94 Impact of a Hydrolyzed Yeast Product on Performance, Hair Coat Shedding, and Behavior of Cows Grazing Pastures Containing Endophyte-Infected Tall Fescue

Abstract

Abstract Endophyte-infected tall fescue creates a multitude of problems for many beef producers, with supplementation being one management strategy to decrease these problems. Our research objective was to determine if supplementation with a hydrolyzed yeast product could alleviate some symptoms of fescue toxicosis in mature cows. Across the 3-yr study, Angus cow-calf pairs (n = 34, 38, 34) were stratified by cow age and body weight then randomly allotted to one of two treatments; control mineral (CON) or hydrolyzed yeast mineral (HYM). Cattle in both treatment groups grazed the same mixed grass pastures (n = 6, 8, 8; 1.21 ha each) which contained varying levels of endophyte (20 – 90%) as measured prior to each year, in a rotational pattern for 126, 133, or 140 d, depending upon year. Prior to entering a new pasture weekly, cows were weighed and assigned a BCS and hair coat score (HC) by two independent, trained personnel. Cow behavior was measured every 15-min within a 2-h block weekly. Percentage of cows active or inactive, outside or inside a barn was recorded. Data were analyzed using the MIXED procedure of SAS. Cow BW change was affected (P < 0.01) by a treatment×year interaction. Cow BCS increased in HYM vs. CON cows (0.34 vs. 0.06; P < 0.01; SEM = 0.08) across the entire trial. Cows consuming the HYM supplement also spent a greater percentage of time outside being active (P < 0.01) and a lower percentage of time inside being inactive (P < 0.01) compared to CON cows. Results from this trial indicate that the hydrolyzed yeast mineral may be an effective tool to aid in combating heat stress associated with fescue toxicosis.