The US Department of Agriculture said Saturday that tests have so far detected no new case of mad cow disease in the same herd where a home-grown case of infection had been found.

The department said 29 cows from the herd tested negative for mad cow disease, and it is still waiting for the results of the remaining 38 cows removed from the same herd for testing. The National Veterinary Service Laboratory in Ames, Iowa, is conducting the tests.

The focus of examination is on the offspring of the infected beef cow and the cows born within a year of the infected cow's birth. The infected Texas State cow is the second case of mad cow disease so far confirmed in the United States. The first case was reported in December 2003 in a Washington State diary cow imported from Canada.

The infected beef cow was slaughtered last November in a pet food plant in Waco, Texas. It did not enter feed or food chain, the Agriculture Department said.

The second US case of mad cow disease was announced on June 24 after being confirmed by tests at an internationally recognized laboratory in England. Previous US tests produced conflicting results, prompting the verification.

Source: Xinhua