National Air Emissions Monitoring Study (NAEMS) Sow Site NC4B:Observations of Farm Operation and Management

Jihoon Kang1*, Wayne P. Robarge1Sang R. Lee1, Albert Heber2, Erin Cortus3, Lilong Chai2, Kaiyang Wang4 and Jiqin Ni2

The NAEMS provides a unique opportunity to continuously observe individual animal confined feeding operations over long periods. Information is presented on the operation and management of a representative sow gestation and farrowing farm (~ 2500 hogs permitted capacity) in eastern North Carolina. Approximately 2200 pigs are on site in three barns: breeding/gestation (~900), gestation (~900), and farrowing (~320; 16 rooms; 20 sows/room). Sows weigh ~140 to 230 kg and farrow an average of 10 - 13 piglets/sow. Piglets grow to 6.4 kg from a birth weight of 1.2 kg in 21 days; 700 to 900 piglets are shipped weekly. A single feed formulation (~ 2.2% N) is provided once daily to pregnant sows. Lactating sows are fed a 3.3% N diet 4x daily. All three barns are force ventilated. Default duty cycle is 10 min. for stage 1 fans, till overridden by the difference between internal and exterior temperature. As internal temperatures increase, various combinations of fans turn on and off changing the total volume of air exiting the barns. Air is pulled into the farrowing rooms via controlled baffles distributed along the sidewalls (2 46-cm and 1 61-cm variable-speed fans). The breeding/gestation barn uses end wall exhaust fans (122-cm dia., 12 total) that draw air through evaporative cooling pads in the center. The gestation barn uses conventional tunnel-ventilation (8 122-cm dia. fans) with adjustable end wall curtain. The breeding/gestation and gestation barns do not have side baffles, but during the “winter” ventilation configuration, the sidewalls are dropped to allow a 1-inch gap for entry of additional fresh air along the length of the barns. Waste is handled through shallow pits (3 pits per breeding and gestation barns, 2 per farrowing room; ~48 cm from animal floor to bottom of the pit). The pit is drained (pull-plug) every 7 – 10 days, then flushed and filled with liquid from the anaerobic lagoon. Pit sludge depth varies along the length of the barn and undoubtedly with age. Presence of sludge in the pits over half the length of the breeding and gestation barns represents a potential source of ammonia and hydrogen sulfide emissions in excess of that from fresh urine and fecal matter and weekly renewal of lagoon liquid. The supplemental information gathered by the NAEMS project will facilitate the development of process-based models to describe gaseous emissions from animal confined feeding operations.

* Jihoon Kang: ; 919-513-3841
1 North Carolina State University, Department of Soil Science, Raleigh, NC 27695-7619
2 Purdue University, Agricultural and Biological Engineering, West Lafayette, IN 47907
3 South Dakota State University, Ag. and Biosystems Engineering, Brookings, SD 57706
4 Zhejiang University, Ag. Bio-Environment Engineering Inst., Hangzhou, P.R. China