Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 7/26/2004
Publication Date: 7/26/2004
Citation: Brito, A.F., Broderick, G.A. 2004. Effects of different protein supplements on nitrogen utilization in dairy cows. i. lactation performance and ruminal metabolism. [abstract]. Journal of Dairy Science. 87(1):161. Interpretive Summary:
Technical Abstract: Sixteen multiparous and 8 primiparous Holstein cows (8 with ruminal cannulae) were randomly assigned to six 4 °' 4 Latin squares to investigate the effects of RDP source on lactation performance and ruminal metabolism. All diets contained (% of DM): 20.7% alfalfa silage and 35.1% corn silage. The following protein supplements were added to the basal diet (% of DM): urea (1.9%; diet A), solvent soybean meal[(SSBM; 12.1%); diet B]; cottonseed meal [(CSM; 14.1%); diet C]; or canola meal [(CM; 16.1%); diet D]. Diets contained 16.6% CP. Yield of milk, fat, protein, and 3.5% FCM were significantly higher for cows fed diets supplemented with SSBM, CSM, or CM. Feeding CM resulted in numerically greater responses, although not always statistically different from SSBM and CSM. Cows fed diet A had the lowest DMI while cows on diet D had the highest; diet C was intermediate but not different from diet B. Milk fat content, total VFA, acetate, and propionate were similar among all diets whereas milk protein content was highest on diets B and D and lowest on diets A and C. Ruminal pH and butyrate also did not differ across diets (data not shown). Overall, use of true proteins improved N utilization versus NPN. However, greater protein yield indicated that SSBM and CM were more effective than CSM.