Effect of vitamin E supplementation and of health status of mammary gland on immunoglobulin concentration in milk of dairy cows.

Variation of milk IgG1, IgG2, IgM, and IgA measured by radial immunodiffusion was studied in monthly samples of 224 lactating dairy cows. Cows were assigned to one of 2 treatment groups: vitamin E supplemented and controls. Vitamin E supplementation was started when cows were dried and continued until 90 days post partum at the rate of 1,000 IU per cow daily and then reduced to 500 IU for the remaining lactation. There were no significant differences between the 2 treatment groups for the different Ig classes. Concentrations of IgG1 were significantly higher in milk from mastitic than non-mastitic cows.