The effect of age and condition on the mineral composition of the ash of the bovine

Approved, May 10-1916, P.F. TrowbridgeTypescriptM.A. University of Missouri 1916It has long been known that the ash constituents or the mineral elements of the body bear an important relation to body structure and life processes of animals. However, the amount of data on the composition of the ash of animals is very small and in most cases incomplete. Furthermore, a great deal of the data as presented by various investigators cannot be compared because of lack of uniformity in reporting results as well as in the selection of samples for analysis. Forbes in his bulletin on "The mineral elements in animal nutrition," comments on this, saying "Our knowledge of the amounts and kinds of mineral matter required by animals is indefinite and fragmentary. Much progress is yet to be made in this field." This is especially true because the purpose of previous investigators seems to have been to get a representative analysis of different animals or parts of animals without any reference to factors which may or may not influence the mineral composition of the animal. To the nutrition chemist, data taken from experiments which have been systematized so that the results are comparable are of great value. The data presented in this thesis are the first to be offered from a series of experiments now in progress. The ultimate end of this combined series is to study the distribution of mineral constituents in the ash of the different parts of steers as well as in the entire animal ash with a special view of determining, if possible, what effect the age or condition of a steer may have upon his ash composition. The entire work is a part of the so-called "Use of Food" experiment. The work offered in this paper consists of data on six steers, three old and three young. The condition of each of the older steers was different but there was a steer in the group of young animals which was in a corresponding condition. These data are limited to the effect of age and condition on the distribution of the ash constituents in the composite skeleton, composite lean and fat, and composite internal organs and internaIncludes bibliographical reference