Vitamin E benefits cattle, too.

Low-level infections in cattle can slow the animals' growth and stress their immune systems. That's why farmers often feed animals small amounts of antibiotics. But such chronic antibiotic use can speed the development of antibiotic-resistant bacteria, which then may end up infecting people.

One alternative to antibiotics is to prime a calf's immune system with vitamin E, says Ted Elsasser of the Department of Agriculture's Agricultural Research Service in Beltsville, Md.

He and his colleagues pretreated six calves with vitamin E before challenging them with a toxin taken from bacterial cell walls. The toxin revs up the calves' immune systems as if they were facing an infection. The researchers also gave six calves the toxin alone and four neither the vitamin nor the toxin. Vitamin E, an antioxidant, counters some biologically harmful compounds.

Compared with the four untreated calves, all the toxin-challenged calves had significantly lower concentrations of the growth factor, IGF-1 in their livers and blood. Toxin-injected calves that had been pretreated with vitamin E, however, had higher concentrations of IGF-1 in their livers and blood than did calves that got toxin alone. The animals getting vitamin E also had a shortened recovery time from the toxin's effects.

Those calves with unusually low concentrations of IGF-1 after the toxin challenge also had proteins with structural modifications associated with stressed immune systems.

Vitamin E pretreatment means "we can maintain [these animals'] rate of growth better and potentially prevent the onset of secondary infections," Elsasser says. This could translate into lower management costs, lower vet bills, and healthier animals, as well as a reduction in antibiotic use, he says.