Effect of crude protein and solubility on performance and blood constituents of dairy cows.
Thirty-six mature Holstein cows were assigned at parturition to isocaloric diets of either 14.4 or 19.0% crude protein from highly soluble or insoluble nitrogen sources. The objective was to determine if elevated dietary crude protein affected milk production or serum metabolites. Cows individually were fed blended rations. Hourly blood samples were taken for a 12-h period during wk 1, 4, 7, and 10 postpartum. Rumen fluid samples were taken during wk 2, 4, and 6 postpartum. Cows fed diets containing 19% crude protein of high nitrogen solubility had larger dry matter intakes and tended to produce more milk than cows fed 14.4% crude protein. High crude protein intakes elevated rumen ammonia and blood urea nitrogen. Cows fed high crude protein, low nitrogen solubility diets had increased acetate to propionate ratio in rumen fluid. Serum insulin was increased in cows consuming high crude protein diets, regardless of the protein source. Serum nonesterified fatty acids decreased and albumin and glucose increased with week postpartum. Body weight change and fat-corrected milk production were not affected significantly by protein intake. Protein intakes in excess of requirements have no adverse effect on the production of early postpartum cows.
D000641:Ammonia / Q000032:analysis; D000704:Analysis of Variance; D000818:Animals; D001806:Blood Urea Nitrogen; D001835:Body Weight; D002417:Cattle / Q000097:blood / Q000502:physiology*; D004044:Dietary Proteins / Q000494:pharmacology*; D005232:Fatty Acids, Volatile / Q000032:analysis; D005260:Female; D007328:Insulin / Q000097:blood; D007743:Labor, Obstetric; D007774:Lactation; D009584:Nitrogen / Q000494:pharmacology; D049590:Postpartum Period / Q000097:blood / Q000502:physiology*; D011247:Pregnancy; D011897:Random Allocation; D012417:Rumen / Q000032:analysis; D012995:Solubility
D004044:Dietary Proteins; D005232:Fatty Acids, Volatile; D007328:Insulin; D000641:Ammonia; D009584:Nitrogen