JOINT DAMAGE IN PIGS REARED UNDER CONFINEMENT

Abstract

Cartilage soundness and condition of synovial fluid were determined for three populations of pigs comprising 645 entire males, 171 females and 119 male castrates. All pigs were reared in confinement, and slaughtered at liveweights ranging from 82 to 116 kg, with joint damage assessed by dissection of the left foreleg. Hip joints were evaluated for one population. Incidence of damage differed among populations but the highest frequency of fully normal cartilage was only 20% and the frequency of moderate to severe damage ranged from 15 to 50%. There were no sex differences. Differences observed in weights of pigs at birth and weaning and in post-weaning growth rate were inversely related to degree of damage. There was no evidence of any association with carcass characteristics, and microbiological tests were negative. No meaningful association was found between visual scores for physical soundness of the live animal and degree of joint damage. Clinical evidence of leg weakness was observed in some animals with normal joints while some pigs with extreme cartilage damage revealed no clinical symptoms. Degree of damage was not related to terminal weight per se but was directly related to duration of test confinement. Damage was greater among pigs confined individually than for those group-fed. Cartilage repair was observed in pigs held on pasture following completion of test.