Kenyans don't usually have a big problem with regurging.
I have notice very good feeders do it if they take a meal and then go into shed or if you feed a gravid female too large a meal. In my experience though, temperature either too high or too low( more often with too low)is almost always the bigger cause. Put one back on aspen for a week or two and test feed that one.
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Steve Perry
North Idaho.