The effects of formic and propionic acids on the aerobic deterioration of grass silage in laboratory units

A technique is described for the quantification of aerobic deterioration by the measurement of carbon dioxide production in standard laboratory units. It was used to compare the aerobic stability of grass silages made with various levels of formic acid, propionic acid and an additive containing a mixture of the two acids. All three additives were effective in restricting aerobic deterioration when applied at a relatively high rate. Variations in aerobic activity were associated more strongly with bacterial than with mould or yeast growth, though there were differences in the type of microbial activity between the additive treatments.