3 research outputs found
Effect of fish oil and sunflower oil on rumen fermentation characteristics and fatty acid composition of digesta in ewes fed a high concentrate diet
14 pages, 9 tables, 2 figures.-- Available online 19 September 2010Studies in ruminants have shown that supplementing the diet with a mixture of fish oil
(FO) and sunflower oil (SO) enhances the concentration of cis-9, trans-11 conjugated
linoleic acid (CLA), 20:5 n-3, and 22:6 n-3 in milk due to alterations in ruminal
biohydrogenation but the intermediates formed under these conditions are not well
characterised. Five ewes fitted with rumen cannula and fed a high concentrate diet were
used to examine the effect of a mixture (30 g/kg DM) of FO and SO (1:2, wt/wt) on
temporal changes in rumen fermentation characteristics and the relative abundance of
biohydrogenation intermediates in ruminal digesta collected after 0, 3, and 10 d on diet.
Appearance and identification of biohydrogenation intermediates was determined based
on complementary gas-liquid chromatography and Ag+-HPLC analysis of fatty acid
methyl esters and gas chromatography-mass spectrometry analysis of corresponding
4,4-dimethyloxazoline derivatives. Inclusion of FO and SO in the diet had no effect on
rumen pH, VFA concentrations or nutrient digestion, but altered the fatty acid
composition of ruminal digesta, changes that were characterised by time-dependent
decreases in 18:0 and 18:2 n-6 and the accumulation of trans 16:1, trans 18:1, 10-O-
18:0, and trans 18:2. Lipid supplements enhanced the proportion of 20:5 n-3 and 22:6 n-3 in digesta and resulted in numerical increases in cis-9, trans-11 CLA concentrations,
but decreased the relative abundance of trans-10, cis-12 CLA. Furthermore, detailed
analysis revealed the appearance of several unique 20:1, 20:2, 22:1, 22:3, and 22:4
products in ruminal digesta that accumulated over time, providing the first indications
of 20 and 22 carbon fatty acid intermediates formed during the biohydrogenation of
long-chain unsaturated fatty acids in sheep. In conclusion, FO and SO in a high
concentrate diet caused a time-dependent inhibition of the complete biohydrogenation
of 18 carbon unsaturated fatty acids resulting in the accumulation of trans 16:1, trans 18:1, trans 18:2, 20, and 22 carbon metabolites in ruminal digesta of sheep, with no
evidence of a shift in ruminal biohydrogenation pathways towards trans-10 18:1
formation.P. G. Toral gratefully acknowledges receipt of a predoctoral research grant from the
Spanish National Research Council (CSIC, I3P Programme). This work was supported
by the Spanish Ministry of Science and Innovation (MICINN; AGL2008-04805-C02-
02) and the Council of Castile and Leon (Project GR158).Peer reviewe