Winter performance of Hereford cows on fescue prairie and in drylot as influenced by fall grazing

Abstract

An experiment was conducted to determine the feasibility of winter grazing pregnant Hereford cows on fescue prairie. The experiment was replicated over a 4-yr period (1988–1991, n = 4) and utilized a 2 × 2 factorial design representing fall grazing (September to November) on annual pasture (winter wheat and corn) or fescue prairie; and winter grazing (November to the end of February) on fescue prairie or feeding in a drylot. The cows weighed an average of 519 kg and had an average of 4.4 mm of backfat in late May when summer grazing on fescue prairie began and 7.2 mm of backfat at the beginning of fall grazing. Measurements of cow backfat and cow weights at each feeding change indicated that during the fall grazing period, average daily gain (ADG) was −0.43 kg and change of backfat was −1.0 mm on fescue prairie compared with + 0.12 kg and + 0.9 mm, respectively, on annual forage. Fall grazing of annual forages had no effect on the ADG of cows in winter but resulted in higher backfat after the winter feeding period (5.3 vs. 4.1 mm, P = 0.009). In later winter, cows kept on fescue prairie over the entire grazing period averaged 3.5 mm of backfat, while the cows grazed on annual forages in the fall and wintered in the drylot averaged 5.7 mm. Cows may be kept on fescue prairie in fall and winter. However, feed supplementation is needed to achieve optimal condition at calving. Fall grazing of annual forages may allow cows to maintain their body weight on fescue prairie, minimizing costly feed inputs prior to calving. Key words: Cows, calves, annual forage, backfat, fall grazing