Nitsch is one of Vienna's famed "Actionists", a radical 1960s avant-garde movement whose members are known for skinning animal carcasses, tying up human bodies and using blood, mud and urine in their works.
The 76-year-old is best known for his long-running Orgies Mysteries Theatre, a performance-based show representing slaughters and religious sacrifices.
The latest edition of the exhibition, which opened in the city of Palermo in Sicily last Friday, sparked outrage among animal rights groups who accused Nitsch of blasphemy and inciting violence.
The exhibition was a "shame" for Palermo and in violation of the 1978 UN Declaration of Animal Rights, said Italian activist Antonio Leto who filed the complaint.
An online petition started by Leto has so far collected 70,000 signatures asking for the show to be shut down ahead of its official closing date on July 20th.
But Nitsch's wife rejected the protests as "blown out of proportion".
"I have been married to my husband for 30 years now and I can tell you that this kind of small ruckus is always part of (his work)," Rita Nitsch told AFP.
"But quality has triumphed over the polemic. The show is a huge success and it annoys me when the media pick up this sort of thing instead of focusing on all the positive reviews we have received."
Palermo mayor Leoluca Orlando who attended last week's launch has also endorsed the show.
Nitsch has at least three museums devoted to his work in Austria and in Italy.