Animal Feed Science and Technology 180 (2013) 18–25 Contents lists available at SciVerse ScienceDirect Animal Feed Science and Technology journal homepage: www.elsevier.com/locate/anifeedsci Medium-chain fatty acids from coconut or krabok oil inhibit in vitro rumen methanogenesis and conversion of non-conjugated dienoic biohydrogenation intermediates Paiwan Panyakaew a,b , Gunjan Goel a,c , Marta Lourenc ¸ o a , Chalermpon Yuangklang b , Veerle Fievez a,∗ a Laboratory for Animal Nutrition and Animal Product Quality (Lanupro), Faculty of Bioscience Engineering, Ghent University, Proefhoevestraat 10, 9090 Melle, Belgium b Department of Animal Science, Faculty of Natural Resources, Rajamangala University of Technology Isan, Sakon-Nakhon Campus, Sakon Nakhon 47160, Thailand c Department of Biotechnology and Bioinformatics, Jaypee University of Information Technology, Solan, India a r t i c l e i n f o Article history: Received 18 April 2012 Received in revised form 4 December 2012 Accepted 14 December 2012 Keywords: Krabok oil Coconut oil Rumen fermentation Methane Biohydrogenation a b s t r a c t Myristic (C14:0) and lauric (C12:0) acid have been suggested to synergistically influence rumen methanogenesis. This experiment compared the effect of krabok and coconut oil on rumen fermentation, in an attempt to assess this synergism using two natural oil sources which contain similar amounts of C12:0 but with krabok oil containing greater proportions of C14:0 than coconut oil. As a simultaneous action on both rumen methanogenesis and biohydrogenation has been reported for another medium chain fatty acid (C10:0), rumen biohydrogenation also was monitored during the current in vitro study. Five treatments were used: one control (CON), without supplementation of coconut or krabok oil, two coconut oil and two krabok oil supplemented incubations. Coconut and krabok oil were supplemented in two doses, providing either 80 (C80 and K80) or 120 mg (C120 and K120) of C12:0 + C14:0 per 100 ml of incubation fluid. A standard concentrate typically fed to rumi- nant livestock in Thailand (200 mg), buffer (20 ml) and rumen fluid (5 ml) were added to each incubation flask, with or without an external PUFA source (20 mg of a mixture of sun- flower and linseed oil). All flasks were incubated at 39 ◦ C for 24 h. Both krabok and coconut oil reduced methane production (P<0.05) and increased propionate production (P<0.05) at the expense of acetate (P<0.05) and butyrate production (P<0.05). Krabok and coconut oil induced similar changes and effects were stronger in combination with linseed and sun- flower oil, whereas the latter, in the amounts supplemented here, did not change methane production nor induced shifts in the production of any of the VFA. A trend for lower amounts of C18:2 n-6 and C18:3 n-3 after 24 h incubation was observed indicating a higher rate of lipolysis and isomerization of C18:2 n-6 and C18:3 n-3, as the inclusion levels of krabok oil increased. Overall, the effect of krabok and coconut oil on rumen biohydrogenation was limited. © 2012 Elsevier B.V. All rights reserved. Abbreviations: DHA, docosahexanoic acid; FA, fatty acids; FAME, fatty acid methyl esters; LCFA, long chain fatty acid(s); MCFA, medium chain fatty acid(s); PUFA, polyunsaturated fatty acid(s); RRF, relative response factor; VFA, volatile fatty acid(s). ∗ Corresponding author. Tel.: +32 9 264 9002; fax: +32 9 264 9099. E-mail address: Veerle.Fievez@UGent.be (V. Fievez). 0377-8401/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.anifeedsci.2012.12.005