Fresh-harvested Gambel oak (Quercus gambelii) browse was mixed with chopped alfalfa hay to formulate six diets , varying in oak content at two phenological stages. Diets included juvenile oak (65 ,80,95%), mature oak (40,80\), and an alfalfa control . Diets we re evaluated for goats using a series of total-collection dige st ion balance trials . Dry matter intake was highest for animal s on mature oak diets, and lowest on diets containing a high percentage of juvenile oak, possibly due to differences in diet dry matter content . Apparent digestibility of dry matter and cell wall components was lowest for mature oak diets, and highest for diets high in juvenile oak. Nitrogen and energy balances were positive in all cases , and all diets provided nitrogen and energy in excess of rnaintenance requirements. This was reflected by weight gains for all animal s in every trial. Fecal and urinary nitrogen losses did not appear to be related to tannin content of the diets, because high-percentage juvenile oak diets resulted in reduced nitrogen outputs , presumably due to reduced nitrogen intakes for these diets. In comparison with previous data using pelleted formulations, the fresh-fed material was consistently higher in digestibility of the various fractions, and associated with lower dry matter intakes.