EFFECTS OF ENFORCED EXERCISE ON THE INCIDENCE OF LEG WEAKNESS IN GROWING BOARS

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Abstract
Twelve boars, three from each of four litters, were assigned at an average weight of 22.3 kg to three treatments to study effects of exercise on a treadmill on the incidence of leg weakness in terms of visual appraisal, cartilage and bone appraisal and blood serum composition. Treatments consisted of a control without enforced exercise, exercise three times/wk at a speed of 2 km/h at 0 slope (LE), and exercise at a speed of 4 km/h at 0 slope (HE). Boars were housed individually and fed a diet similar to that used in the Canadian Record of Performance for Swine program. Daily feed intake, weight gain and efficiency of feed conversion to 90 kg liveweight and average backfat and loin area at slaughter were not significantly influenced by treatment, suggesting that the degree of exercise had little influence on energy expenditure. Forelegs of non-exercised boars showed more abnormalities on visual appraisal than those of LE or HE boars and the degree of unsoundness increased from wk 6 to wk 10 for control boars, but not for LE and HE boars. When all sites were combined, there were no significant differences in mean lesion scores for joint cartilage evaluation, but there were significant differences between appraisal sites. Abnormalities of forelegs based on visual appraisal were significantly correlated with cartilage appraisal of both the proximal radius–ulna (P < 0.01) and the distal humerus (P < 0.05). Exercise had no apparent influence on bone mineralization or on the blood serum chemistry profile. The results indicate that exercise will reduce the incidence of visual abnormalities such as bow legs, flexion of the carpus and sickle leg in boars.