Investigations into the method of estimating vitamin E

Abstract

The response of pregnant female rats to vit. E is of the "all or nothing" kind and the relationship between dose and response is expressed in a sigmoid curve of the type associated with quantal response. The relation between dose and % fertility in groups of animals is expressed by the equation log DM = log DT [long dash]0.35yT +1.74 where DM and Dt are the mean fertility dose and the test dose respectively and yT is the probit of the response to the dose Dt. The author recommends the use of virgin animals receiving a diet proved satisfactory by a) its ability to give full term litters when adequately supplemented with vit. E only and b) its ability to produce 100% of resorptions in implanted animals fed no supplementary vit. E. He also recommends distributing the dose over some fixed number of days, e.g., 10, following positive mating and insists that the most accurate estimates of relative vit. E activity can only be made by comparing mean fertility doses. Even so, the test, when carried out with the maximum number of animals generally found practical, has a very high error. For other technical details of the test, two earlier papers may be consulted. (Bacharach and Allchorne, Biochem. J., 1938, 32, 1298; Bacharach, Allchorne and Glynn, Biochem. J., 1937, 31, 2287.).