About 500 hogs have been culled on a pig farm in central Alberta where the herd was found to be infected with the new swine flu virus.

Authorities in Edmonton said the decision to kill the animals came after discussions between the producer and federal and Alberta officials.

They said it was the best course of action for the welfare of the herd and it eased overcrowding conditions on the farm.

The remaining herd of 1,700 pigs remains under quarantine. Health officials said because of the quarantine the producer was unable to ship hogs to market and, as a result, the farm had reached maximum capacity.

Herman Simons, chairman of Alberta Pork, said the cull cost the farmer $120 to $125 per pig at market value.

"Definitely it's been having a big impact on his [the farmer's] emotional state. Overall, though, we feel that he's fairly strong and holding up pretty good ...," Simons said.

"His first concern is the human health on this, his second concern is the industry and his third concern is the farm."

More people affected

Meanwhile, Alberta recorded four more human cases of swine flu Saturday, to bring the total of confirmed illnesses in the province to 46.

The Alberta Health website said two children and two adults have tested positive for the new H1N1 virus, but have experienced only mild symptoms.

The two children are a boy and a girl from the Calgary area. The two adults are women from the Edmonton area.

The girl had contact with a traveller to Mexico, but the boy did not, while the travel history of the two women is unknown.

The news comes one day after health officials in Alberta confirmed the death of a woman in the northern community of Gift Lake was associated with swine flu.

There are 281 confirmed human cases of swine flu in Canada.