Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/20/2007
Publication Date: 8/1/2007
Citation: Powers, W.J., Zamzow, S.B., Kerr, B.J. 2007. Reduced Crude Protein Effects on Aerial Emissions from Swine. Applied Engineering in Agriculture. 23(4):539-546. Interpretive Summary: Animal production is becoming more concentrated and air emissions of potentially harmful compounds (e.g., ammonia and hydrogen sulfide) are under increased scrutiny due to human health and environmental implications. Although diet modification to reduce nitrogen inputs into the animal by reducing dietary crude protein without negatively impacting performance is a proven method of reducing nitrogen excretion, there has been limited research conducted that directly measures emissions following diet modification. This research demonstrated that rates of ammonia emissions can be dramatically reduced, as pigs fed the control, moderate dietary crude protein, and low crude protein diets corresponded to a daily ammonia emission of 88.0, 68.9, and 46.0 mg per kg BW, respectively. No dietary effects were observed for hydrogen sulfide. This information is important for scientists at regulatory agencies, universities, feed companies, and swine production facilities showing that feeding pigs a reduced crude protein, amino acid supplemented diet can be used to dramatically reduce ammonia emissions.
Technical Abstract: The effect of feeding reduced crude protein (CP) diets on air emissions was evaluated using barrows fed over the course of four feeding phases: grower-1 (beginning at 24.5 kg BW), grower-2 (55.3 kg), finisher-1 (87.2 kg), and finisher-2 (111.4 kg). Pigs were offered a control diet (C), a low CP diet (LCP) or an ultra low CP diet (ULCP). Both the LCP and ULCP diets were supplemented with synthetic amino acids to avoid performance loss. Analyzed CP of grower-1 was 22.1%, 18.8%, and 17.2% for the C, LCP, and ULCP diets, respectively. Dietary treatment had no effect on pig performance (P < 0.05). Ammonia concentrations were reduced 24% (2.93 ppm) in the ULCP diets compared to the LCP diet and 36% compared to the C diet. Pigs fed the LCP diet produced exhaust ammonia concentrations 16% less than pigs fed the C diet (3.86 vs. 4.57 ppm). Rates of ammonia emissions for the C, LCP, and ULCP diet, corresponded to a daily mass of ammonia emitted of 88.0, 68.9, and 46.0 mg per kg BW, respectively. Feeding phase effects were observed for ammonia concentration, ammonia emission rate, daily mass emitted and daily mass per unit BW, hydrogen sulfide concentration, and daily emitted mass of hydrogen sulfide. No diet effects were observed for hydrogen sulfide. Diet had no effect on mass of manure produced; however total-N and ammonia-N concentration decreased with decreasing diet CP (79, 67, 57 g kg-1 and 54, 44, and 35 g per kg, respectively, for C, LCP and ULCP diets).