Chemical Composition and Gas Production Substrates of Maize Cobs Treated with Combinations of Urea and Wood Ash

Effect of treating maize cobs with a combination of urea and wood ash (WA) on chemical composition and in vitro gas production truly degraded substrate (TDS) were examined. The treatments were: 100U = (100% urea +0% wood ash), 75U25WA = (75% urea +25% wood ash), 50U50WA = (50% urea +50% wood ash), 25U75WA = (25 % urea + 75% wood ash) and 0U0WA = (Untreated maize cobs). Samples were analyzed for dry matter (DM), organic matter (OM), ash, crude protein (CP), neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL) and also incubated in vitro for 6, 12, 24, 48 and 72 hrs and their DM degradation kinetics described using the equation y = a + b (1- e-ct). It was observed that crude protein contents declined as urea is substituted with WA while the ash contents increased. Treatment 25U75WA had the highest reduction in both NDF and ADF (660 and 360 g/kg) compared to those of 100U (700 and 380g/kg) and 0U0WA (840 and 430 g/kg). In contrast treatment 25U75 had the highest neutral detergent soluble (340 g/kg) while 0U0WA had the least (160 g/kg).Treatment 25U75WA had the highest gas production (73.5ml per 0.5mg sample; P=0.0001) and truly degraded substrate (TDS) (70.53%) while 0U0WA had the least. Treatment 25U75WA also resulted in the highest microbial mass protein (MMP) (53.55 mg) while 0U0WA had the least (25.20 mg). Treatment 25U75WA had the highest efficiency of microbial mass protein (EMMP) and partitioning factor (PF) (23.68 and 2.883) while 0U0WA had the least (12.00 and 2.500). It was concluded that combinations of 25% urea and 75% WA in the treatment of maize cobs had beneficial synergic effect and improved its nutritive value compared to treating it with urea alone. This strategy will reduce cost of treatment and incorporate minerals present in ash.