There is a considerable literature on the effect of grinding and pelleting roughages on their intake and digestibility by ruminants. It is also well established that intake is correlated with digestibility, which parameters are themselves correlated with the rumen degradability of the roughages concerned (Hovell et al. (1986)). However there is little information in which the effect of processing on the intake and digestibility of roughages of known degradation characteristics has been examined. The objective of the experiment reported here was to examine the effect of grinding and pelleting on the voluntary intake and digestibility of two roughages whose degradation characteristics had been defined.

Four mature 63-69 kg Finn-Dorset ewes fitted with permanent rumen cannulae were used. The roughages were a hay (potential degradability 0.81), and a barley straw (potential degradability 0.57) given coarsely chopped, or ground and pelleted. The composition of the hay and straw is shown in Table 1, and the particle size distribution of the two forms is given in Fig. 1. Urea was added to the straw at 18 g/kg and to the hay at 3.6 g/kg (air dry), with 0.13 g sodium sulphate per g urea. A mineral/vitamin supplement was also given. The experimental design was a latin-square with 21 d periods. Food was offered to 10-15% excess of voluntary intake. Voluntary intakes and digestibility were measured during the last 7 d of each period.