Impact of Storage Conditions on Equine Fecal Inoculum for Estimating In Vitro Digestibility.
Authors: O'Donnell Delaney, Sukovaty Lacy, Webb Gary
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary: Fecal Storage Conditions and In Vitro Digestibility Testing Accurate in vitro digestibility measurements depend on viable microbial populations in fecal inocula, yet equine practitioners and nutritionists rarely have guidance on how storage conditions affect these microbial communities before laboratory analysis. O'Donnell Delaney and colleagues investigated whether fecal samples could be stored under non-ideal conditions without compromising the reliability of dry matter digestibility (DMD), neutral detergent fibre digestibility (NDFD), and acid detergent fibre digestibility (ADFD) estimates across six different forage types. Using pooled faecal material from three Quarter Horse geldings, they compared anaerobic storage at 39°C for 15 minutes (the standard control) against three alternative conditions: aerobic storage at room temperature (22°C) for 6 hours, refrigerated aerobic storage at 3°C for 6 hours, and frozen storage at −18°C for 24 hours. Whilst significant interactions emerged between forage type and storage condition, the aerobic room-temperature sample (SC1) performed identically to the control across all digestibility parameters, whereas refrigeration reduced DMD estimates by 3.86% and freezing by 4.08%. For practitioners collecting faecal samples for digestibility testing, this research suggests that samples can tolerate brief delays at ambient temperature without affecting results, but refrigeration or freezing introduces measurable underestimation of digestibility—a consideration particularly important when coordinating multi-site trials or managing sample logistics in field settings.
Read the full abstract on PubMed
Practical Takeaways
- •If using equine fecal inoculum for in vitro digestibility testing, samples can be stored aerobically at room temperature (22°C) for up to 6 hours without compromising microbial viability or digestibility estimates
- •Cold storage at 3°C or freezing at -18°C should be avoided as both reduce dry matter digestibility estimates by approximately 4%, potentially affecting forage quality assessments
- •Fresh or room-temperature-stored fecal inoculum is preferable for accurate in vitro digestibility trials in equine nutrition research
Key Findings
- •Fecal material stored aerobically at 22°C for 6 hours produced digestibility estimates similar to fresh anaerobic control samples (p > 0.8)
- •Storage at 3°C for 6 hours decreased dry matter digestibility by 3.86% compared to control
- •Storage at -18°C for 24 hours decreased dry matter digestibility by 4.08% compared to control
- •Significant interactions existed between forage type and storage condition for digestibility measurements (p < 0.05)