Clearly, it's vampires. Or else aliens are doing it to study the cows. Maybe satanic cults are committing ritualistic sacrifices. No, wait: It's unseen monsters like El Chupacabra that are feasting on the livestock!
Well, something is happening, goddamn it.
In the 1970s, the ATF and even the FBI investigated the cattle-mutilation phenomenon. Their results? They found no evidence of anything other than natural causes and the occasional psychopath. No cult activity, no aliens, no monsters.
No missing sisters, no cigarette-smoking men, no hot redheads. Working in the FBI is surprisingly dull.
Natural causes that appear as surgical wounds? What about the removed organs? How is that possible? In most cases, scavengers such as foxes, buzzards and other critters that like beef au natural saunter by the decomposing corpse and have a bite or two -- thus the organ removal.
The surgical look comes later, when insects chew at the edges of the wounds. See, flies like soft foods, because flies don't have teeth. Same reason we go to Taco Bell: no standards and less work. And also much like Taco Bell, they prefer the softer parts of the animal: eyes, tongues, genitals, anuses and the rough edges of those aforementioned scavenger wounds. Also, if the animal's been lying around for long enough (or even short periods in the hot sun), it'll bloat and burst open, often with very clean, surgical-looking tears. And then come the maggots, which eat anything they can get their little teeth on.