effect of zinc sulfate and organic chromium supplementation on the perfor-mance, body temperature, carcass characteristics, tibia ash and serum bio-chemical parameters of japanese quails under heat stress conditions

this study was conducted to investigate the effects of different levels of zinc sulfate and chromium picolinate on performance, body temperature, carcass characteristics, tibia ash and serum biochemical parameters of japanese quails under heat stress condition. the birds (n = 540; 7-d-old) were randomly assigned to 9 treatment groups consisting of 3 replicates of 20 birds each in a 3 × 3 factorial arrangement of treatments (zinc; chromium). birds were kept in floor cages in a temperature controlled room at either thermoneutral zone or heat stress for 8 h/d (0900 to 1700 h) until the end of the study, and fed a basal (control) diet or the basal diet supplemented with either 40 or 80 mg of zn as znso4 and 500 or 1000 g cr as crpic/kg of diet. a linear decrease in feed intake and improvement in feed conversion ratio were found in zn and cr supplemented quails reared under heat stress conditions. chromium supplementation increased daily weight gain linearly.quails body temperature before and during heat stress tends to decrease linearly as dietary zn and cr supplementation increased. supplementation with zn decreased the relative weight of the small intestine, rectum, and weight to length ratio of the small intestine. tibia ash was increased with zn and cr supplementation. supplementation of quail's diet with zn and cr did not have any effect on serum biochemical parameters. the results of this study revealed positive effects of zn and cr supplementation on the performance, body temperature, carcass characteristics and tibia ash of quails under heat stress. it seems that supplementation of the quail's diets with 80 mg/kg znso4 and 1000 g/kg crpic can be greatly helpful for improving the adverse effects of heat stress.