Floor Design

The design of the floor can have a large impact on the odor generated from a swine building. Research in both the United States and Europe has indicated that solid concrete floors with scrapers or small flush gutters tend to increase the production of odor. Wet, manure covered surfaces emit more ammonia and other odorous compounds than slotted floors. The reason for this is that slotted floors in well ventilated facilities can be kept drier since liquids drain through to a manure pit or gutter. Many swine producers are aware of this and as a result most new swine facilities utilize either fully slatted or partially slatted floors.

Slotted floors can be used with the following types of manure collection systems: slats over a flush gutter, slats over hair-pin gutters, slats over pit-recharge gutters, or slats over a manure storage pit.

For all types of slotted floors the best strategy for maximum odor control is to exhaust a portion of the ventilation air through the pit or gutter. Pit annexes can be used to exhaust the minimum continous and the mild weather ventilation air through the slots in the floor. Such "pit ventilation" will insure that fresh air is available at animal level, and will keep the slats dry. The result is a better environment for the pigs and a reduction in odor emmissions. The following publications provide additional information on pit ventilation of swine buildings:

Swine Housing Handbook (MWPS-8), and

Mechanical Ventilating Systems for Livestock Housing

(MWPS-32, Midwest Plan Service, Iowa State University).

The value of a well ventilated facility using pit ventilation is best demonstrated by data taken from a barn that had a poor ventilation system and was retrofitted to provide pit ventilation for the minimum ventilation rate. Manure is stored in a concrete tank below the slotted floor for approximately eight months. The following table provides gas measurement data for the old and new ventilation systems during cold weather and at the minimum ventilation rate. The data shown in the table indicate that the air quality in the barn was greatly improved once the pit ventilation system was installed.

Effect of Improving Ventilation in a Slotted Floor Barn

Gas	Target Value	Old System	New Pit Ventilation System
Carbon Dioxide	3,000 ppm	5,000 ppm	2,500 ppm
Ammonia	15 ppm	25 ppm	15 ppm

On-farm data indicates that the ammonia concentration in swine finishing buildings is not a function of ventilation type, that is mechanical vs. natural. The most important factors are ventilation rate, and the quality of the waste removal system. The naturally ventilated building had lower ammonia due to higher ventilation rates as indicated by lower carbon dioxide concentrations. The pit ventilated barn was actually under ventilated during winter.

Air-Quality Measurements During Minimum Ventilation Conditions in Swine Finishing Buildings With Under-Barn Manure Storage

Building Type	Carbon Dioxide	Ammonia
Pit Ventilated, 1,000 Head	4,350 ppm	22 ppm
Naturally Ventilated, 1,000 Head	3,050 ppm	19 ppm

Return to Management of Odor and Sources Return to Odor Control Return to The Land Application of Animal Manure.