Characterization of fungal species and mycotoxins contaminating silages in Belgium

Silages are of great importance in animal farm forage. In Belgium, it represents the base of the cattle forage during winter, and partly during summer as well. There are different crops used for ensilage such as whole corn plant, CCM (corn cob mix), grass, sugarbeet pulp, etc. More recently, ensilaging of immature cereals has recieved increasing interest due to the low prices of grain cereals, especially of wheat and barley.
The quality of silages greatly impact the health and development of animals. Fungal contamination and mycotoxin production is often a problem in silage and is frequently suspected to be responsible of animal death or health damage. However only scarce data are available concerning the risk assessment of such contaminations mostly because most of the suspected effects are unspecific (reduction of fertility, reduction of productivity, immunosupressive effects, etc.) and not solely influenced by the feed quality. The presence of molds is a good warning sign as to a likely possibility of mycotoxin problems.
In the first part of the project, selection of farmers from various geographic regions and using various cropping systems will be done to depict of the state of ensilage in Belgium. Therefore, collection of information is necessary on the raw material of silage (plant species, variety, fenologic state of the plant at harvesting time), the ensilage system (type of silo, design etc.) and on husbandry (diseases, fertility problems, allergic reactions, etc.) to have some background information on the possible effects of mycotoxins.
Isolation of fungal species from moldy and healthy silage and the characterization of those strains is predisposed to valorizing the biological material available in the BCCM/MUCL collection by improving and expanding the existing knowledge on the characteristics of the material. The core research of this project relates to the biological and metabolic diversity of silage contaminating fungi. Morphological characterization of the isolated strains will be be combined to molecular taxonomic and phylogenetic studies to enrich the MUCL strain collection. Data for the diversity within the different species isolated from the different type of silages will be analyzed using RAPDn and AFLP and sequence analysis. Morphological, taxonomic and diversity studies will enrich the database of the subcollection.
New methods will be developped for the extraction and HPLC analyzes of selected mycotoxins from different silages. Analyses of mycotoxins will also be performed on samples from in vitro cultures of the fungi and special attention will be devoted to less known mycotoxins or even unknown fungal metabolites. The information related to mycotoxin and metabolite production of the isolated strains will be useful in order to refine the characterization of fungal strains.
Toxicological analyses will be performed on the silage extracts and on the pure fungal culture extracts to have a better insight in the hazards related to some well known mycotoxins but also to some less known and even unknown compounds. Based on transgenic cell cultures pure mycotoxins and silage extracts will be evaluated on their potential to induce specific stress genes in both biosensor systems. This will allow for mode of action analysis and consequently grouping of contaminating mycotoxin families within the silage under study. As the technology uses living cells, mixture effects (e.g. synergy, additivity, potentiation, masking, …) are taken into account.
The private partners will gain a better insight in the overall problematic of fungal contamination and mycotoxin production in silage. Several techniques will be optimised for routine application in silage monitoring, which will in time allow for preventive measures as opposed to the post hoc analysis and evaluation which is common practice today. This will eventually lead to improved quality of silage feed, reduction of contamination events and hence reduction of costs