Effects of capric acid on rumen methanogenesis and biohydrogenation of linoleic and α-linolenic acid

Abstract

Capric acid (C10:0), a medium chain fatty acid, was evaluated for its anti-methanogenic activity and its potential to modify the rumen biohydrogenation of linoleic (C18:2n-6) and a-linolenic acids (C18:3n-3). A standard dairy concentrate (0.5 g), supplemented with sunflower oil (10 mg) and linseed oil (10 mg) and increasing doses of capric acid (0, 10, 20 and 30 mg), was incubated with mixed rumen contents and buffer (1 : 4 v/v) for 24 h. The methane inhibitory effect of capric acid was more pronounced at the highest (30 mg) dose compared to the medium (20 mg) (285% v. 234%), whereas the lower dose (10 mg) did not reduce rumen methanogenesis. A 23% decrease in total short-chain fatty acid (SCFA) production was observed, accompanied by shifts towards increased butyrate at 20 mg and increased propionate at 30 mg of capric acid ( P , 0.001). Capric acid linearly decreased the extent of biohydrogenation of C18:2n-6 and C18:3n-3, by up to 60% and 86%, respectively. This reduction was partially due to a lower extent of lipolysis when capric acid was supplemented. Capric acid at 20 and 30 mg completely inhibited the production of C18:0 ( P , 0.001), resulting in an accumulation of biohydrogenation intermediates, mainly C18:1t10 1 t11 and C18:2t11c15. In contrast to effects on rumen fermentation (methane production and proportions of SCFA), 30 mg of capric acid did not induce major changes in rumen biohydrogenation as compared to the medium (20 mg) dose. This study revealed the dual action of capric acid, being inhibitory to both methane production and biohydrogenation of C18:2n-6 and C18:3n-3.

Performance and methane emissions of Nellore steers grazing tropical pasture supplemented with lipid sources

“…In contrast, this was not observed, since the palm oil treatment reduced the fiber digestibility in a manner similar to a source rich in UFA (linseed oil). The medium-chain fatty acids such as lauric and myristic acids found in high amounts in the palm oil diets may be toxic to the bacteria and methanogenic archaea in the rumen (Soliva et al 2004a and2004b); and the dissociation of these acids in bacterial cells has been proposed as a mode of antimicrobial action (Goel et al, 2009). Manso et al (2006) also observed a negative effect on NDF digestibility with increasing level of palm oil included in diets of sheep.…”

The role of microbes in rumen lipolysis and biohydrogenation and their manipulation

“…There is substantial overlap between the inhibitory effects of long chain length PUFA and medium chain SFA (10:0 to 14:0) on biohydrogenation (Jenkins et al, 2008;Goel et al, 2009), methanogenesis (Martin et al, 2009) and protozoal growth (Matsumoto et al, 1991;Boeckaert et al, 2007b;Sato and Karitani, 2009). Henderson (1973) discovered, in a pure culture study, that both a Butyrivibrio spp.…”

“…and a ruminal methanogen were inhibited by 10:0 to 14:0, while other Gram-negative species were not. Comparisons in which effects of FA on both biohydrogenation and methanogenesis are measured, such as that carried out by Goel et al (2009), are rare, however. Goel et al (2009) found that capric acid (10:0) inhibited both processes.…”

“…Comparisons in which effects of FA on both biohydrogenation and methanogenesis are measured, such as that carried out by Goel et al (2009), are rare, however. Goel et al (2009) found that capric acid (10:0) inhibited both processes. The concentration dependence of how capric acid inhibited biohydrogenation differed from that of methanogenesis, indicating that there were separate sites of action of capric acid, one being methanogenic archaea, the other biohydrogenating bacteria.…”

“…Thus, this group of oils probably do not benefit FA composition of ruminant products, despite the inhibitory effect of lauric acid (12:0) on B. fibrisolvens (Henderson, 1973). In contrast, Goel et al (2009) found that capric acid (10:0) inhibited biohydrogenation in vitro, as well as lipolysis.…”