Nutrient Digestibility and Growth of Local Bull Calves as Affected by Feeding Urea and Urease Enzyme Sources Treated Rice Straw

The experiment was conducted for a period of 75 days to study the effect of treatment of straw with urea or with urea and a urease containing chick pea seed meal and midden soil on chemical composition of treated rice straw, feed intake of the animals, nutrients digestibility, body weight gain, and feed conversion efficiency. For the study twelve indigenous growing bulls aged approximately 20 months and weighing 115.16 ± 1.50 kg were divided into four groups having three animals in each group. The animals of group A received 3.5% urea treated fresh straw, group B received 3.5% urea treated ensiled straw, group C received 3.5% urea + 2.5% midden soil treated ensiled straw and group D received 3.5% urea + 2.5% chick pea treated ensiled straw. All the animals were supplied with treated rice straw, green grass and concentrate mixture. Rice straw treated with 3.5% urea resulted an improvement in crude protein content of rice straw from 3.33 to 7.70 and 8.10 % (without ensiling and ensiling) which was further increased by 8.20 and 9.50% with the addition of 2.5% midden soil and 2.5% chick pea seed meal at the time of treatment. Significantly higher (P<0.05) daily dry matter intake was observed in animals fed diet D (4.42) followed by diet C (4.39), diet B (4.34) and diet A (4.12). The total CP intake by the animals of D groups was significantly higher (P<0.01) than that of the animals receiving diet A, B and C. During the 75 days trail, the total live weight gains were 30.50, 35.17, 38.17 and 39.83 kg for bull calves fed diet A (3.5% urea treated straw without ensiling), diet B (3.5% urea treated straw with ensiling), diet C (3.5% urea + 2.5% midden soil treated straw) and diet D (3.5% urea + 2.5% chick pea seed meal treated straw) respectively. The daily live weight gains were 0.41, .047, 0.51 and 0.53 kg in groups A, B, C and D respectively. Midden soil and chick pea seed meal addition with treated rice straw not only significantly (P<0.01) increased the coefficient of digestibility of DM, CP, and CF but also significantly (P<0.05) increased the coefficient of digestibility of OM, NFE than only urea treated straw (both without ensiling and ensiling). Addition of urease sources also increased (P<0.01) the digestible crude protein (DCP), digestible ether extract (DEE). Digestible nitrogen free extract (DNFE), digestible organic matter (DOM) and total digestible nutrients (TDN) contents were significantly (P<0.05) higher in diet D in comparison to diet A, B and C.