The objective of this thesis was to investigate factors to improve the silage quality of different types of forage crops. The focus was on the influence of crop maturity, silage additives and laceration on the quality of whole-crop cereals silages. The ensilability of whole-crop cereals was highly dependent upon the stage of maturity. An important factor related to the stage of maturity and influencing the ensilability of whole-crop cereals seems to be the concentration of WSC in the fresh forage. Ensiling at the milk stage was found to be a more suitable time to harvest whole-crop cereals since there is a sufficient concentration of water soluble carbohydrates (WSC) that provides the conditions for lactic acid bacteria (LAB) to rapidly dominate the silage microflora and produce enough acids to reduce pH thereby giving a better protection of the silage against the spoilage microflora. The low WSC concentration of whole-crop cereals at dough stage seems to restrain good fermentation. However, silages harvested at the milk stage still appear to have a low aerobic stability. Precision chopping had variable affects on silage fermentation and showed that laceration is not a guarantee of a good silage quality of whole-crop cereals. At the milk stage, precision chopping improved the silage fermentation, whereas the dough-stage silages tended to give clostridial fermentation resulting in poor quality and high DM losses. Precision chopping promoted a higher silage density at the milk stage and resulted in reduced DM losses at the dough stage. Application of silage additives was the most important factor in improving silage quality. A mixture of sodium benzoate, sodium propionate, hexamine and sodium nitrite seems to be the most suitable additive to secure the silage quality and improve the aerobic stability in whole-crop cereals as well as in moderate and highly -wilted clover-grass forages. No remaining toxic residues of the nitrite concentration were found in the silages. A similar influence on the ensiling process is found when using the combination of sodium benzoate, sodium propionate and propionic acid. The results of mixtures of formic acid and propionic acid were closely related to the chop length of the forage. These additive combinations seem to improve the silage quality and storage stability in precision-chopped silages at both maturities, while the quality of long-cut treated silages often appeared to be low. The variable efficiency of inoculation of whole crop cereals with LAB seems to be associated with types and numbers of epiphytic bacteria in the herbage. The inoculation of homofermentative LAB successfully reduced pH of both precision-chopped and long cut-silages but abundant production of lactic acid did not secure the aerobic stability of thes
