For more: http://www.extension.org/67657 Odorous reduced sulfur compounds are produced during manure decomposition and emitted from confined animal feeding operations. Feeding high-sulfur distiller’s byproducts may increase the emission of these compounds. The objectives of a series of feedlot pen studies was to (i) determine if emissions of reduced sulfur compounds from fresh manure and from the feedlot surface where affected if cattle were fed varying levels of distillers byproducts, and (ii) determine the areas within a pen that emit greater amounts of reduced sulfur compounds.
Dan Miller, Mindy Spiehs, andBryan Woodbury
USDA-ARS, Lincoln & Clay Center, NE
Reduced sulfur emissions and feeding distillers byproducts
Why Study Reduced Sulfur in Cattle Feedlots?
• Reduced sulfur gases very smelly• H2S (rotten eggs)• Methyl sulfides (even worse!)
• H2S reporting issue (not in feedlots)• ATSDR 30 & 70 ppb• H2S levels very low
Koelsch et al, 2004
How is TRS related to distillers byproducts?
• Wet distillers grains with solubles (WDGS)• Depleted in starch• Enriched in CP, oil, P and S• Sulfate due to sulfuric acid use• Fed at high levels (up to 50%)
Methyl SulfidesRumen Bacteria
Q: How does diet
effect sulfur emissions?
Q: Where are cattle
feedlot pen ‘hot spots’?
Q: Sulfur sources:
manure or soil?
WDGS Study #1
• 160 steer calves, 10 per pen• Concrete floor• Four levels WDGS (0, 20, 40, 60% on
DM basis)• Pens cleaned 3-4 weeks• Collect manure composite for each pen
at monthly intervals• Measure H2S content of manure• Determine relative TRS emission
Feeding >20% WDGS increases H2S content in the manure.
WDGS in diet (% DM basis)
Constituent 0% 20% 40% 60% SEM
Total S (mg/g DM) 5.1a 8.7b 11.7c 14.2d 0.3
H2S-S (mg/g DM)
1.57a 3.07a 8.85b 16.41c 0.88
Varel et al., JEQ 2008
Measuring Relative TRS Emission
• Fresh manure sample (consistent surface area)
• Air flow 1 L/min (internal fan to mix)• Sample airstream for total reduced S (TRS)
Three highest values averaged & background subtracted
TRS Emission ProfilePen 3 (40% WDGS) 8/20/07
0 2 4 6 8 10 12
• Feeding >20% wet distillers increases H2S emission.
• Similar result for large-scale feedlot?
WDGS Study #1WDGS Study #1
0 20 40 60
Percentage Wet Distillers Grains
a aa a
WDGS Study #2a(During Production)
• Eight pens• Working feedlot (concrete & soil)• Two levels WDGS (0 & 40% on DM
basis)• Collect manure composite (feed
bunk area) for each pen at roughly monthly intervals
• Determine relative H2S emission
Study #2 Relative TRS Emission
• 0.7 to 2.5-fold increase for WDGS • Low moisture content on 5/5 and 6/16
2008 Feedlot Study
4/14 5/5 6/2 6/16
P = 0.001
P = 0.079
P = 0.002
P = 0.088
WDGS Study #2b(Post Production—Lingering
• Four pens (2 WDGS, 2 DRC)• Utilize EC to select 20 sites per pen
Represent entire surfaceClassified sites as ‘Mound’ or ‘Edge’
• Measure H2S flux with chambers• Collected soil samples for analysis
Moisture contentOrganic matter content
Comparing Field Emissions
Analysis of Results—Pen Average
Source Pr > F
DRC 8a 14.5b
WDGS 11.5a 21.0c
WDGS Study #3Multi-year, pen emission
• Ten pens (5 per diet treatment)• Twelve sites per pen (mound vs.
edge)• Two levels WDGS (0 & 40% on DM
basis)• Determine relative TRS emission
from the soil over two production cycles
WDGS Study #3Relative TRS emission
• WDGS flux 0.3 to 4-fold higher on 5 of 7 dates.
WDGS Study #3Edge versus Mound
• Larger relative emission in control diet.
• WDGS consistent but not significant
Diet Mound EdgeWDGS 3.35 5.56Control 2.21A 2.99B
T-test 0.001 0.028
Q: Diet? Q: Location?Q: Source?
A: 40% WDGS
A: Pen edges more important
A: Manure strongest source.
Future Directions• What mechanism for soil emission?
• Degasing or sulfate reduction in the soil?
• Does this matter at the fence line?• What about low S WDGS?