The effect of decanoic,dodecanoic and tetradecanoic acids on silage fermentation

The ability of decanoic (C₁₀), dodecanoic (C₁₂) and tetradecanoic (C₁₄) acids to restrict the fermentation of ryegrass and lucerne was investigated with laboratory silos. With ryegrass, addition of the C₁₂ acid alone at 1 kg t^?1 of fresh crop had no effect on extent or pattern of fermentation compared to that of the untreated crop, though at 2 kg t^?1 the acid appeared to reduce the content of butyric acid but not ammonia-N in the silage. Formic acid, added alone or with C₁₀, C₁₂ and C₁₄ acids restricted extent of fermentation and butyric acid production, but in this experiment addition of these acids had relatively little effect on the content of ammonia-N in the silages. With lucerne, extent of fermentation was similar for all treatments, though the untreated silage and those which received C₁₂ or formic acid alone at 1 kg t^?1 or 1 kg t^?1 of C₁₄ acid with 1 kg t^?1 of formic acid contained butyric acid in excess of 3% of the dry matter (DM). It is concluded that acids in the range C₁₂-C₁₄ are not effective in restricting silage fermentation and that their effectiveness is not increased by reduction in pH produced by the addition of formic acid. Microbiological assessments largely confirmed these findings.