Effects of echium and flaxseed oil on ruminal fatty acid metabolism in vitro
Echium oil (EO) contains high level of γ-linolenic acid (c6, c9, c12) and stearidonic acid (c6, c9, c12, c15) and is considered to be a more desirable source of n-3 fatty acids (FA) than flaxseed oil (FO). However, there is little information on the metabolism of EO in the rumen. An in vitro study was designed as 2 × 2 (oil type × dose) + 1 (control) to assess the effect of EO and FO on ruminal FA profiles. A mixture of barley silage, barley grain and minerals and vitamin supplement (75:22:3, DM basis) was incubated with 0 (control), 3 or 6% of EO or FO in serum vials with rumen fluid. Each treatment was triplicated and incubated for 0, 3, 6, 24, and 48 h. The experiment was repeated (run) three times. The statistical model included run and treatments for the fixed effects and vial as unit. The whole content was freeze-dried and extracted for total FA which was used to determine the individual FA profile by GC. Percentage of C18:0 (g/100g total FA) was lower (P < 0.001) for 6% EO treatment than in other treatments at both 24 and 48 h of incubation. Both oil treatments had higher (P < 0.001) cis 15-C18:1 percentage than control. Inclusion of 3% and 6% FO resulted in higher (P < 0.001) cis 15-C18:1 than EO at 6, 24 and 48 h. However, incubation with 6% EO yielded FA with the highest (P < 0.001) trans 9-C18:1 and trans 11-C18:1 percentage at 24 and 48 h. Cis-9, trans-11-C18:2 was increased (P < 0.001) by both oil treatments. The total unsaturated FA and trans FA were higher (P < 0.01) with the addition of oil groups and 6% EO was the greatest (P < 0.001). The increased trans 11-C18:1 with EO but not FO suggests that EO is more desirable in that it produced more trans 11-C18:1, the precursor of cis-9, trans-11-C18:2 which has been reported to benefit human health.
Keywords: echium oil, fatty acids, in vitro