Fungal and chemical diversity in hay and wrapped haylage for equine feed

Abstract

The presence of fungi and mycotoxins in silage (fermented maize) for cattle and other ruminants have been studied extensively compared to wrapped haylage (fermented grass) for horses and other monogastric animals. The purpose of this work was to examine the fungal diversity of wrapped haylage and conventional hay and to analyse the forage sample for fungal metabolites. Faeces samples were also analysed to study the fate of fungi and metabolites. Fungal diversity of the samples was determined by direct plating on DG18, V8 and MEA and chemical analyses were done using LC-MS/MS. The results show that Sordaria fimicola was common in both hay and haylage, while Penicillium spp. was prevalent in haylage and Aspergillus spp. in hay. Communiols were found in all types of samples together with gliocladic acid. Roquefortines and fumigaclavines were found in haylage with no visible fungal growth, but not in hay. In haylage hot spot samples, a series of Penicillium metabolites were detected: Andrastins, fumigaclavines, isofumigaclavines, marcfortines, mycophenolic acid, PR toxins, and roquefortines. Penicillium solitum was found repeatedly in haylage and haylage hot spot samples and viridicatols were detected in a hot spot sample, which has not been reported before. Even haylage with no visible fungal growth contained more metabolites than hay. Individually, the metabolites detected in haylage may, in high doses, be mutagenic, neurotoxic or immunosuppressive; but the synergistic effect of small doses may also have other or greater negative health effects on equines than on ruminants.