Inaccurate prediction of silage intake is a major source of error in ration calculation. Improvement in accuracy depends on the introduction of new routine methods to characterise better the silage fermentation. Electrometric titration has the potential to fill this role as it measures the main fermentation end-products in silage, residual sugar and gives absolute data on buffering characteristics (Offer et al., 1993).

Results are presented for years 1 and 2 of a 3 year study of the use of electrometric titration of silage juice to improve the prediction of silage true DM (TDM) intake (SDMI). Fifty seven silages have been made using a variety of grass and grass-clover mixtures and a wide range of cutting dates (between 25 May and 29 September) and ensilage methods. The following additives were used : none, formic acid (2.5 l/tonne), formic acid (>5 l/tonne), Lactobacillus inoculant, molasses (16 l/tonne), molasses + inoculant. A range of wilting times (0 to 48 hr) was used and in some cases grass was left uncovered in a heap (up to 72 hr) before ensiling.