EFFECT OF STEAM-TREATED GRASS SILAGE ON ANIMAL GAIN

Four crops as unwilted silage were compared for weight gain with steers: (a) mixed grasses harvested 14–15 June at early head stage with 61% digestible dry matter (DM) in vitro; (b) similar grass, steamed while standing, with the Dutch Thermal Unit, harvested 14–15 June at early head stage with 63% digestible DM; (c) second harvest of grass from the same area as a but harvested 22–24 Aug. at early head stage with 59% digestible DM; (d) grass-legume, second harvest on 22–24 Aug. at early head-early bloom stage with 62% digestible DM. One group of steers were fed each of the four silages alone and an equal number of steers were given 1 kg of ground barley with the silage. Animal gains when these silages only were offered were, for (a) 0.45; (b) 0.71; (c) 0.47 and (d) 0.71 kg per head per day. There was an increase of 57% in weight gain resulting from the steaming of the standing grass sward prior to ensiling. This was greater than the 30% increase in weight gain obtained by supplementing the conventional silage ration with 1 kg per day of barley.