An experiment was conducted with twenty crossbred male calves (7-15 days old) divided into 4 different experimental groups on the basis of body weights to study the effect of vitamin E supplementation on the serum α-tocopherol concentration and immune response of the calves. All the calves were fed on milk and calf starter up to 13 weeks and afterwards, they were fed on concentrate mixture and oat hay up to 32 weeks of age. In addition, the calves in groups I, II, III and IV were supplemented with 0, 125, 250 and 500 IU feed grade DL-α-tocopheryl acetate, respectively. Blood samples were collected at 0 day and subsequently at 1, 2, 3, 4, 6 and 8 months of age to monitor the serum α-tocopherol concentration in crossbred calves. After 24 weeks of experimental feeding, 4 animals from each group were intramuscularly inoculated with single dose (3 ml) of Haemorrhagic septiceaemia (Pasteurella multocida P52 strain) oil adjuvant vaccine. The cumulative group mean serum α-tocopherol concentration (µg/100 ml) was 88.12, 210.11, 235.21 and 294.02 in-groups I, II, III and IV, respectively and differed significantly (p<0.001) among the four groups. Lymphocyte stimulation indices (LSI) did not differ among the groups significantly. The pooled mean ELISA antibody titer against Pasteurella multocida (P52 strain) was 788.02, 926.85, 1,214.00 and 1,109.51 for group I, II, III and IV, respectively, which indicated higher antibody titer in groups supplemented with vitamin E as compared to the control group. It may be concluded that vitamin E supplementation increased the αtocopherol concentration in serum and dietary supplementation of vitamin E at higher level has a humoral immune enhancing effect against killed bacterial antigen.
