BEIJING (Reuters) - Chinese animal feed maker Tangrenshen Group said on Tuesday that tests on feed made by one of its units had ruled out the presence of the deadly African swine fever.

The company said on Sunday that authorities in eastern Anhui province had reported finding what they suspected was African swine fever in feed made by its 51 percent-owned subsidiary, Bili Meiyingwei Nutrition Feedstuff.

In a statement to the Shenzhen Stock Exchange, Tangrenshen said authorities had notified its subsidiary on Monday afternoon that their tests had failed to confirm the presence of the deadly disease in any of the raw material or finished product samples collected last week.

The company said it had resumed normal operations on Tuesday and was working to eliminate the negative impact on its operations.

Tangrenshen’s shares closed up 2.27 percent on Tuesday at 4.95 yuan ($0.7117) a share.

China has struggled to stem the rapid spread of African swine fever, which has now reached most of the country’s pig-farming regions. The disease cannot be cured and has no vaccine, posing a major threat to the world’s top pork producer.

Beijing earlier said many of the cases were caused by feeding kitchen waste to pigs that was not properly processed to kill the virus. However, feed supplies can also become contaminated with the virus, where it can survive for weeks.