The 53-year-old cleaner told police he did not fancy women and only cows and horses got him randy.
Getulino Ferreira Paraizo said he chose the more tranquil animals before engaging in sex acts with them.
But police say it is even more bizarre.
They accuse him of torturing the animals, sometimes ripping out their eyes before having sex with them and then killing them.
Among the clues he left behind at every scene were empty packages of the same cookies.
Police found another packet on him when they arrested him.
Paraizo, of Aragoiania, in central Brazil, told reporters he can’t have sex with women since sexual abuse as a teenager.
“I tried once but couldn’t do it. I only feel like it if it’s a cow or a horse.”
He added: “I need to stop doing this rubbish. I want treatment.”
Police chief Alvaro Cassio dos Santos said: “We estimate he killed around four hundred cows in the last four years.
“At first we thought it was part of some black magic ritual as neither the meat nor the skin were taken away.”
Paraizo could get up to five years in jail for material damages against local farmers.
And this: The octopus porn guy avoids jail!!!