EFFECTS OF VITAMIN-E ON MAMMARY AND BLOOD LEUKOCYTE FUNCTION, WITH EMPHASIS ON CHEMOTAXIS, IN PERIPARTURIENT DAIRY-COWS

Objective-To determine the effect of vitamin E supplementation on the immune system of dairy cows. Design-The following immune parameters we re followed: production of chemotactic factors and superoxide by mamma ry macrophages and chemotactic responsiveness of blood neutrophils. An imals-16 healthy Holstein dairy cows. Procedure-Dairy cows were assign ed to 1 of 2 experimental groups: control (no vitamin E supplementatio n) and vitamin E supplemented. Supplementation of vitamin E started 4 weeks before and continued up to 8 weeks after parturition, and includ ed oral supplementation of vitamin E at the rate of 3,000 IU/cow/d. in addition, the same group of cows received 1 injection of vitamin E (5 ,000 IU) 1 week prior to the expected date of parturition. Blood sampl es were collected weekly throughout the experimental period. Results-V itamin E supplementation enhanced by 30 to 83% (P < 0.05) chemotactic responsiveness of blood neutrophils beginning 2 weeks before to 4 week s after parturition, compared with controls. There were no differences in production of superoxide or chemotactic factors by mammary macroph ages between control and vitamin E-supplemented cows. Conclusions-Vita min E supplementation prevents the periparturient inhibition of neutro phil chemotaxis. It is unlikely that vitamin E affects directly the fu nction of mammary macrophages.