The Effect of different dietary amino acid levels in early ages and strain on performance, immune organ weight and heterophile-to-lymphocyte ratio in Arian broiler chickens

This study was carried out to examine the effect of reducing dietary amino acid (DAA) levels (recommended dose by Arian and 6% less than recommended dose up to 25 d of age) and strain cross (classic and new) on performance and some of immune system characteristics (ISC) of Arian broilers. Five hundred 1-d-old male and female chicks were allocated in four experimental groups with 5 replicates in each group for 44 days and data were analyzed in a factorial experiment with a completely randomized design. The amounts of DAA were calculated according to the amount of digestible lysine. On 21 and 42 d of age, blood sample were taken from 2 birds (male and female) of each pen via the wing vein and hetrophile and lymphocyte were counted. The data on performance were recorded in different ages and weights of immune organs were measured in 44 d of age. Feed intake in 18 d of age and feed conversion ratio in 18 and 25 d of age increased significantly by decreasing the DAA (P