Diet Modification to Reduce Odors, Gas Emissions and Nutrient Excretions from Swine Operations

Can Changing Pig Diets Reduce Odor Emissions?

The pork industry has undergone a rapid change in the past two decades, with a decrease in farm numbers and an increase in farm size. These changes magnify the stress of the compatibility of pork production with neighbors in rural America. Concerns of the potential impact of the swine operation on water and air quality and health are also raised due to numerous compounds often produced from anaerobic degradation of animal manures, such as, sulfurous compounds, volatile fatty acids (VFAs), and ammonia (NH3). Since the pig is the point source of excreted nutrients resulting in gas and odor emissions, diet modification has the potential to reduce nutrient output and improve air quality.

Our hypothesis is that by utilizing a low nutrient excretion diet formulation and an alternative manure management strategy, the amount of nutrient output and gas/odor emissions will be reduced over the wean-finish period.


A total of 1, 920 pigs (initial BW = 5.29 kg) were used in a 2 x 2 factorial, wean-finish experiment to determine the effects of diet (control, CTL vs. low nutrient excretion, LNE) and manure management (6 mo. deep-pit, DP vs. monthly pull plug-recharge, PP) on growth performance, nutrient output, and air quality. Pigs were housed in a 12-room environmental building.

Pigs were split-sex and phase-fed to meet or exceed their nutrient requirements (NRC, 1998) at different stages of growth. The CTL and LNE diets were corn-soybean meal based and formulated to an equal Lysine:calorie. The LNE diet formulation had reduced CP and P, increased synthetic amino acids, phytase, non-sulfur trace mineral premix and added fat. Improvements in pig performance were observed over the wean-finish period.

Did Lysine Affect Performance or Odorous Emissions?

Pigs fed the LNE diets were 4.3 kg heavier (131.2 vs. 126.9 kg) at market, gain was increased by 0.03 kg/d (0.83 vs. 0.80 kg/d), feed intake was reduced by 0.16 kg/d (1.95 vs. 2.11 kg/d), and overall feed efficiency was increased by 11.6% (0.43 vs. 0.38) compared to CTL fed pigs (P<0.01). In addition, manure generation was reduced by 0.39 L/pig/d when the LNE diets were fed vs. the CTL diets (4.05 vs. 4.44 L/pig/d, P<0.008).

Excretion of total N, P, and K was reduced (P<0.001) by 27.5, 42.5, and 20.4%, respectively, from LNE fed pigs. Pigs fed the LNE diets had a 25.5, 23.8, 32.3, 18.5, 35.8, and 26.7% reduction (P<0.05) in manure acetate, iso-butyrate, iso-valerate, valerate, and total VFA production, respectively, compared to CTL fed pigs. Using the PP manure strategy reduced manure ammonium N and VFA production by 10.3 % (16.5 vs. 18.4 g/pig/d; P<0.002) and 20.5% (26.0 vs. 32.7 mM/pig/d; P<0.001), respectively, compared to DP strategy. Pigs fed LNE diets had a 13.6% (P<0.001) reduction in aerial NH3 emissions over the wean-finish period compared to pigs fed CTL diets. Aerial H2S and SO2 emissions and odor were not different (P>0.10) between dietary treatments.

Why is This Important?

Feeding LNE diet formulations are effective in reducing environmental impacts of pork production while maintaining growth performance. In addition, utilizing a monthly pull plug-recharge manure management strategy can improve air quality parameters, however can be more labor intensive.

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By Scott Radcliffe, Brian Richert, Danielle Sholly, Ken Foster, Brandon Hollas, Teng Lim, Jiqin Ni, Al Heber, Alan Sutton – Purdue University

This report was prepared for the 2008 annual meeting of the regional research committee, S-1032 “Animal Manure and Waste Utilization, Treatment and Nuisance Avoidance for a Sustainable Agriculture”. This report is not peer-reviewed and the author has sole responsibility for the content.