Supplements of readly digestible cellulose and hemicellulose enhance fibre degradation by promoting the growth of eellulolytic microbes in the rumen. In the current study supplements of ammonia treated straw were fed to a basal diet of untreated straw and intake, fibre digestion and rumen fermentation assessed.

Four mature castrated male sheep weighing 50.5 to 69.6kg and fitted with permanent rumen cannulae were used. The experiment had a 4 x 4 latin square design such that the sheep were fed four diets and measurements taken oyer four periods. Each period consisted of 10 days adaptation and measurements taken for a further 8 days.

The diets comprised untreated straw (control) ammonia treated straw (AS) or untreated straw together with 200g AS or 400g AS (200AS and 400AS respectively). Straw was treated with 3.5% ammonia (w/w). Untreated straw was supplemented with 1% urea (w/w). In addition both straws were supplemented with minerals and vitamins. Straw was chopped (4cm screen) prior to feeding. For diets 200AS and 400AS the treated and untreated stsaws were given in seperate troughs.