The Role of Plant Pigments in Digestion Trial Studies

REID et al. (1950) first used natural occurring plant pigments as a marker in digestion trial work. In their studies the acetone extract of hays and feces produced absorption curves which invariably crossed one another at 406 mμ They assumed that no changes occurred at this isobestic point and satisfactorily demonstrated its applicability as a marker in digestion trials under the experimental conditions imposed. In a later paper Reid et al. (1952) related the chromogen concentration of the dry matter of the feces to the percent of dry matter digested, thus providing a technique for studying forage digestion under grazing conditions. Kane et al. (1951) in a study of digestion trial techniques concluded that satisfactory results could be obtained in orchard grass studies using chromium oxide and plant pigments whereas lignin, total methoxy and lignin methoxy were unsatisfactory. Cook and Harris (1951) reported that the chromogen technique as a method of studying digestibility was unsatisfactory for sheep on desert range plants.