Effects of pasture allowance level after calving on performance of beef cows on hill country

Abstract

Eighty-two Angus and Friesian beef cows, which had been offered a pasture allowance of 8 kg DM/cow per day for about 2 months before calving, were allocated to post-calving allowances of 8, 12, or 16 kg DM/cow per day; designated groups T8, T12, and T16 respectively. The mean calving date was 24 August 1978. After subsequent mating, all cows were offered 16 kg DM/cow per day until weaning, 174 days after calving. Over the treatment period, from calving to mating, T8 and T12 cows consumed about 75% of the pasture offered, and T16's, 66%.0 Residual herbage levels for the T8, T12, and TI6 groups were 550, 650, and 890 kg DM/ha respectively. Herbage levels before grazing averaged 2600 kg DM/ha for all treatments. From mating until weaning, the cows consumed 66% of herbage offered, leaving 1100–1300 kg DMha. Pasture quality declined as the season advanced: the proportion of dead DM in the sward increased from 12% at calving to 45% before weaning. At mating, T16 cows averaged 43 kg heavier than T8 cows, but at weaning this difference had declined to 14 kg. The T16 cows showed first oestrus, and conceived at weights about 20 kg heavier than the T8 cows after adjustment for post-calving liveweight and calving date, indicating that nutrition affected oestrus and conception independently of a liveweight effect. Interval to first oestrus was affected by a treatment Ö age interaction which probably existed because of wide variation within the T16 group. The main treatment effects on interval from calving to first oestrus, although not significant, were 80, 78, and 75 days for the T8, T12, and T16 cows respectively. The intervals from calving to conception were 95, 85, and 85 days for the T8, T12, and T16 groups respectively. Pasture allowance treatment also affected the percentage of cows pregnant at weaning; 78% of the T8 cows were pregnant compared with 93% of the T12 and T16 cows. Calf weight at mating was affected by pasture allowance treatment, but at weaning these effects were not significant.

Keywords:

• cows
• meat animals
• restricted feeding
• animal feeding
• diet performance
• nutrition
• hill country
• pastures
• reproduction