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This Article Full Text Full Text (PDF) All Versions of this Article: jas.2006-385v1 85/5/1228    most recent 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 Or-Rashid, M. M. Articles by McBride, B. W. Search for Related Content PubMed PubMed Citation Articles by Or-Rashid, M. M. Articles by McBride, B. W.

Fatty acid composition of ruminal bacteria and protozoa, with emphasis on conjugated linoleic acid, vaccenic acid, and odd-chain and branched-chain fatty acids¹

Department of Animal and Poultry Science, University of Guelph, Ontario, Canada N1G 2W1

² Corresponding author: bmcbride{at}uoguelph.ca

Knowledge of the fatty acid profile of microbial lipids is of great nutritional importance to the animals and, subsequently, their products. This study was conducted to examine the fatty acid profiles of mixed rumen bacteria and protozoa. Bacterial and protozoal cells were isolated by differential centrifugation of rumen contents. The main fatty acids were palmitic (16:0) and stearic (18:0) in both the bacterial and protozoal fractions. Palmitic acid was 74% greater in the protozoal fatty acids than in the bacterial fatty acids, whereas bacteria had 2.25-times greater stearic acid (18:0) proportions compared with protozoa. The total odd-chain plus branched-chain fatty acids were 16.5% of bacterial fatty acids and 11.0% of protozoal fatty acids. The anteiso-17:0 proportions in bacterial and protozoal fatty acids were 1.4 and 2.9%, respectively. The most abundant trans-18:1 isomer, vaccenic acid (18:1 trans-11), was 6.6% of total fatty acids in protozoa and 2.0% of total fatty acids in bacteria. The cis-9, trans-11 CLA was 8.6-times greater in the protozoal fraction (1.32% of total fatty acids) than in the bacterial fraction (0.15%). These results suggest that the presence of protozoa in the rumen may increase the supply of CLA and other unsaturated fatty acids for lower gut absorption by ruminants.

Key Words: conjugated linoleic acid • odd- and branched-chain fatty acid • rumen bacteria and protozoa • vaccenic acid

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