Japanese self-sufficiency rate of feeding-stuff is 25% (as of 2009) and that of concentrate diet is 11%, so Japan imports a lot of cereal crops for feeding-stuff of barn animals.

There are two types of feeding-stuffs of barn animals, one is coarse feed and the other is concentrate diet. Coarse feed is the feeding-stuff for the main energy contains lots of string like fresh forage, hay, and straw.
On the other hand, concentrate diet means diet contains a lot of protein like corns, and Japan relys on import most of this concentrate diet.

Among the world agricultural produce trading, Japan imports the 1st ranking of corns, the 3rd ranking of barley, the 4th ranking of soy beans and common wheat.

And in the amount of domestic consumption including imported cereal crops and home grown cereal crops, for animal consumption is more than edible use.
So, we feed our burned animals cereal crops more than eat directly.

But there are some countries where people eat corns as main dishes in the world.And they are poor developing countries.
The amount of cereal produce in the world is limited, so if developed countries buy up cereal crops for their barn animals, poor countries cannot buy.

The mass imports of cereal crops of Japan cause not only downing self-sufficiency rate of Japan, but also suffering people in developing countries.