Recent research at this Institute has shown marked improvements in animal performance following the use of bacterial inoculants as silage additives (Gordon, 1989 and Mayne, 1990). Other studies with additives based on antimicrobial carboxylic salts (Maxgrass - BP Chemicals) have also shown large improvements in animal performance relative to untreated silage (Chamberlain et al, 1990). However with constraints on milk output in the form of milk quotas, it is important to investigate the potential “concentrate sparing” effect of these differing silage additives, whilst producing a constant yield of milk constituents.

Five silages with a range of fermentation characteristics were produced by ensiling first regrowth herbage either untreated (C) or treated with four differing silage additives including: an inoculant of lactic acid bacteria (I); an inoculant of lactic acid bacteria plus enzymes (I+E); formic acid applied at 2.54 litres/t grass (FA) and antimicrobial carboxylic acids applied at 5.95 litres/t grass (CA).