Limitations of Plasma or Serum Analysis in Assessing Vitamin E Status of Domestic and Wild Animals


Ullrey, Duane E, Stacey A. Moore-Doumit, Joni B. Bernard, and Sunder P. Shrestha (1995). Limitations of plasma or serum analysis in assessing Vitamin E status of domestic and wild animals. In Proceedings of the First Conference on Zoo and Wildlife Nutrition, AZA Nutrition Advisory Group, Scarborough, OT.


Venipuncture is a relatively noninvasive means of sampling tissues for determination of deviations from physiologic norms. To the extent that norms can be defined and deviations from norms can be associated with abnormality, blood analyses may be medically useful. However, studies of vitamin E metabolism have shown that neither the magnitude of body stores nor the availability of dietary supplies are consistently reflected in alpha-tocopherol concentrations within single samples of plasma or serum. Vitamin E is the major antioxidant within cell membrane lipids and protects them against oxidative damage from free radical attack. If vitamin E intake exceeds need, stores accumulate, particularly in liver , muscle, and adipose tissue. However, the kinetics of absorption, transport, and retention vary with the amount and form of vitamin E, and different tissues have different rates of vitamin E turnover. Studies with swine, horses, elephants, and white-tailed deer that were repeatedly sampled showed that individual animals had plasma or serum alpha- tocopherol concentrations that differed up to two to three- fold from those of other individuals even though age, diet, or work history were the same. Plasma or serum alpha-tocopherol concentrations in young animals with limited vitamin E stores are more likely to reflect the balance between intake, stores, and need, but that reflection is frequently distorted by individually characteristic factors. Thus, a single plasma or serum analysis is unlikely to accurately portray vitamin E status of an animal group, and it may be necessary to use repeated plasma or serum assays or functional tests that relate directly to protection against oxidative cell damage.

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