RANGE OR MEADOW REGROWTH AND WEANING EFFECTS ON 2-YEAR-OLD COWS

Eighty 2-year-old spring calving primiparous cows were assigned to 2 w eaning and 2 grazing treatments (20 cows/treatment) from 7 September t o 7 November in 1991, 1992, and 1993. Grazing treatments were native s andhills range or subirrigated meadow regrowth. Weaning treatments wer e weaning on 7 September or 7 November. Calves weaned on 7 September g razed subirrigated meadow regrowth after weaning. Crude protein of die ts from esophagelly fistulated cows averaged 7.6% on range and 12.35% on subirrigated meadow on an organic matter (OM) basis. In vitro organ ic matter digestibility was 55.1% on range and 61.1% on subirrigated m eadow. No year X grazing treatment or weaning X grazing treatment inte ractions were detected (P>0.10) for any traits measured. Forage organi c matter consumed by cows differed between years: 7.7 kg day(-1) in 19 91 and 10.5 kg day(-1) in 1992; but was similar (P>0.10) for all grazi ng and weaning treatments. Cows grazing meadow gained more body weight and body condition than cows grazing range. Dry cows gained more weig ht and body condition (P<0.01) than lactating cows. Lactating cows gra zing meadow maintained body weight and body condition, while lactating cows grazing range lost body weight and body condition. Calves nursin g cows on meadow gained 28.8 kg more (P<0.01) than calves nursing cows on range and 34.4 kg more than weaned calves grazing meadow. Body wei ght gains of weaned calves grazing meadow and calves nursing cows on r ange were similar (P>0.10). We concluded that dry cows and cows that g razed subirrigated meadow regrowth during September and October increa sed body condition score over lactating cows and cows grazing range, r espectively. Calf body weight gains were greatest for nursing calves o n subirrigated meadow, but grazing weaned calves on subirrigated meado w was an effective alternative for calf growth to calves nursing cows on range.