Carcass analysis - Direct methods in Body composition techniques

Carcass analysis

The (chemical) analysis of carcasses is a time-consuming exercise and requires very precise approaches to the task. The carcass has to be carefully dissected into the different tissues that are then exactly weighed, after which the chemical analyses have to be performed. To avoid errors it is important that no unaccounted water losses occur during the analytical work. As early as the nineteenth century, it was rec-ognized that the variation in chemical body composi-tion was reduced when results were expressed as a fraction of the fat-free body. The data on the chemical composition of only a few human cadavers form the basis for the assumptions that are normally used in indirect methods. These chemical analyses were per-formed in five men and one woman. It was concluded that, on the basis of FFM, the mean amounts of water, protein, and minerals in the body are 72.6%, 20.5%, and 6.9%, respectively. The variability in these figures is about 13% for protein and minerals and 4% for water. Although one can question the quality of these data as a basis for other methods (low number, high variation in age, variation in gender, some carcasses were not analyzed immediately after death), they form the basis for many indirect and doubly indirect body composition methods. Chemical carcass analy-sis also revealed that the amount of potassium in the FFM is fairly constant. This fact is used as the basis for the calculation of the amount of FFM or for body cell mass from total body potassium, determined by 40K scanning.

In the 1980s, cadaver studies were performed again in the “Brussels study.” Unfortunately, only informa-tion at a tissue level and not at atomic or molecular level was collected. However, the need for cadaver studies has greatly diminished given that the same information can now be obtained in vivo by IVNAA.