Effects of vegetable oil supplementation on feed intake, rumen fermentation, growth performance, and carcass characteristic of growing swamp buffaloes M. Wanapat ⁎, C. Mapato, R. Pilajun, W. Toburan 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 17 November 2009 Received in revised form 8 June 2010 Accepted 9 June 2010 Fifteen, one year old swamp buffalo males with average liveweight of 200.5 ± 9.5 kg were randomly assigned according to a completely randomized design to receive three dietary treatments of supplemental vegetable oils in concentrate contained 140, 750, and 16 g of crude protein, total digestible nutrient, and ether extract, respectively (T1 = unsupplemented, T2 = supplemental coconut oil and sunflower oil in ratio 50:50 at 6% of concentrate, and T3 = supplemental sunflower oil at 6% of concentrate) during a 5-month feeding trial. Urea- treated rice straw was offered ad libitum and concentrate was supplemented at 150 g/kg BW. The results revealed that supplementation of vegetable oils decreased dry matter intake in sunflower oil supplemented group. Combination of coconut oil and sunflower oil supplementation resulted in similar average daily gain as those found in control and in sunflower oil supplemented groups. Rumen microorganism population, ammonia–nitrogen, blood urea–nitrogen and total volatile fatty acid concentrations were decreased as vegetable oils were supplemented. Oil supplementation slightly reduced growth rate, hot carcass percentage, loin eye area particularly on sunflower oil supplemented group. Based on these findings, vegetable oil resulted in decreased performance of swamp buffaloes although the combination of coconut oil and sunflower oil could reduce negative effect of unsaturated oil supplementation. However, further analyses of conjugated fatty acids (CLA) in meat could offer useful information in determining pronounced effects of vegetable oil supplementation. © 2010 Elsevier B.V. All rights reserved. Keywords: Vegetable oil Rumen fermentation Growth performance Carcass characteristic Swamp buffalo Rice straw 1. Introduction Swamp buffaloes play an important role in small holder farming systems by providing draft power for paddy fields, meat, use of by-products etc. (Chantalakana, 2001). The rumen of swamp buffalo has been found to contain a larger population of bacteria particularly the cellulolytic bacteria, fungi zoospores and lower protozoa (Wanapat and Rowlin- son, 2007; Wanapat and Cherdthong, 2009; Wanapat et al., 2009). In addition, higher ruminal pH and ammonia–nitrogen concentration have been found as compared to those in cattle indicating higher rumen N-recycling (Wanapat et al., 2003). Manipulation of diets will enhance rumen fermentation and subsequent uses by the ruminants (Thu and Preston, 1999; Wanapat, 2000, 2001; Wanapat and Rowlinson, 2007; Wanapat et al., 2008). Buffalo meat consisted of crimson, bigger muscle fiber thickness and with white fat while cattle meat has vermilion, powdery and yellow fat (Valin et al., 1984). Dressing percentage of buffalo ranges from 42 to 53% and contains 2–3% less marbling than those found in cattle (Robertson et al., 1986). Rumen fermentation is of prime importance which could produce fermentation end-products, particularly volatile fatty acids and ammonia–nitrogen (Russell and Rychlik, 2001). It has been clearly shown that rumen fermentation can supply 70–100% of a ruminant animal's amino acid and Livestock Science 135 (2011) 32–37 Abbreviation: BW, body weight; CLA, conjugated fatty acid; WBS, Warner–Bratzler shear force; TPA, texture profile analysis; S.E.M., standard error of the means; LI, longissimus dorsi; SM, semimembranosus. ⁎ Corresponding author. Tel./fax: + 66 43 202368. E-mail address: metha@kku.ac.th (M. Wanapat). 1871-1413/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.livsci.2010.06.006 Contents lists available at ScienceDirect Livestock Science journal homepage: www.elsevier.com/locate/livsci