Optimum Supplemental Levels Of Iron, Copper, Zinc And Manganese In 0～3 Weeks Broiler Diet

D-optimal design was used to study the optimum supplemental levels of dietary iron, copper, zinc and manganese of broiler chickens from 0 to 21 d of age. The added level of each element was from zero to twice as much as the requirements of NRC (1994). 960 one-day-old Avian broilers were divided into sixteen groups randomly, four repetitions each group and fifteen birds each repetition. Growth performance, development of thyroid gland and spleen , concentrations of iron, copper, zinc and manganese in liver, heart, tibia ash and excreta were determined and the multiple regression analysis was used to estimate the optimum supplemental levels of these four elements in broiler diet. The results indicated as follows:1.The optimum supplemental levels of iron, copper, zinc and manganese obtained from growth performance and development of thyroid gland and spleen were more consistent than that obtained from the concentrations of trace elements in liver, heart, tibia ash and excreta, which were affected more by the interactions of dietary elements. It seemed that the concentrations of trace elements in liver, heart, tibia ash and excreta were not suitable parameters to evaluate the supplemental levels of iron, copper, zinc and manganese when they were considered together.2. The regression equations obtained from day weight gain, feed consumption, gain/feed, and the relatively weight of spleen and thyroid respectively were showed as follows: y day weight gain=28.07-0.27x1+0.58x3+0.24x12+0.264x1x2-0.348x1x4+0.296x2x3+0.538x3x4 y feed consumption=53.652+0.413x2+0.268x3+0.481x4+0.588x12+1.029x42-0.441x1x3 -0.580x1x4-0.191x2x3-0.162x2x4+0.423x3x4 y feed/gain=1.912+0.028x1-0.035x3+0.017x4-0.013x32+0.029x42-0.008x1x3+0.015x1x4 -0.0450x2x3 -0.011x2x4-0.010x3x4 y spleen=0.091-0.001x1 -0.002x4 +0.003x1x2+0.002x1x4-0.003x2x3+0.006x2x4 +0.001x3x4 y thyroid=0.412+0.007x1+0.006x2+0.007x3-0.004x4+0.027x12+0.015x22 +0.038x32 -0.009x1x3-0.007x1x4-0.010x2x3-0.002x2x4+0.014x3x4The optimum supplemental levels of iron, copper, zinc and manganese obtained from these parameters were 0,16,80 and 120 mg/kg,0,0,80 and 120 mg/kg,0,0,0 and 44 mg/kg,0,0,80 and 0 mg/kg, 0,16,0 and 0 mg/kg, respectively。3. The basal diet contained iron, copper , zinc and manganese at 243.1,13.7,44.4 and 16.34 mg/kg, respectively, which could meet the elemental requirement of the broilers in some extent.4.According to all the results obtained , the optimum supplemental levels of iron, copper, zinc and manganese recommended in 0 to 21 d of broiler chickens diet were 0,0,0 and 44 mg/kg,respectively.