Effect of Protein Source on Amino Acid Supply, Milk Production, and Metabolism of Plasma Nutrients in Dairy Cows Fed Grass Silage
- 1 December 2002
- journal article
- Published by American Dairy Science Association in Journal of Dairy Science
- Vol. 85 (12) , 3336-3351
- https://doi.org/10.3168/jds.s0022-0302(02)74422-6
Abstract
This study conducted according to a 4 x 4 Latin square with 28 d periods and four ruminally cannulated Finnish Ayrshire cows investigated the effect of protein supplements differing in amino acid (AA) profile and rumen undegradable protein content on postruminal AA supply and milk production. Mammary metabolism of plasma AA and other nutrients were also studied. The basal diet (Control; 13.4% crude protein) consisted of grass silage and barley in a ratio of 55:45 on a dry matter basis. The other three isonitrogenous diets (17.0% crude protein) were control + fishmeal (FM), control + soybean meal (SBM), and control + corn gluten meal (CGM). The protein supplements replaced portions of dry matter of the control diet maintaining the silage to barley ratio constant for all diets. Dry matter intake was limited to 95% of the preexperimental ad libitum intake and was similar (mean 19.8 kg/d dry matter) across the diets. Protein supplements increased milk, lactose, and protein yields but did not affect yields of energy-corrected milk or milk fat. Milk protein yield response was numerically lowest for diet SBM. Protein supplements increased milk protein concentration but decreased milk fat and lactose concentrations. Microbial protein synthesis and rumen fermentation parameters were similar across the diets, except for an increased rumen ammonia concentration for diets supplemented with protein feeds. Protein supplements increased N intake, ruminal organic matter and N, and total tract organic matter, N, and neutral detergent fiber digestibilities. Protein supplements also increased N and AA flows into the omasum, with SBM giving the lowest and CGM the highest flows. This was associated with an unchanged microbial N flow and a higher undegraded dietary N flow. The omasal flows of individual AA reflected differences in total N flow and AA profile of the experimental diets. Differences in AA flows did not always reflect plasma AA concentrations. The results indicated that AA supply of dairy cows fed a grass silage-cereal diet can be manipulated using protein supplements differing in ruminal protein degradability and AA profile. Lower milk production response to SBM than that to FM and CGM appeared to be related mainly to lower N and AA supplies arising from a high ruminal protein degradability of SBM. Histidine appeared to be the first limiting AA for milk protein synthesis on the control diet. Mammary gland may regulate AA uptake according to requirements.Keywords
Funding Information
- Rehuraisio Ltd.
This publication has 32 references indexed in Scilit:
- Evaluation of Isoleucine, Leucine, and Valine as a Second-Limiting Amino Acid for Milk Production in Dairy Cows Fed Grass Silage DietJournal of Dairy Science, 2002
- Effects of Abomasal Infusions of Histidine, Glucose, and Leucine on Milk Production and Plasma Metabolites of Dairy Cows Fed Grass Silage DietsJournal of Dairy Science, 2002
- Responses of milk production to the intravenous infusion of amino acids in dairy cows given diets of grass silage and cereal‐based supplementsJournal of Animal Physiology and Animal Nutrition, 2001
- Estimates of the efficiency of transfer of L‐histidine from blood to milk when it is the first‐limiting amino acid for secretion of milk protein in the dairy cowJournal of the Science of Food and Agriculture, 2001
- Responses to Graded Postruminal Doses of Histidine in Dairy Cows Fed Grass Silage DietsJournal of Dairy Science, 2000
- Effects of Insulin and Postruminal Supply of Protein on Use of Amino Acids by the Mammary Gland for Milk Protein SynthesisJournal of Dairy Science, 2000
- Rumen protected amino acids for dairy cattle: what is the future?Animal Feed Science and Technology, 1996
- The influence of a formulated excess of rumen degradable protein or undegradable protein on milk production in dairy cows in early lactationAnimal Science, 1988
- Flow of nitrogen from the rumen and abomasum in cattle and sheep given protein-free nutrients by intragastric infusionBritish Journal of Nutrition, 1986
- Response of Lactating Dairy Cows to Abomasal Infusion of Amino AcidsJournal of Dairy Science, 1976