Influence of Threonine Supplementation on Antioxidant Enzyme Activities and Haemato-biochemical Parameters of Commercial Layers in Sub-Tropics

A study was conducted to see the effects of threonine supplementation on antioxidant enzyme activities and haemato-biochemical parameters of commercial layers. Sixteen hundred and eighty (1680) BV-300 laying birds of 40 weeks age with an average body weight of 1353±5.86g were allocated in a completely randomized design with five (5) groups of 336 birds in each. Groups were formed according to the dose of supplemented threonine in various rations i.e. NRC specification, BV-300 strain requirement, 110% of BV-300 strain requirement, 120% of BV-300 strain requirement and 130% of BV-300 strain requirement. With the increasing levels of supplemental L-threonine, GSH-Px activity and serum SOD level increased linearly (p=0.005 and p=0.002, respectively). Among hematological parameters, though non-significant, Heterophils/Lymphocyte ratio tended to decrease linearly (p=0.02). The sugar and total protein concentration increased linearly (p<0.001) while albumin and globulin concentration increased linearly and quadratically. There was a linear decrease (p<0.001) in blood cholesterol level. It may be concluded that L-threonine supplementation at 130% of BV-300 recommendation has a better antioxidant function and better haemato-biochemical parameters.