It is well known that the process of ensiling forage has a deleterious effect on intake. It is likely that the soluble constituents, produced during the fermentation, are responsible for a major part of this effect, although studies of infusion of constituents into the retlculo-rumen have shown that there Is no simple post-ingestive mechanism. Studies on feeding behaviour have shown that ruminants eat silage more slowly than unensiled forage and from this it has been concluded that ruminants may be aversive to the taste, smell or sight of silage. The question, however, of whether is this aversion to silage could explain reduced intake, when silage is the only food offered, remains. To provide a more definitive test of this question, soluble constituents were added to a high-quality low dry matter silage in combinations and levels typical of those reported in the literature. The effects of these additions on intake by sham-fed sheep was measured.