Effect of dietary fat and vitamin E on alpha-tocopherol in milk from dairy cows.
Diets with different fat treatments and with 25, 125, or 250 IU of supplemental vitamin E (all-rac alpha-tocopheryl acetate)/kg of dry matter (DM) were fed for 28 d to midlactation Holstein cows to determine factors affecting concentrations of alpha-tocopherol in milk. Diets contained no supplemental fat or 2.25% added fat from roasted soybeans or tallow. Vitamin E treatment had no effects on production, but fat supplementation increased milk yield (37.2 vs. 35.1 kg/d). Cows fed RSB ate more DM (24.0 vs. 21.9 kg/d) and produced more milk fat than cows fed tallow. Supplemental fat increased plasma concentrations of alpha-tocopherol and cholesterol. Increased intake of alpha-tocopherol linearly increased concentrations of alpha-tocopherol in plasma but the rate of increase was 1.9 times greater when fat was fed. Plasma alpha-tocopherol concentrations were linearly related to concentrations in milk, but a change in plasma alpha-tocopherol resulted in a smaller change in milk alpha-tocopherol when fat was fed than when it was not. Fat treatment did not affect plasma alpha-tocopherol expressed relative to plasma cholesterol (mg alpha-tocopherol/g cholesterol) or relationships between plasma alpha-tocopherol/g of cholesterol and milk alpha-tocopherol. These data suggest that concentrations of alpha-tocopherol in milk are a function of the alpha-tocopherol enrichment of the plasma lipid fraction and enrichment of that fraction is saturable.
Weiss
W P
WP
Department of Animal Sciences, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster 44691, USA. weiss.6@osu.edu
Wyatt
D J
DJ
D000821:Animal Feed; D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage / Q000493:pharmacokinetics; D002417:Cattle / Q000097:blood / Q000378:metabolism / Q000502:physiology*; D002784:Cholesterol / Q000097:blood; D004041:Dietary Fats / Q000008:administration & dosage* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D007774:Lactation / Q000378:metabolism; D008892:Milk / Q000737:chemistry* / Q000378:metabolism; D011897:Random Allocation; D014810:Vitamin E / Q000008:administration & dosage* / Q000493:pharmacokinetics; D024502:alpha-Tocopherol / Q000032:analysis* / Q000097:blood
D000975:Antioxidants; D004041:Dietary Fats; D014810:Vitamin E; D002784:Cholesterol; D024502:alpha-Tocopherol