The point is, wood shavings DO break down slower than straw. There was NO evidence of straw in either pile. I have bought BOTH wheat straw and oat straw over the years. What happened was the spread out manure piles were affected by the weather and broke down quicker. When I created a mound, like horse-people suggest you do to heat up and kill worms and flies, it didn't weather and break down the wood shavings. BTW, I talk to a U of I Vet a few years back and he said that his father used to WINTER his Shires on oat straw, no hay!