New protein sources, fiber, and fat levels shift the gut microbiome, so mild soft stool early in a transition is a common adaptive response.
The standard approach is a seven-to-ten-day gradual mix starting at one quarter new food, stretched to two weeks for sensitive stomachs.
If softness persists beyond a few days, or you see watery stool, blood, vomiting, or lethargy, stop the transition and see a vet; that is not ordinary adaptation.
Logging the food, mixing ratio, and stool quality helps the vet assess; constantly jumping between foods also burdens the gut on its own.
