This study aimed to explore the difference between two Chinese local broilers, one slow- and one fast-growing, in their response to a stress challenge. We conducted the study on slow- (Weining chicken) and fast-growing (Jinlinghua chicken) breeds, with 50 chickens from each breed either feed restricted to 70% for 30 days as a stress or given ad libitum to evaluate the effects on behavior, corticosterone, and microbial programming. Standing behavior was more frequent while exploration was less common in fast-growing breeds compared to slow-growing breeds. Food seeking and ingestion, exploration, and drinking increased, while resting decreased in the feed restricted treatments. There was no difference in corticosterone concentration between slow- and fast-growing chickens, but the level was affected by feeding treatments, and the interaction of breed and feed restriction. At the genus-level, the relative abundance of Bacteroides and Lactobacillus was higher, while Cloacibacillus and Megasphaera was lower in the slow-growing breed compared to the fast-growing breed. Feed restricted birds had a higher abundance of Mucispirillum, but lower abundance of Cloacibacillus, Clostridium XlVa and Clostridium IV. In conclusion, feed restriction to 70% for 30 days as a chronic stress stimulation caused more activity, elevated the stress response, and altered gut microbiota composition, but some changes were only evident in slow- or fast-growing chickens.

Electrical stunning is widely utilized prior to a neck cut to induce unconsciousness in order to improve animal welfare and slaughter efficiency in the broiler production industry. However, slaughter without stunning is still very commonly used in China, in part because there is a belief that stunning reduces meat quality. The purpose of this study was to determine whether the physical (hemorrhages, pH, drip loss, and shear force) and chemical (inosinic monophosphate concentration and reducing sugar content) properties of broiler meat differed between chickens in preslaughter stunning and nonstunned slaughter groups, and whether the groups differed in their levels of cortisol as an indicator of stress. Serum cortisol levels of the nonstunned group were nearly twice as high as those in the stunned group (p < 0.05). Several meat quality indicators were better in the stunned group than in the nonstunned group. We concluded that electrical stunning prior to slaughter significantly decreases the stress caused by slaughter, resulting in both improved animal welfare and meat quality traits.