QUALITY OF GRASS-SILAGE INFECTED WITH SPORES OF CLOSTRIDIUM-TYROBUTYRICUM

The influence of adding clostridial spores to silage was studied in 2 successive years. Direct-cut, precision-chopped herbages were infected with spores of Clostridium tyrobutyricum in doses varying from 0 to 1 0(6) g(-1) fresh material (FM), and ensiled in experimental silos. The material was treated with or without 4 ml formic acid (85%) kg(-1) FM . Silo contents were studied after 4, 20 (or 50) and 100 days of ensil ing. Contents of dry matter, water-soluble carbohydrate, nitrate as we ll as buffering capacity of FM varied between the 2 years at harvest, whereas the numbers of clostridial spores were about the same (<10(2) g(-1)). Infecting the crop with clostridial spores negatively affected the quality of silage in the first year. After 50 days spore numbers in the silages had increased by 40 x 10(3) to 150 x 10(3) times in the infected silage, compared with 5 x 10(3) in the uninfected silage, No effect was seen in the second year. Silage with high spore counts sho wed no residual nitrate content, Formic acid improved silage quality f rom a chemical point of view but had no anti clostridial effect. Ensil ability of a crop seems to be more important than the initial count of clostridia for a successful ensiling process.