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

Objective To determine the biochemical changes in articular cartilage compo sition associated with the development of avian degenerative joint disease (DJD) in ad libitum fed broiler fowl, in comparison to feed-restricted broi lers and J-line fowl (non-susceptible to DJD). Methods Articular cartilage from the distal tibiotarsus (DTT) was character ised up to age 180 days. Proteoglycan content was determined by uronic acid and sulphated glycosaminoglycan analysis, cellularity by assay for DNA con tent, and collagen content and crosslinking by hydroxyproline and pyridinol ine analysis, respectively. Results Disease development was accompanied by increased hydration and prot eoglycan content (particularly sulphated proteoglycans) and decreased cellu larity: 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 obser ved in other animal models. This bipedal model is exceptional however since cartilage alterations occur spontaneously and in a load-dependent manner.