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) 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 Vanhatalo, A. Articles by Huhtanen, P. Search for Related Content PubMed PubMed Citation Articles by Vanhatalo, A. Articles by Huhtanen, P.

Effects of Various Glucogenic Sources on Production and Metabolic Responses of Dairy Cows Fed Grass Silage-Based Diets

MTT, Agrifood Research Finland, Animal Production Research, FIN-31600 Jokioinen, Finland

Corresponding author: A. Vanhatalo; e-mail: aila.vanhatalo{at}mtt.fi.

Four rumen cannulated Finnish Ayrshire cows in midlactation were used in an experiment designed as a 4 x 5 incomplete Latin square with 2-wk periods to compare effects of glucogenic substrates on grass silage-based diets. The five treatments were continuous infusions of 1) water (control), 2) casein 300 g/d, 3) glucose 300 g/d, 4) propionic acid 247 g/d, and 5) barley starch 270 g/d. Substrates were infused either into the rumen (propionic acid) or into the abomasum (other substrates). As a basal diet, cows were fed a formic acid treated grass silage ad libitum (digestible organic matter 690 g/kg dry matter [DM], crude protein [CP] 131 g/kg DM) and a barley-rapeseed concentrate (CP 141g/kg DM) at a rate of 7 kg/d. Production responses to glucogenic substrates other than casein were negligible, suggesting that glucose supply of the cows did not primarily limit milk production. However, with casein cows produced significantly more milk, milk protein, and lactose than with other glucogenic substrates. Casein increased urea and essential amino acid (EAA), and decreased nonessential AA (NEAA) in arterial plasma compared with other substrates, suggesting that casein provided precursors both in terms of NEAA for gluconeogenesis and EAA for milk protein synthesis. This puts forward that providing the AA needs of the mammary gland for milk protein synthesis are met, glucose supply may become the next limiting factor for milk protein synthesis in cows fed diets based on restrictively fermented grass silage. The limited supply of AA from the basal diet, and possibly the low production levels of cows partly invalidated the hypothesis of monitoring differing glucogenic substrates for grass silage-based diets.

Key Words: grass silage • glucogenic sources • dairy cow • amino acids

Abbreviation key: AV = arteriovenous, EAA = essential amino acids, G = glucose, NEAA = nonessential amino acids, P = propionic acid, S = barley starch, TAA = total amino acids

This article has been cited by other articles:

				M. C. Rudolph, J. L. McManaman, T. Phang, T. Russell, D. J. Kominsky, N. J. Serkova, T. Stein, S. M. Anderson, and M. C. Neville Metabolic regulation in the lactating mammary gland: a lipid synthesizing machine Physiol Genomics, February 12, 2007; 28(3): 323 - 336. [Abstract] [Full Text] [PDF]

				G. Raggio, S. Lemosquet, G. E. Lobley, H. Rulquin, and H. Lapierre Effect of casein and propionate supply on mammary protein metabolism in lactating dairy cows. J Dairy Sci, November 1, 2006; 89(11): 4340 - 4351. [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]