Effect of Temperature and Fermentation Time on Fermentation Characteristics and Biogenic Amine Formation of Oat Silage

Temperature is known to have a clear influence on the formation of biogenic amines during fermentation. To improve the quality of oat silage, the impact of ensiling temperature on the fermentation, microbiological and chemical characteristics, as well as biogenic amines (BAs) was investigated. Vacuum bag mini silos of oat forage were incubated at four different temperature levels (10, 20, 30 and 37 °C) and opened on day 0, 1, 3, 7, 15 and 60. All oat silages were sampled to evaluate the fermentation quality and biogenic amine production. Results showed that putrescine, cadaverine and tyramine were the most prevalent biogenic amines in oat silage, representing approximately about 90% of the total biogenic amines (TBAs) investigated. Ensiling increased the β–phenylethylamine, putrescine, cadaverine, histamine and tyramine accumulation in oat silage at the four incubation temperatures. On day 60, the β–phenylethylamine, cadaverine, histamine, tyramine and TBAs levels at a high temperature (37 °C) were significantly higher than those at a lower temperature (10, 20 and 30 °C); 10 °C fermentation increased the putrescine content in oat silage. A closed relationship between fermentation properties and BAs showed that the silages containing higher lactic acid, propionic acid and ammonia nitrogen and lower pH value had more BA content in oat silage. In conclusion, the ensiling process caused a significant increase in the amounts of BAs, except spermidine and spermine. The oat silage made in elevated temperature (30 and 37 °C) environments may accumulate more BAs than at a low temperature (10 °C), but low temperature (10 °C) fermentation may increase the putrescine levels in silage. The results suggested that ensiling at the proper temperature could retard BA formation and enhance the quality of oat silage.