Separate grazing does not shorten the postpartum anoestrous interval in anoestrous cows.

摘要

Anoestrous cows were grazed separately (split group) or grazed in the main herd (control group) for 28 days, and were untreated or treated with progesterone (CIDR) and oestradiol benzoate (Cidirol) from 7 days before the planned start of mating. By28 days after the start of treatment, oestrus had been detected in 54.7, 46.3, 93.5 and 86.8% of cows in the control, split, CIDR and split + CIDR groups respectively (P<0.05). Compared with controls, conception to first insemination was no different between the split and CIDR groups, but was reduced in the split + CIDR group (P<0.05). The percentage of cows pregnant by 28 days after examination was 26.4, 18.9, 42.1 and 31.4 for the control, split, CIDR and split + CIDR groups respectively (P<0.05). There was no overall effect of separate grazing on milk solids production or cow live weight, but milk solids varied between herds (P<0.001). It was concluded that separate grazing did not improve the reproductive performance of anoestrous cows.