Biohydrogenation Of Linolenic Acid Research Articles

Rumen biohydrogenation of linoleic and linolenic acids is reduced when esterified to phospholipids or steroids.

Manipulation of rumen biohydrogenation (BH) is of great importance, since decreased BH of linolenic acid (LNA) and linoleic acid (LA) is linked to increased content of the beneficial polyunsaturated fatty acids (PUFA) in dairy products and decreased content of trans fatty acids (FAs). We hypothesized that PUFA esterified to the complex lipid fractions are less prone to BH compared with PUFA esterified to the simple lipid fractions due to reduced lipolysis. In vitro rumen BH of different single lipid fractions was investigated, including free fatty acids (FFA), and esterified FA to triglycerides (TG), cholesterol esters (CE), and phospholipids (PL). A mixture of a buffer solution and rumen fluid was incubated with different lipid fractions, and C18 FAs were quantified by gas chromatography. In vitro BH kinetic parameters were quantified according to Michaelis–Menten equation and the maximum BH (Vmax) and time to achieve 50% of maximum amount (KM) estimated. Regardless of fatty acids, BH in CE and PL was lower than FFA and TG. The highest amount of cis‐9, trans‐11 conjugated linoleic acid (CLA) and trans‐10, cis‐12 CLA was observed in lipid fractions containing LA and LNA, respectively, regardless of lipid fractions. The present study demonstrates the importance of lipid fractions on BH of LNA and LA and formation of CLA isomers. The results show that BH of FAs depends on the lipid fractions.

Garlic oil reduces ruminal fatty acid biohydrogenation in vitro

Nutritional policies recommend that animal products should be made to contain more polyunsaturated FA, especially n‐3 FA. This means finding ways to limit ruminal lipolysis and/or biohydrogenation. In pursuit of this goal, we performed an in vitro study to test the ability of four feed additives, typically used for other purposes, to reduce ruminal biohydrogenation of a linolenic acid‐rich substrate. The four additives tested were cinnamon essential oil, brown algae (Ascophyllum nodosum), synthetic vitamin E, and garlic essential oil. The first three additives had no effect on ruminal fermentation and biohydrogenation. Garlic essential oil led to a decrease in methane production (P < 0.001), an increase in propionate (P = 0.002) and butyrate (P < 0.001) production at the expense of acetate (P < 0.001), and a decrease in biohydrogenation evaluated by the disappearance of linolenic acid (P = 0.083) and linoleic acid (P = 0.008). Stearic acid proportion in FA decreased, while biohydrogenation intermediates such as C18:2t11c15 and vaccenic acid proportion increased (P < 0.001).Practical applications: Garlic essential oil emerges as a promising additive for decreasing biohydrogenation, but its efficiency needs to be confirmed in vivo in different dietary conditions, and possible side effects of the incorporation of garlic oil in diets will have to be evaluated.When garlic oil is added to a control substrate in an incubator containing rumen contents, biohydrogenation of linolenic acid (18:3c9c12c15) is reduced, and proportion of different unsaturated FA increases at the expense of stearic acid (18:0) which decreases from 71.8 to 62.2%. If this is confirmed in vivo, this may contribute to reduce saturated FA in milk and meat from ruminants.

Effect of pH on conjugated linoleic acid (CLA) formation of linolenic acid biohydrogenation by ruminal microorganisms

Conventional beliefs surrounding the linolenic acid (LNA; cis-9 cis-12 cis-15 C18:3) biohydrogenation (BH) pathway propose that it converts to stearic acid (SA) without the formation of conjugated linoleic acid (CLA) as intermediate isomers. However, an advanced study (Lee and Jenkins, 2011) verified that LNA BH yields multiple CLAs. This study utilized the stable isotope tracer to investigate the BH intermediates of (13)C-LNA with different pH conditions (5.5 and 6.5). The (13)C enrichment was calculated as a (13)C/(12)C ratio of labeled minus unlabeled. After 24 h, eight CLA isomers were significantly enriched on both pH treatment, this result verifies that these CLAs originated from (13)C-LNA BH which supports the results of Lee and Jenkins (2011). The enrichment of cis-cis double bond CLAs (cis-9 cis-11 and cis-10 cis-12 CLA) were significantly higher at low pH conditions. Furthermore, the concentration of cis-10 cis-12 CLA at low pH was four times higher than at high pH conditions after a 3 h incubation. These differences support the LNA BH pathways partial switch under different pH conditions, with a strong influence on the cis-cis CLA at low pH. Several mono-, di-, and tri-enoic fatty acid isomers were enriched during 24 h of incubation, but the enrichment was decreased or restricted at low pH treatment. Based on these results, it is proposed that low pH conditions may cause a changed or limited capacity of the isomerization and reduction steps in BH.

Effects of oil source and fish oil addition on ruminal biohydrogenation of fatty acids and conjugated linoleic acid formation in beef steers fed finishing diets

Four Hereford steers (500 +/- 4.5 kg of BW) cannulated in the proximal duodenum were used to evaluate the effects of vegetable oil source or fish oil quantity on ruminal biohydrogenation (BH) and CLA outflow. Steers were fed 1 of 4 treatment diets in a 2 x 2 factorial arrangement of treatments (oil source: canola vs. corn oil; fish oil quantity: 0 or 1%) in a 4 x 4 Latin square design. The remainder of the diet included chopped bermudagrass hay, dry-rolled corn, and protein/mineral supplement. Duodenal samples were collected for 4 d after 11-d diet adaptation periods. Data were analyzed with animal, period, oil source, fish oil, and 2-way interaction among oil source and fish oil quantity in the model. All interactions among oil source and fish oil inclusion were nonsignificant with the exception of trans-11 vaccenic acid (TVA) and trans-9 octadecenoic acid. Intake and duodenal flow of total long-chain fatty acids did not differ between treatments. Apparent ruminal DM digestibility was not altered by oil source or fish oil inclusion. Apparent ruminal digestion of fatty acids did not differ among oil sources but was increased (P = 0.03) with fish oil supplementation. Ruminal BH of oleic and linolenic acids was increased (P = 0.01) for diets containing supplemental canola oil compared with corn oil. Ruminal BH of linoleic acid was greater (P = 0.01) for diets containing supplemental corn oil compared with canola oil. Fish oil addition reduced (P = 0.01) oleic acid BH but did not alter (P > 0.26) linoleic or linolenic acid BH. Duodenal flow of palmitic acid was greater (P = 0.05) for steers supplemented with corn oil compared with canola oil. Fish oil inclusion in the diet increased (P = 0.01) flow of n-3 fatty acids (eicosapentaenoic acid, docosapentaenoic acid, docosahexaenoic acid), trans-10 octadecenoic acid, trans-12 octadecenoic acid, and cis-9, trans-11 CLA. Trans-9 octadecenoic acid and TVA flows to the duodenum were increased (P = 0.01) when fish oil was included in the canola oil-supplemented diet; however, no changes were observed when fish oil was included in the corn oil-supplemented diet (P of interaction = 0.06 and 0.08). Fish oil inclusion increased the outflow of n-3 fatty acids, trans-10 octadecenoic acid, and the majority of CLA isomers including cis-9, trans-11. These results suggest that fish oil addition alters ruminal formation of BH intermediates that is dependent on oil source supplemented in the diet.

Biohydrogenation Pathways for Linoleic and Linolenic Acids by Orpinomyces Rumen Fungus

The objective of this study was to identify biohydrogenation pathways for linoleic, linolenic, oleic and stearic acids by Orpinomyces species of rumen fungus during in vitro culture. Biohydrogenation of linoleic acid produced conjugated linoleic acid (cis-9, trans-11 C18:2), which was then converted to vaccenic acid (trans-11 C18:1) as the end product of biohydrogenation. Biohydrogenation of linolenic acid produced cis-9, trans-11, cis-15 C18:3 and trans-11, cis-15 C18:2 as intermediates and vaccenic acid as the end product of biohydrogenation. Oleic acid and stearic acid were not converted to any other fatty acid. It is concluded that pathways for biohydrogenation of linoleic and linolenic acids by Orpinomyces are the same as those for group A rumen bacteria.