عنوان مقاله [English]
نویسندگان [English]چکیده [English]
The aim of this study was to compare the effects of two levels of crude protein using poultry by-product meals (PBPM) fed during late gestation on the performance, blood metabolites, and colostrum composition of Holstein dairy cows. Sixteen multiparous cows 26±6 d before expected calving were assigned randomly to two treatments containing 1) 14% and 2) 16% crude protein. The cow’s BCS was 3.56 ± 0.5 on average, at the beginning of the trial. Yields of milk, protein, lactose, fat, and SNF were not affected by prepartum dietary CP level. Colostrum composition (fat, CP and Total solids), blood metabolites (Ca, Glucose, Total protein, Albumin, Globulin and Urea N), and metabolic diseases incidence were not influenced by prepartum dietary CP level. There was no significant difference between treatments in body weight and BCS changes. As expected, blood urea N before calving was higher in the cows fed 16% CP diets. Serum cholesterol during prepartum and postpartum periods was significantly decreased as the CP increased in the diet. In general, although postpartum glucose level increased in cows which received 16% CP in the diet, it seems that no other obvious advantages over feeding the 14% CP diet are apparent. So feeding this last diet is recommended to close up cows.