A number of workers have demonstrated the ability of high rates of methonoic add applied to grass at ensiling to restrict subsequent fermentation and preserve the grass sugars (Carplntero et al, 1979; Henderson et al, 1989). Other recorded effects have included an increased proportion of protein nitrogen (N) in the silage total N (Carplntero et al, 1979) and increased dry matter (DM) intake of silage by cattle and sheep (Henderson et al, 1989). There appears to be less information on the effect of high levels of methanolc acid on digestion and nitrogen utilisation of silage and in particular when applied in a mixture with other carboxylic adds.

A first cut perennial ryegrass based herbage was cut between 18 and 21 May 1988. The herbage was wilted for a maximum of 6h and was ensiled in bunker silos (capacity 50t DM) having been treated with either no additive or 5.95 1 t-1 of a mixture of aliphatic carboxylic acids. The mixture produced by BP Chemicals Ltd contained (gkg-1) 870 methanolc acid (85%), 100 propanoic add and 30 octanoic acid. Digestibility, energy value and utilisation of silage N was examined in mature wether sheep.