. Principles of agricultural chemistry [microform] . estion experiment is to determine, bytrials on animals, the actual amounts of the different nutrientswhich are digested. In a digestion experiment, a known quantityof food is fed, the excrement from it collected, and both foodand excrement are subjected to analysis. The quantity of eachnutrient fed and digested is calculated, and the quantity ofnutrient digested is divided by the quantity fed. The dividend,expressed as percentages, is the coefficient of digestibility. DIGESTION 399 With men, the faeces from different meals are not mixed inth
. Principles of agricultural chemistry [microform] . estion experiment is to determine, bytrials on animals, the actual amounts of the different nutrientswhich are digested. In a digestion experiment, a known quantityof food is fed, the excrement from it collected, and both foodand excrement are subjected to analysis. The quantity of eachnutrient fed and digested is calculated, and the quantity ofnutrient digested is divided by the quantity fed. The dividend,expressed as percentages, is the coefficient of digestibility. DIGESTION 399 With men, the faeces from different meals are not mixed inthe body, and can easily be separated by appropriate , at the meal before beginning the experiment, the manswallows a capsule of charcoal. Then for two or three days heeats the ration to be tested. At the end of the period he takesanother capsule of charcoal. The dividing line between excre-ments from the meal without charcoal and the one with charcoal,is easily distinguished, and the excrement from the ration testedcan be separated Fig. 85.—Sheep arranged for digestion experiment. Wyoming Stalion. With domestic animals, the food from different meals is mixedso thoroughly in the stomach and intestines that not only is it im-possible to distinguish one meal from another, but the residuesfrom a given meal may appear in the excrement for three orfour days. Such animals are fed a uniform quantity of foodlong enough to ensure the elimination of previous food residues,and the excrement is collected for a definite number of days. It 400 PRINCIPLES OF AGRICULTURAL CHEMISTRY is assumed that the excrement corresponds to the food fed oncorresponding days. This assumption is justified if the periodof collection is long enough to compensate for the irregularitiesin elimination of the excrement. A period of only three or fourdays is likely to give incorrect results. The collection periodshould not be shorter than six days for pigs, eight days for sheep,and ten days for cat
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