JDS
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Journal of Dairy Science Vol. 80 No. 7 1281-1287
© 1997 by American Dairy Science Association ®
This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Prosser, C. G.
Right arrow Articles by McLaren, R. D.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Prosser, C. G.
Right arrow Articles by McLaren, R. D.

Effect of Atropine on Milk Protein Yield by Dairy Cows with Different ß-Lactoglobulin Phenotypes

C. G. Prosser 1 and R. D. McLaren 1

1 Agresearch, Ruakura Research Centre, Private Bag 3123, Hamilton, New Zealand

The objective of this study was to determine the response of individual milk proteins to a reduction in amino acid (AA) availability induced by atropine and to determine whether the response was different in cows with different ß-lactoglobulin (LG) phenotypes. Six cows that were homozygous for the A variant of ß-LG and six cows that were homozygous for the B variant of ß-LG were each given a single subcutaneous injection of saline or 20 mg of atropine. In both groups of cows, atropine decreased milk yield by 30% and reduced the concentration of alpha-lactalbumin (LA) by 25 to 30% at 8 h following injection. Eight hours after atropine injection, yield of ß-LG was 41% lower than it was following saline injection, and yield of ß-casein (CN) after atropine injection declined 16% relative to saline. Concentrations of BSA and the ratio of gamma-CN to ß-CN, which reflects plasmin activity in milk, were significantly increased after administration of atropine. Although the response to atropine tended to be more pronounced in cows that were homozygous for ß-LG B, they were not significantly different from the response of cows that were homozygous for ß-LG A. The differential response of individual proteins to a reduction in AA concentrations in whole blood suggested that susceptibility to restriction in substrate availability differed for individual proteins. The concentration of lactose in plasma did not change, which implied that the integrity of the mammary epithelial barrier was not compromised when AA derived from blood were diminished. The consistent concentration of lactose combined with the minimal increase in total yield of BSA in milk following atropine treatment indicated that the increased concentration in milk of proteins derived from serum was due to the concentrating effect of lower milk volume.

Key Words: atropine • protein composition • milk • ßbeta;-lactoglobulin

Submitted on June 14, 1996
Accepted on December 9, 1996




This article has been cited by other articles:


Home page
 J DAIRY SCIHome page
G. Bobe, G. L. Lindberg, L. F. Reutzel, and M. D. Hanigan
Effects of lipid supplementation on the yield and composition of milk from cows with different {beta}-lactoglobulin phenotypes
J Dairy Sci, January 1, 2009; 92(1): 197 - 203.
[Abstract] [Full Text] [PDF]

Home page
 J DAIRY SCIHome page
J. K. Kay, T. R. Mackle, M. J. Auldist, N. A. Thomson, and D. E. Bauman
Endogenous Synthesis of cis-9, trans-11 Conjugated Linoleic Acid in Dairy Cows Fed Fresh Pasture
J Dairy Sci, February 1, 2004; 87(2): 369 - 378.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 1997 by the American Dairy Science Association ®.