Effect of dietary supplementation of zinc on humoral immunity in guinea pigs

Male guinea pigs (40; 1m old of 208.2±6.6 g BW) divided into four equal groups were fed a basal diet (maize hay 25, maize grain 30, gram grain 22, de-oiled rice bran 9.5, soybean meal 6, fish meal 6, mineral supplement 1.45% (without zinc) and ascorbic acid 0.05%) and 10-20g of available green fodder (Gp I), or Gp I supplemented with 20 ppm zinc either as zinc sulphate (Gp II), as zinc amino acid complex (Gp III), or zinc sulphate + zinc amino acid complex in equal parts (Gp IV) for 70 days. Results revealed that the serum zinc levels increased (P<0.05) in all the zinc supplemented groups as compared to control. The enzyme-linked immunosorbent assay (ELISA) showed that the serum antibody level increased (P<0.05) with peak reaching on 21^st day post-vaccination in all the groups and also the values were higher (P<0.05) in all the zinc supplemented groups as compared to control group. However, on 28^th day post-vaccination, the highest (P<0.05) serum antibody level was observed in Gp III. It indicated that supplementation of 20ppm of zinc in the diet could significantly improve the humoral immune response in male guinea pigs and organic source of zinc elicited greater immune response as compared to its inorganic (ZnSO₄) source.