National Air Emissions Monitoring Study (NAEMS) Finisher Hog Site NC3B: Observations of Farm Operation and Management.

The NAEMS provides a unique opportunity to continuously observe individual animal confined feeding operations over long periods of time. Information is presented on operation and management of a representative swine finisher farm in eastern North Carolina. Animal numbers in the three tested barns (880 capacity) being monitored ranged from ~750 to ~830 hogs/barn for each 20 week growth cycle, Death rates are low (< 2 head/barn/week). Growth rate vary within the population, with an initial grade out of 110 – 120 kg hogs at 16 wks (~185 hogs). A second grade out typically occurs between 17 – 19 wks, prior to final “runout” at 20 wks (~ 500 hogs). Four different feed formulations available on demand are used each cycle. Percent total nitrogen content of these formulations ranges from 2.2 to 3.5% N. The barns are tunnel-ventilated (3 122-cm dia. and 2 91-cm dia. fans), but also contain baffles above the side-curtain walls that work in combination with the endwall curtain to ensure a well-mixed and uniform environment for the hogs. Default duty cycle is 10 min. for the stage 1 fan (91-cm dia.), till overridden by the difference between internal and exterior temperatures. Waste generated by the hogs is handled through a shallow pit (~48 cm from animal floor to bottom of the pit). The pit is drained (pull-plug) once per week and then flushed and filled with liquid from the anaerobic lagoon. Sludge depth within the pit varies the length of the barn (2.5 to 12.5 cm) and undoubtedly with age, complicating attempts to quantify a nitrogen balance. TAN content and pH of pit liquid is consistently higher (~ 1800 mg TAN/L; pH 7.6) than that found in the primary lagoon. Presence of a surface crust on the pit liquid will complicate modeling the air-water exchange of gases.