Range or meadow regrowth and weaning effects on 2-year-old cows

Abstract

Eighty 2-year-old spring calving primiparous cows were assigned to 2 weaning and 2 grazing treatments (20 cows/treatment) from 7 September to 7 November in 1991, 1992, and 1993. Grazing treatments were native sandhills range or subirrigated meadow regrowth. Weaning treatments were weaning on 7 September or 7 November. Calves weaned on 7 September grazed subirrigated meadow regrowth after weaning. Crude protein of diets from esophageally fistulated cows averaged 7.6% on range and 12.3% on subirrigated meadow on an organic matter (OM) basis. In vitro organic matter digestibility was 55.1% on range and 61.1% on subirrigated meadow. No year X grazing treatment or weaning X grazing treatment interactions were detected (P > 0.10) for any traits measured. Forage organic matter consumed by cows differed between years: 7.7 kg day-1 in 1991 and 105 kg day-1 in 1992; but was similar (P>0.10) for all grazing and weaning treatments. Cows grazing meadow gained more body weight and body condition than cows grazing range. Dry cows gained more weight and body condition (P<0.01) than lactating cows. Lactating cows grazing meadow maintained body weight and body condition, while lactating cows grazing range lost body weight and body condition. Calves nursing 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 weight gains of weaned calves grazing meadow and calves nursing cows on range were similar (P>0.10). We concluded that dry cows and cows that grazed subirrigated meadow regrowth during September and October increased body condition score over lactating cows and cows grazing range, respectively. Calf body weight gains were greatest for nursing calves on subirrigated meadow, but grazing weaned calves on subirrigated meadow was an effective alternative for calf growth to calves nursing cows on range.