HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Interpretive Summary Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Raggio, G. Articles by Lapierre, H. Search for Related Content PubMed PubMed Citation Articles by Raggio, G. Articles by Lapierre, H.

Effect of Casein and Propionate Supply on Mammary Protein Metabolism in Lactating Dairy Cows

G. Raggio^*, S. Lemosquet, G. E. Lobley, H. Rulquin and H. Lapierre^,1

^* Department of Animal Science, Université Laval, Québec, Québec, Canada, G1K 7P4
Institut National de la Recherche Agronomique, Unité Mixte de Recherches Production du Lait, 35590 Saint-Gilles, France
Rowett Research Institute, Aberdeen, UK, AB21 9SB
Dairy and Swine Research & Development Centre, Agriculture and Agri-Food Canada, Sherbrooke, Quebec, Canada, J1M 1Z3

¹ Corresponding author: lapierreh{at}agr.gc.ca

The effects of casein (CN) and propionate (C3) on mammary AA metabolism were determined in 3 multiparous Holstein cows fitted with both duodenal and ruminal cannulas and used in a replicated Youden square with six 14-d periods. Casein (743 g/d in the duodenum) and C3 (1,041 g/d in the rumen) infusions were tested in a factorial arrangement. For each period, L-[1-¹³C]Leu (d 11) and NaH[¹³C]O₃ (d 13) were infused into a jugular vein, and blood samples were taken from the carotid artery and the mammary vein to determine Leu kinetics and net uptake of AA. Both CN and C3 treatments separately increased milk protein concentration and yield. With CN there was a general response in mammary protein metabolism, involving increases in Leu net uptake (30%), the uptake:output ratio (8%), protein synthesis (11%), secretion in milk protein (21%), and oxidation (259%). In contrast, C3 treatments tended to increase only Leu in milk protein (7%) and, when in combination with CN, to reduce Leu used for protein synthesis (5%). Across all treatments, most Leu uptake by the mammary gland was accounted for as Leu in milk or oxidized, and the Leu balance was therefore achieved without involvement of either net peptide use or production. Mammary uptake of group 1 AA increased to match milk output with all infusions. In contrast, mammary uptake of group 2 AA exceeded output to a greater extent with CN than with C3 infusions, whereas the increment in uptake of group 3 AA increased with C3 treatments. Overall, these data suggest that different mechanisms operate to improve milk protein production when either protein or energy is supplied.

Key Words: casein • propionate • mammary gland • protein metabolism

This article has been cited by other articles:

				L. Doepel, G. E. Lobley, J. F. Bernier, P. Dubreuil, and H. Lapierre Differences in splanchnic metabolism between late gestation and early lactation dairy cows J Dairy Sci, July 1, 2009; 92(7): 3233 - 3243. [Abstract] [Full Text] [PDF]

				S. Lemosquet, E. Delamaire, H. Lapierre, J. W. Blum, and J. L. Peyraud Effects of glucose, propionic acid, and nonessential amino acids on glucose metabolism and milk yield in Holstein dairy cows J Dairy Sci, July 1, 2009; 92(7): 3244 - 3257. [Abstract] [Full Text] [PDF]