This study was conducted to evaluate nutrient compositions and effects of seven different forage to concentrate (R: C) ratios (100:0, 70:30, 60:40, 50:50, 40:60, 30:70 and 0:100) on gas and methane (CH4) production, in vitro organic matter digestibility (IVOMD), metabolizable energy (ME) and concentration of short-chain fatty acids (SCFA) using in vitro gas production technique. Different roughage feeds: Alfalfa hay (ALFH), grass hay (GH), maize stover (MS), corn silage (CS) and wheat straw (WS) based diets were formulated. Methane production was analyzed after 24h of incubation. Results showed that crude protein (CP) content, gas production (ml) at 24 and 48h incubation, IVOMD, ME, and SCFA concentration were increased (P <0.01) as the proportion of concentrate diet increased, while methane emission, NDF and ADF contents were reduced with increasing ratio of concentrate in the diet. Significantly (P <0.01) lower CH4 emission was noticed in R: C ratio of 60:40, 50:50, 40:60, 30:70 in GH, MS and WS based diets. It was concluded that inclusion of 40 to 70% concentrate feed into GH, WS and MS can reduce CH4 emission from low quality roughage feeds. However, the in vitro results need to be verified using in vivo studies.

Keywords: Girma Chalchissa*, Ajebu Nurfeta