Effect of the sex separate and straight-run type of rearing on the performance, carcass and meat chemical composition in fast growing broilers.

The aim of the study was to assess the effect of the type of rearing (sex separate vs. straight-run) in broiler chicks on their performance, carcass and meat quality. The trial was carried out in the experimental poultry farm of the Institute of Animal Science – Kostinbrod with the fast growing hybrid Cobb-500. The one day old chickens were sexed, marked and separated into three groups (n = 100): two sex separate groups containing male and female chickens respectively and one straight-run reared into deep litter. The chickens were fed ad libitum starter, grower and finisher diet and the major zootechnical parameters were controlled. The carcass quality and meat chemical composition were analyzed at 35 d of age.The effect of the rearing system was slight in the male birds and was mainly related to the weight gain and the feed intake per kg weight gain at 35 days of age showing certain advantage for the straight-run chickens. The female straight-run birds,on the other hand, showed lower weight gain at 35 and 49 days of age (P < 0.05) as well as higher feed intake per kg body weight and weight gain (P < 0.001) at 49 days. Significant difference between the sex separate reared groups and the straight-run one were observed in regard to the content of the abdominal fat (lowest in the male sexed chicks) and leg (highest in the male sexed and straight run chicks). Except for the ash content, the type of rearing did not exert any significant differences in the major chemical components of the breast and leg meat between the groups.