Effects of rearing systems on growth performance, carcass yield, meat quality, lymphoid organ indices, and serum biochemistry of Wannan Yellow chickens.

This study was conducted to investigate the effects of free-range system (FRS) and conventional cage-rearing system (CRS) on growth performance, carcass yield, meat quality, lymphoid organ indices, and serum biochemistry of Wannan Yellow chickens. At 56 days of age, a total of 640 male chickens were randomly allocated to FRS and CRS groups, each of which included 4 replicates with 80 chickens in each replicate. The experiment lasted from 56 to 112 days of age. The results showed that CRS chickens exhibited better final body weight, average daily feed intake, average daily gain, and feed conversion ratio, whereas FRS chickens showed better breast and leg yields, shear force, meat color, lower drip loss, and decreased abdominal fat deposition. Moreover, the absolute thymus weight and thymus to body weight ratio of FRS birds were significantly higher than those of CRS birds (p < 0.05). Additionally, FRS chickens had significantly reduced glucose, total protein, triglyceride, and cholesterol contents, but enhanced levels of high-density lipoprotein cholesterol (p < 0.05). In conclusion, the FRS has advantages in breast and leg yields, meat quality, and some serum biochemical parameters of Wannan Yellow chickens, whereas it has negative effects on growth performance.