EFFECT OF ADDITIVES ON THE QUALITY OF BIG-BALE SILAGE

Big-bale silages were prepared from grass swards at 25, 35 and 50% dry matter (DM) after infection with spoilage flora. The bales were either inoculated with lactic acid bacteria (LAB) (106 LAB g-1) or treated with formic acid (4 or 81 t-1). The spoilage flora inocula consisted of spores of Clostridium tyrobutyricum and Aspergillus flavus. Chemical and microbial characteristics were determined after 120 days of storage, while hydrogen gas was monitored during storage. Wilting and additives increased silage quality; i.e. reduced pH and the contents of ammonia-N, butyric acid and clostridial spores. Neither the formic acid treatment nor inoculation with LAB had any significant effect on the number of clostridia. Strains of Clostridium tyrobutyricum isolated from late-blown cheeses grew well in big-bale silage. The LAB were apparently more effective than formic acid when used to preserve silage; i.e. the former treatment led to a significantly lower pH, higher amounts of organic acids and less growth of moulds on the surface of the bales. Formic acid treatment favoured growth of moulds like Fusarium spp. and Arthrinium phaeospermum. Penicillium roqueforti was the dominating mould species in LAB-inoculated and control bales. No Aspergillus flavus growth was observed. Inoculation with LAB favoured yeasts such as Hansenula anomala and Candida lambica. © 1990.