Effects of carbon dioxide on fermentation and aerobic stability of maize silage

Abstract

AbstractThe effects of carbon dioxide level (100% versus 20% v in nitrogen) during ensiling on microbial populations and subsequent aerobic stability were studied in whole‐crop maize silage. In five trials, fresh maize was chopped and ensiled in 10‐litre silos with the two different gas atmospheres. Changes in populations of lactic acid bacteria, acetic acid bacteria, enterobacteria, Bacillus spores and moulds were only slightly affected by carbon dioxide level. In four of the five trials, fermentation products and pH were unaffected by treatment. Yeast counts were altered by carbon dioxide level but not consistently. The yeast population in maize silage made from one source was inhibited by high levels of carbon dioxide whereas the opposite occurred in the silages from two other sources. Aerobic stability was inversely related to yeast population. In two other experiments, maize silage taken from a bunker silo was re‐ensiled in 700‐litre and 10‐litre silos, respectively, and the same two gas treatments were used. Carbon dioxide level had little effect on microbial numbers except yeast counts, which tended to be higher in the 20% v carbon dioxide environment. Little effect on aerobic stability due to treatment was noted in either experiment. High carbon dioxide levels do not appear to improve aerobic stability consistently.