Digestibility and Consumption of Pasture Forage by Grazing Sheep1

The digestibility and consumption of pasture forage by grazing sheep of three age groups are presented. The age of sheep did not affect their digestion, but the advance in stage of maturity of the grass resulted in a significant decrease in digestibility. The average digestibility of dry matter by the chromogen method was 64.4, 57.6 and 56.2 for the bloom, seed, and second-cutting stages, respectively. The daily average dry matter consumption was 0.8, 1.7 and 2.2 pounds per 100 pounds body weight for the adult rams, yearlings, and lambs, respectively. When digestibility and consumption as determined by the chromogen method were compared with other available methods, the nitrogen content of feces method suggested by Lancaster (1949 a) gave comparable results. The percent digestible energy as proposed by Lofgreen (1951) gave lower values of T.D.N.—61, 54, and 54—as compared with 64, 57, and 57 by the chromogen technique, for the bloom, seed, and second-cutting stages of pasture forage maturity.