ABSTRACT
Present study was aimed at investigating the effects of threonine supplementation on antioxidant enzyme activities and haemato-biochemical profile of commercial broilers in sub-tropics. Three hundred thirty -day old straight run commercial broiler chicks (Vencobb-400) with initial average body weight of 44.04±0.42g were allocated into five experimental groups, in a completely randomized design (CRD) with 42 days experiment. Groups were formed according to the dose of supplemental L-threonine in various rations i.e. NRC specification, 100% of Vencobb-400 strain specification, 110% of Vencobb-400 specification, 120% of Vencobb-400 specification and 130% of Vencobb-400 specification group. The mean serum GSH-Px and serum catalase concentration increased linearly {(p=0.001) and (p=0.04), respectively} whereas the mean serum SOD level increased both linearly (p=0.002) and quadratically (p=0.04) with the increasing levels of supplemental L-threonine. Among the hematological parameters of blood, the H:L ratio decreased linearly (p=0.02) with the increasing levels of threonine. The serum glucose and total protein concentration increased linearly (p=0.002) with the increasing levels of supplemental L-threonine. There was a linear increment (P<0.001) in serum globulin level with a linear decrease (p<0.05) in albumin: globulin ratio on increased levels of supplemental L-threonine in the ration. There was a linear decrease (p<0.001) in cholesterol and VLDL level with the increasing levels of supplemental L-threonine, however, a linear increment (p=0.04) in the serum HDL level was noticed. It may be concluded that L-threonine supplementation at 130% threonine (of Vencobb-400 specification) has a better antioxidant function and better haemato-biochemical profile