TOKYO (Asahi News Service) - The nation's two reported cases of mad cow disease could have resulted from possible contamination of cattle feed from a mill in Hokkaido, feed producers acknowledge. Processing facilities the plant uses to produce cattle feed are also used to make animal feeds containing meat and bone meal (MBM), they said.

The plant in June began to clear its four conveyor lines by running corn and soybean residue along the belts before using them to make cattle feed.

Before the procedure was changed, however, the belts were simply run empty for several minutes before starting a batch of cattle feed.

At that time, MBM, made of ground bone and scrap, was a typical additive in hog and chicken feed.

The nation's two cases of bovine spongiform encephalopathy (BSE), in September and earlier this month, were fed cattle feed from the plant, run by Hokuren, an agricultural cooperative that covers Hokkaido.

The sources say that since there were at that time no special precautions about mixing MBM into cattle feed, abnormal prions-the elements that can cause mad cow disease-could have contaminated the line, and might have tainted the feed later given to the two cows.

The Ministry of Agriculture, Forestry and Fisheries issued instructions in June to separate feed production lines for cattle feed and feed for hogs, chickens and other livestock.

If the lines could not be separated, the ministry said equipment should be cleared with crop residue, such as soybeans, which would absorb leftover abnormal prions.

Hokuren sources were not certain there was never any MBM contamination of cattle feed, since at the time, such contamination was not a major concern, and the meal they used came from Zenno, the national federation of agricultural cooperative associations. They said they felt the MBM they received was safe, because it was made from Hokkaido-bred cattle.

Agricultural officials said Nov. 26 that 219 head of cattle have been shipped from a farm in Sarufutsu, northern Hokkaido, where the second BSE case was reported, since April 1995, a year before the infected cow was born. Of the total, 185 were shipped to other Hokkaido farms, and 34 were sent elsewhere.

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