Relationship of Specific Nutrient Deficiencies to Antibody Production in Swine

Studies were conducted with 30 baby pigs in two trials to determine the effect of a vitamin A deficiency upon antibody production in swine. Using a semisynthetic milk diet the pigs were fed either a complete diet or a diet deficient in vitamin A. Pigs were weaned at 5 days of age and 12 hours of age in the first and second trials respectively. The average serum vitamin A level of the deficient pigs dropped to 13.8 µg/100 ml 8 weeks after allotment to treatment in the first trial and 12.6 µg/100 ml 4 weeks after allotment to treatment in the second trial. A series of antigen injections was begun when the average serum vitamin A concentration of the deficient pigs in each trial fell below 14 µg/100 ml. The net serum antibody titer of the pigs deficient in vitamin A was significantly lower (P < 0.01) than the titer of the control pigs. The correlation coefficient between serum vitamin A and antibody titer was 0.70 and highly significant. Only in the second trial did the pigs on the deficient diet gain less (P < 0.01) and require more feed per unit gain (P < 0.05). The correlation coefficient between serum vitamin A concentration and rate of gain was 0.35 and not statistically significant. The deficient pigs had greater percentages of serum α-globulin (P < 0.01) and γ-globulin (P < 0.01) and a lesser percentage of serum albumin (P < 0.01) than the control pigs. Following a repletion period of 6 to 7 weeks, the formerly vitamin A-deficient pigs had values of serum vitamin A, serum protein, and antibody titer which were similar to the control pigs. In the second trial, pigs which were formerly vitamin A-deficient continued to gain weight more slowly (P < 0.05) during repletion than the control pigs.