WINTER PERFORMANCE OF HEREFORD COWS ON FESCUE PRAIRIE AND IN DRYLOT AS INFLUENCED BY FALL GRAZING

An experiment was conducted to determine the feasibility of winter gra zing pregnant Hereford cows on fescue prairie. The experiment was repl icated over a 4-yr period (1988-1991, n = 4) and utilized a 2 x 2 fact orial design representing fall grazing (September to November) on annu al pasture (winter wheat and corn) or fescue prairie; and winter grazi ng (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 beg an and 7.2 mm of backfat at the beginning of fall grazing. Measurement s 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 ann ual 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 gr azing period averaged 3.5 mm of backfat, while the cows grazed on annu al forages in the fall and wintered in the drylot averaged 5.7 mm. Cow s may be kept on fescue prairie in fall and winter. However, feed supp lementation is needed to achieve optimal condition at calving. Fall gr azing of annual forages may allow cows to maintain their body weight o n fescue prairie, minimizing costly feed inputs prior to calving.