Rearing Housing System as a Determinant of Chicken Muscle Morphology and Technological Meat Properties

This study evaluated the effect of rearing conditions with outdoor access on carcass traits, technological meat quality, and muscle fibre morphology in broiler chickens. Hubbard JA757 broilers were reared until 81 days of age under either control or experimental conditions. Both groups were housed indoors under identical management until day 35; thereafter, the experimental group had access to an outdoor paddock, while the control group remained indoors. At 81 days of age, birds were slaughtered, carcass composition was recorded, and breast (pectoralis major) and thigh (biceps femoris) muscles were analyzed for pH, colour, cooking loss, and shear force. Muscle fibre characteristics were assessed histochemically. Control birds showed higher slaughter and chilled carcass weights, whereas experimentally reared birds exhibited higher carcass yield, lower breast proportion, higher thigh proportion, and reduced abdominal fat. Experimental rearing was associated with higher L* values, higher shear force, and lower cooking loss in both muscles. In the pectoralis major, fibre density was higher in controls, while fibre diameter was higher in the experimental group. In the biceps femoris, the experimental group showed a higher proportion of oxidative βR fibres and larger fibre cross-sectional areas. These results demonstrate that the rearing system influences carcass composition, technological meat properties, and muscle fibre characteristics, leading to distinct phenotypic and technological differences between the groups.