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Single versus Duplicate Determinations for the Estimation of Vitamin A and Tocopherol in Calf Livers¹

Storrs (Conn.) Agricultural Experiment Station

H. L. Lucas, Jr.

North Carolina State College, Raleigh

ABSTRACT

In calf nutrition studies, in which the objective is to determine the effect of different treatments, e.g., on the concentration of vitamin A or tocopherol of the liver, the error variability used in statistical tests of significance consists of two general sources: differences in the liver concentrations between calves on the same treatment, calf variability, and differences within the liver of a single calf, such as those due to between-samples from the same liver, between-duplicate determinations from a single sample, etc., measurement variability. If the first source of variability is relatively large in comparison with the second, little reduction in the error variability is accomplished by increasing the number of samples for a particular liver, or the number of determinations per sample. Data from eight randomized-block experiments, conducted during 1952-56, in which calves were fed fixed levels of vitamin A and/or its precursor, carotene, and/or tocopherol for periods ranging from 4 to 16 wk., were used to ascertain the effect on the error variability of using the first duplicate determination for vitamin A or tocopherol concentration, as contrasted to using the average of the first and second duplicates.

¹ This study was supported in part by funds provided by the Chas. M. Cox Co. and the Chas. H. Hood Dairy Foundation, Boston, Mass., and the Am. Dehydrators Assoc, Kansas City, Kansas. The authors are most grateful to A. P. Grifo, Jr., Mrs. Mae Miller, and Mrs. Elaine Trantum for technical assistance, as well as to R. H. Benson and Patricia MacLeod for their helpful suggestions in the preparation of the manuscript.