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 Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Latham, M. J. Articles by Sharpe, M. E. Search for Related Content PubMed Articles by Latham, M. J. Articles by Sharpe, M. E.

Fermentation and Microorganisms in the Rumen and the Content of Fat in the Milk of Cows Given Low Roughage Rations

National Institute for Research in Dairying, University of Reading, Reading RG2 9AT, England

ABSTRACT

In five lactating fistulated cows the effect of progressively substituting flaked maize for part of the hay and concentrates in a high roughage ration (8 kg hay; 10 kg dairy concentrates daily) on the rumen fermentation, rumen microflora, and fat content of milk was investigated.

With 1 kg/day of hay, the amount of concentrates and flaked maize required to depress milk fat below 2.0% varied from 1 to 6 and from 4 to 9 kg/day, respectively. Cows which developed high-buty-rate fermentation during the change of ration maintained a normal milk fat content. To assess the influence of rumen fermentation on milk fat content, molar proportions of butyric as well as acetic and propionic acids must be taken into account.

There were low numbers of cellulolytic and fiber-digesting bacteria and large numbers of lactic and propionic acid-producing bacteria in the rumen of cows given rations that depressed milk fat. However, there were particularly large variations between cows in the proportions of individual lactogenic or propionogenic genera and in the numbers of ciliate protozoa.

Unstable microbial populations developed which may have caused variability in rumen fermentation and in milk fat content.