestibility was higher (P = 0.04) in the YC group (27.2%) compared to controls (21.1%). Neutral detergent fiber digestibility was also higher (P = 0.03) in the YC group (51.4%) compared to the control group (48.1%). Cows supplemented with YC had similar milk production to control at day 60 in lactation but greater (P = 0.05) milk production at 120 days in lactation compared to control (13.2 vs. 10.1 lbs/day). No differences were found in calf birth weights or weaning weights (P > 0.20). Supplementation of Saccharomyces cerevisae increased organic matter intake and fiber digestibility compared to controls later in the summer grazing period when fiber levels were increasing. This corresponded to higher milk production compared to controls during the later grazing period.