Evaluation of dietary vitamin E supplementation on performance characteristics and immuno-competence of broiler chickens.

SUMMARY A 56 day feeding trial was carried out to investigate the effects of graded levels of dietary vitamin E on broiler chickens using growth performance and immune response to Newcastle disease vaccinations as response criteria. One hundred and sixty (160) day-old broiler chicks (Arbor acre breed) were randomly divided into 4 dietary treatments and fed diets supplemented with 0, 100, 200 and 300 mg/kg of vitamin E. The treatments were replicated 4 times with 10 birds each in a completely randomized design. The birds were vaccinated with Newcastle disease vaccines using a stipulated vaccination regime. The results revealed that of the growth performance indices measured only the total feed intake (TFI) was significantly influenced by the dietary treatments with birds fed diet containing 300mg/kg of vitamin E having the highest feed consumption (4.18kg/bird) and those fed the control diet the lowest (3.48kg/bird). The antibody titre values were significantly (p<0.05) different among dietary treatments after the 2 nd ND vaccination and birds fed diet supplemented with 100mg/kg vitamin E had the highest titre (log210), while those fed the control and 300mg/kg of vitamin E diets had the least titre (log28). Of the haematological indices measured, only the lymphocytes were significantly (p<0.05) influenced with birds fed 100mg/kg vitamin E supplemented diet having the highest value (67.33%) and lowest (61.33%) in birds fed 300mg/kg vitamin E supplemented diet. It was more profitable to supplement vitamin E at 200mg/kg with % cost reduction/kg diet of 11.49 compared with 9.25 and 8.91 observed in diets with 100 and 300mg/kg vitamin E supplementation respectively. It can therefore be concluded that while the FBW and TWG numerically improved with vitamin E supplementation in diets, the immune response of the birds to vitamin E activity varied with age