Earlier work has shown that newly-housed, previously-pastured lambs are reluctant to eat straw. This experiment monitored intake and diet-induced behaviour patterns in newly-housed lambs with the aim of determining the effect of ammoniation on rate of adaptation to straw diets.

Sixteen, 35 kg lambs were selected from a flock of seven month old, Suffolk cross Mule lambs which had been pastured from weaning and had no previous experience of straw. Lambs were housed in October in individual, continuously- lit, open-side pens and fed untreated or ammonia-treated (100 1/t of 320 g/kg ammonia) winter wheat straw. Ammonia treatment was by the stack method (Sundstol and Coxworth, 1984) and the straw offered was collected in 20 kg wads every other day from stacks kept in an open-sided barn. A completely randomised design with eight replicate lambs per treatment was used to compare straw types. Sufficient straw was offered to allow daily refusals of at least 300 g/kg offered during the 21-day trial. A barley-based supplement was fed at 240 g dry matter (DM)/d. Nitrogen contents of both straw types were monitored with a LECO FP-228 automatic nitrogen determinator while the total content of neutral and acid detergent fibres were analysed using the method of Goering and Van Soest (1970). Thein vitro dry matter digestibility (DMD, Tilley and Terry, 1963) of the straw offered was also monitored. A concurrent behaviour study involved recording the activity (eating, drinking, idling or ruminating) every 5 minutes for 9 h on day 1 and 12 h on days 8 and 16 of the 21-day trial.