EFFECTS OF FEED RESTRICTION, SEX AND DIETHYLSTILBESTROL ON THE OCCURRENCE OF JOINT LESIONS WITH SOME HISTOLOGICAL AND BIOCHEMICAL STUDIES OF THE ARTICULAR CARTILAGE OF GROWING-FINISHING SWINE

Abstract

Forty crossbred pigs were reared from 28 to 90 kg liveweight to study the effects of feed intake, growth rate, sex and dietary estrogen on the incidence and severity of limb joint abnormalities. No significant treatment effects were observed. However, all pigs showed some degree of osteochondrotic or osteoarthrotic lesions. Osteochondrotic joints exhibited thickening of articular cartilage and failure of endochondral ossification. The latter was associated with cell necrosis, reduced amounts of proteoglycan and collagen in the tissue, and decreased percentage of released uronic acid by tissue autolysis. Osteochondrotic joints also showed a loss of proteoglycan or had clefts in the deeper region of the articular cartilage. Connective tissue was frequently found within the area of the clefts. In the cartilage beside the cleft, cell clustering and a loss of cellularity were often observed. Involvement of physical stress was suggested as an etiological factor of osteochondrosis. Osteoarthrotic joints were associated with local losses of both proteoglycan and cellularity in the articular cartilage. Cell clustering and granulation tissues were also observed in the affected regions.