Seventy-one-year-old nudist Hansi was shown using his finger to sexually stimulate his female birds on the final episode, broadcast on Monday night to 8.6million viewers.
He explained: “I do what the cockerel would usually do, only with my finger. It is like an orgasm for the chicken.”
The gruff farmer added: “Hansi is always happy when the chickens are happy.”
A Peta spokesperson told German newspaper Bild: “This behaviour is an offence and is not acceptable.”
The pressure group also lodged an official complaint.
Hansi – famed for walking around in nothing but his wellies – has become an unlikely TV hero in Germany.
He was looking for a new bride after his nudism caused first wife Elsa, 71, to leave him.
She said: “When I found out that he regularly went to nudist beaches, I divorced him.”
But an unrepentant Hansi claims: “My wife was such a prude. She wouldn’t do the gardening topless even once and she drank too much for my liking.
“So I just looked at the naked ladies on the beach instead!”
The Farmer Wants A Wife, based on an old British TV series, involved nine men looking for Mrs Right.
Unsurprisingly Hansi’s search was one of the five that failed – with his choice of lady, Marianne, walking off after seeing his chicken-pleasuring routine.
She raged: “You always hear jokes about what lonely farmers do to their animals.
“I am disgusted. This is not my world.”