Effect of different levels of threonine amino acid on performance and immune response of Arian broiler chickens in the starter period

To investigation the effect of different levels of the threonine amino acid on performance and immune response of Arian strain broiler chickens in the first period (1 to 21 days), an experiment was conducted by using 600 broiler chicks in a completely randomized design with 6 treatments, 5 replications and 30 birds per each experimental unit (rep). Experimental treatments were consisting of 0.66, 0.76, 0.86, 0.96, 1.06 and 1.16 percent of threonine amino acid. To prevent the inhibitory effects of other amino acids, amino acids levels were adjusted higher than the recommendations. Factors measured were including daily gain, feed intake, feed efficiency and immune response. The results showed that yield and immune response in a non-linear responded to increased levels of threonine. So that the daily gain, feed intake, feed conversion ratio and immunoglobulin M showed a significant difference (p0.05).