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dc.contributor.author B. en_US
dc.contributor.author Richard J. en_US
dc.contributor.author D. en_US
dc.contributor.author V. en_US
dc.date.accessioned 2009-07-22T15:03:08Z
dc.date.available 2009-07-22T15:03:08Z
dc.date.issued 2006 en_US
dc.identifier.citation Vlaeminck , B , Dewhurst , R J , Demeyer , D & Fievez , V 2006 , ' Effect of forage:concentrate ratio on fatty acid composition of rumen bacteria isolated from ruminal and duodenal digesta ' Journal of Dairy Science , pp. 2668-2678 . en_US
dc.identifier.other PURE: 113583 en_US
dc.identifier.other dspace: 2160/2723 en_US
dc.identifier.uri http://hdl.handle.net/2160/2723
dc.description.abstract Four dairy cows were used to examine the effect of the dietary forage:concentrate ratio [35:65, 50:50, 65:35, and 80:20 on a dry matter (DM) basis] on the fatty acid composition of rumen bacteria isolated from the liquid (LAB) and solid (SAB) phase of the rumen and duodenal digesta. Rumen contents were sampled 4 h after the morning feeding. Solid and liquid phases were separated from rumen contents and duodenal bacteria from a composite duodenal sample by differential centrifugation. Total fatty acid content in bacterial DM was 1.6 to 2.8 times higher in SAB compared with LAB, and increased with dietary concentrate. In combination with published reports, the data show that bacterial fatty acid content and composition is closely related to dietary fatty acids except for C18:2n-6 and C18:3n-3. A decrease in forage:concentrate ratio increased bacterial concentration of trans-10 C18:1, and this increase was 3.4 times higher in LAB compared with SAB. Analysis of odd- and branched-chain fatty acids showed large differences between SAB and LAB, which probably reflected a difference in species composition. The variation in odd- and branched-chain fatty acids between SAB and LAB was used to estimate their relative proportions in duodenal bacteria by means of linear programming, and showed an increased proportion of SAB from 64.7 to 74.8% with increasing forage:concentrate ratio. In addition, increasing the proportion of dietary forage was closely related to the proportion of anteiso C15:0 in total odd- and branched-chain fatty acids (rpearson = −0.771). The bacterial concentration of iso C17:0 closely reflected the bacterial growth rate as shown by the relation with cytosine:N (rpearson = −0.729). These strong relationships suggest that odd- and branched-chain fatty acids might be used as tool to evaluate nutrient supply to rumen bacteria. en_US
dc.format.extent 11 en_US
dc.relation.ispartof Journal of Dairy Science en_US
dc.title Effect of forage:concentrate ratio on fatty acid composition of rumen bacteria isolated from ruminal and duodenal digesta en_US
dc.contributor.pbl Aberystwyth University en_US
dc.contributor.pbl Institute of Biological, Environmental and Rural Sciences en_US


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