Effect of dietary protein concentration and degradability on response to rumen-protected methionine in lactating dairy cows
Open Access
- 1 June 2009
- journal article
- Published by American Dairy Science Association in Journal of Dairy Science
- Vol. 92 (6), 2719-2728
- https://doi.org/10.3168/jds.2008-1277
Abstract
An incomplete 8 × 8 Latin square trial (4-wk periods; 12 wk total) using 32 multiparous and 16 primiparous Holstein cows was conducted to assess the production response to crude protein (CP), digestible rumen-undegraded protein (RUP), and rumen-protected Met (RPM; fed as Mepron; Degussa Corp., Kennesaw, GA). Diets contained [dry matter (DM) basis] 21% alfalfa silage, 34% corn silage, 22 to 26% high-moisture corn, 10 to 14% soybean meal, 4% soyhulls, 2% added fat, 1.3% minerals and vitamins, and 27 to 28% neutral detergent fiber. Treatments were a 2 × 2 × 2 factorial arrangement of the following main effects: 15.8 or 17.1% dietary CP, with or without supplemental rumen-undegraded protein (RUP) from expeller soybean meal, and 0 or 9 g of RPM/d. None of the 2- or 3-way interactions was significant. Higher dietary CP increased DM intake 1.1 kg/d and yield of milk 1.7 kg/d, 3.5% fat-corrected milk (FCM) 2.2 kg/d, fat 0.10 kg/d, and true protein 0.05 kg/d, and improved apparent N balance and DM and fiber digestibility. However, milk urea N and estimated urinary excretion of urea-N and total-N also increased, and apparent N efficiency (milk-N/N-intake) fell from 33 to 30% when cows consumed higher dietary CP. Positive effects of feeding more RUP were increased feed efficiency and milk fat content plus 1.8 kg/d greater FCM and 0.08 kg/d greater fat, but milk protein content was lower and milk urea N and urinary urea excretion were elevated. Supplementation with RPM increased DM intake 0.7 kg/d and FCM and fat yield by 1.4 and 0.06 kg/d, and tended to increase milk fat content and yield of milk and protein.Keywords
This publication has 34 references indexed in Scilit:
- Effect of Supplementing Rumen-Protected Methionine on Production and Nitrogen Excretion in Lactating Dairy CowsJournal of Dairy Science, 2008
- Effect of Ruminally Protected Methionine on Splanchnic Metabolism of Amino Acids in Lactating Dairy CowsJournal of Dairy Science, 2006
- Sources of Variation in Rates of in Vitro Ruminal Protein DegradationJournal of Dairy Science, 2004
- Effects of Varying Dietary Protein and Energy Levels on the Production of Lactating Dairy CowsJournal of Dairy Science, 2003
- Intestinal Disappearance and Mesenteric and Portal Appearance of Amino Acids in Dairy Cows Fed Ruminally Protected MethionineJournal of Dairy Science, 2001
- A Statistical Evaluation of Animal and Nutritional Factors Influencing Concentrations of Milk Urea NitrogenJournal of Dairy Science, 1997
- Response of Lactating Cows to Methionine or Methionine Plus Lysine Added to High Protein Diets Based on Alfalfa and Heated SoybeansJournal of Dairy Science, 1997
- The effect of roasting temperature applied to whole soybeans on site of digestion by steers: I. Organic matter, energy, fiber, and fatty acid digestionJournal of Animal Science, 1995
- Determination of protein degradation rates using a rumen in vitro system containing inhibitors of microbial nitrogen metabolismBritish Journal of Nutrition, 1987
- Predicting Digestibility of Different Diets with Internal Markers: Evaluation of Four Potential MarkersJournal of Animal Science, 1986