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

Animal Manure Management September 29, 2015 Print Friendly and PDF

Reprinted, with permission, from the proceedings of: Mitigating Air Emissions From Animal Feeding Operations Conference.

This Technology is Applicable To:

Species: Swine
Use Area: Manure Storage
Technology Category: Diet Manipulation
Air Mitigated Pollutants: Ammonia, Hydrogen Sulfide, Volatile Fatty Acids, Volatile Organic Acids, Odor

System Summary

Odor and gas emissions from pork operations primarily come from the anaerobic degradation of manure. Since the pig is the initial point source of nutrients excreted and resultant gas and odor emissions, diet modification has the potential to reduce nutrients excreted and thereby reduce gas and odor emissions.

A wean-finish pig study was conducted to determine the effect of feeding a low nutrient excretion (LNE) diet on nutrient excretion, gas and odor emissions. Overall, pigs fed the LNE diet grew faster while consuming less feed and a better overall feed efficiency compared to control (CTL)-fed pigs. Carcass weights were heavier for LNE-fed pigs compared to CTL-fed pigs. Daily excretion of dry matter, nitrogen (N), ammonium N, phosphorus (P), potassium (K), ash, and volatile fatty acids were greater for CTL-fed pigs compared to LNE-fed pigs and linearly increased over time. Pigs fed LNE diets consistently excreted 26-28% less ammonium N, 40% less P and 17-18% less K for LNE-fed pigs compared to CTL-fed pigs. Pigs fed LNE diets reduced aerial NH3 emissions over the wean-finish period by 13.6% compared to pigs fed CTL diets. Aerial H2S and SO2 emissions and odors were not different among dietary treatments. Aerial NH3, H2S, and CH4 concentrations were increased by 43.4, 68.3, and 29.0%, respectively, from wk 4 to wk 16. Conversely, the concentration of CO2 was reduced by 13.6% during wk 20 compared to wk 4.

Applicability and Mitigating Mechanism

  • Increasing available nutrients and reducing excess nutrients in pig diets have the potential to reduce nutrient excretion and gas and odor emissions
  • When economics allow, pork operations producing a majority of pigs implement the diet modification techniques described


  • Greatest limitation is the cost of the technology on feed and net economic returns
  • The availability of feed ingredients to implement consistent diets is imperative
  • Selection of feed ingredients impacts available nutrients for the pig, nutrient excretion and gas and odor emissions


An economic analysis was conducted with this study and the cost per kg of feed was computed using average corn, soybean meal, and hog prices for the last two years and current prices for other ingredients. Carcass value was based on the Indiana Packers Carcass Buying Program ( as of March 2008. The cost of feed per kg was essentially constant for all formulations and phases. The higher gain to feed ratio for the LNE-fed pigs regardless of sex favors the use of LNE diets from a net return over feed cost standpoint. The estimated economic benefits range from $8.92 per head for barrows to $10.82 per head for gilts. A model used to include the decisions about cropping patterns, manure management, and crop fertilization in conjunction with their choice of feed rations for livestock further reinforces the potential economic benefits of the LNE diets. The economic benefits for the LNE diets range from $7.21 per pig space for gilts to $8.79 per pig space for barrows.


Scott Radcliffe, Brian Richert, Danielle Sholly, Ken Foster, Brandon Hollas, Teng Lim, Jiqin Ni, Al Heber, Alan Sutton; Purdue University
Point of Contact:
Alan L. Sutton,

The information provided here was developed for the conference Mitigating Air Emissions From Animal Feeding Operations Conference held in May 2008. To obtain updates, readers are encouraged to contact the author.

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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.