Variations in fermentation, bacterial population and aerobic stability in maize silage

Whole crop maize in dough stage physiological maturity of grain (387 g kg(-1) dry matter) was ensiled in big (1.2 m diameter x 1.2 m height) bales and in 3-litre mini silos with either viable lactic acid bacteria (LAB) inoculant Lactococcus lactis and Lactobacillus buchneri or without any additives. Silos were opened after 120 days, silage was sampled and the nutrient composition, fermentation products and microbial colony counts were determined. Big bale and laboratory silage was exposed to air, and aerobic stability was determined. Significant variation was observed between inoculant treated and untreated big bales, and inoculant treated and untreated laboratory silage. Viable LAB caused reduction in acidity (pH) value, a decrease in dry matter (DM) loss, concentrations of butyrate, ammonia nitrogen (NH3-N) and alcohols, and an increase in the concentrations of lactic and acetic acids in both big bale and laboratory silage. Inoculated silage had lower counts of yeasts and moulds after ensiling and after air exposure, which improved their aerobic stability relative to the untreated silage. The untreated silage had a relatively large proportion of visibly spoiled silage at the surface of the big bales. The similarities observed between the big bale and laboratory silage showed that small scale silage can serve as a model for big bale silage and can be used to test the efficacy of silage additives in laboratory conditions.