Intake and Utilization of Nutrients in Growing Crossbred Bull Calves Fed on Cereal Grain Withdrawn Diet With Dry or Green Forage

摘要

Withdrawal of cereal grain from the diet based on wheat straw or maize fZea mays) green fodder was evaluated to assess comparative nutritional performance of 25 growing crossbred bull calves (250 kg BW, 13-16 months age) divided in to five similar groups (S_1S_2 S_3 G_2 and GJ and fed on five different rations composed of iso-nitrogenous concentrate mixtures (C) with (WO and 50%;) and without cereal grain plus dry (wheat straw, WS) or green (maize fodder, GMF) roughages. Groups fed on C with reducedlevels of cereal grain plus WS were represented as S_1, S_2 and S_3 and those with maize fodder groups were designated as G_2 and G_3 The concentrate mixtures were offered at the rate of 1.0% of calf's live weight and the forages were fed ad libitum. Theintake of DM, CP and energy (TDN/ME) and digestibility of different nutrients over 18 weeks experimental period showed non-significant difference due to withdrawal of cereal grain from the diet. However, the effect of roughage source showed higher nutrient intake in GMF fed groups as compared to WS and also, had higher digestibility (%) of DM (67.4 vs 60.6), OM (69.7 vs 62.9), CP (68.9 vs 65.4), total carbohydrates (69.9 vs 62.9) and fiber components (NDF61.3 vs 51.0; ADF 51.8 vs 43.51. The GMF fed groups had higher N intake (134.1 vs 106.9g/d), but did not have significant effect on N balance and utilization. No significant effect on N intake and balance parameters was observed due to withdrawal of cereal grains. In the same fine the live weight gain(g/d) was not significantly influenced due to grain withdrawal in either WS fed groups (449, 437 and 430 in S_1 S_2 and S_3 respectively) or GMF fed groups (506 in G2 and 514 in GJ, but the source of roughage showed significantly (P<0.05) higher gain inthe later groups than the former. The present feeding system resulted in saving of 3.0q cereal grain and 44 kg oil cakes at 50% withdrawal and 5.9q and 80kg, respectively at 100% withdrawal of cereal grain on WS based feeding, and the corresponding values were same for grains whereas these increased by 216 and 255 kg of oil cakes on GMF based feeding with a net price save of 7.76, 13.85, 14.59 and 22.14 % in S_2 S_3 G_2 and G_3 respectively based on relative market price of the concentrate ingredinets.