By comparison, Canada was able to move from a voluntary to a mandatory animal identification and traceback system within a year. The US should move to implement the system in the same time period says the Center for Science in the Public Interest (CSPI), a US food advocacy group. "While the USDA's announcement of a new proposal on animal identification and traceback systems represents an important food safety improvement, the timeline for implementation is another Bush-administration bow to the cattle producers," said CSPI food safety director Caroline Smith DeWaal. "Delaying until 2009 this essential food and animal health protection means the US is lagging even further behind many of our trading partners on food safety issues." The USDA proposals would require ranchers to identify the premises and animals according to standards set by the tracking programme in January 2008. The USDA also proposes requiring the full recording of animal movements by January 2009. The proposed national animal identification system (NAIS) would require tagging to identify specific animals in the US and record their movement over their lifespans. It would also allow regulators to trace an animal's movement over a 48-hour period it eventually became sick or exposed to a sick animal. In response to the CSPI's attack USDA spokeswoman Amy Spillman said the US had a much larger and more complex livestock market than Canada. The proposed mandatory tagging and traceback system would also cover all livestock in the US, not just cattle but also sheep, swine and poultry, making it more difficult to implement. "We want to get it right," she said. "That is why we need more time. I disagree with the CSPI's statement." The USDA is also looking at implementing a radio-frequency tagging system for cattle. Canada's tagging system initially used a barcode to identify individual cattle but that country is now shifting to using radio frequency identification. Canada began implementing its identification system after the detection of Bovine spongiform encephalopathy (BSE) or mad cow disease was discovered in an Alberta heifer in May 2003. Two other cases were subsequently discovered. The US and other countries then closed their borders to Canadian beef. Two other cases of BSE were subsequently found in Canada this year. One case of BSE was discovered in the US in Washington state in December 2003. Top markets for US beef (accounting for over 90 per cent of total beef exports) Vol: millions of lbs. carcass weight. Val: $m 2002 2003 2004 Volume Value Volume Value Volume Value Japan 771 843 920 1,167 12 0.6 Mexico 629 596 589 604 334 372 South Korea 597 610 588 749 1 0.4 Canada 241 286 226 321 56 94 Several countries also banned US beef imports as they previously did Canadian imports. While some have relaxed restrictions, Japan, the largest foreign market for US beef, has not. Scientists believe eating the BSE infected beef is the cause of the human variant, Creutzfeldt-Jakob disease, a fatal brain disorder that led to the death of about 150 people, mostly in the UK in the 1990s. This month the US agriculture secretary, Mike Johanns, unveiled the proposals on the national animal identification system and opened them to comments from the industry and interested parties. A study released in April by the Kansas Agriculture Department estimates the industry lost up to $4.7 billion last year because of the mad cow case in Washington.