SOUTH AFRICAN JOURNAL OF ANIMAL SCIENCE, vol.49, no.6, pp.1127-1138, 2019 (SCI-Expanded)
This study compared growth and carcass traits of 2 medium-growth crossbred, 4 slow-growth crossbred, 1 commercial slow-growth and 1 commercial fast-growth broiler strains raised in indoor and free-range production systems. One hundred twenty chicks of each strain were raised in each production system. Chicks were raised in indoor pens at a density of 10 chicks per m(2). From day 29 until slaughter at 84 days of age, chicks in the free-range system were given outdoor access through doors that were open between 8.00 - 17.00 hours. The study found live weight, feed efficiency, and mortality were significantly affected by strain. However, no significant differences were found between the production systems. Outdoor access varied significantly among strains, with the commercial high-growth and medium-growth crossbred strains making less use of outdoor areas. In terms of performance traits, none of the strains showed any significant differences in performance between the indoor and free-range production systems. However, significant differences among the strains in carcass traits, pH, and colour values of thigh and breast meat were observed in connection with differences in growth rate. Moreover, carcass and breast yields were greater in fast and medium-growth broilers, while ratios of edible inner organs were greater in medium and slow-growth broilers.