A Compression Method Indicates Fat Content of Elk (Wapiti) Femur Marrows

Abstract

Chemical analyses may not be feasible for fat content of femur marrows of big game animals, and to describe color and textures of marrows subjectively is difficult except for extreme characteristics. It was found that the ether-extractable fat content of a femur marrow is related inversely to compressibility of the marrow. A known length of femur marrow reveals its compression and this is easily measured in percent. The freshly obtained femur marrows from 291 elk (wapiti) (Cervus canadensis) were measured at room temperature by the method described and the percent compression compared to the ether-extractable fat content of identical marrows. The amount of compression was also related to fat content of femur marrows of mule deer (Odocoileus h. hemionus), pronghorn antelope (Antilocapra americana), moose (Alces americana), and cattle. By chemical analysis, fat content varied up to 10 percent between fresh and frozen subsamples of a marrow. The method of measuring femur marrow compression indicates fat content accurately enough for some studies, without delay or laboratory costs. The color and consistency of femur marrows are correlated with the alcohol-etherextraction fat content and indicate condition of white-tailed deer (Odocoileus virginianus) (Cheatum 1949). Marrow of deer in good condition is white and solid; that of undernourished deer is gelatinous, and yellow or red. Riney (1955:435) used a system of index values for various colors and textures to permit visual estimation of fat in femur marrow of red deer (Cervus elaphus). Marrow characteristics have limitations in assessing condition of black-tailed deer (Odocoileus hemionus columbianus), according to Bischoff (1954). He considered that only consistency of a marrow was an adequate measure of its condition. Collections of big game animals provide femur marrows that may be chemically analyzed or grossly examined as a criterion for condition. Under some circumstances the laboratory analysis for fat content in femurs may not be feasible. Femur consistency is difficult to describe and is subject to variable evaluations among different observers. A quantitative method was devised to evaluate femur consistency in 1 A contribution from Montana Federal Aid Project W-83-R. which determinations are easily repeated by the same person, as well as duplicated by other persons.