Effect of Dietary Supplementation with Vitamin E for Lactating Dairy Cows Fed Tall Fescue Hay Infected with Endophyte

Abstract

In a replicated 2-yr study, 32 Holstein cows in midlactation were fed diets containing tall fescue hay that was free of or infected with endophyte and with or without added vitamin E in a 7-wk trial to examine the effect of vitamin E supplementation on symptoms associated with fescue toxicosis. Treatments were 1) uninfected tall fescue, 2) tall fescue infected with endophyte, 3) infected tall fescue plus 1000 IU of vitamin E/d, and 4) infected tall fescue plus 2000 IU of vitamin E/d. Feed intake, milk yield, rectal temperature, and body weight change were not significantly altered by dietary treatment. Concentration of prolactin in plasma was lower for cows fed the infected tall fescue than for those fed the uninfected tall fescue. No differences in alkaline phosphatase content of plasma were detected because of tall fescue or vitamin E treatment. Vitamin E supplementation had no effect on symptoms that were associated with fescue toxicosis in lactating dairy cows fed tall fescue hay that was infected with endophyte.