Its actually small parasites similar to gnawing flies. There will be hundreds of them attracted to the dead animals and they eat the easiest parts first.they leave very clean chew lines. Much like some insect damage to leaves. Has been studied a lot but somehow media just never taketime to research that fact.
So why is it only cows? Why haven’t hunters come across any other dead animals with only their reproductive organs missing?
It’s not only cows, I’ve heard of similar with sheep and goats.
I suspect the reason hunters don’t come across similar among game animals is for several reasons, one, game animals live in the woods where the number of predators and scavengers is much higher and who would likely find and dispose of the carcass before the occasional hunter would.
Domestic animals are generally checked on on a regular basis by their owners, so are the more frequently found and cattle are the number one domestic farm animal, so the stories tend to be about cows.