For the last 70 years, the penal code has avoided mention of bestiality, as the laws on animal cruelty were seen as adequate to cover such assault. Previous rules only prohibited sex with animals if it could be proved that the animal suffered mental or physical harm.
The move was backed by Rural Affairs Minister Eskil Erlandsson who has long been behind a push to make bestiality illegal in Sweden.
"There should be no doubt whatsoever that bestiality is unacceptable," he said in June.
Cattle farmer Gudmun Stenström told The Local he did not think the law would have any effect.
"I don't care either way, I don't see any bigger point to it, apart from someone trying to win some kind of political point," he said. "It doesn't help to punish someone like that."
About six years ago, Stenström thought his cows were being murdered at his farm in Slöinge, southern Sweden. From his house, he heard his cows stamping their feet and protesting in the barn. Worried, he made his way over to find a middle-aged man having intercourse with a calf.
"I had to joke with him, telling him the calves weren't sexually mature yet," Stenström told The Local.
While the man tried to flee, Stenström was hot on his heels, and managed to pin him down. Dragging him back to the barn, Stenström said he spent three hours teaching him about animal insemination and the difference between calves and heifers.
"Ninety percent of these people are sick, you need to get the psychologists in to have a proper chat with them," said Stenström, who pointed out that if the cows had been in heat, the attacker wouldn't have provoked such nervous frenzy among the animals. "They would have stood still."
He said that a colleague in Stockholm had encountered a much worse scenario, when he intercepted a man who had slashed the cows' genitals .
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"That person is cruel," Stenström said, adding that the case on his own farm was "not so bad" by comparison.
"Some of us like girls, others boys, some like cows."
Rural Affairs Minster Eskil Erlandsson came under fire in 2008 for his use of a graphic example to demonstrate that "what counts as sexual abuse of animals" isn't always easy to define, much to the surprise of fellow MPs.