"Wheat middlings" are a byproduct of the wheat milling process. It refers to the small particles, like crumbs or flakes, that are left behind when wheat is ground into flour. Full definition
Other example of moderately fermentable fiber include wheat middlings and brans form wheat, rice and corn. (musclebully.com)
The corn gluten meal, wheat gluten or wheat middlings added to pet foods are in reality, leftovers after the grain has been processed for human use, containing no real nutritional value. (thewholedog.com)
At the lowest end, they can be floor sweepings, though there are better quality wheat middlings. (dogfoodinsider.com)