GROWTH-DEPENDENT CHANGES IN THE CHEMICAL-COMPOSITION OF PROXIMAL TIBIAL ARTICULAR-CARTILAGE AND GROWTH-PLATE OF BROILER-CHICKENS

Chemical composition of the proximal tibial articular cartilage and gr owth plate of broiler chickens from seven age groups (1, 8, 14, 22, 29 , 36, and 43 d old) was studied. In the articular cartilage, the conte nts of dry matter, collagen measured as hydroxyproline, and keratan su lfate increased (P < 0.05), and the content of sialic acid decreased ( P < 0.05) as age advanced. The content of chondroitin sulfate measured as uronic acid and the proportion of hyaluronic acid in total glycosa minoglycan (GAG) were relatively constant (P > 0.05) among the age gro ups. In the growth plate, the contents of chondroitin sulfate and kera tan sulfate increased (P < 0.05) with age, while the contents of dry m atter, sialic acid, and collagen were similar among the age groups. Th e proportion of hyaluronic acid in total GAG decreased at the age of 8 d, and remained relatively constant thereafter. The growth dependent changes observed in the concentration of chondroitin sulfate in the br oiler chicken cartilage were different from those in other species whi ch have been reported to show a decrease during early postnatal growth .