Cow-calf and feedlot operations usually use silage as part of the animal feed.
Silage (chopped corn) is stored in either tower silos (which may be gastight or stave types), or in horizontal trenches or bunkers.
Horizontal storage bunkers may be concrete-lined, but are often just trenches in the ground. The silage is packed and covered with plastic sheeting.
The margins of improperly packed and covered silage provide conditions favorable for fly breeding in horizontal storage systems.
Spillage around the base of tower storage facilities likewise provides a habitat for fly breeding.
Sometimes the silage is piled above ground without proper compacting and covering to suppress fly breeding.
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