Abstract

Fifty-two multiparous dairy cows were allocated to four treatments with an apparent daily intake of 5.8, 8.9, 10.0 or 11.2 kg dry matter (DM)/cow/day of pasture for 27±9.6 days precalving. This equated to 1.3, 2.0. 2.3 and 2.6% of liveweight (not including the conceptus weight; LW). Following calving, all cows were fed generously on pasture. Daily milk yields were recorded postcalving and fat, protein and lactose concentrations determined on 2 days each week for 5 weeks. Blood was sampled 17 days precalving, on the day of calving and on days 1, 2, 3, 4, 7, 14, 28 and 35 postcalving. Precalving plasma concentrations of insulin-like growth factor-1 (IGF-1) increased (P<0.05) quadratically with increasing pasture intake. Concentrations of growth hormone declined (P<0.05) linearly and concentrations of non- esterified fatty acids declined (P<0.001) quadratically with increasing DM intake. Plasma concentrations of these metabolites postcalving showed no effect of precalving feeding. Level of feeding precalving did not affect milk yield or the yield of fat, protein or lactose in milk, but postcalving DM intake was negatively (P<0.1) related to precalving DMI. These results indicate that 0.93 MJ metabolisable energy/kg LW0.75 was required in the final three weeks of gestation to maintain cow energy balance.

JR, Roche, JK Kay, ES Kolver, PW Aspin, J Lee, B Sugar, and AR Napper

Proceedings of the New Zealand Society of Animal Production, Volume 64, Hamilton, 227-231, 2004