Estimation of Zn requirement in wheat-soy diet through growth performance responses in broiler chickens

The present study was conducted to determine the zinc (Zn) requirement in broiler chickens fed wheat-soy based diet. Two hundred fifty day-old broiler chicks (Ross 308), were randomly assigned to a completely randomised design (CRD) experiment with 5 treatments, and 5 replicates of 10b each. The experimental treatments included five dietary Zn levels (30, 70, 110, 150, and 190 mg/kg) provided by the addition of reagent grade “ZnSO4.7H2O”. The experiment lasted from 1-42d of age. Increasing dietary Zn level to 70mg/kg significantly increased 10, 24 and 42d live body weight (LBW), feed intake (FI) and weight gain (WG) during 1-10, 25-42 and 1-42d of age and feed efficiency (FE) during 1-10d of age. The linear broken-line (LBL), quadratic-broken line (QBL) and the quadratic polynomial (QP) regression models were used to estimate the Zn requirement. The Zn requirement for optimal final LBW and FI, WG, and FE during 1-42d of ages by LBL model were 68.77, 83.12, 66.99 and 62.75 mg/kg of diet, and by QBL model 70.00, 79.93, 69.63 and 58.01 mg/kg of diet, respectively. In conclusion, Zn requirement varied between 58-83 mg/kg, which is higher than NRC and is lower than strain recommendation in the broiler chickens fed wheat-based diet.