Effects of rearing system and environmental enrichment on production performance and welfare of slow-growing broilers

Although consumers place significant emphasis on healthy poultry products, research on welfare-oriented production systems for broilers remains relatively scarce. This study aimed to explore a tailored production system to improve the welfare of slow-growing broilers. Totally 1350 females of Mountain Plum Blossom chickens from Southwest China were randomly allocated into four production systems, each with three replicates per group and 90 chickens per replicate. The systems included plastic net rearing without environmental enrichment (PNR+NEE group), free-range rearing without environmental enrichment (FR+NEE group), plastic net rearing with environmental enrichment (PNR+EE group), and free-range with environmental enrichment (FR+EE group). The environmental enrichment provided in this experiment consisted of sand bathing pool, perches, ramps, platforms, and hide houses. Results showed that the broilers reared in the PNR+NEE and PNR+EE groups had higher final weight than those in the FR+NEE and FR+EE groups (P < 0.05). However, the FR groups, with or without environmental enrichment, showed a higher eviscerated percentage and lower abdominal fat weight and abdominal fat index than the PNR groups without environmental enrichment (P < 0.05). Meanwhile, the FR groups, with or without environmental enrichment, showed higher redness (a*) and yellowness (b*) values in breast muscles than the PNR groups with or without environmental enrichment (P < 0.05). Monounsaturated fatty acids in both breast and thigh muscle from the FR+NEE and FR+EE groups were higher than those from the PNR+NEE and PNR+EE groups (P < 0.05). Broilers in the FR+EE and PNR+EE groups had better welfare indicators, with lower feather scores and TI duration than the FR+NEE and PNR+NEE groups (P < 0.05). Notably, FR treatment increased serum dopamine levels compared with PNR treatments, regardless of with or without environmental enrichment (P < 0.05). In addition, serum TNF-α levels were lower in the FR+EE and PNR+EE groups than in the FR+NEE and PNR+NEE groups (P < 0.05). These results indicated that the production system with environmental enrichment optimized both animal welfare and meat quality, providing a practical system for broiler production.