lots of hits on Google

There are many hits on google for the term "grain crusher". It seems to come in many sizes and shapes, some manual others tractor-driven.

On a bilingual Dutch site (http://pv.wur.nl) with a bilingual search function, I found that "Rapport 120 "Korrelkneuzen bij de oogst van snijmaïs" was translated as "Effect of rolling forage maize at harvest". Citation from the English summary
"Quite often when forage maize is included in the ration the whole kernels are still detectable in the dung of the cattle. This is especially apparent with maize which has been allowed to ripen beyond the hard-dough stage. In order to avoid this, harvesting is often performed with an additional rolling mechanism attached to the chopper. This, according to several foreign researchers with differing degrees of succes. Some researchers suggest that as an indirect result of rolling (reduction in particle size) a reduction in digestibility of the cell-wall fraction is responsible for the varying results. "
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The term grain crusher has many hits on google and is actually what is meant by kneuzen = crush and not threshing. The grain at this point has already been removed from the stalk. It is often used to prepare grain for feeding to animals in particular cattle