I remember this kind of thing from the 70’s…
Four calves have been found dead in a pasture just north of the New Mexico state line in recent weeks.
The dead calves had their skins peeled back and organs cleared from the rib cage. One calf had its tongue removed.
But rancher Manuel Sanchez has found no signs of human attackers, such as footprints or ATV tracks. And there are no signs of an animal attack by a coyote or mountain lion. Usually predators leave pools of blood or drag marks from carrying away the livestock.
Two officers from the Costilla County Sheriff’s Office have investigated the mutilations but say they don’t know what’s killing the calves.
I wonder if the Phantom Hitchhikers are back. I’m not a vegetarian, so I’m not going to get all PETA about this. I hope that no one tortured the animals. It’s a sure thing that something from this planet took them out. Any other planet an alien might have traveled from is very far away. So the unfortunate calves were probably done in by something mundane.
ALTERNATE EXPLANATION: They went out for a cup of coffee, and given the relativistic time-dilation effect their coffee break brought them back thirty years later, Earth time.
Kmareka.com 
The world is a strange and interesting place. However, aliens are more likely folks from other countries trying to get a piece of the action rather than beings from another world attempting to get a piece of a cow. Unfortunately, 4.5 billion-year-old planet Earth, so far as is known remains an “experiment” with a sample size of exactly 1; there is zero evidence for anything that passes for “alive” now or ever, anywhere we have looked, or listened or probed. Of course in a 13.5 billion-year-old universe, we are not even middle-age, and somewhere in the countless suns and planets, circumstances “just so” must have existed to get the breath of life into a non-living amalgam of this and that. But nothing that we have seen or noticed provides evidence, cattle mutilations or not. It may very well be the case that we are a lonely species and much better for us to take care of this world and each other for it may be all that we have or will ever know.