The effect of reduced zinc levels on performance parameters of broiler chickens

Abstract

The experiment was conducted to determine the effect of reduced supplemental zinc levels on broiler growth and carcass yield. A total of 160 male broiler chicks (Ross 308) divided into four groups were allotted to 16 cages with 10 birds per cage in each of group and kept in a temperature-controlled room. During the trial, chicks were ad libitum access to feed and water. The experiment started at 11 days of broiler age and chicks were fattened up to 35 days of age. It consisted of 4 dietary treatments with 4 replications per treatment. A corn-wheat-soybean meal basal diet containing 25.84 mg Zn.kg^-1 was formulated and zinc levels of 120, 40 or 20 mg.kg^-1 was supplied as zinc oxide to give four dietary treatments. At the end of the feeding trial, 24 birds from each group were randomly selected, slaughtered and carcass evaluation was performed. The results show that different levels of zinc had no significant effect on body weight of broilers or feed consumption ratio. These parameters increased by decreasing zinc levels from 120 to 20 mg Zn.kg^-1 similarly as the carcass yield, percentages of breast meat and leg meat, but differences between these groups were not significant. In case of relative liver weight and zinc concentration in liver there were significant difference (p <0.05) between group given supplemented zinc of 40 mg.kg^-1 and group without zinc supplementation and 120 mg.kg^-1 and 40 mg.kg^-1, respectively. No signs of disorders such as loss of appetite, growth depression or abnormalities of the skin was appeared in chicks. It seems that reduced supplemented zinc levels from 120 to 20 mg.kg^-1 (total Zn 153.13 mg.kg^-1 to 45.28 mg.kg^-1 respectively) not influenced growth performance parameters of broilers fed corn-wheat-soybean meal diet.