Changes in proteoglycan content of articular cartilage during avian degenerative joint disease.

OBJECTIVE To determine the biochemical changes in articular cartilage composition associated with the development of avian degenerative joint disease (DJD) in ad libitum fed broiler fowl, in comparison to feed-restricted broilers and J-lin fowl (non-susceptible to DJD). METHODS Articular cartilage from the distal tibiotarsus (DTT) was characterised up to age 180 days. Proteoglycan content was determined by uronic acid and sulphated glycosaminoglycan analysis, cellularity by assay for DNA content, and collagen content and crosslinking by hydroxyproline and pyridinoline analysis, respectively. RESULTS Disease development was accompanied by increased hydration and proteoglycan content (particularly sulphated proteoglycans) and decreased cellularity, with no significant differences in either total collagen content or in mature collagen cross-linking. CONCLUSION The biochemical features of avian DJD are similar to those observed in other animal models. This bipedal model is exceptional however since cartilage alterations occur spontaneously and in a load-dependent manner.