Effect of supplemental vitamin E on the immune system of calves.

The effect of vitamin E on immune responses of Holstein calves was investigated. Treatments were: 0,1400, and 2800 mg of dl-alpha-tocopheryl acetate given orally at weekly intervals or 1400 mg of dl-alpha-tocopherol weekly by injection. Calves were fed milk for 6 wk and then fed a complete calf starter ad libitum. Calves were on experiment until they were 12 wk of age. Lymphocyte stimulation indices were significantly higher for calves given the high amount of oral supplementation and for injected calves than for unsupplemented calves. There were no significant differences at any of the individual weeks between unsupplemented and orally supplemented calves. Injected calves showed significantly higher values than unsupplemented calves at wk 4 and than all other calves at wk 8. There were no significant differences in the concentrations of immunoglobulins G1 and G2 among treatments. Immunoglobulin M was significantly higher at wk 6 in calves given the high amount of oral supplementation than in all other calves. At wk 12, serum from calves given the high amount of oral supplementation and calves given injections inhibited infectious bovine rhinotracheitis viral replication in tissue cultures as compared with those of unsupplemented calves. In supplemental experiments serum alpha-tocopherol and lymphocyte stimulation indices of yearling heifers determined 7 d after a single injection of 2000 IU of dl-alpha-tocopherol were significantly higher than preinjection values. In vitro addition of vitamin E to lymphocyte cultures did not increase phytohemagglutinin-induced blastogenesis.