Berhanu K. Tesfaye1, Graeme J. McCrabb1, Salvador Fernandez-Rivera1, Solomon M. Ayele2, and Michael Blummel1. (1) International Livestock Research Institute, C/o SLP Office, P.O.Box 5689, Addis Ababa, Ethiopia, (2) Haramaya University, P.O.Box 138, Dire-Dawa, Ethiopia
Our objective was to measure methane emissions and energy partition of Bos indicus cattle fed on three typically used tropical feeds in Ethiopia. Six Borana breed bulls (232-285 kg) aged 2.0-2.5 years were used in a Latin Square experimental design using two head box respiration calorimeters. The treatment diets were (1) mature mixed sward grass hay (75% Cynodon dactylon) representing dry season feed, (2) immature Napier grass (Pennisetum purpureum) of intermediate quality representing wet season feed and (3) Tef (Eragrostis tef) straw supplemented with concentrate mixtures of wheat bran and noug (Guizotia abyssinica) cake at 35% of the total dry matter intake. Methane production was measured over 4 days and feed digestibility over 7 day period The analysis considered the effects of period, head box chamber, treatment diets and animals nested within the head box. Cattle fed on Napier grass had the highest (5.6± 0.14, P<0.01) voluntary DM. Dry matter digestibility was 63, 5, and 46% for Napier grass, tef straw based diet and grass hay, respectively. The digestibility of Napier grass was higher (P<0.01) for almost all nutrients compared tograss hay and tef straw based diets. Methane production (g/d) for cattle fed on grass hay (185.7 ± 13.6) was higher (P<0.05) than that for cattle fed on both tef straw supplemented with concentrate mixture (141.8 ± 13.6) and Napier grass (124.1 ± 13.6). Methane conversion rate (MJ of methane produced per 100 MJ of GE intake) was not significantly different (P>0.05) between animals fed on Napier grass (6.8 ± 0.84) and tef straw based diet (7.8 ± 0.84), but higher (P<0.05) in cattle fed on grass hay (12.6 ± 0.84). Opportunities for reducing methane emissions and improving productivity from cattle in Ethiopia have been explored and will be discussed. This research was supported by the US Environment Protection Agency.