Estudo do padrão de crescimento ósseo em frangos de corte de diferentes grupos genéticos criados em duas densidades populacionais

Abstract

: The aim of this experiment was to study the pattern of long bone development on broiler chickens belonging to different genetic groups under different rearing densities. Evaluations of performance, carcass yield, bone growth, bone mineral content, bone breaking strength and optical radiographic density of tibia, femur and humerus were performed. The experimental design was a split-splot where the main plots were a combination of three genetic groups and 2 rearing densities in a factorial arrangement, and age was considered a secondary plot, so there were 6 treatments with 5 replications per each one. The three genetic groups evaluated were Ross 308, Hybro PG and Isa Label JA57, which were reared in 2 densities: 10 and 16 birds/m2. All broilers fed the same diets: initial - 1-21 days; growing - 22-35 days and final -36-42 days of age. For the evaluation of bone growth, two broilers per replication were slaughtered at 1, 7, 14, 21, 28, 35 and 42 days of age. The long bones (tibia, femur and humerus) were collected and frozen for later analyses. There were no significant interactions between genetic groups and rearing densities for the evaluated parameters. These results did not show differences between genetic groups reared at different densities, being humerus width of Ross 308 and Hybro PG and bone breaking strength of Isa Label JA57 the exceptions. This genetic group also presented a lower performance and bone development when compared to Ross 308 and Hybro PG. Therefore, it was concluded that the three genetic groups presented the same standard bone growth curve, which is genetically defined and expressed no matter the genetic improvement program or rearing density adopted.