Why Would Aliens Want Our Cattle?

"Predators don't drink 11 pounds of blood and leave the carcasses intact." says a cattleman about the latest round cattle mutalations on his ranch. This has been going on for decades in and around the south and western United States. Dead cattle appear in fields , drained of blood and their reproductive organs, eyes and ears removed with surgical precision. Don't believe it is aliens? Fine. Take a look at the photos and then you figure it out. Who would do this and why?