EVALUATION OF CHEMICAL COMPOSITION AND IN-VITRO DIGESTIBILITY AND GAS PRODUCTION OF MAIZE (ZEA MAYS L.) STOVER AND COMMON BEAN (PHASEOLUS VULGARIS L.) STRAW ENSILED WITH ACTIVATED EFFECTIVE MICROORGANISMS AND UREA

Abstract

This study was conducted in Haramaya University compound with the aim to evaluate chemical composition, in vitro dry matter digestibility, in-vitro gas and methane production of activated Effective microorganisms( EM) plus urea treated maize (Zea mays L.) stover and common bean (Phaseolus vulgaris L.) straw mixed at different proportions. The experiment was conducted using completely randomized design (CRD) and each treatment replicated 3 times. The dried and chopped maize stover (MS) and common bean straw (CBS) were combined in different proportions to form five experimental treatment groups: T1 (75% MS + 25% CBS), T2 (50% MS + 50% CBS), T3 (25% MS + 75% CBS) were treated by the EM-Urea solution which was prepared by combining 2 liters of EM solution and 2 liters of Urea solution for each 4kg of stover and straw combination treatments and T4 (100 % untreated MS) and T5 (100 % untreated CBS) were ensiled in airtight plastic bags for 21 days. Representative samples of silages were collected and analyzed in the laboratory of animal nutrition at Hawassa University for nutritional composition, in- vitro dry matter digestibility (IVDMD), in vitro gas and methane production. Sensory evaluation and visual appraisal indicated that there was no fungus development. In all types of silages, treatment affected the chemical composition through decreasing the neutral detergent fiber (NDF) (72.25, 70.27 and 69.20 %) as compared to the two controls (T4 and T5) and methane (CH4) production (22.47, 21.93 and 21.97ml) as compared to the one control (T4) where as crude protein (CP) (8.37, 10.48 and 10.52%) and Ash (13.07, 13.63 and 13.84%) increased as compared to one control (T4) for T1, T2 and T3, respectively. There was significant difference (P<0.05) in in-vitro dry matter digestibility (IVDMD) among experimental treatments in which, T2 and T3 showed the highest IVDMD value (62.97 and 63.72%) respectively. The CP and IVDMD contents increased with increasing proportions of CBS across T1 to T2. The gas production parameters increased by the additive treatment as compared to the two controls. The in vitro gas production increased with increasing the incubation time across all treatments. The metabolisable energy and rate of gas production (c) decreased in the order of T2 > T3 > T1 > T5 > T4. Gas production from insoluble but fermentable fractions (b) and potential gas production (a + b) had positive correlation with ash and CP and negative correlation with fiber (NDF and ADF). This indicated that treating both crop residues combined in different proportion by activated EM and urea had improved the nutritive value. However, T2 (50% MS + 50% CBS) was the most effective treatment in most of nutritional quality parameters included in this study. Thus, the T2 fermentation products are recommended for ruminant animals feeding during dry season.