Effects of Stocking Density on Performance and Immunity in Ross 308 Broiler Chickens

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 m(2)). The results were recorded in three periods of 0-24, 25-42 and 0-42 d. 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 m(2) 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 m(2) 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 m(2) was significantly higher in 18 chicks density group (32%), it's seems economically 18 chicks per m(2) is the best stocking density.