All diets were subject to proximate analysis (EEC, 1971a,b; EC, 1992, 1993). The neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL) were determined as indicated by Van Soest et al. (1991). Particle size distribution of the pellets was measured in duplicate using a wet sieve analysis. Briefly, 50 g of feed were weighed into a tumbler and then 1000 mL of water heated to