EFFECT OF GROWTH RATE ON THE INCIDENCE OF OSTEOCHONDROSIS IN GROWING SWINE

Abstract

Eighty-eight, 4-wk-old Yorkshire × Landrace pigs (44 barrows and 44 gilts) averaging 8.0 kg were used to study the effect of growth rate on the incidence of osteochondrosis and some characteristics of hind limb bones. Forty-eight pigs (Group I) were fed control diets through the starter to finisher phases, while for the remaining 40 pigs (Group II), nutrient densities of starter and grower diets were increased to enhance growth rate. At an average liveweight of 94 kg, animals wer slaughtered, and humeri, ulnae, radii, and femurs were visually and histologically examined for soundness of cartilage and subchondral bone. Average daily gain was greater for Group II than for Group I during both the starter (0.58 vs. 0.43 kg, P < 0.01) and grower (0.84 vs. 0.74 kg, P < 0.05) phases, as was intended, and also greater (0.74 vs. 0.68 kg, P < 0.05) for Group II for the overal experimental period. The faster growth rate in Group II did not affect (P > 0.05) the incidence and severity of osteochondrosis in any joint (or bone) site examined. This was consistent with the nonsignificant (P > 0.05) correlations between growth rate and soundness scores of joint and bone, and the similarity (P > 0.05) of the soundness scores of pigs with fast growth rate (average daily gain, 0.82–1.00 kg), intermediate growth rate (0.74–0.76 kg), and slow growth rate (0.53–0.67 kg). Bone characteristics of the femur, tibia, and metatarsal bones were not influenced (P > 0.05) by growth rate. Key words: Growth rate, osteochondrosis, bone characteristics, swine