Estudo comparativo de linhagens comerciais de frango de corte por meio de variáveis de desempenho e fisiológicas

Abstract

This present research had as objectives to study the physiological differences in performance and carcass quality of different strains of broiler chicken. One hundred day old chicks of commercial lines Hubbard Flex, Cobb 500, Ross Ap95 and a new French lineage, males and females, were used. The birds were created in a completely randomized design in factorial arrangement 4X2 (lineage X sex), forming eight treatments with ten replications totaling 80 experimental plots. The birds received the same diets and were weighed weekly for subsequent calculation of feed intake, weight gain and feed conversion. At 21 and 42 days of age, blood was collected from one bird per plot to perform blood analysis. At 42 days of age two birds per plot were slaughtered and the yield of carcass, cuts and viscera determined. The tibias of the slaughtered birds were collected to determine seeder rate, percentage of bone ash and bone resistance test. The non -linear model of Gompertz was applied using body live weight to evaluate a growth curve for each gene line under study. Interactions occurred between the factors in most of the performance variables, except for CA up to the fifth week of age. Among males the Ross AP 95 strain presented the best performance results in all phases evaluated. For variable carcass yield there was no significant difference between the lines (P> 0.05). The cobb line presented higher breast yield and the Hubbard line had higher thigh yield. The females had a higher yield of edible viscera. Contrasting the values estimated by Gompertz with the observed values, showed that the model is suitable to estimate and evaluate the growth of different lines of broiler chicken. The precocity of the Ross AP95 lineage was predicted by the proposed model. The males had higher values for the bone parameters in relation to the females and there were no significant differences (P <0.05) for the hematological analyzes. Based on the presented results it was observed that there are differences between males and females and between the studied lines, but the differences occur in different levels within each line.