|Olmos Colmenero, J - UW-MADISON|
Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: July 23, 2003
Publication Date: July 23, 2003
Citation: OLMOS COLMENERO, J.J., BRODERICK, G.A. EFFECT OF DIETARY CRUDE PROTEIN LEVEL ON MILK YIELD AND RUMINAL METABOLISM OF LACTATING DAIRY COWS. JOURNAL OF DAIRY SCIENCE. 2003. v. 86 (Suppl. 1). Abstract p. 273. Technical Abstract: Optimizing dietary CP is important for improving N efficiency in dairy production. Forty lactating Holstein cows (10 ruminally fistulated) were used in an incomplete 5 x 5 Latin Square design with 4-wk periods to assess the effects of different dietary CP levels on milk yield and ruminal metabolism. Diets contained (% of DM) 25% alfalfa silage, 25% corn silage, and 50% concentrate. High moisture corn was replaced with solvent soybean meal to increase CP from 14.4% (diet A), to 15.4% (diet B), 16.5% (diet C), 17.2% (diet D), and 18.4% (diet E). DMI and milk and lactose yield followed the same response patterns, with that on diet C being greater than that on diets A and D. Yield of FCM and protein had a similar pattern except that diet C was only greater than diet A. Milk/DMI, fat yield, and ruminal propionate and total VFA did not differ. As expected, MUN and ruminal ammonia increased linearly with dietary CP content. Digestibility of DM and NDF was higher on diets B and C than on diets A, D, and E and significant quadratic effects were noted for both traits. Overall, poorer N utilization was associated to diets higher in CP. A diet containing 16.4% CP was adequate to sustain production under the conditions of this study.