The pigs chosen are a breed called Rongchang, named after an area in the southwest of the country and famed for their physique and for the quality of their meat.
http://news.bbc.co.uk/2/hi/asia-pacific/4690651.stm
http://www.kget.com/entertainment/wierd_news/story.aspx?content_id=E963D79B-90CA-490A-B78A-DFD4C90F3987

Some 40 grams of pig sperm will be taken on board the Shenzhou VI spacecraft
China became the third nation to send a human into space, after the United States and Russia, two years ago.