Effect of reduced growth rate on the prevalence and severity of osteochondrosis in gilts.

Ninety-six recently weaned gilts were assigned to 3 groups. Group-1 gilts were fed a corn-soybean meal diet ad libitum and were killed when they weighed 110 kg. Gilts in groups 2 and 3 were fed 70% of the feed consumed by group-1 gilts. Group-2 gilts were killed when they weighed 110 kg, and group-3 gilts were killed at the same age as group-1 gilts. At slaughter, the right pelvic and thoracic limbs from all gilts were removed, and the distal end of each femur and humerus was sectioned serially at 5-mm intervals. Articular-epiphyseal cartilage complexes from these sites were examined grossly, radiographically, and histologically. Effects of treatment (ad libitum vs limited energy intake) and average daily gain on the prevalence and severity of lesions were analyzed statistically, using chi 2 analysis, a categoric-modeling technique, analysis of variance, and correlation coefficients. Of humeri and femora, 49 and 70%, respectively, had lesions of osteochondrosis, and 86% of the gilts had a lesion at one or both sites. Group-2 gilts (killed at 110 kg, but approx 70 days older than group-1 gilts) had significantly lower prevalence (P = 0.009) and severity (P = 0.002) of osteochondrosis of the distal end of the femur than did gilts in groups 1 and 3. When each group was evaluated individually, gilts that had a higher average daily gain had an increased prevalence and severity of lesions.