Treatment of poor quality roughages with ammonia or sodium hydroxide (NaOH) has been demonstrated in numerous studies to improve the nutritive value of these materials. Ammonia is usually applied in anhydrous or aqueous forms in stacks at ambient temperature or anhydrous in high temperature ovens (e.g. Mason et al., 1989) while NaOH is usually applied as an aqueous solution either as a spray or by immersion of the test material (e.g. Wanapat et al., 1985). The objective of this study was to determine the effects on composition and subsequent rumen fermentation when low digestibility grass hay was treated with ammonia and/or NaOH by a procedure which might be readily used at farm level.