There was little difference in digestive (voluntary food intake, dry matter digestibility and nitrogen balance) and blood measurements (venous concentrations of corticosteroids, serum aspartate aminotransferase (EC 2.6.1.1), protein-bound iodine, urea and glucose) of intact sheep (eight animals) and of sheep prepared with rumen cannular (sixteen animals) and subsequently with either simple 'T-shaped' (eight animals) or re-entrant cannulas (eight animals) at the duodenum and ileum, when fed ad lib. a chopped medium-quality-hay ration. 2. Wool growth rates of the intact sheep were similar to those in sheep with rumen cannulas and with rumen cannulas plus simple 'T-shaped' cannulas, but higher (P less than 0-01) than those with rumen cannulas plus re-entrant cannulas. 3. When the sheep were subsequently given a restricted intake (800 g/d) of dried grass, retention times of solid- and liquid-phase digesta markers in the rumen and caecum were similar in all sheep. 4. The use of the different preparations in digestive physiology studies is discussed.
