Effects of stocking density on growth performance, carcass yield, and immune status of a local chicken breed.

An experiment was conducted to evaluate the effect of stocking density on growth performance, carcass yield, and immune status of a local chicken breed. In total, 840 one-day-old male Suqin yellow chickens were placed into 4-m(2) cages in groups of 50 (low), 70 (medium), or 90 (high) birds. Each treatment was represented by 4 replicates (cages). The cages measured 2.84 × 1.42 m; half of the area of the cage (2 m(2)) was used from 1 to 28 d and the whole cage was used from 29 to 42 d. Stocking densities were 25, 35, and 45 birds/m(2) from 1 to 28 d and 12.5, 17.5, and 22.5 birds/m(2) from 29 to 42 d (low, medium, and high, respectively). Final production (live bird mass after fasting) per unit area was 14.46, 19.46, and 24.23 kg/m(2), respectively, at 42 d of age. Several immune parameters were evaluated, and the growth performance, carcass yield, and meat quality were determined. Body weight at 28 and 42 d of age was significantly reduced as the stocking density increased (P < 0.05). A depression in daily weight gain was noticed from 1 to 28 d and 1 to 42 d of age, and daily feed intake decreased significantly in each period as density increased (P < 0.05). The feed/gain from 29 to 42 d and from 1 to 42 d of age decreased as density increased (P < 0.05). At 42 d, there was no effect of the stocking density on carcass, eviscerated carcass, breast, and abdominal fat yields (P > 0.05). The thigh yield of chickens in the medium-density group improved significantly (P < 0.05) compared with those of the other 2 groups. The water-loss rate, shear force, and meat color of the muscle were unaffected (P > 0.05) by the stocking density, but pH values increased slightly as density increased. No significant difference was noted in the immunological parameters, but the blood total protein and potassium were significantly affected by stocking density (P < 0.05). The findings of this study suggest that increasing the stocking density advantageously affected feed/gain and decreased the final BW, whereas no evidence was found that stocking density caused changes in any of the measured immune parameters.