Proteolysis during ensilage results in a reduction in the nutritive value of the crop due to the degradation of protein to peptides, amino acids and ammonia. Williams et al. (1990) characterised these nitrogenous constituents in ryegrass silages prepared with no additive or with formic acid or an enzyme additive. Although all the silages appeared well fermented neither of the additives reduced proteolysis. The present study was designed to follow changes in the microbiological as well as the chemical composition of ryegrass silages made without or with a wider range of additives thought likely to reduce proteolysis and to control it in different ways.

Perennial ryegrass was ensiled in laboratory silos (1 kg fresh matter), either untreated (U) or treated with formic acid (F) (ADD-F, BP Chemicals, UK; 3.3 1/tonne), aliphatic carboxylic acids (A) (Maxgrass, BP Chemicals, UK; 6.0 1/tonne), 1.75M Na diethyl dithiocarbamate (D) (BDH, UK; 6.0 1/tonne) or an inoculant (I) (Live System, Genus Animal Health, UK; 3.01/tonne at 106 Lactobacillus plantarum cells/g fresh matter (FM). Triplicate silos for each treatment were opened after storage for periods of 1, 2, 4, 14, 60 and 90d.