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Published online by Cambridge University Press: 18 August 2016
Switchgrass (Panicum virgatum cv. Alamo) standing hay was cut and offered to 16 rams. The rams were randomly allocated to one of the following levels of feeding: 0·5; 1·0; 1·5 and 2·0 ✕ maintenance. The forage was offered twice a day to the animals; no supplements were given. The animals were individually penned and fitted with faeces collection bags. After 8 days for adaptation, in vivo dry matter apparent digestibility (DMD) and proportion of blades and stem + sheath of the consumed forage were measured for 8 days. DMD varied from 0·310 (0·5) to 0·391 (2·0) and the proportion of the blade fraction in the diet from 0·44 (0·5) to 0·78 (2·0). The short-term intake rate (STIR) of rams was measured for 5 days. The animals were divided randomly into four blocks, with one ram of each treatment in each block. After 4 h without food and 15 min intervals between blocks, the amount of forage consumed during 4 min of active eating was measured. The amounts consumed were (in g DM per min per 50 kg live weight): 0·5: 8·2; 1·0: 7·8; 1·5: 5·3 and 2·0: 5·3 (0·5 = 1·0 > 1·5 = 2·0; P < 0·01). The results show that offer rate of P. virgatum affects the blade: stem + sheath ratio of intake and, therefore, the nutritive value of the diet. Level of feeding before measuring STIR influences the amount of forage consumed during the test.