Substituition of urea for soybean meal and forced intake of minerals on the performance of growing crossbred calves

ABSTRACT Forty eight crossbred calves, 24 males and 24 females, with weight and age of 203.6±3.7kg and 11.8±1.0 months were allotted to the following treatments: MT- mineral salt ad libitum and sugar cane mixed with 10g kg-1 mixture of urea and ammonium sulfate in a 9:1 proportion; MA - sugar cane mixed with 16g kg-1 of a concentrate of urea (550g kg-1), ammonium sulfate (60g kg-1) and minerals (390g kg-1); SU - sugar cane mixed with 50g kg-1 of a concentrate of soybean meal (830g kg-1), urea (52g kg-1) and minerals (118g kg-1) and MC - corn silage mixed with 10g kg-1 of a concentrate of urea (500g kg-1), ammonium sulfate (50g kg-1) and minerals (450g kg-1). Minerals mixed with sugar cane (MA) resulted in greater weight gain (0.258 x 0.188kg d-1) for similar intakes of DM (3.29 x 3.30kg d-1). Substitution of part of urea nitrogen in the MA by soybean meal (SU) resulted in greater ADG (0.538 x 0.258kg d-1), due to higher sugar cane intake (4.10 x 3.13kg d-1). ADG of calves receiving corn silage was greater (0.406 x 0.258kg d-1) than for calves receiving sugar cane.

摘要：本试验选取48头杂交犊牛，公母各24头，初始体重为203.6±3.7kg，月龄为11.8±1.0月龄，随机分为4个处理组：MT组：自由采食矿物盐，同时在甘蔗饲粮中添加比例为9:1的尿素与硫酸铵混合物，添加量为10g/kg；MA组：在甘蔗饲粮中添加16g/kg的复合浓缩料，该浓缩料由尿素（550g/kg）、硫酸铵（60g/kg）与矿物质（390g/kg）配制而成；SU组：在甘蔗饲粮中添加50g/kg的复合浓缩料，该浓缩料由豆粕（830g/kg）、尿素（52g/kg）与矿物质（118g/kg）配制而成；MC组：在玉米青贮饲粮中添加10g/kg的复合浓缩料，该浓缩料由尿素（500g/kg）、硫酸铵（50g/kg）与矿物质（450g/kg）配制而成。
试验结果显示：MA组干物质（Dry Matter, DM）采食量与MT组相近（3.29 vs 3.30kg/天），但平均日增重（Average Daily Gain, ADG）更高（0.258 vs 0.188kg/天）；将MA组中部分尿素氮以豆粕替代的SU组，其平均日增重进一步提升至0.538kg/天，显著高于MA组的0.258kg/天，这得益于该组更高的甘蔗饲粮采食量（4.10 vs 3.13kg/天）；采食玉米青贮饲粮的MC组犊牛平均日增重为0.406kg/天，显著高于采食甘蔗饲粮的犊牛（0.258kg/天）。