The Effect of Different Sources of Urease Enzyme on the Nutritive Value of Wheat Straw Treated with Urea as a Source of Ammonia

Wheat straw samples (3-4 cm) were sprayed with solutions of urea (U) alone or with a dry addition of garden soil (GS), midden soil (MS), soya bean meal (SM) or jack bean meal (JM) as crude urease sources and with a pure urease (UR) enzyme. Each of the urease sources was included at two levels: 30 and 60 g/kg except pure urease, which was added at a level of 2.5 & 5.0 g/kg treated straw dry matter. Untreated straw without urease source was used as a control. After treatment, samples were sealed in polythene bags and stored for 2, 7, 14, 21 and 35 days at $19{^{\circ}C}$. The urease sources, their levels and treatment time produced significant effects on ammonia production (p<0.01). The addition of urease offered more flexibility in hydrolyzing urea in the shortest possible time. Incorporation of soya bean and jack bean meal was effective in reducing the modified acid detergent fiber (MADF) content of straw and the same time increasing organic matter (OM) digestibility. Overall effect, addition of soya bean to urea at a ratio of 1:1 appeared to be the most satisfactory urease source for the treatment of urea and wheat straw.