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

This Article 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 Counotte, G.H.M. Articles by Prins, R.A. Search for Related Content PubMed PubMed Citation Articles by Counotte, G.H.M. Articles by Prins, R.A.

Role of DL-Lactic Acid as an Intermediate in Rumen Metabolism of Dairy Cows^1,2,

University of Utrecht, The Netherlands

Abstract

The role of DL-lactic acid as an intermediate in the rumen of a Friesian x Holstein dairy cow adapted to a diet of hay ad libitum plus 12 kg of a concentrate mixture was studied in vitro and in vivo. Concentrations of soluble sugars in the rumen fluid became maximal at 30 min postfeeding, but at 90 min no sugars were detectable. The DL-lactate concentration increased very rapidly to about 30 mm at 30 min after feeding, whereas the maximum total VFA concentration was reached 15 min later. More than 80% of the DL-lactate fermented to VFA was converted by Megasphaera elsdenii. Whereas only 16% of L-lactate was fermented to propionate, 75% of the D-lactate was converted to propionic acid. When all soluble sugars had been fermented, the participation of M. elsdenii to lactate fermentation declined and fermentation patterns for D- and L-lactate became similar yielding mostly acetate. Except for a brief period, immediately after feeding, DL-lactate did not appear to be an important precursor of VFA in the rumen of a cow adapted to concentrate feeding. DL-lactate may become a more important intermediate in rumen fermentation temporarily when dairy cows are gradually changed from a hay diet to a diet including concentrates. The first 30 d after parturition, when the changeover takes place, is an unstable period, during which the microbial population is changing to fit the new environment.

¹ The authors thanks Dr. R.H.A.M. Janssen and Dr. M.J.A. de Bie, Laboratory of Organic Chem., Univ. of Utrecht, for measuring the ¹³C-FT-NMR spectra. Thanks are due to Dr. L.M.G. van Golde for critical reading of the manuscript

² The investigation was supported by the Foundation for Fundamental Biological Research (BION), which is subsidized by the Netherlands Organization for the advancement of Pure Research (ZWO)

³ From a thesis submitted by the senior author in partial fulfillment of the requirements for the degree of Doctor of Science. Present address: Gezondheidsdienst voor Dieren, P.O.B. 13, 8000 AA Zwolle, The Netherlands

⁴ Laboratory of Animal Nutrition, Yalelaan 1, 3584 CL Utrecht

This article has been cited by other articles:

				B. J. Suarez, C. G. Van Reenen, N. Stockhofe, J. Dijkstra, and W. J. J. Gerrits Effect of Roughage Source and Roughage to Concentrate Ratio on Animal Performance and Rumen Development in Veal Calves J Dairy Sci, May 1, 2007; 90(5): 2390 - 2403. [Abstract] [Full Text] [PDF]