WASHINGTON (Reuters) -The U.S. government on Friday confirmed its second case of mad cow disease, prompting consumer groups to call for broader testing of cattle as the meat industry defended existing safeguards.

The U.S. Department of Agriculture said it was investigating the herd of the infected beef cow, which was described as at least 8 years old. Meat from the cow was not sold to consumers or as animal feed.

U.S. Agriculture Secretary Mike Johanns said the USDA would change some testing procedures, but defended current safeguards as more than adequate to protect consumers.

&#34The BSE threat to humans in this country is so remote that there”s a better chance you”ll get hurt crossing the street to get to the grocery store than by the beef you buy in the grocery store,&#34 Johanns said at a news conference.

The announcement came a week before the U.S. Independence Day celebration on July 4, where Americans traditionally barbecue hamburgers at a rate that makes it one of the year”s biggest days of beef consumption.

The first case of the disease 18 months ago prompted Japan and Korea to halt imports of billions of dollars of U.S. beef. Neither has yet resumed American purchases, but Johanns said he did not expect the new case to hurt negotiations.

Officials said the infected animal was born before a 1997 ban on recycling cattle remains into cattle rations. There was no evidence the infected animal was imported, said the USDA, which was doing DNA testing to confirm its herd of origin.

The previous U.S. confirmed case of mad cow disease, or bovine spongiform encephalopathy (BSE), was found in December 2003 in a Washington state dairy cow imported from Canada.

Officials said two confirmed infections was a tiny number considering the 30 million cattle slaughtered annually in the United States.

&#34The presence of the disease is extremely low in the United States. Our safeguards are working exactly as they should,&#34 Johanns said.

Ron DeHaven, head of the USDA”s Animal and Plant Health Inspection, said the infected animal was slaughtered at a pet food plant.

Neither official would identify the state where the cow came from. Published reports have said it was sent to slaughter last November in Texas, the nation”s biggest cattle state.

Mad cow disease is believed to be spread through infected livestock feed.

The second case of U.S. case of mad cow disease first surfaced on June 10, when it was revealed the animal had tested positive for the brain-wasting disease after initially returning inconclusive results. Laboratories in the UK and United States then conducted further tests.

Johanns acknowledged some missteps with the case, and said he directed USDA scientists to develop a new protocol to deal with &#34inconclusive&#34 screening tests for BSE. He said the USDA would also review how carcasses of suspect animals are segregated and stored while being tested. He said the infected animal”s remains were improperly stored with four other animals during the first round of testing.

After the first BSE case was found, the USDA expanded its testing to check more, but not all, sickly or &#34downer&#34 cattle.

Consumer groups and some lawmakers called for tougher feed rules and BSE testing on all high-risk cattle.

&#34We really feel they are continuing to drag their feet,&#34 said Jean Halloran of Consumers Union. She said the government pledged more than a year ago to widen the ban.

Cattle blood still can be used as a feed supplement, she said, and chicken litter and restaurant scraps — both of which could contain beef — can be used in cattle feed.

Bob Stallman, president of the American Farm Bureau Federation, said the fact that both cases were found in animals born before the 1997 feed ban &#34validates our scientific knowledge of BSE, including how to contain it and how to prevent it in the first place.&#34

He said the positive test &#34should not be used as an excuse for any nation to ban U.S. beef or stop progress on any trade negotiations.&#34

Taiwan recently said it would reinstate a ban on U.S. beef if a second case was confirmed. But a Japanese farm ministry official said on Friday that even if the United States confirmed a second case, the ministry would still take steps to resume some imports of U.S. beef.

USDA officials said the new BSE case was a different strain from the first U.S. case and the outbreak that occurred in Britain in the 1980s. Some experts had speculated the conflicting test results were due to an unusual type of BSE.

Live cattle futures closed lower in light volume at the Chicago Mercantile Exchange as the market awaited the outcome of the latest tests. One livestock trader said the positive result had been priced into the market.