I recall an example of putting round holes instead of horizontal slots in cattle trailers and how it reduces suffocation of the livestock! 
It's on EcoModder somewhere. I don't trust Google to find it though.
Speed holes
https://i.kinja-img.com/gawker-media...jzd2eihqoc.jpg
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.Without freedom of speech we wouldn't know who all the idiots are. -- anonymous poster
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.Three conspiracy theorists walk into a bar --You can't say that is a coincidence.
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