EFFECT OF DIETARY SUPPLEMENTATION OF VITAMIN C ON PIG PERFORMANCE AND THE INCIDENCE OF OSTEOCHONDROSIS IN ELBOW AND STIFLE JOINTS IN YOUNG GROWING SWINE

Seventy-two, 4-wk-old weanling pigs averaging 6.9 kg were assigned to three treatments consisting of a 19% crude protein starter diet to which 0, 350 or 700 ppm vitamin C were added. After a feeding period of 44 days, the crude protein level of the diet was decreased to 16% but vitamin C supplementation continued at the same level throughout the growing-finishing phase. At approximately 90 kg body weight, pigs were slaughtered, and elbow and stifle joints were examined for soundness. Average daily gain, average feed intake and feed:gain ratios, measured for each week or for the whole period of the starter phase, were similar among pigs fed vitamin-C-supplemented diets and those fed the control diet. There were also no significant treatment differences in performance of growing-finishing pigs. Plasma vitamin C concentration of pigs, measured during the growing-finishing phase, was significantly (P < 0.01) increased by dietary supplementation of vitamin C. Locomotory ability was similar between pigs fed 350 ppm supplemental vitamin C and control pigs, but appeared to be superior (P < 0.05) for pigs fed 700 ppm supplemental vitamin C. Dietary supplementation of vitamin C did not reduce the incidence and severity of osteochondral lesions in the elbow and stifle joints of the pigs. The medial femoral condyle, the medial humeral condyle, and the proximal ulna were the major joint sites affected. Positive correlations were observed between average daily gain and locomotory ability scores (r = 0.45, P < 0.01), and average daily gain and soundness scores of the distal humerus (r = 0.42, P < 0.01). Dietary supplementation of vitamin C did not significantly influence hydroxyproline concentrations of the lateral femoral condylar cartilage. Key words: Vitamin C supplementation, plasma vitamin C, osteochondrosis, pigs, hydroxyproline