Juice was extracted from a ryegrass silage after fermentation times of 0, 51 or 291 h. Three solutions of D/L lactic acid were prepared to have the same neutralizing values (NV) as the silage juices. Experiment A measured the mtakes by sheep of dried silage residues remaining after juice extraction. Experiment B measured the effect of adding each of the juices and lactic acid solutions (1·5 l/kg) on intake of unmolassed sugar-beet nuts. Intakes were measured daily and also over 3 h following an overnight fast.
Fermentation time had no effect on the composition or intake of the residues (P < 0·05). Increasing fermentation time from 0 to 51 to 291 h reduced silage juice pH (5·07, 4·96 and 4·10), increased lactic acid (gfl 6·2, 7·1, 18·7), NV (meq/l 29, 40, 157) and osmolality (mosmol/l 1000, 1010, 1390). Corresponding values for the lactic acid solutions were 2·82, 2·74, 2·41 (pH), 3·1, 4·3,18·3 (lactic), 26, 38,154 (NV) and 32, 42,176 (osmolality).
Total daily DM intake (g/kg live weight1·473) was unaffected by NV but was significantly higher overall (P < 0·05) for the silage juices (7·49) than for the lactic acid solutions (6·64) although this difference was mostly due to the extra dry matter (DM) contained in the added silage juice. Short-term DM intake (g per 3 h per kg live weight1·473) decreased with increasing NV, being significantly lower (P < 0·05) for the highest NV than for the others (3·58, 3·34 and 3·11) but lactic acid and silage juice gave similar responses (P > 0·05). Effects on short-term intake were influenced mainly by NV and suggested effects on immediate feedback mechanisms or palatability.