Silage is an important supplement in New Zealand dairy systems, however quality can be variable. Challenges with pasture silage lie mainly in the fermentation process, while maize silages tend to have a better fermentation profile, but are prone to heating and spoilage at feed-out. A series of laboratory scale silo trials were used to investigate the effect of different silage inoculants on aerobic stability in maize silage (n=8) and fermentation quality in pasture silage (n=6). Inoculants affected aerobic stability in maize silage, and pH, fermentation losses, ammonia-N and fermentation acid profile in pasture silage, however products differed in their efficacy. Farmers can make better inoculant purchase decisions by choosing products that have supporting trial data as well as guaranteed bacteria numbers.