Prevalence of mycotoxins from silage in a small beef cattle feedlot over a storage season: a case study

Challenges exist worldwide for the storage of animal feed, though year-long feeding of livestock is especially difficult in northern climates, including Canada. Usage of silage allows for crops to be harvested at the optimal nutritional value and stored for extended periods in customized storage systems. This case study investigated various feed management practices typical of small beef cattle feedlot farms in Southwestern Ontario, Canada. Crop samples were collected monthly and analyzed for mycotoxins and fungal secondary metabolites by liquid chromatography mass spectrometry (LC-MS/MS). Stored barley contained modest concentrations of deoxynivalenol and related compounds, as well as near trace amounts of fumonisin. Stored hay contained low concentrations of deoxynivalenol and beauvericin from the field. Hot spots of the Penicillium metabolite citrinin were detected after 7-8 months of storage in barley (39.2 ng g-1). Citrinin was also detected after 7-8 months in hay (16.3-17.5 ng g-1) along with the appearance of trace amounts of other storage toxins, including penitrem A (8.84 ng g-1), griseofulvin (34.8 ng g-1) and sterigmatocystin (14.1-261 ng g-1). This case study was a unique opportunity to use 'citizen science' to observe the onset of postharvest fungi and associated mycotoxins in various storage conditions allowing for the farmer to make necessary modifications before major problems begin. An improved understanding of the storage conditions that foster fungal growth and mycotoxin production in this working farm led to better agronomic practices, ultimately improving feed quality, livestock health, and profitability. Le stockage des aliments pour animaux pose des problemes dans le monde entier, meme si l'alimentation du betail tout au long de l'annee est particulierement difficile dans les climats nordiques, y compris au Canada. L'utilisation de l'ensilage permet de recolter les cultures a leur valeur nutritionnelle optimale et de les stocker pendant de longues periodes dans des systemes de stockage personnalises. Cette etude de cas a examine diverses pratiques de gestion de l'alimentation animale typiques des petits parcs d'engraissement de bovins de boucherie dans le sud-ouest de l'Ontario, au Canada. Des echantillons de cultures ont ete preleves chaque mois et analyses par spectrometrie de masse a chromatographie liquide (LC-MS/MS) pour detecter la presence de mycotoxines et de metabolites secondaires fongiques. L'orge stockee contenait des concentrations modestes de deoxynivalenol et de composes apparentes, ainsi que des quantites presque infimes de fumonisine. Le foin stocke contenait de faibles concentrations de deoxynivalenol et de beauvericine provenant du champ. Des points chauds de citrinine, un metabolite de Penicillium, ont ete detectes apres 7-8 mois de stockage dans l'orge (39,2 ng g-1). La citrinine a egalement ete detectee apres 7-8 mois dans le foin (16,3-17,5 ng g-1) ainsi que l'apparition de traces d'autres toxines de stockage, y compris le penitrem A (8,84 ng g-1), la griseofulvine (34,8 ng g-1) et la sterigmatocystine (14,1-261 ng g-1). Cette etude de cas a ete une occasion unique d'utiliser la "science citoyenne" pour observer l'apparition des champignons post-recolte et des mycotoxines associees dans diverses conditions de stockage, ce qui a permis a l'agriculteur d'apporter les modifications necessaires avant que des problemes majeurs ne se posent. Une meilleure comprehension des conditions de stockage qui favorisent la croissance fongique et la production de mycotoxines dans cette exploitation agricole a permis d'ameliorer les pratiques agronomiques et, en fin de compte, la qualite des aliments pour animaux, la sante du betail et la rentabilite.