Evaluation of the Utilization of Dietary Nitrogen by Dairy Cows Based on Urea Concentration in Milk

• Published in: Journal of dairy science Vol. 81; no. 2; pp. 579 - 584
• Main Authors: Schepers, A.J., Meijer, R.G.M.
• Format: Journal Article
• Language: English
• Published: Savoy, IL Elsevier Inc 01.02.1998; Am Dairy Sci Assoc; American Dairy Science Association
• Subjects: ACCURACY; Animal Nutritional Physiological Phenomena; Animal productions; Animals; Biological and medical sciences; Cattle - metabolism; CHEMICAL COMPOSITION; DAIRY COWS; DIET; Dietary Proteins - administration & dosage; Dietary Proteins - metabolism; DIGESTION; ENERGY BALANCE; Energy Metabolism; Feeding. Feeding behavior; Female; FORECASTING; Fundamental and applied biological sciences. Psychology; INTESTINES; Lactation; MILK; Milk - chemistry; milk urea concentration; Nitrogen - administration & dosage; Nitrogen - metabolism; NUTRITION PHYSIOLOGY; Parity; protein nutrition; PROTEINS; Rumen - metabolism; RUMEN DIGESTION; rumen-degradable protein; SMALL INTESTINE; Terrestrial animal productions; UREA; Urea - analysis; Vertebrates; Vertebrates: anatomy and physiology, studies on body, several organs or systems; DVE; rumen-degradable protein; milk urea concentration; NEB; OEB; protein nutrition; DVEB; Dairy animal; Farming animal; Nutrition; Animal feeding; Dairy cattle; Biological indicator; Metabolism; Protein; Urea; Vertebrata; Mammalia; Diet; Female; Cow milk; Artiodactyla; Ungulata
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.S0022-0302(98)75611-5

The objective of this study was to determine whether milk urea concentration is a valuable tool to monitor the utilization of dietary N by dairy cows. Data from 11 feed trials (n=2828 observations of 356 cows) were used in this study. Dietary protein utilization was evaluated according to the Dutch DVE-OEB system. A close correlation (0.8) was found between rumen-degraded protein balance in the ration and urea concentration in milk. The effects of the balance of true protein digested in the small intestine and net energy on milk urea concentration were small but significant. Parity and stage of lactation did not significantly influence milk urea concentration. Because of the large variation among and within cows, the monitoring of protein utilization of an individual cow was inaccurate. However, milk urea concentration in bulk milk is a valuable tool to monitor the rumen-degraded protein balance in the ration.