Osteochondrosis and arthrosis in pigs. VI. Relationship to feed level and calcium phosphorus and protein levels in the ration.

Eight feeding experiments, each comprising 48 boars or gilts, were carried out. The factors feed level, Ca, P and protein levels were varied within practical physiological limits. The animals were slaughtered at close to 100 kg live weight. Lesions in joints and bones were of a noninfectious, non-rachitic nature and of the osteochondrosis and arthrosis type. Ten to 12 g Ca and approx. 10 g P/kg ration gave histomorphologically seemingly more optimum structure of the spongious bone tissue and a higher ash percentage in bones than 7 g Ca and 6 g P, or unbalanced mineral levels in the ration. However, there was no significant difference in degree or incidence of joint and bone lesions between mineral groups. Neither were there such differences present between feed level groups or protein level groups. This may for the feed level groups be partly due to the low feed level pigs having a longer period of time during which they were highly susceptible to the development of lesions. The low feed level animals had longer long bones at 100 kg live weight than the high feed level animals. The length of the vertebral column was, however, approximately similar in the 2 feed level groups. The angles of the condyles and head of the femur according to the length axis were influenced by feed level or growth rate, most probably by an effect on the endochondral ossification.