Study of the presence of biogenic amines in silage destined for animal feed

Silage is a technique that preserves animal fodder via fermentation. The health hazard associated with silage is the presence of pathogenic microorganism and/or their metabolites, including mycotoxins or biogenic amines (BAs). BAs can also occur in the rumen produced by microbial flora during normal fermentation. Then ruminants could receive these substances from both dietary and microbial sources. High exposure to BAs provokes lowered intake and is also linked to acute and subacute toxicity. Moreover, several studies have demonstrated that low levels of BAs have adverse effects on both growth performance and meat quality.

This work aimed to evaluate the presence of 6 BAs (putrescine, cadaverine, histamine, tyramine, spermine, and spermidine) in different types of silage (corn, grass, ryegrass, and unifeed mix) destined for animal feed. For this purpose, 18 silage samples were analyzed, determining pH, dry matter (DM), and BA content. The quantification of BAs was carried out by extracting the amines with trichloroacetic acid from the freeze-dried samples, followed by a Dansyl-chloride derivatization procedure and further HPLC-DAD analysis. The pH levels of the silages analysed were within the range of 3.7-8.3, and no correlation with the type of raw material was found. The results obtained showed the presence of putrescine, cadaverine, histamine, and tyramine in all of the samples, with tyramine being the BA providing the highest values, ranging from 10 to 227 ppm (DM basis). Putrescine came in closely, raising data ranging from 13 to 197 ppm (DM basis). The concentration of each amine varied among samples, indicating that factors such as the raw material and the fermentation process could determine the accumulation of BAs in silages. Due to the effect of BAs on animal performance and meat quality, more studies are needed to characterize this chemical hazard and to establish control strategies to prevent their presence in silage.