From what I understand, this mushroom practice was stopped in the mines because there were too many risks of mushroom poisoning, and even more so when they are wild because they absorbed the remains of the materials from said mines
How does fluffies learn the difference between edible and poisonous mushrooms?
Does fluffies learn from older and more experienced members of their herds or is knowledge gained from dangerous games of trial and error?
I can see how herds with a discriminatory attitude to bad colours would use poopy babies as food testers to find out whether a newly encountered strain of fungi is fit for consumption or not.
In theory it would be a good idea, but mushroom poisoning in most cases is slower and is something that is commonly confused with a stomach ache. A classic mistake is to think that all white mushrooms are edible xD
Imo fluffies have good sense of smell. Its what makes domestics super picky about kibble, foal formula, ect and cry like little bitches when runaways have to eat garbage.
In a recent story I had a fluffy find and dig up a truffle it found because I figured fluffies probably have pig DNA.