¹Department of Animal Science, Science and Research Branch, Islamic Azad University, Tehran, IRAN
²Department of Animal Science, Varamin-Pishva Branch, Islamic Azad University, Varamin, IRAN DOI : 10.9775/kvfd.2017.18869 To investigate the effect of stocking density on productive traits, blood parameters and immunity, 1305 Ross 308 male broiler chicks (initial weight: 45±1.5 g) were used as a completely randomized design with 2 treatments and 15 replications. Treatments included 1) 12 chicks per pen 2) 18 chicks per pen (1.2x1.2 m2). The results were recorded in three periods of 0-24, 25-42 and 0-42 days. From 0 to 24 d of age, the stocking density had no significant effect on feed intake and body weight gain (P>0.05), but feed conversion ratio significantly decreased in 12 chicks density group (P<0.05). Feed conversion ratio, body weight gain and feed intake were improved significantly in 12 chicks compared to 18 chicks density for 25-42 and 0-42 periods (P<0.05). The production per m2 was significantly higher in 18 chicks density group at 0-42 d period (P<0.05). High stocking density caused to increase the moisture content of bedding in 4-6th weeks of age (P<0.05). Stocking density had no significant effect on mortality percentage (P>0.05). Also the relative weights of spleen, bursa of fabricius, abdominal fat, thigh and breast were not affected by experimental treatments (P>0.05). Increasing the number of chicks per m2 caused to increase heterophile count and decrease lymphocyte count and increase heterophile to lymphocyte ratio (P<0.05). Newcastle"s titer was not affected by treatments (P>0.05). Given that performance indices were better under low stocking density, but live body weight per m2 was significantly higher in 18 chicks density group (32%), it"s seems economically 18 chicks per m2 is the best stocking density. Keywords : Broiler chickens, Immune system, Performance traits, Stocking density