Abstract

Reproductive performance was recorded in a total of 21 two-year-old Hereford x Friesian and Simmental x Friesian primiparous cows before and after restriction of calf suckling. Cows were allocated one of two pastures allowances from day 112 to 212 of gestation so that the high nutrition (HN) group gained 0.75 kg/d, and the low nutrition (LN) group gained 0.17 kg/d during mid-gestation. Suckling was suppressed for 7 days by fitting nose plates to 46-day-old calves in the restricted suckling (RS) group, whereas the normal suckling (NS) group remained as a control. Dominant follicles in the ovaries occurred in all cows by day 32 post partum and underwent a pattern of growth and atresia before first ovulation. Restricted suckling cows had a shorter interval from calving to conception than NS cows (76.0 ± 5 vs 94.1 ± 6 days, P<0.05, whereas genotype and nutritional treatment had no effect on interval to conception. However, the beneficial effect of suckling restriction on days from calving to conception only occurred in cows fed the high herbage allowance in mid-gestation. RS calves spent more time grazing during the period of attachment of nose plates and differences in behaviour remained over a further 5 days after nose plates were removed (62.4 ± 7 vs 38.6 ± 7 minutes spent grazing; P<0.001), but were lighter at weaning (146.7 ± 3 vs 162.4 ± 3 kg; P<0.01). Despite the lower calf liveweight at weaning it is concluded that manipulation of suckling through fitting nose plates to calves can be used to initiate earlier re-breeding in primiparous cows.

GT, De Nava Silva, DL Burnham, MF McDonald, and ST Morris

Proceedings of the New Zealand Society of Animal Production, Volume 54, , 307-310, 1994