Comparison of Grazing Stockpiled Tall Fescue Versus Feeding Hay With or Without Supplementation for Gestating and Lactating Beef Cows During Winter

Spring-calving beef cows (yr 1, n = 106, BW = 619.6 ± 6.2 kg; yr 2, n = 93, BW = 624.5 ± 6.8 kg) were wintered on 1 of 3 treatments (3 replicates): tall fescue hay (HY; yr 1, 7.7% CP, 71.6% NDF; yr 2, 8.0% CP, 74.2% NDF), hay supplemented to meet NRC requirements (HS), or strip-grazed non-endophyte-infected stockpiled tall fescue pasture (STF). Years were divided into initiation to calving (period 1) and calving until spring forage growth (period 2). Stockpiled forage had greater CP and lower NDF and ADF than hay in both years (P < 0.001). Cows fed HS and STF gained BW, whereas those on HY lost BW in period 1 of yr 2 (P ≤ 0.02). In yr 1, STF cows lost less BW than cows on HY and HS during period 2 (P ≤ 0.004). During period 2 of yr 2, HS and STF cows lost less BCS than HY cows (P ≤ 0.02). Overall in yr 1, STF cows gained BW, whereas HS and HY cows lost BW (P ≤ 0.06), and HS cows lost backfat thickness compared with increases (P ≤ 0.08) for HY and STF cows. Cows fed HS and STF lost less BW, BCS, and backfat thickness during yr 2 than HY cows (P < 0.04). Posttreatment, HY cows had the highest BCS gains until breeding (P < 0.05) and weaning (P ≤ 0.06) in yr 2. Tall fescue-based hay in this study had lower nutritive value than STF, requiring supplementation for cows to achieve similar performance.