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ARS Home » Midwest Area » Madison, Wisconsin » U.S. Dairy Forage Research Center » Research » Publications at this Location » Publication #198838
Title: EFFECT OF RDP SOURCE ON RUMINAL DIGESTION IN LACTATING DAIRY COWS

Author
item REYNAL, S - UNIV. OF WISCONSIN-MADISO
item Broderick, Glen
item LEIBOVICH, J - ARGENTINA

Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 7/10/2006
Publication Date: 7/10/2006
Citation: Reynal, S.M., Broderick, G.A., Leibovich, J. 2006. Effect of RDP source on ruminal digestion in lactating dairy cows [abstract]. Journal of Dairy Science. 89(suppl. 1):80.

Interpretive Summary:

Technical Abstract: Eight lactating dairy cows fitted with ruminal cannulas and averaging 116 DIM were assigned to two 4 x 4 Latin squares to determine the effect of feeding diets differing in the proportions of RDP coming from urea and non-urea sources on ruminal digestion of nutrients. Diets contained (DM basis) 15% alfalfa silage, 40% corn silage, 29 to 27% high-moisture corn, and 16 to 18% concentrate mix. The RDP from soybean meal (SSBM) was replaced with RDP from urea by changing the proportions of concentrates (DM basis) in diets A to D in equal increments as follows: ground shelled corn, from 0 to 6.3%; SSBM, from 14 to 0%; lignosulfonate-treated SBM, from 0 to 8.0%, and urea, from 0 to 1.2%. Diets contained on a DM basis 16.1% CP, 10.5% RDP, 5.6%RUP, 26% NDF, and 1.58 Mcal of NEl/kg. Diets A B C D SE Linear Quadratic Urea, % of DM 0 0.4 0.8 1.2 OM Intake, kg/d 21.0 19.7 20.4 19.2 0.6 0.02 0.84 Digestibility, % 40.4 41.5 40.4 41.1 2.2 0.90 0.90 NDF Intake, kg/d 5.54 5.52 5.95 5.46 0.22 0.80 0.12 Digestibility, % 32.5 40.6 36.0 35.4 2.8 0.72 0.09 ADF Intake, kg/d 3.18 3.12 3.36 2.97 0.14 0.40 0.09 Digestibility, % 36.5 43.7 40.9 39.6 2.9 0.57 0.10 Total N Intake, g/d 569 545 561 534 18 0.09 0.90 Flow, g/d 603 559 573 508 27 <0.01 0.52 Rumen NH3-N, mg/dl 8.2 9.3 10.3 10.8 0.86 <0.01 0.52 Omasal flows of N decreased linearly while rumen ammonia concentrations increased linearly with increasing addition of urea to the diets, suggesting a lesser utilization of dietary urea-N by microbes. Replacing RDP from SSBM with RDP from urea depressed OM intake and N flows from the rumen in lactating dairy cows.