Gervais was part of a chorus of anger after four of the animals were killed last month as part of matador training in Colmenar Viejo, Spain.
The comedian branded them “c*** academy” – but now they have doubled down on the practice.
Pupils at the bullfighting academy have now killed 24 of the creatures – believed to be under the age of two – in just four days.
Video captured by activists from Animal Guardians and La Tortura No Es Cultura (Torture Is Not Culture) show the bullfighters are clearly teenagers.
The bullring is almost empty, but children are among those watching, with one boy seen recording the slaughter on his tablet.
“If you choose to fight a bull, I hope it kills you”
Some of the younger children are later presented with ears carved from the dying animals as a gruesome trophy.
Marta Esteban of Animal Guardians said the exact ages of the would-be matadors could not be determined, but some youths start training at just 14.
She said: “They usually start killing animals from 14 years old onwards and they usually stay in bullfighting schools until they are 18, although some stay until they are 21.
“This event violates the right of children and adolescents to live in an environment free of violence and it is imperative that something be done about it.”
Gervais has previously openly condemned bullfighting, which is a considered a tradition in some parts of Spain.
He has given no sympathy when matadors get gored in the fights, and shared videos of the bulls coming out on top.
Last year, he tweeted: “How the fuck is this entertainment? Or art? Or Culture?
“If you choose to fight a bull, I hope it kills you.”
The calf-fights, known in Spanish as becerradas, are considered “practical classes” by the bullfighting schools.
Calves are often used when inexperienced matadors or untrained guests enter the bullring, because they are less of a danger to humans.
However, calves feel more keenly the agony of the swords and banderillas.
And those they face are less experienced and the blows are less likely to be fatal, prolonging the torture.
Now the activists are launching an international petition to ensure the calf-fights are banned from the country.
Carmen Ibarlucea, president of La Tortura No Es Cultura, said: “It is inconceivable that these acts of extreme violence towards sentient beings can be considered a form of entertainment.
“They are an atrocity and should be banned.
“We ask people to sign our petition and write to the city council of Colmenar Viejo asking for the end of these spectacles.”