Why US states fear ‘Super Pigs’ could invade them?

Experts said there is an increasing number of ‘super pigs’ invading (入侵) the northern states of the United States. These pigs are difficult to be removed. The problems date back to the 1980s when farmers were encouraged to raise (飼養) wild boars in Canada. However, when the market collapsed (崩潰) in 2001, some farmers simply set the animals free. These super pigs are often cross-breeds (雜交繁殖). They ...Read More