Effect of Stocking Density and Methionine Levels on Growth Performance and Immunity of Broiler Chicks

The experiment was conducted to investigate the effect of stocking density and incremental methionine levels on performance, immune response, carcass traits, and digestive organs of broiler chicks. A total of 390 day-old broiler chicks (Ross 308) were allocated to six dietary treatments and five replicates base on 3 × 2 factorial arrangement in a completely randomized design. Experimental diets included three levels of stocking density (12, 16 and 18 birds/m2) and two levels of methionine (100 and 120% requirement recom-mended for Ross 308) applied during 42 days of experiment. The results showed that 18 birds density de-creased body weight and weight gain, feed intake and increased feed conversion ratio (P<0.05) in overall rearing period. The 120% methionine level tended to increase body weight at 42 day of age. Stocking den-sity significantly (P<0.05) affected the relative weight of proventriculus, pancreas, gizzard and duodenum. The jejunum relative weight and ileum length of chicks received 120% methionine level significantly in-creased. Antibody titer against sheep red blood cells (SRBC), Influenza and Newcastle viruses, heterophil to lymphocyte ratio and lymphoid organs except spleen were not affected by dietary treatments (P<0.05). As a conclusion, broiler performance of chicks adversely affected by stocking density and methionine lev-els had no considerable effect on their performance.