Biogas is a combustible gas produced by anaerobic fermentation of organic materials by methanogenic bacteria. The study was conducted using portable floating drum biogas plants of 0.5 m3 capacity, to study the quantity and composition of Biogas produced from the excreta of cattle, buffalo and goat. Two kilograms of representative sample of each excreta were taken and diluted to 10% dry matter level. The hydraulic retention time is for 25-30 days. The gas volumes were taken at constant pressure. The methane and carbon dioxide concentrations were analyzed using Gas Chromatography. The result showed a significant difference (P<0.01) between the substrates for both quantity and composition of biogas. The volume (m3) of biogas and methane concentration was highest in the excreta of goat followed by cattle and buffalo were as carbon dioxide concentration was highest in goat followed by cattle and buffalo.