Avaliação de linhagens de frangos caipiras criadas em sistema semi-intensivo no Norte de Minas Gerais

Abstract

This study aimed to evaluate the performance, carcass characteristics, physiological variables and behavior of five strains of free-range broiler reared in semi-intensive system in northern Minas Gerais. We used 400 birds that were 28 days old, from five free-range strains of bred chickens, which composed the five treatments: 1= Naked Neck Label Rouge; 2= Red neck feathered (Pesadão); 3= Griss Barre Plume (Carijó); 4= Master Griss ; 5= Color. We used a completely randomized design with four replications for each treatment. Data from the behavior of the birds were collected daily at 8, 10, 12, 14 and 16 hours, and the environmental variables were also collected at the same times, ( dry bulb temperature, wet bulb temperature, black bulb temperature and wind speed). The performance variables (weight gain, feed intake and feed conversion), together with the physiological variables (rectal temperature, respiratory rate and head, back and thigh temperature) were collected every seven days. The physiological variables were collected at 9 and 15 hours. At 85 days four birds per plot were slaughtered for analysis of carcass yield, cuts and edible bowels. There was no significant difference (P > 0.05) between strains for the performance variables. There were significant differences for carcass traits (P 0.05), getting seated and practicing movements of discomfort at the hottest times of the day. We conclude that Carijó and Red neck feathered (Pesadão) are the most suitable for hearing in semi-intensive system in northern Minas Gerais, since presented a better carcass characteristics.