11/10/2025
🐢Tortoise Gut Health Update - Collaboration with AnimalBiome
This summer, we sent in f***l samples from our sanctuary tortoises to AnimalBiome for microbial sequencing. They were so kind to do this sequencing at no cost to us! It took a while to collect all the samples, but I finally got it done and we now have results! I took some time to do the data analysis and have found some interesting trends!
🐢 Results
Tortoises with more fiber-fermenting bacteria overall tended to have higher growth rates— and this effect was even stronger when those fermenters were also diverse instead of dominated by a single type. The combination of abundance and diversity of fermenters seems especially important for herbivores.
A few microbes, like Staphylococcus or Sarcina, showed up more when the gut community was out of balance. These usually aren’t harmful on their own, but they may signal less efficient digestion. Others, like Sphaerochaeta, may play a helpful role by supporting fermentation and energy production.
🐢 What This Means for Care
1. Diet diversity matters
Tortoises benefit from a varied diet rich in high-fiber foods. A wide range of plants helps maintain a balanced community, so if one type of microbe dips, others can cover the same function. One tip to keepers - when you keep them outdoors, leave the grass and weeds as is! I notice people removing the native plants and adding wood chips etc. Leave the natural foliage and let them graze from a wide variety of plants without much effort on your part.
2. Gut imbalance isn’t disease
Finding microbes such as Staphylococcus or Sarcina doesn’t mean a tortoise is “sick.” Instead, it suggests the gut is less efficient and may improve with diet adjustments. This is helpful for me to know which tortoises scored low here so I can make a focused effort to monitor them as they may be more sensitive to environmental changes.
3. Fiber is important — and more is better
All tortoises, even omnivores, thrive on fibrous, plant-based diets. Both the amount and diversity of fiber-fermenting bacteria were linked to better growth in all tortoises. For me this was a good reminder that even redfoots and other omnivores should still be grazing for a good portion of their diet. Our redfoots definitely graze and sometimes I even see them turn a nose up to some other food types and go to graze instead.
🏆 “Microbiome Awards”
Best Fiber Fermenter Abundance -
Tex, Phil, Milo, Frankie, Eli
Best Fiber Fermenter Diversity / Efficiency -
Simone, Biggie, Gief, Phil, Milly
Honorable Mention — Highest SCFA Producer -
Noodle, Simone, Jake, Buggie, Hazel
👉 See the full table below to find where each tortoise’s gut microbes measured in these categories.
🐢Takeaway for Keepers
Offering variety and abundance of high-fiber foods may help improve gut diversity, support more efficient digestion, and keep tortoises thriving.
