Abstract
We investigated the effects of dry matter intake, nutrient balance on milk production and plasma metabolites of cows during early lactation under high ambient temperature. Sixteen cows calved in June and July were used in this experiment. Dry matter intake per body weight (%) were 1.79 at 1 week postpartum, 2.05 at 2 week postpartum and 2.32 at 3 week postpartum. Total nutrient digestibility (TDN), crude protein (CP), calcium (Ca) and phosphorus (P) sufficiency (%) were 58, 84, 80, and 69 at 1 week postpartum, 65, 95, 93, and 79 at 2 week postpartum and 70, 103, 102, and 88 at 3 week postpartum, respectively. One week postpartum, TDN sufficiency was negatively correlated (P<0.01) with milk fat concentration and was positively correlated (P<0.01) with milk lactose concentration. TDN and CP sufficiency did not have the apparent effect on milk protein concentration. At 1 week postpartum, Ca sufficiency was negatively correlated (P<0.01) with milk Ca concentration. At 1 week postpartum, P sufficiency was negatively correlated (P<0.01) with milk P concentration. Plasma NEFA concentration was negatively correlated with TDN sufficiency at 1 week postpartum (P<0.01), at 2 week postpartum (P<0.05), at 3 week postpartum (P<0.01). These results showed that nutrients intake have effects on milk production and plasma metabolites.
