An anaerobic fungal survey of equines was performed (i), with faecal samples collected from over 70 equines and analysed using methodology that was developed and validated within the project. Animals sampled included domesticated equines (horses, ponies, donkeys, mules and hinnies) as well as zebras kept under managed conditions. Anaerobic fungi were detected in all animals, but their faecal concentrations were approx. six-fold higher in donkeys compared to horses/ponies and zebras, with mules/hinnies being intermediate of the parent equine types (i.e. donkeys and horses/ponies). No anaerobic fungal taxon was found that was common to all equines, with Caecomyces being predominant in donkeys and mules/hinnies and an uncultivated anaerobic fungal genus AL1 that was found to be predominant in horses/ponies and zebras.
As the diet of the animals was not controlled in the survey, a study was performed where faecal microbiota was collected from ponies, donkeys and mules/hinnies after four weeks of being fed the same diet (ii). In contrast to the previous findings, anaerobic fungal concentrations were not affected by equine type, and Caecomyces was predominant in all the animals. However, the uncultivated genus SK3 was present only in donkeys, and anaerobic fungal diversity was also highest in donkeys. This is consistent with previous reports that dietary fibre degradation in donkeys was more complete compared to that of horses/ponies.
Due to the different findings of the two studies regarding anaerobic fungal concentrations, a third study was conducted where the effect of seasonal differences in diet on faecal anaerobic fungal concentrations was assessed (iii). Faecal samples were collected from a group of donkeys that were sampled during summer (pasture/straw) and winter (haylage/straw) periods over two consecutive years. Interestingly, anaerobic fungal concentrations differed between both years for the summer diet, but not for the winter diet, warranting further analysis as well as more extensive and longer surveys in the future. Determination of the forage consumed by the animals, using an alkane marker technique, is currently in progress, which will provide additional insight into the findings.
Faecal samples have been widely used in the project, however, how representative they are of anaerobic fungal community composition along the hindgut is not known. A collaborative study found large differences in both anaerobic fungal community composition and concentrations along the hindgut of a horse (iv). Following up on this, an in vitro study was performed using horse gut content collected from three different hindgut sites in order to assess anaerobic fungal fermentation of forage along the equine hindgut. An antimicrobial treatment was used to enrich anaerobic fungi from each of the three sites. Independent of gut site, the enrichments resulted in an increased proportion of acetate (the major fermentation end product of anaerobic fungi) compared to the untreated controls. This suggests that the treatment was effective at enriching equine anaerobic fungi, and indicated that anaerobic fungi can make a significant contribution to hindgut fermentation of plant material.
Three manuscripts have been submitted for peer-review (i & ii), with two other papers planned after data analyses have been finalized (iii & iv). As a result of collaborative activities, two papers have also been published and a further two are planned. Study findings and a congress paper on equine anaerobic fungi have been presented at three international equine congresses, where delegates included equine professionals as well as researchers. Outreach activities have also brought anaerobic fungal information to the general public via a microbial exhibit at the Artis Micropia museum in Amsterdam (NL) and three anaerobic fungal videos and a project video that were shared on YouTube and other social media. Information about the project activities and outputs have also been regularly disseminated via the project website. No exploitation activities were conducted within the duration of the project.
