Effects of different levels of lysine and pyridoxine on growth, carcass characteristics and some blood parameters of broilers under heat stress condition

Effects of different levels of lysine (90، 100 and 110% of Ross strain requirement) and pyridoxine (3، 6 and 9 mg/kg) on growth، carcass characteristics and some blood indices of broiler chickens exposed to a high ambient temperaturewere investigated. For this purpose،four hundred and fifty one-day-old Ross broiler chicks were used in a 3*3 factorialexperiment. Different levels of lysine and pyridoxine had no effect on weekly body weight gain، feed intake and feed conversion ratio of broiler chickens but birds fed the high lysine level had the lower body weight gain. Lysine had no effect on blood hematocrit. But pyridoxine affected the blood hematocrit (P<0. 05) and consumption of medium pyridoxine level increased the blood hematocrit. Both the lysine (P<0. 05) and pyridoxine (P<0. 01) changed the blood cholesterol. At the lowest lysine level، consumption of 6 and 9 mg pyridoxine caused the higher blood cholesterol. At the medium level of lysine، only 6 mg pyridoxine increased the blood cholesterol. At the highest level of lysine، pyridoxine supplementation didn’t affect the blood cholesterol. Increasing the lysine level resulted in higher blood cholesterol and the highest lysine fed birds had the higher blood cholesterol as compared to the birds fed the lower levels of lysine. Although pyridoxine supplementation caused the increased blood hematocrit، it didn’t affect the other parameters. Furthermore، supplementation of lysine and pyridoxine together had no advantage on the parameters of recent experiment.