Abstract

The aim of this study was to determine whether supplementation with pasture from 6 weeks before calving would alter the postpartum anoestrous interval (PPAI) in heifers calving with low body condition score (BCS). Metabolic hormones and metabolites were measured during the pre- and postpartum period. Forty Friesian heifers were managed during the last five months of gestation to achieve a BCS (1-10) of 4.0 (restricted; R; n=27) or 5.0 (fully fed; FF; n=13) by 6 weeks prepartum. One group with low BCS then received pasture ad libitum until calving (restricted + fully fed; R+FF; n=12). Live weight (LW) and BCS were assessed weekly. Blood samples were collected weekly from 10 weeks prepartum to 10 weeks postpartum to measure glucose, urea, non-esterified fatty acids (NEFA), betahydroxybutyrate (BOH) and cholesterol content. The patterns of metabolites measured differed between groups at different times, future work to investigate the relationship these profiles and PPAI would be of value. The percentage of cows cycling as measured by an elevated milk progesterone concentration was 69%, 75% and 8% for FF, R+FF and R groups, respectively. Fully feeding heifers, with low condition score, 6 weeks before calving decreased PPAI when compared to heifers receiving restricted feeding.

LM, Chagas, SR Morgan, PJS Gore, BA Clark, and GA Verkerk

Proceedings of the New Zealand Society of Animal Production, Volume 61, Christchurch, 188-191, 2001