The situation is worse than that : monarch butterflies can be reared in controlled laboratory conditions from eggs to death , varying only exposure to bt maize pollen .
Dna testing of the animal is currently underway to determine its subspecies , which may offer clues to whether it had been poached from the wild or reared in captivity .
A 2006 study by researchers at the university of chicago 's department of the geophysical sciences found that intensively reared chicken generates 1.67g of " co2 equivalent " per kcal .
2006年芝加哥大学地球物理学院一项研究发现集中饲养的鸡每大卡产生1.67克“二氧化碳等价物”。
In order to meet this growing appetite , animals will no doubt be reared more intensively and cheaply with factory farming and aquaculture ( fish farming ) causing further pollution , water and land usage .
There is no evidence of any health dangers . In 2008 , following a five-year investigation , the us food and drug administration declared meat and milk from cloned cows and their offspring to be indistinguishable from that from traditionally reared livestock .
