Click on the title to link to the original scientific article describing how they found many antimicrobial compounds secreted by frog’s skin.
This study was inspired by the old practice of Russians in putting frogs in their milk to keep it fresh!
The ancestral art of keeping milk fresh had a clever, simple solution for Russians; put a russian brown frog, aka the common frog (Rana temporaria) in it! This frog (which ranges across Europe and has many congeners across temperate areas such as the US) secretes a battery of antimicrobial compounds, preventing the milk from bacterial or fungal growth and souring.
I doubt it affected the milk flavor much if at all. I don’t think it’s disgusting; what sure is gross though is tasting or smelling rotten milk!
The only other way known to keep milk fresh without refrigeration (also accomplished of old by constructing chambers to trap cold air from springs or cold creeks), is to let the microbes take over and grow cheese or yogurt!
Note there is a frog in the tropics called “milk frog,” but since its name comes from the toxic milky secretions it exudes from its skin, it may not be a good choice as a milk preservative!