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ARS Home » Midwest Area » Madison, Wisconsin » U.S. Dairy Forage Research Center » Cell Wall Biology and Utilization Research » Research » Publications at this Location » Publication #255352

Title: Effect of feeding varied levels of crude protein and absorbable methionine on milk yield in lactating dairy cows

item Broderick, Glen
item Patton, Robert
item Heimbeck, Winfried
item Parys, Claudia

Submitted to: Journal Dairy Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 4/23/2010
Publication Date: 7/12/2010
Citation: Broderick, G.A., Patton, R.A., Heimbeck, W., Parys, C. 2010. Effect of feeding varied levels of crude protein and absorbable methionine on milk yield in lactating dairy cows. Journal of Dairy Science. 93(E-Supplement 1):444.

Interpretive Summary:

Technical Abstract: Supplementing with limiting AA should allow less CP to be fed; reducing dietary CP will decrease urinary N and ameliorate the environmental impact of dairying. Rumen-protected Met (RPM), fed as Mepron to provide 9 g/d of absorbable Met, allowed similar milk yield at 15.8% CP as at 17.1% CP without RPM (Broderick et al., J. Dairy Sci. 92:2719, 2009). A lactation trial was conducted to assess response to RPM at different CP levels. TMR were prepared from alfalfa and corn silages, dry- and high-moisture corn, and solvent and expeller soybean meals. Diets were formulated to 28% NDF and 12, 14, 16 or 18% CP (DM basis); at each level of CP, RPM provided 0, 4.5, 9.0 and 13.5 g/d of absorbable Met, assuming 25 kg/d of DMI and 0.6 g absorbed Met/g of Mepron (total = 16 diets). Sixty-four cows were blocked by DIM into 16 squares and randomly assigned to balanced 4x4 Latin squares. The 4 levels of RPM were fed at each CP level for four 4-wk periods. Data from the last 2 wk of each period were analyzed for linearity of response to dietary CP and RPM using the mixed model of SAS; LS means were reported. Analysis of TMR extracts with the Met-nitroprusside reaction confirmed that RPM was fed in desired amounts, but CP was higher than formulated. Dietary CP increased DMI, BW gain, and yield of milk, 3.5% FCM, fat and protein, but did not affect milk/DMI. Production was not increased when diets contained 15.8% or more CP. Although the NRC model indicated that diets had Lys/Met ratios ranging from 3.3 to 3.7, and observed milk yield was more than MP-allowable milk on 12.9 and 15.8% CP, more absorbable Met had no effect on production in this trial.