Response of lactating cows to 300 mg of supplemental vitamin E daily.

Ten Holstein cows in mid-lactation which had been fed only stored feeds for several years were paired on milk production. One cow from each pair was assigned to either the control or group treated with supplemental vitamin E for a 12-wk experiment. All cows were fed 3 kg alfalfa-brome hay, corn silage ad libitum, and concentrate at 1 kg/3 kg milk produced daily. This ration provided about 500 mg of vitamin E (total tocopherols) daily. Five cows were fed an additional 300 mg vitamin E daily as D-alpha-tocopherol acetate in their concentrate mix. Feeding the supplemental vitamin E increased the vitamin E content of milk fat 15 to 20% from 18 microgram/g fat to over 21 microgram/g fat. However, this change in vitamin E content of milk was not sufficient to improve the oxidative stability of the milk. Blood characteristics indicative of vitamin E status generally were unaffected by vitamin E supplementation although red cell hemolysis, glutamic oxaloacetic transaminase, and lactate dehydrogenase of serum were lower in blood of supplemented cows.