| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
MTT Agrifood Research Finland Animal Production Research FIN-31600 Jokioinen, Finland
Corresponding author:
Mikko Korhonen; e-mail address:
mikko.korhonen{at}mtt.fi.
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.
Abbreviation key: AV = arteriovenous, BCAA = branched chain AA, CGM = corn gluten meal, EAA = essential AA, FM = fish meal, MPS = microbial protein synthesis, NEAA = nonessential AA, SBM = soybean meal, TAA = total AA, WSC = water soluble carbohydrate
Key Words: amino acid • dairy cow • grass silage • protein
This article has been cited by other articles:
|
|
 |
|
  A. Vanhatalo, K. Kuoppala, S. Ahvenjarvi, and M. Rinne Effects of feeding grass or red clover silage cut at two maturity stages in dairy cows. 1. Nitrogen metabolism and supply of amino acids J Dairy Sci, November 1, 2009; 92(11): 5620 - 5633. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. F. Brito, G. A. Broderick, and S. M. Reynal Effect of varying dietary ratios of alfalfa silage to corn silage on omasal flow and microbial protein synthesis in dairy cows. J Dairy Sci, October 1, 2006; 89(10): 3939 - 3953. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. J. O. Colmenero and G. A. Broderick Effect of Dietary Crude Protein Concentration on Ruminal Nitrogen Metabolism in Lactating Dairy Cows J Dairy Sci, May 1, 2006; 89(5): 1694 - 1703. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Vanhatalo, T. Varvikko, and P. Huhtanen Effects of Casein and Glucose on Responses of Cows Fed Diets Based on Restrictively Fermented Grass Silage J Dairy Sci, October 1, 2003; 86(10): 3260 - 3270. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
