Effects of Supplemental Chromium on Lactation and Some Blood Parameters of Dairy Cows in Late Gestation and Early Lactation

摘要

This study was carried out to evaluate the effects of chromium supplementation as chromium-L-methionine (Cr-Met) on lactation performance and some blood components of Holstein dairy cows in late gestation and early lactation. Sixty multiparous Holstein dairy cows according to prior lactation, parity, body weight and expected calving date were divided equally (30 cows/treatment) and were randomly allocated to one of the two groups. Group 1 received no Cr supplement and served as the control. Group 2, received supplemental Cr at manufacturer?s recommended level (8 mg/head per day) from 21 days before expected calving date until 21 days of lactation. Milk productions of animals were recorded every 15 days until 60 days in milk (DIM). Blood samples were collected at -7, 0 and 21 days relative to actual calving time for determination of serum protein fraction, maternal serum IgG concentration, serum Ca and P and urea nitrogen. Adding chromium to the diet of dairy cows increased milk yield in the first month of lactation. Percentage of lactose and lactose yield increased significantly through the experiment in the supplemented group. In the first month of lactation, milk protein yield increased significantly while a tendency was observed for fat yield in the supplemented group. Cr supplementation increased albumin and albumin to globulin ratio in 21 days postpartum. Maternal serum IgG concentration tended to increase at parturition. Supplemental Cr had no effect on serum Ca, P and urea concentration in periparturient period. The results suggest that Cr supplementation improves milk yield and some blood parameters of dairy cows in late gestation and early lactation.