Dry matter (DM) digestibility and voluntary intake (VI) of reed canarygrass (RC) and tall fescue (TF) astures were studied in June, late July, early Octoger, early November, and late November. Three applications of nitrogen (N), totaling 314 kg/ha, were made. Relationships were established between fecal N and DM digestibility by feeding freshly cut forage to steers indoors. Chromic oxide was administered daily to gazing steers, feces were sward sampled, digestibility of grazed forage was predicted, and VI estimated. Data are also presented on yield, percentage DM, pemcentage and apparent digestibility of crude protein, and nutritive value.
In only one instance, early October, was TF superior to RC in VI, although TF was more digestible in all periods except June. In June, TF was more mature, and its digestibility and VI were lea than RC. In late July, grazing steers consumed less TF in spite of its higher digestibility, compared with RC regrowth and wth firstgowth TF. In early November, TF was superior to RC in digestibility, VI, percentage crude protein, and yield. In late November, however, TF was lower than RC in VI and crude protein, findings difficult to explain. Dry matter digestibility and VI values were more closely related for RC than TF. Voluntary intake of steers grazing TF was more variable than the predicted digestibility. Thus, although digestibility is a good measure of nutritive value in RC, it does not seem so for TF.