A Review on Rumen Anaerobic Fungi: Current Understanding on Carbohydrate Fermentation and Roughages Digestion in Ruminants

Anaerobic fungi have long been in the attention for their well-known potential in roughages degradation and ruminant nutrition. Although numerous studies have given new insights into anaerobic fungi in lignocellulosics digestion owing to their decisive fibrolytic activity, however, little is known about their role in carbohydrate fermentation. Furthermore, very limited information is available on the newly discovered genera of anaerobic rumen fungi, their mechanism of ruminal digestion, and their application as feed additives in ruminants. Therefore, this review aims to represent the current new understanding of various anaerobic fungal genera and their secretory fibrolytic enzymes, role in lignocellulosic digestion, volatile fatty acids (VFAs) formation and productivity in different ruminant species. This article further reviewed the use of superior anaerobic fungi like Neocallimastix sp., Orpinomyces sp., Piromyces sp. and Anaeromyces sp. as probiotic-feed additives and their role in improving digestibility, fermentation, VFAs production and productivity of ruminants. However, there is very less research focussed on the newly discovered anaerobic fungi and their fermentation profile. In addition, our review will lead to greater understanding of interactions between anaerobic rumen fungi and ruminal fermentation, which will help in devising a new, economical fungal based probiotic feeding system for better livestock productivity.