Ruminal methanogenesis as influenced by individual fatty acids supplemented to complete ruminant diets

Abstract

F. DOHME, A. MACHMÜLLER, A. WASSERFALLEN AND M. KREUZER. 2001. The objective of the present study was to investigate the effects of seven different pure fatty acids on rumen fermentation using the rumen simulation technique (RUSITEC). The fatty acids were supplied to a complete ruminant diet at a proportion of 50 g kg−1 dietary dry matter and compared with an unsupplemented control. Methane release and methanogenic counts were suppressed by the fatty acids C12 : 0, C14 : 0 and C18 : 2 whereas C8 : 0, C10 : 0, C16 : 0 and C18 : 0 showed no corresponding effects. Apart from C12 : 0 and C18 : 2, C8 : 0 and C10 : 0 also adversely affected ciliate protozoa suggesting independence from the methane‐suppressing effect of medium‐chain fatty acids (MCFA). Although MCFA but not C18 : 2 reduced ruminal fibre degradation, the influence on other fermentation traits remained low. In conclusion, the supply of certain fatty acids to ruminant diets seems to have the potential to reduce methane release.

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

“…In contrast, Dohme et al (2001) did not observe any effect of capric acid on ruminal methanogenesis. These contrasting observations might be linked to the interaction between capric acid and the basal substrate.…”

“…Dohme et al (2001) observed the shifts in SCFA proportions pattern towards more butyrate and lower propionate at 30 mg per 50 ml of incubation fluid. The varying effects on proportions of SCFA at different concentrations of capric acid were unexpected.…”

“…In some preliminary trials, we also did not observe any reduction in methane when hay was used as substrate (data not shown), which indicates that inclusion of roughage in the basal substrate reduces the methane-suppressing effect of capric acid. The addition of sunflower and linseed oil added as PUFA sources was another difference between the current study and the one of Dohme et al (2001). PUFA might also affect rumen methanogenesis and fermentation and a confounding effect between capric acid and the PUFA sources cannot be excluded in the current study.…”

“…The antimethanogenic activity of other MCFAs has been attributed to their antimicrobial activity. Lauric acid (C12:0) and myristic acid (C14:0) as pure FA have been reported to decrease methane production by 12% when incubated at 30 mg per 50 ml of incubation fluid (Dohme et al, 2001) whereas a 74% reduction in methane was observed when C12:0 was incubated alone (Soliva et al, 2004a) and it was 96% when incubated in a mixture with C14:0 (C12:0 : C14:0, 2 : 1) (Soliva et al, 2004b) at 30 mg per 30 ml of incubation fluid. Coconut oil rich in these MCFA was reported to decrease methane by 26% in lambs (Machmü ller et al, 2000).…”

“…In this context, the medium chain fatty acids (MCFA) have been suggested as effective dietary fats to suppress ruminal methanogenesis through their antimicrobial activity. Indeed, several studies have reported decreased ruminal methanogenesis when supplementing MCFA such as lauric (C12:0) and myristic acid (C14:0), either in pure forms or in products rich in these fatty acids under in vitro (Dohme et al, 2001;Soliva et al, 2004a and2004b) or in vivo conditions (Blaxter and Czerkawski, 1966;Machmü ller et al, 2000). Dissociation of these MCFA in the bacterial cell has been suggested as the mode of antimicrobial activity.…”