The voluntary intake of grass silage (VFI) is influenced by the presence of silage fermentation products. Ammonia-N concentration has been used in prediction equations for silage VFI as an indicator of the negative effects of fermentation products upon VFI but accounts for only a small proportion of the variance. The objective of this experiment was to improve understanding of the factors in silage that limit VFI by relating the time-course of the silage fermentation to the development of intake characteristics.

Second cut perennial ryegrass was precision chop harvested without wilting. The grass was ensiled untreated (C) or treated (I) with 106Lactobacillus plantarum / g grass (Ecosyl, Zeneca Bio-Products) in 200 l containers (10 / treatment). Two containers / treatment were frozen immediately (0) or after 0.2, 1, 2 or 42 days fermentation to give 10 treatments. Juice was extracted using a cider press from silage immediately on thawing, bulked and then re frozen until required for feeding. For feeding, juice was thawed and maintained at 4° until fed.