For more: http://www.extension.org/67674 During the last part of the 20th century, animal manure management became an environmental concern. In response to these concerns, legislation was enacted to control manure management and the emission of undesirable gasses (e.g., methane, ammonia, nitrous oxide) from animal production systems. The purpose of this paper is to illustrate how mineral phosphorus (P) supplements, forage types and amounts, and the crude protein (CP) fed to lactating cows impact manure chemistry and the fate of manure nutrients in the environment.

1. What Dairy Cows are Fed
Impacts Manure Chemistry
and the Environment
J. Mark Powell and Glen A. Broderick
USDA-ARS
US Dairy Forage Research Center
Madison, WI
Waste-to-Worth Conference
Denver, CO
April 4, 2013
USDA

2. Why this Research?
Manure management had been included
in two legislative initiatives of USEPA
(1) Clean Water Act
Abate phosphorus (P) loss in runoff from agricultural land
(focus on manure P management)
(2) Clean Air Act
Abate ammonia from animal agriculture
Animal agriculture implicated
in global climate change
(focus on CO2, CH4 and N2O)

3. Research
summary
points
•Dairy nutritionists evaluate dietary
impacts on cows
•Soil scientists evaluate dietary impacts on
manure chemistry and the environment

4. •All diets are representative of what is fed
on commercial dairy farms in Wisconsin
•Very few of the tested diets had any
significant impacts on milk production
(just on manure and the environment)
Research
summary
points

5. Manure Nutrients
and the Environment
Nutrient Environmental Implication
Phosphorus Runoff (Clean Water Act)
Nitrogen
Leaching (Clean Water Act)
Ammonia volatilization (Clean Air Act)
Denitrification (Global Climate Change)
Carbon Methane emissions (Global Climate Change)
Soil CO2 flux (Global Climate Change)

6. Chronology
Dairy Nutrition – Environmental Research
Research periods
2000 2003 2006 2012
Dietary
Phosphorus
Dietary CP and Forages
2009
NH3
loss
Soil C and N
transformations,
plant response
Diet CP-MUN-UUN
NH3 and N2O
emissions

7. Forage
45 - 65%
Grain
20-30%
Protein
Suppl.
20-30%
Minerals &
Vitamins
1-2%
Manure
65-80%
Milk
20-35%
Typical Lactating Dairy Cow Diet
Feed protein and phosphorus
conversion efficiency
Typical Lactating Cow Rations
& Conversion Efficiencies
(confinement dairy)

8. Some dairy ration impacts
on manure chemistry
Phosphorus
Fecal P
Fecal soluble P
Nitrogen
Fecal N: Urinary N ratio
Fecal endogenous N
Fecal fiber N
Urinary urea N
Carbon
Fecal structural CHO
Fecal Non-structural CHO
Forage
Grain
Protein
Suppl.
Minerals
Vitamins

9. Phosphorus
•Fecal P excretions
•Manure land spreading
•Soil test P (Bray-1)
•Runoff P
Minerals
The dietary P story
(A response to water quality legislation)

10. Ration P above NRC recommended level (0.35%)
is excreted as water-soluble P in feces
Pexcretioninfeces(g/cow/d) insoluble-P soluble-P
Ration P (% DMI)
Satter et al., 2005
Requirement

11. …..which increases runoff of water-soluble P
after manure application (no-till corn silage)
0
20
40
60
80
100
0.32%
0.48%
Spring
application
Fall
application
DRPload(g/ha)
b b
a
a
Ebeling et al., 2002

12. …..which increases the cropland requirement
for manure P spreading
(P-based regulations)
Acres
Ration P (%)
Powell et al., 2004

13. -5
0
5
10
15
20
25
0.35
I
0.55
I
0.38
I
0.48
I
0
1.25
2.50
Annual Increase
in Bray-1 P (ppm)
Ration P (%)
…..and increases soil-test P levels
(N-based management)
Powell et al., 2004
Manure P in excess
of crop needs (kg/ha)

14. Nitrogen
and the
Environment

15. Impacts of ration
CP level and CP forms
• Fecal N: Urinary N ratio
• Urinary urea N
• Ammonia emissions
• Nitrous oxide emissions
• Fecal N mineralization in soil
• Plant N uptake
The dietary CP story
(A response to air quality legislation
and global climate change)
Protein
Suppl.

16. Excessive CP in rations reduces CP use
efficiency and increases urine N excretion
Castillo et al., 2000

17. 13.6% CP 19.4% CP
Manure N
g/cow/d
222 314
% Urine N 52 68
% Fecal N 48 32
Excess ration CP
increases manure N
and urine N excretions
a
ab
b
….and also ammonia emissions
after manure land application
%ofmanureNlostasammonia
Manure type
Misselbrook et al., 2005

18. TRADEOFFS
Ration CP impacts ammonia loss
but also manure N availability to plants
Powell et al., 2011
LP HP
SoilinorganicN
After cessation of NH3 volatilization (48h)
Slurry
Powell et al., 2006
-120
-100
-80
-60
-40
-20
0
20
40
60
0 100 200 300 400
HP LP
NetsoilIN(mgkg-1)
Days after feces application to soil
Y=-15.8+0.57x-0.002x2 R2 =0.77
Y=-49.2+0.18x-0.0009x2 R2 =0.91
LP
HP
SoilinorganicN
Feces
Day after application to soil

19. 0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
LCP HCP
0
5
10
15
20
25
b
a
b
a
b
Oat DM Oat N
Nuptake(mgpot-1)
DMyield(gpot-1) LP HP
0
0.2
0.4
0.6
0.8
1.0
1.6
1.2
1.4
0
5
10
15
20
25
Powell et al., 2006
……and crop yield and N uptake

20. Dairy cow component
Ammonia Amino acids
Liver
Bloodstream (BUN)
Urea
Udder Kidney
MUN UUN
Dietary Nitrogen
Urea
Rumen Intestine
Post UUN excretion components
NH4
+
NO3
-
NH3
N2O
NO3
-
NH4
+
(barns, manure storage, soils)
Relationships
Dietary N,
Milk urea N,
Urinary Urea N
and
NH3 and N2O
emissions

21. Relationships
Dietary CP, MUN, UUN
UUN = 16.2 * MUN - 34.2
R² = 0.79
100
120
140
160
180
200
220
240
8 10 12 14 16 18
MUN (mg/100mL)
UUNexcretion(g/cowperday)
I
154
I
166
I
178
I
190
I
201
Ration CP (g/kg)a

22. Distribution of milk urea N (MUN)
197 herds, 37,800 cows
WisconsinPercentofallcows
≤10 11-12 13-14 15-16 >16
0
5
10
15
20
25
30
MUN (mg/100mL)
53% to 73% overfed
dietary CP
}
Desirable MUN

23. Use MUN as management tool
to minimize dietary N, UUN excretion
NH3 and N2O emissions
0
30
60
90
120
150
180
10 11 12 13 14 15 16
- 3
- 6
MUN (mg/100mL)
NH3-N N2O-N
- 9
DailyUUNlossasNH3–NandN2O-N(g/cow)

24. • NH3 emissions by 35 to 42%
• N2O emissions by 18 to 21%
On Wisconsin dairy farms
feeding balanced rations
for MUN concentrations
of 12 to 10 mg/dL
would reduce
Percentofallcows
≤10 11-12 13-14 15-16 >16
0
5
10
15
20
25
30
MUN (mg/100mL)
53% to 73% overfed
dietary CP
}
Desirable MUN

25. Forage
• Fecal endogenous N excretion
• Fecal fiber N excretion
• Mineralization of fecal N in soil
• Plant N uptake of fecal N
The forage story
(Enhanced energy & protein use efficiency)
Forage

26. Feed
components
NDIN
(%)
C:N
CS LP 8.3 15.5
CS HP 6.4 14.8
AS LP 4.8 18.3
AS HP 5.3 18.1
Powell et al., 2006
Forage type in dairy ration impacts C:N ratio
in manure, manure N mineralization,
crop N availability and crop yield

27. Silage type impacts fecal N
mineralization in soil
Days of feces incubation in soil
|
100
|
200
|
300
|
400
a
b
b
Oat DM Oat N
CS AS
DMyield(g/pot)
0
0.5
1.0
1.5
2.0
2.5
3.0
Nuptake(mg/pot)
0
5
10
15
20
25
a
b
3.5
….which impacts
crop production and N uptake
Powell et al., 2006

28. y = -3.9661x + 106.59
R2 = 0.653
0
10
20
30
40
50
60
12 14 16 18 20
Carbon/Nitrogen ratio in dairy feces
OatNuptake
(%appliedfecalN)
Forage type in dairy ration impacts C:N ratio in
manure, manure N mineralization,
crop N availability and crop yield
Powell et al., 2006

29. Forage tannins
reduce urine N excretion
Alf BF-T-
Low
BF-T-
High
Manure N
g/cow/h
12.3 15.8 17.1
% Urine N 55 60 40
% Fecal N 45 40 60
….and ammonia emissions
after manure land application
0
5
10
15
20
25
30
35
Fresh manure Stored manure
%manureNlostasammonia
a
a
b
b
c
a
Misselbrook et al., 2005

30. Feces
(Organic N)
+
Urine (urea N)
NH3 solNH4 sol
NH3 gas
urease
enzymes
Mineralization
Dietary Tannins
Decrease
Urease Activity
in Dairy Feces
0
2
4
6
8
10
12
0 3 6 9 1215182124273033363942454851
0T LT MT HT
NH3-N(mg)
*
*
*
1 3 6 12 24 36 48
*
Time after dairy slurry application (h) Powell et al., 2011

31. Summary
Ration Impacts
• Minerals, protein supplements and forages
impact manure P, N and C excretions, and
their transformations in water, air and soil
• Dietary P can be monitored using fecal P
• Dietary N can be monitored using MUN

32. Summary
Ration Impacts
•Dairy rations can be formulated to satisfy
the nutrition requirements of healthy, high
producing cows while producing excreta less
susceptible to environmental loss
•These are win-win strategies that enhance
feed use (and in most cases reduces costs) and
environmental impacts of dairy production