Manure removal and management with modern pig production facilities is accomplished with various arrangements of slotted floor made of wire mesh, concrete slats, or expanded metal. The floor may be totally or partially slotted.
In the partial slotted arrangement, the pens are about one-half concrete floor and one-half slotted.
Sectional drawing of a partially-slotted floor pig house. 
Feeders and waterers are usually in the solid floor area, which slopes toward the slotted portion.
The manure falls through and is flushed through the slotted floor to a concrete pit area beneath. However, the supports along the margins of the slotted floor have no openings, and provide an area for manure accumulation and fly breeding.
The concrete pit is relatively shallow if it is frequently flushed to an outside holding pond.
An alternative is to use a deep pit beneath the slotted floor, to allow long-term storage of the manure slurry. Periodically, slurry is pumped out or allowed to flow by gravity, either to a lagoon or into a spreader for distribution on cropland.
The manure pit needs to be well ventilated (usually plenum and fans) to reduce odors and prevent the accumulation of gases which are detrimental to the swine and corrode equipment.
The trend to larger pig production units and the use of specialized high-density confinement facilities has increased the problem of manure management and fly control.
Pockets of manure may accumulate along the edges of pens and may not be forced through the slotted floors.
Flushing out the manure beneath the slotted floor requires large volumes of water, and manure removal may not be complete.
If there is insufficient water in the deep pit, crusts and piles of partially dry manure may develop, which allow fly breeding.
Flushing manure into an anaerobic lagoon is a common method which is also used for dairy and poultry manure disposal. If the lagoon is too small, islands of solids will accumulate and provide a habitat for fly breeding.
In mild climates, partially slotted floors and manure flushing systems are also used in less sophisticated partially open-front buildings with curtain sides.
In simpler open-front buildings with outside pens, floors and pens are solid, and manure is either flushed out with hoses, or removed with scrapers.
In both of these housing systems there are many areas along the pen walls, beneath railings and fences, and in corners where manure can accumulate and provide a habitat for fly breeding.
