Comparison of the bacterial community structure within the equine hindgut and faeces using Automated Ribosomal Intergenic Spacer Analysis (ARISA).

The study investigates the bacterial structures in the equine hindgut and faeces, comparing their similarities and differences. There is a focus on the validity of using faecal samples in understanding the hindgut bacterial ecosystem, and two DNA extraction methods are evaluated.

Study Aims and Methods

• The main goal of the study was to examine and compare the bacterial structures of the equine hindgut (caecum, right ventral colon) and faecal matter. This was done to determine the accuracy and validity of using faecal samples as a representation of the hindgut’s bacterial community.
• A specific fingerprinting technique called Automated Ribosomal Intergenic Spacer Analysis (ARISA) was applied to realize this comparison.
• The researchers evaluated two different DNA extraction techniques to further enrich their findings. These samples were taken from four adult fistulated horses, post their morning meal (approximately three hours after meal intake).
• The main elements of the equine diet consisted of meadow hay and pelleted concentrate.

Findings of the Study

• The Principal Component Analysis of ARISA profiles elucidated significant individual effects (P<0.0001) regardless of the intestinal segment in question. In other words, the bacterial community varied greatly between individual horses.
• Across the study, the structure of the bacterial community within the faecal matter was significantly different (P<0.001) from that of the caecum and colon. Importantly, the bacterial communities within the two hindgut regions did not show significant differences.
• The use of a QIAamp(®) DNA Stool Mini kit increased the quality of DNA extracted, irrespective of the type of sample.
• The observed differences between the faecal and hindgut bacterial ecosystems challenge the assumption that faecal samples can be used as accurate representations of the hindgut’s bacterial activity.

Conclusion and Future Directions

• The study defers the acceptability of using faecal samples as a valid representation for studying hindgut’s bacterial activity. It, therefore, challenges some common practices in equine bacterial researches.
• It’s appended that more research should be undertaken to compare bacterial activity in the hindgut and faeces. Such investigations would aid in understanding the validity and applicability of using faecal samples in such studies.