Effect of Various Levels of Dietary Protein in Transition Period on Colostrum Quality and Serum Immunoglobulin Concentration in Holstein Cows and their Newborn Calves

This experiment was conducted to investigate the effect of 2 levels of crude protein (CP) content in the diet during transition period on lactation performance, colostrum quality and serum immunoglobulin concentration of dairy cows and their newborn calves. Thirty dry Holstein cows (607±75 kg) were blocked according to their parity and expected calving date, and then randomly assigned to one of 2 treatments of 15 cows in completely randomized block design. Dietary treatments were: 1) moderate CP level in transition diet (prepartum: 11.9%; postpartum: 14%); and 2) higher CP level in transition diet (prepartum: 14.2%; postpartum: 16.8%). Furthermore, milk samples were collected on two days (15 and 30) postpartum for milk composition analysis. At the same time, milk yield also was recorded. After parturition calves were fed mother’s colostrum. Colostrum samples were collected during the first milking postpartum. Blood samples of cows were taken on days 21 and 2 before projected calving date and on days 15 and 30 after parturition. Blood samples of calves were collected at 72 h postcalving and then on days 7, 14, 21 and 28 after birth. Applied treatment had no effect on average milk production on days 15 and 30 postpartum. Colostrum density was lower in cows fed higher CP level in transition diet than in those fed the diet with moderate CP content (P<0.05). However, the chemical composition of colostrum was not affected by CP level. Serum IgG concentration was higher for calves from higher CP group than for those from moderate CP level group at 21 days of age (P<0.05). In conclusion, the increased protein level during periparturient period tended to improve immune status of calves.