Growth performance, carcass traits, and breast meat quality of slow-growing broiler strains reared in a free-range system: effects of genotype and sex at different slaughter ages.

This study evaluated the effects of strain and sex on growth performance, carcass characteristics, and meat quality of slow-growing broilers reared in a semi-intensive free-range system at different slaughter ages. A total of 864 one-day-old chicks from four commercial slow-growing strains (Pescoço Pelado Hubbard, Pescoço Pelado Sasso, Pesadão Hubbard, and Pesadão Sasso) were assigned to a completely randomized 4 × 2 factorial design (strain × sex). Growth performance was evaluated at 70, 77, and 84 d of age, and carcass traits and meat quality parameters were assessed at each slaughter age. Male birds showed greater body weight, higher feed intake, and better feed conversion ratio than females at all evaluated ages (P < 0.05). Pescoço Pelado Hubbard and Pesadão Hubbard strains exhibited superior growth performance compared with the Sasso strains (P < 0.05). Females showed greater breast yield, whereas males had higher thigh-drumstick yield (P < 0.05). A significant strain × sex interaction was observed for carcass yield at 77 d (P < 0.05), with Pescoço Pelado Hubbard males showing greater carcass yield than females of the same strain, whereas no sex differences were observed within the other strains. Meat quality traits differed according to strain and sex at specific slaughter ages, particularly in colour parameters, pH, cooking loss, and shear force (P < 0.05). A significant strain × sex interaction was observed for cooking loss at 84 d (P < 0.05), with Pesadão Sasso females showing greater cooking loss than males of the same strain, whereas no sex differences occurred within the other strains. These interactions demonstrate that the effect of sex on specific carcass and meat quality traits can vary among genotypes at particular slaughter ages. Overall, Hubbard strains demonstrated superior productive performance under semi-intensive free-range conditions, while the genotype-specific sex responses observed for carcass yield and cooking loss highlight the importance of considering both factors when defining slaughter strategies.