Ergosterol and polyphenols: Potential biochemical indicators of silage safety

Abstract

Background: Silage, one of the most important feed sources for cattle, is vulnerable to contamination by spoilage moulds and mycotoxin production because ensilage forage crops are excellent substrates for fungal growth. Whereas there are many factors involved in mycotoxins contamination such as biological factors, harvesting, storage, and processing conditions, the climate is the most important factor. Silage additives can improve the safety of silage and inhibit moulds and other detrimental silage microorganisms; however, their efficacy varies with the type and level of toxigenic fungi contamination. Several studies provided evidence showing that the presence of various mycotoxins was correlated with the presence of ergosterol in cereals and feedstuffs. Therefore, ergosterol ( ERG ) has been suggested as a potential indicator of fungal contamination with polyphenols concentration analysis allowing accurate prediction on silage safety. The main goal of this study was to use the ERG and polyphenols content as potential biochemical indicators to predict the silage safety in ensiled grasses. The study was carried out using ten orchardgrass varieties (untreated and treated with biological and chemical additives). The determination of the samples was performed on high-performance liquid chromatography using UV detection (ERG) and spectrophotometer UV/VIS (polyphenols). Results: Interestingly, in the silage ‘Bepro’ was the unique variety that no presented content of ERG (0.0 mg kg -1 dry matter) in comparison with other varieties in the first cut in 2012. The biological additives reduced the content of ERG in both cuts in 2012 compared with untreated silage. In contrast, the chemical additives in silage grass had a negative effect ( P < 0.05) by increasing the ERG and polyphenols content in comparison with untreated silage. Conclusions: These results of this study provide indisputable evidence that silage contaminated with fungi increase the concentration of polyphenols, which prove a progressive deterioration of silage quality. In consequence, ERG and polyphenols seem to be relevant as a rapid method for screening silage safety.