The response decreased, with variations, when either vitamin E or selenium was absent. And it was weakest when both were absent. Naturally occuring Vitamin E can be destroyed by grinding, exposure to air, storage and contact with trace minerals. As the Michigan State research suggests, selenium and vitamin E work hand in hand. Both are tissue antioxidants.
Vitamin E works in cell membrane fractions.
Selenium has its effect in the cytosol fraction. Thus, the functions are independent and additive. To get the maximum benefit from both vitamin E and selenium, they need to be fed through gestation and lactation. Nursing pigs get a much needed boost when their dams receive supplemental vitamin E. Pigs are born with almost no vitamin E because there is very little placental transfer. Thus, the newly born pig must rely on passive immunity derived from the dam's colostrum.