Comparative vitamin E requirements and metabolism in livestock.
It has been over 50 years since vitamin E was originally described as a lipid-soluble dietary constituent required for normal reproduction in rats. Vitamin E is recognized as an essential vitamin required for all classes of animals functioning predominantly as an intracellular antioxidant in maintaining the integrity of biological cell membranes. Although a wealth of information has been gathered on clinical signs of vitamin E deficiency, establishing its requirements for animals has been exceedingly difficult because of interrelationships with other dietary constituents. Vitamin E requirements for animals cannot be defined in isolation. Requirements are influenced by the amount and type of fat (particularly with monogastrics) and degree of fat oxidation in the diet; the presence of antioxidants; dietary selenium (closely interrelated with vitamin E), iron, copper, and sulphur amino acids, as well as the physiological status of the animal. Other factors to be considered in assessing vitamin E needs of animals under commercial production conditions include: a) variability of vitamin E content in feedstuffs; b) poor stability of vitamin E during processing and storage of feeds; and c) management practices resulting in overstressed animals. Information on the function of or requirements for vitamin E in animals is very incomplete. Estimated dietary vitamin E requirements for most animal species are in the range of 10-40 IU/kg of diet. Of particular concern is the lack of vitamin E requirement information regarding young dairy and beef calves. Although good experimental evidence indicates a beneficial role of supplemental vitamin E above physiological levels on overall performance, enhanced immunocompetence and preservation of meat and milk products, levels of vitamin E required to produce these desired effects needs to be firmly established. Present estimated dietary requirements for vitamin E across species may need to be redefined as new information becomes available about the role this nutrient plays in growth, health and overall metabolism.
Hidiroglou
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N
East Tennessee State University, College of Medicine, Department of Surgery, Johnson City 37604.
Cave
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N
Atwall
A S
AS
Farnworth
E R
ER
McDowell
L R
LR
D000042:Absorption; D000821:Animal Feed; D000818:Animals; D000829:Animals, Domestic / Q000378:metabolism*; D001692:Biological Transport; D002417:Cattle / Q000378:metabolism*; D005260:Female; D011200:Poultry / Q000378:metabolism*; D013552:Swine / Q000378:metabolism*; D014810:Vitamin E / Q000008:administration & dosage* / Q000493:pharmacokinetics
D014810:Vitamin E