Effect of higher dietary concentrations of α-tocopherol on growth performance and immune response in growing quails

A five-week growth bioassay was conducted to investigate the effect of higher dietary concentrations of vitamin E on production performance and primary immune response in broiler quails. For the purpose, 320-day-old heavy body weight quail chicks were randomly selected and divided into 20 groups of 16 chicks each. They were reared in electrically heated battery cages fitted with feeders and waterers. A basal diet composed of ground yellow maize, soybean meal, fish meal, rice bran etc. and having 24% crude protein and 2700 kcal ME/kg was formulated. From this basal diet, five experimental diets were prepared by incorporating vitamin E (as α-tocopherol acetate) at graded levels of 75, 150, 225 and 300 mg/kg in diet. Each experimental diet was offered ad libitum as mash form to four groups of quail chicks for Five weeks. Production performance in terms of body weight gain, feed intake, feed conversion ratio and mortality were recorded. For immunological studies, on 28th day of experimental feeding, two birds from each replicated group were intravenously injected with 0.2 ml of 2.5% SRBC suspension. The blood samples were collected at 0 and 6th day post inoculation for HA antibody titre estimation. During 4th week of experimental feeding, two birds/replicate/treatment were also injected with PHA-P (1 mg/ml PBS) intradermally to monitor the in vivo cell mediated immune response by measuring the footpad index. At the end of experiment, two birds/replicate/treatment were again picked up randomly and sacrificed to measure the lymphoid organ weights.