Abstract

The aim of this study was to determine the association between age, interval from calving (PPI) and breeding worth (BW) and prevalence of postpartum anoestrus (AA), as well their effect on response to hormonal treatment by anoestrous dairy cows. Individual cow details were collated from 6649 cycling and 2446 AA animals in 29 herds. Probability of AA was influenced by herd and was negatively related to PPI and age (p<0.001); but was not related to BW (p>0.05). Response of AA cows to treatment with progesterone and oestradiol benzoate was evaluated using a subset of 1482 anoestrous cows. Within 7 days of treatment, oestrus was detected in 87.1% cows and conception rate to insemination during this period was 42.2%. Oestrous response varied between herds but was not influenced by BW, PPI or age (p>0.1). Conception rate was positively related to PPI (p<0.001), but was not influenced by BW or age (p>0.1). It is concluded that in commercial dairy herds the likelihood of a cow being AA is greatest in young and recently calved animals, but is not influenced by breeding worth.

FM, Rhodes, BA Clark, DP Nation, VK Taufa, KL Macmillan, ML Day, AM Day, and S McDougall

Proceedings of the New Zealand Society of Animal Production, Volume 58, , 79-81, 1998