Leg weakness in pigs. I. Incidence and relationship to skeletal lesions, feed level, protein and mineral supply, exercise and exterior conformation.

Out of 373 Landrace boars and gilts involved in feeding experiments, 18.2 % showed severe degree leg weakness and 30 % mild degree leg weakness at 100 kg live weight. Of the boars at pig A.I. stations 23.9 % were slaughtered because of leg weakness, 75 % of these being under 1½ years. The practical significance of leg weakness is greatest in young breeding stock. High feed level in slaughter pigs resulted in poorer locomotory ability than medium feed level. Exercise resulted in pigs showing better movements. Variations of minerals and protein within limits used in practical feeding did not have any influence on the incidence of leg weakness. There was no statistically significant relationship (P > 0.05) between joint lesions and locomotory ability in pigs at 100 kg live weight, although severe lesions seemed to lead to poorer mobility. The joint regions which seemed to be mainly involved in severe degree leg weakness in boars were the elbow and stifle joints (31.3 %), the lumbar intervertebral joints (28.1 %) and the hip region (15.6 %). There was a significant relationship between narrow lumbar region, broad hams, large relative width between the stifle joints, and poor locomotory ability in slaughter pigs.