Relationship of Dietary Crude Protein to Composition of Uterine Secretions and Blood in High-Producing Postpartum Dairy Cows

Open Access
Publisher Website
Google Scholar
Abstract
Effects of dietary crude protein on constituents of plasma and uterine secretions were examined at various stages of the estrous cycle of high producing Holstein cows. Isocaloric diets (74% total digestible nutrients) containing either 12 or 23% crude protein (dry matter) were fed to 18 cows on day 40 postpartum. Uterine secretion and coccygeal blood samples were collected at estrus, days 5 and 15 of the 1st estrous cycle after day 50 postpartum, and at the subsequent estrus. The 23% crude protein diet resulted in higher concentrations of NH3 in blood, urea in blood plasma and uterine secretion, and P and K in plasma. Zn increased during the estrous cycle in plasma of cows fed 23% crude protein and decreased in cows fed 12% crude protein. Mg concentrations in uterine secretions were lower in cows on 23% crude protein. K and P also were lower in uterine secretions of cows fed 23% crude protein but only during the luteal phase of the estrous cycle. Zn concentrations in uterine secretions decreased faster during the estrous cycle in cows fed 12% crude protein than in cows fed 23% crude protein. Thus, the crude protein content of the diet altered concentrations in blood of NH3 and concentrations in plasma of urea, P, K and Zn. Crude protein content of the diet altered concentrations in uterine secretion of urea, Mg, K, P and Zn.