Effect of fish oil on ruminal biohydrogenation of C18 unsaturated fatty acids in steers fed grass or red clover silages

Abstract

Red clover and fish oil (FO) are known to alter ruminal lipid biohydrogenation leading to an increase in the polyunsaturated fatty acid (PUFA) and conjugated linoleic acid (CLA) content of ruminant-derived foods, respectively. The potential to exploit these beneficial effects were examined using eight Hereford 3 Friesian steers fitted with rumen and duodenal cannulae. Treatments consisted of grass silage or red clover silage fed at 90% of ad libitum intake and FO supplementation at 0, 10, 20 or 30 g/kg diet dry matter (DM). The experiment was conducted with two animals per FO level and treatments formed extraperiod Latin squares. Flows of fatty acids at the duodenum were assessed using ytterbium acetate and chromium ethylene diamine tetra-acetic acid as indigestible markers. Intakes of DM were higher (P , 0.001) for red clover silage than grass silage (5.98 v. 5.09 kg/day). There was a linear interaction effect (P 5 0.004) to FO with a reduction in DM intake in steers fed red clover silage supplemented with 30 g FO/kg diet DM. Apparent ruminal biohydrogenation of C18:2n-6 and C18:3n-3 were lower (P , 0.001) for red clover silage than grass silage (0.83 and 0.79 v. 0.87 and 0.87, respectively), whilst FO increased the extent of biohydrogenation on both diets. Ruminal biohydrogenation of C20:5n-3 and C22:6n-3 was extensive on both silage diets, averaging 0.94 and 0.97, respectively. Inclusion of FO in the diet enhanced the flow of total CLA leaving the rumen with an average across silages of 0.22, 0.31, 0.41 and 0.44 g/day for 0, 10, 20 or 30 g FO/kg, respectively, with a linear interaction effect between the two silages (P 5 0.03). FO also showed a dose-dependent increase in the flow of trans-C18:1 intermediates at the duodenum from 4.6 to 15.0 g/day on grass silage and from 9.4 to 22.5 g/day for red clover silage. Concentrations of trans-C18:1 with double bonds from D 4-16 in duodenal digesta were all elevated in response to FO in both diets, with trans-11 being the predominant isomer. FO inhibited the complete biohydrogenation of dietary PUFA on both diets, whilst red clover increased the flow of C18:2n-6 and C18:3n-3 compared with grass silage. In conclusion, supplementing red clover silage-based diets with FO represents a novel nutritional strategy for enhancing the concentrations of beneficial fatty acids in ruminant milk and meat.

Lipid metabolism in the rumen: New insights on lipolysis and biohydrogenation with an emphasis on the role of endogenous plant factors

“…These results also support the argument for there being a relationship between dietary NDF levels and iso C14:0 and iso C15:0 levels in ruminal microorganisms (Vlaeminck et al, 2006c). A relationship also Lee et al (2008b), and Dewhurst et al (2007), adapted. occurred between linear odd chain fatty acids (OCFA) and the proportion of propionate in the rumen because amylolytic bacteria contains high levels of OCFA (Vlaeminck et al, 2004b(Vlaeminck et al, , 2006c, suggesting that it may be possible to predict rumen fermentation patterns from milk OBCFA, rather than from the chemical composition of the diet. In particular, the lower values of the root mean square prediction error between milk OBCFA and ruminal VFA (3.0%, 9.0% and 8.9% for acetate, propionate and butyrate, respectively), during the validation of the prediction equation (Vlaeminck et al, 2006c), suggest that this new approach is correct.…”

Role of trans fatty acids in the nutritional regulation of mammary lipogenesis in ruminants

“…Nevertheless, recent in vitro and in vivo studies have provided additional insight into possible biochemical pathways accounting for the formation of specific intermediates during the metabolism of LA ( Figure 2) and LNA ( Figure 3). Fish oil or marine algal oil rich in long chain polyunsaturated fatty acids (PUFA) in the diet are known to inhibit the complete biohydrogenation of C18 unsaturated fatty acids resulting in an increase in ruminal trans 18:1 and trans 18:2 outflow Kim et al, 2008;Lee et al, 2008). Incubations with rumen micro-organisms have shown that eicosapentaenoic acid (EPA; cis-5, cis-8, cis-11, cis-14, cis-17 20:5) and docosahexaenoic acid (DHA; Figure 2 Putative pathways describing cis-9, cis-12 18:2 metabolism in the rumen (adapted from Harfoot and Hazlewood, 1988;Hudson et al, 1998;Wallace et al, 2007;Shingfield et al, 2008a).…”

Effect of short-term versus long-term grassland management and seasonal variation in organic and conventional dairy farming on the composition of bulk tank milk

“…Further, higher proportions of C18:1 trans FA and C18:2 cis-9,trans-11, partly deriving from the rumen biohydrogenation intermediate C18:1 trans-11, indicate an inhibition of the terminal biohydrogenation step in cows on ORG farms. An accumulation of biohydrogenation intermediates has been observed by including fish oil in the diet (Lee et al, 2008;Shingfield et al, 2012) or by feeding botanically diverse forages (Lourenço et al, 2008).…”