Two cattle farmers in Nagaoka City in Niigata Prefecture bought rice hay for their cows from a seller in Miyagi Prefecture and fed their cows. 24 cows were later sold in Niigata and Tokyo. Now the rice hay has been found to contain 10,500 to 20,600 becquerels/kg of radioactive cesium.
Niigata Prefecture is on the Japan Sea side, and is most noted for its excellent premium rice brand, "Koshihikari".
Many Japanese thought Niigata was relatively safe from radioactive fallout from Fukushima I Nuclear Power Plant. Unfortunately there are more than one way to get the fallout, and buying rice hay from Miyagi (not even Fukushima) was one of them.
(Radioactive cesium of Fukushima-origin was indeed detected from the raw milk in Niigata.)
By the way, it turns out that the rice hay that cattle farmers in Tohoku fed their cows with was not due to the shortage or unavailability of other types of feed. Rice hay is an integral part of the cows' diet, as it nicely blend fat with the red meat ("Shimofuri") when ingested. So the cattle farmers feed their meat cows with rice hay before the cows are sent to be processed.
If that's the case, it looks like the bureaucrats in the Ministry of Agriculture, Forestry and Fisheries didn't know how the cattle farming was done, but the farmers must have assumed that these government bureaucrats knew what they were doing and issued orders to the farmers accordingly.
Government regulations crafted by the desk-bound bureaucrats serve to dull the keen sense of the farmers on the fields. For that matter, of anybody. The answer isn't "more regulations" (just look at the current sets of regulations have done so far) but sadly that's what people will be calling for.
From Jiji Tsushin (7/18/2011):
新潟県は18日、同県長岡市の畜産農家2戸が保管していた宮城県産稲わらから、国の暫定規制値（1キロ当たり300ベクレル）を超える1万500～2万 600ベクレルの放射性セシウムを検出したと発表した。乾燥する前の水分を含んだ状態に換算すると、規制値の8～15倍に相当する。うち1戸の農家からは 新潟県内と東京都のと畜場に肉牛計24頭が出荷されたことも分かった。これらの農家はいずれも宮城県内の業者から稲わらを購入したという。
Niigata Prefecture announced on July 18 that 10,500 to 20,600 becquerels/kg of radioactive cesium was detected from the rice hay at two cattle farms in Nagaoka City in Niigata. The rice hay was harvested in Miyagi Prefecture. The provisional safety limit for cattle feed is 300 becquerels/kg for cesium. If the rice hay is reconstituted with water, the above numbers are 8 to 15 times the limit of the provisional safety limit. It has been revealed that one of the two farms shipped 24 meat cows in Niigata and Tokyo. Both farms purchased the rice hay from a dealer in Miyagi Prefecture.
Niigata Prefecture has requested the two cattle farms not to ship or move the cows that have been fed with the contaminated rice hay, and started to trace the movement of the cows already shipped. The prefectural government will also test for cesium in the rice hay at other cattle farms in the prefecture who use the rice hay from Miyagi Prefecture.