Effect of coconut oil and garlic powder on in vitro fermentation using gas production technique P. Kongmun, M. Wanapat ⁎, P. Pakdee, C. Navanukraw Tropical Feed Resources Research and Development Center (TROFREC), Department of Animal Science, Faculty of Agriculture, Khon Kaen University, Khon Kaen, 40002, Thailand article info abstract Article history: Received 13 February 2009 Received in revised form 4 August 2009 Accepted 18 August 2009 An in vitro gas technique trial was conducted to investigate the effect of coconut oil (Co), garlic powder (G) and their mixtures on in vitro fermentation. Incubation was carried out using rumen fluid obtained from swamp buffaloes. The experimental design was a completely randomized design (CRD). The dietary treatments were ratio of Co and G supplementation at 0:0, 16:0, 8:4, 4:8 and 0:16 mg with rice straw as a roughage source. Cumulative gas production was recorded at 0, 2, 4, 6, 8, 12, 18, 24, 36, 48, 60 and 72 h of incubation. In vitro true digestibility (IVTD) was determined after 48 h incubation. Cumulative gas production at 72 h was significantly lowest (P < 0.05) at Co:G, 16:0 mg. Garlic powder supplementation at 16 mg decreased (P < 0.05) NH 3 –N concentration and increased (P < 0.05) in vitro true digestibility (IVTD) while supplemented coconut oil at 16 mg decreased (P< 0.05) IVTD. Total volatile fatty acids (VFAs) were lowest (P < 0.05) by garlic powder supplementation at 16 mg. However, supplementation of Co:G, 8:4, 4:8 and 0:16 mg tended to increase the proportion of propionate, decrease C2:C3 ratio and reduce (P < 0.05) methane (CH 4 ) production. Protozoal population was significantly lowest (P< 0.05) at Co:G, 8:4 mg. Moreover, application of quantitative PCR to quantify predominant cellulolytic bacteria (16S rRNA) and fungi (18S rRNA) targets revealed that treatments did not have an effect on Ruminococcus flavefaciens and total fungi population. However, it was found that supplementation of Co:G at 8:4 mg increased Ruminococcus albus population (P < 0.05). Based on this study, it suggests that supplementation of Co:G at 8:4 and 0:16 mg could improve ruminal fluid fermentation in terms of volatile fatty acid profile, reduced methane losses and reduced protozoal population. © 2009 Elsevier B.V. All rights reserved. Keywords: Coconut oil Garlic powder In vitro fermentation Real-time PCR 1. Introduction Modification of ruminal fermentation using feed additives, such as antibiotics, has proved to be a useful strategy to improve production efficiency in dairy cattle. The use of antibiotics as feed additives has proved to be a useful tool to reduce energy and nitrogen losses from the diet (McGuffey et al., 2001). However, the use of antibiotics as feed additives in dairy cows has been of increasing concern due to the potential appearance of residues in milk. Furthermore, the use of antibiotics as a feed additive has been banned in the European Union (Russell and Houlihan, 2003). For this reason, scientists are interested in evaluating the potential use of natural antimicrobials such as herbs and plant extracts. Currently, the use of plant herbs has resulted in improving rumen ecology (Kamra, 2005; Wanapat et al., 2008a). Garlic (Allium sativum) is an herb or spice plant that has been used by humans as a source of antimicrobial agents for the gastrointestinal. It has a complex mixture of many secondary plant products including allicin (C 6 H 10 S 2 O), diallyl sulfide (C 6 H 10 S), dialyl disulfide (C 6 H 10 S 2 ) and allyl mercaptan (C 3 H 6 S) among others (Lawson, 1996). These compounds could manipulate rumen fermentation such as decreased in the proportion of acetate and increased in proportion of propionate and butyrate, inhibition of methanogenesis and decreased in the CH 4 :VFA ratio (Busquet et al., 2005b). Livestock Science 127 (2010) 38–44 ⁎ Corresponding author. Tel.: +66 43 202 368. E-mail address: metha@kku.ac.th (M. Wanapat). 1871-1413/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.livsci.2009.08.008 Contents lists available at ScienceDirect Livestock Science journal homepage: www.elsevier.com/locate/livsci