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Research Paper
Effects of temperature and dairy cattle excreta characteristicson potential ammonia and greenhouse gas emissionsfrom housing: A laboratory study
Jose Pereira a,b,*, Tom H. Misselbrook c, David R. Chadwick c, Joao Coutinho d,Henrique Trindade b
aAgricultural Polytechnic School of Viseu, Instituto Politecnico de Viseu, Quinta da Alagoa, 3500-606 Viseu, PortugalbCITAB e Centre for the Research and Technology of Agro-Environment and Biological Sciences, Department of Agronomy, Universidade de
Tras-os-Montes e Alto Douro, 5001-801 Vila Real, PortugalcRothamsted Research, North Wyke, Okehampton, Devon EX20 2SB, United KingdomdChemistry Centre, Department of Biology and Environment, Universidade de Tras-os-Montes e Alto Douro, Apartado 1013, 5001-801 Vila
Real, Portugal
a r t i c l e i n f o
Article history:
Received 30 October 2011
Received in revised form
23 March 2012
Accepted 29 March 2012
Published online 22 April 2012
* Corresponding author. Agricultural PolytecPortugal. Tel.: þ351 232 446 600; fax: þ351 23
E-mail addresses: [email protected], j1537-5110/$ e see front matter ª 2012 IAgrEdoi:10.1016/j.biosystemseng.2012.03.011
Dairy cattle housing is a significant source of NH3 and GHG emissions to atmosphere.
However, the climate, temperature in particular, and the characteristics of the excreta of
the housed cattle, may have a strong influence on the magnitude of such emissions. The
objectives were to assess the effects of temperature and excreta characteristics of heifers,
dry cows and lactating cows on potential NH3, N2O, CO2 and CH4 emissions. The experi-
ment was conducted using laboratory chambers where constant amounts of urine and
faeces were applied to a concrete floor. Potential NH3 and GHG emissions were measured
over 120-h following application at 5, 15, 25 and 35 �C.
Increasing temperature promoted a significant increase in NH3 emissions. At temper-
atures �15 �C, total NH3 emissions accounted for more than 100% of the ureaeN content of
the urine for the three dairy cattle types, indicating that other organic N compounds of
urine and faeces are an important source of NH3. The cumulative amount of N2O released
did not vary significantly with temperature and ranged from 1 to 2% of total N deposited.
Cumulative CO2 emissions were ca. 14e58% of total C deposited and the cumulative CH4
emissions were significantly higher at 25 �C than at all other temperatures. It was
concluded that increasing temperature from 5 to 35 �C significantly increased potential
NH3, CO2 and CH4 emissions but did not significantly influence N2O emissions. Also, the
diet supplied to lactating cows led to significantly higher NH3, N2O and CO2 emissions
relative to heifers and dry cows.
ª 2012 IAgrE. Published by Elsevier Ltd. All rights reserved.
hnic School of Viseu, Instituto Politecnico de Viseu, Quinta da Alagoa, 3500-606 Viseu,2 426 [email protected] (J. Pereira).. Published by Elsevier Ltd. All rights reserved.
Nomenclature
Symbols
A Exposed surface area of the floor, m2
CO2-equivalents Cumulative N2O and/or CH4 emissions
expressed as CO2 using the conversion
factors, g m�2 or %
F Ammonia emission rates, mg m�2 h�1
NHþ4 Ammonium, g l�1 or g kg�1
NO�3 Nitrate, g l�1 or g kg�1
t Duration of the sampling period, h
TAN Total ammoniacal N concentration, g l�1 or g kg�1
V Volume of the acid trap solution, l
Abbreviations
ANOVA Analysis of variance
DM Dry matter
EMEP-CORINIAR Air pollutant emission inventory
guidebook
EN European normalization
GHG Greenhouse gas emissions
IPCC Intergovernmental Panel on Climate Change
N Number of replications
NIR Near-infrared detection
PVC Polyvinyl chloride
TGA Trace gas analyser
TOC Total organic carbon
Total C emissions Total cumulative C (CO2 þ CH4)
emissions
Total N emissions Total cumulative N (NH3 þ N2O)
emissions
b i o s y s t em s e ng i n e e r i n g 1 1 2 ( 2 0 1 2 ) 1 3 8e1 5 0 139
1. Introduction management systems. In many farms the cattle houses are
In warm climate areas, such as the Mediterranean regions,
important amounts of gaseous emissions may be released to
the environment from urine and faeces deposited to indoor
and outdoor concrete areas of dairy cattle housing systems.
Some of the greenhouse gases (GHG) emitted such as nitrous
oxide (N2O), carbon dioxide (CO2) and methane (CH4) are well
known to increase global warming, and N2O is also implicated
in stratospheric ozone depletion (IPCC, 2007). Ammonia (NH3)
emission leads to the formation of secondary particulates that
are a potential health hazard (Ansari & Pandis, 1998) and also
leads to soil acidification and nutrient-N enrichment of
ecosystems following deposition (Erisman, Bleeker, Galloway,
& Sutton, 2007).
The emission of these gases is highly influenced by the
excreta (urine and faeces) characteristics (N availability and
pH) (Sommer et al., 2006), the place where excreta are
deposited and climatic parameters such as air temperature
and velocity (Elzing & Monteny, 1997; Morsing, Strøm, Zhang,
& Kai, 2008; Samer et al., 2012). Excreta deposited on concrete
floors of animal housing systems can result in high NH3 and
CO2 emissions due to hydrolysis of the urea content of urine
(Ni, Vinckier, Hendriks, & Coenegrachts, 1999). In addition, the
ammoniacal N present in excreta may lead to N2O emission
through nitrification and/or denitrification processes and,
where anaerobic conditions exist, CH4 emissions may also
occur (Ellis, Webb, Misselbrook, & Chadwick, 2001;
Misselbrook, Webb, Chadwick, Ellis, & Pain, 2001).
Previous studies have indicated that an increase in tempera-
ture leads to proportional increases of NH3 (Cortus, Lemay,
Barber, Hill, & Godbout, 2008; Elzing & Monteny, 1997), N2O
(Sommer et al., 2006), CO2 (Ni et al., 1999) and CH4 emissions
(Adviento-Borbe et al., 2010; Kashyap, Dadhich, & Sharma, 2003).
Hence, in Mediterranean countries with temperate or hot
climates, it may be hypothesised that air temperature will
contribute to an increase in N and C emissions compared with
countries with colder climates (e.g. Northern Europe), leading to
a higher environmental impact in these regions.
Milk production in Portugal, as in many countries, occurs
under a range of climatic conditions, housing and manure
shared by cattle of different ages and at different stages of the
production cycle (Pereira, Misselbrook, Chadwick, Coutinho, &
Trindade, 2010). The type and amount of crude protein (CP)
supplied to dairy cattle will influence the total N excretion
(Powell, Broderick, Grabber, & Hymes-Fecht, 2009). Several
studies have demonstrated that an excess of CP in the diet,
relative to the amount effectively required for the production
level, leads to an increase in N excretion, mainly as urea in
urine (Misselbrook, Powell, Broderick, & Grabber, 2005; Smits,
Valk, Elzing, & Keen, 1995; Sommer et al., 2006). Also, the type
of carbonaceous compounds supplied in the diet (as cellulose,
lignin and soluble carbohydrates) can influence the excreted
carbon fractions (Cardenas et al., 2007; Velthof, Nelemans,
Oenema, & Kuikman, 2005) and subsequent C emissions.
These carbonaceous compounds, and the presence of
condensed tannins or polyphenols, could change the propor-
tion of N excreted in urine relative to faeces (Misselbrook et al.,
2005; Powell, Fernandez-Rivera, & Hofs, 1994), and thereby
influence N emissions. Despite the large body of research
aiming to better understand the main factors affecting C and
N dynamics in animal housing systems, to our knowledge, the
effect of temperature on N and C emissions after deposition of
excreta from different types of dairy cattle to concrete floor
surfaces has not been studied.
The objectives of our study were to assess the effects of
temperature and dairy cattle excreta characteristics (i.e. from
heifers, dry cows and lactating cows) on potential NH3, N2O,
CO2 and CH4 emissions, using a laboratory system simulating
a dairy house concrete floor.
2. Material and methods
2.1. Urine and faeces
Urine and faeces were collected separately from heifers, dry
cows and lactating cows (Holstein) at a dairy farm located in
the NW of Portugal. Cattle were housed all year in freestall-
type housing, as is typical in NW Portugal (Pereira et al.,
2010). Dry cows and heifers were fed a diet of grass silage,
Table 1 e Composition of the diets supplied to heifers, dry cows and lactating cows from which urine and faeces werecollected (N [ 8).
Parameters Heifers Dry cows Lactating cows
Dry matter (g kg�1) 589a (24) 589a (24) 497b (1)
Crude protein (g kg�1 DM�1) 168b (7) 174b (8) 191a (4)
Neutral detergent fibre (g kg�1 DM�1) 657a (6) 659a (6) 410b (1)
DM intake (kg animal�1 day�1) 8.7b (0.4) 8.7b (0.4) 21.9a (0.3)
Milk production (kg cow�1 day�1) 29.3 (0.7)
Values between parentheses represent standard error of the mean.
Values followed by the same superscript in a same row are not significant different (P < 0.05).
b i o s y s t em s e n g i n e e r i n g 1 1 2 ( 2 0 1 2 ) 1 3 8e1 5 0140
straw and specific concentrates while lactating cows were fed
a diet of maize silage, straw and raw materials. Details of the
composition of the diets supplied to the dairy cattle are
described in Table 1.
Urineand faeceswerecollected separately fromarandomly
selected subgroup of 10 animals of each type of dairy cattle
housed on the farm. Over a period of 72-h, total urine and
faeces were collected manually (directly under the tail of the
animals) into plastic containers embedded in ice. The total
urine and faeces collected was subdivided in individual doses
(100 g) and then frozen until required for the laboratory
experiments. Subsamples were retained and analysed for the
physico-chemical properties shown inTable2.UrinepHvalues
were determined directly and faecal pH values were deter-
minedafter 2-hof contactwithoccasional agitation ina faeces/
deionised water (1:5 w/v) suspension according to the Euro-
pean standard EN 13037 (ES, 1999). Dry matter (DM) content of
the faeces was determined by drying in an oven to a constant
weight at 102 �C. Total C of the faeces was determined by dry
combustion followed by near-infrared detection (NIR) using an
elemental TOC analyser (Primac, Skalar, Breda, The
Netherlands). UreaeN content of the urine was determined by
reacting with diacetyl monoxime in the presence of thio-
semicarbazide (to intensify the colour) in acid conditions and
reading theabsorbanceat 520nm(Sullivan&Havlin, 1991). The
total N content of the urine and faeces was determined using
Table 2eCharacteristics of composite urine and faeces samples
Parameters Heifers
Urinea
pH 8.29a (0.02)
Total N (g l�1) 2.96b (0.46)
UreaeN (g l�1) 2.16c (0.07)
TAN (g [N] l�1)b 0.06c (0.00)
NO�3 eN (g l�1) 0.00a (0.00)
Faecesc
pH 8.23a (0.14)
Dry matter (%) 15.25a (0.15)
Total C (g kg�1 DM) 567.97a (10.17)
Total N (g kg�1 DM) 14.76a (2.29)
TAN (g [N] kg�1 DM) 1.68a (0.15)
NO�3 eN (g kg�1 DM) 0.00a (0.00)
Values between parentheses represent standard error of the mean.
Values followed by the same superscript in a same row are not significan
a Values expressed on a fresh weight basis.
b TAN ¼ Total ammoniacal N (NHþ4 eN þ NH3eN).
c Values expressed on a dry matter basis.
a modified Kjeldahl method (Novozamsky, Houba, Van Eck, &
Van Vark, 1983). Mineral N content of the urine and faeces
was extracted with 2 M KCl in a 1:10 (excreta:extractant) ratio
(Mulvaney, 1996). Total ammoniacal N (NHþ4eN þ NH3eN) and
NO�3 contents of the extracts were determined by automated
segmented-flow molecular absorption spectrophotometry
(Houba, Van der Lee, & Novozamsky, 1995). The segmented-
flow analyser (SanPlus, Skalar, Breda, The Netherlands) was
equipped with dialysers to prevent interferences from colour
or suspended solid particles in the extracts.
2.2. Experimental set-up
2.2.1. Laboratory chambersLaboratory chambers were used to simulate a solid concrete
cattle house floor or outdoor yard. The chamber system (Fig. 1)
was as used by Misselbrook et al. (2005). Chambers were
constructed from PVC drainage tube with 110 mm of internal
diameter and 190 mm height. The main body of the chamber
was filled with cement (to simulate a concrete floor), leaving
a headspace of 0.42 l. The internal surfaces of the chambers
were sprayed with a Teflon coating (Loctite�, provided by
Fisher Scientific, Loures, Portugal) to minimise adsorption of
NH3 on internal walls. The airflow rate (4 l min�1) was regu-
lated through a needle valve coupled to a flow meter (model
GD 100; KDG-Mobrey, Crawley, West Sussex, UK) and the
collected fromheifers, dry cows and lactating cows (N[ 4).
Dry cows Lactating cows
8.26a (0.11) 8.14a (0.02)
4.15b (0.25) 6.72a (0.51)
3.02b (0.28) 6.28a (0.20)
0.09b (0.00) 0.13a (0.00)
0.00a (0.00) 0.00a (0.00)
8.22a (0.06) 7.74b (0.03)
13.98b (0.12) 14.01b (0.42)
569.42a (3.26) 566.68a (13.83)
14.67a (1.56) 18.08a (3.07)
1.24b (0.04) 1.94a (0.06)
0.00a (0.00) 0.00a (0.00)
t different (P < 0.05).
Concrete
Urine + faeces
AIR OUTLET
SAMPLING POINTS FOR GHG
AIR INLET
GAS METER
VACUUM PUMP
FLOW METERACID TRAPACID TRAP CHAMBER
Fig. 1 e Schematic diagram of laboratory system for gaseous emission measurements from a simulated concrete floor.
b i o s y s t em s e ng i n e e r i n g 1 1 2 ( 2 0 1 2 ) 1 3 8e1 5 0 141
exact volume flow through each chamber was recorded by
a gas meter (Gallus 2000 G1.6; Schlumberger Elaborate, Reims,
France). We used a high number of headspace changes per
minute (10 exchanges min�1) to ensure that the emission rate
was not greatly affected by small differences between cham-
bers (Kissel, Brewer, & Arkin, 1977).
The chambers were constructed one year in advance and
during this period the cement was periodically fouled with
faeces, to encourage thedevelopmentofureaseactivity (Braam
& Swierstra, 1999). Immediately before the beginning of the
experiments, urease activity was measured on the concrete
floors of the nine chambers at 15 �C using the methodology
described in detail by Braam, Ketelaars, and Smits (1997),
Braam and Swierstra (1999) and Pereira et al. (2011).
2.2.2. TreatmentsThe experiment was conducted using the system of nine
laboratory chambers (three replicates for each excreta type:
heifers, dry cows and lactating cows) tomeasureNH3 and GHG
emissions for 120-h following applications of constant
amounts of a mixture of urine (8 ml) and faeces (8 g), leaving
an emitting layer of 1 mm thickness as used by Misselbrook
et al. (2005). The experiments were performed over 120-h to
assess the potential gaseous emissions after excreta deposi-
tion on concrete areas considering the maximum cleaning
interval used in cattle houses of NW Portugal (Pereira et al.,
2010). The effect of temperature on gaseous emissions was
assessed by conducting experiments at 5, 15, 25 and 35 �C(�0.5 �C). For this, the laboratory set-up was housed in
a climatic room (EVK 211, EVCO SPA, Belluno, Italy). For each
experiment, individual samples of urine and faeces from
heifers, dry cows and lactating cows were thawed (over 24-h
at 4 �C) and then brought to each experimental temperature
immediately before being deposited to the concrete floor of
chambers. Subsamples were retained for chemical analysis.
Since the same set of nine laboratory chambers were used
to evaluate the four experimental temperatures levels, at the
end of each trial any excreta remaining in the main body of
each chamber was removed and the chambers were carefully
cleaned with deionised water. To avoid potential contamina-
tion from carry-over from a previous experiment, a new
experiment was initiated only when gas concentrations from
the chamber outlets were similar to those of the air inlet.
2.3. Measurement of ammonia and greenhouse gasemissions
Ammonia, N2O, CO2 and CH4 emissions were performed over
a period of 120-h. Acid traps containing 150 ml of 0.02 M
orthophosphoric acid were used to measure NH3 emissions in
each chamber and at each temperature level. An acid trapwas
connected before each chamber to remove NH3 from inlet air
and a second acid trap on the outlet side of each chamber was
used to collect the NH3 emitted during the measurement
period (see Fig. 1). Acid traps were changed after 1, 3, 6, 12-h
and then every 12-h until 120-h. At the end of each sampling
period, the volume of solution in the acid traps was measured
and subsamples were analysed for total ammoniacal N
(NHþ4 eN þ NH3eN) content by automated segmented-flow
spectrophotometry (Houba et al., 1995).
Ammonia emission rates (F, mg [N] m�2 h�1) for each
sampling period were determinate according to Eq. (1):
F ¼ ½TAN�VAt
(1)
Where, [TAN] was total ammoniacal N concentration of the
acid trap (mg l�1), V the volume of acid trap solution (l), A was
the exposed surface area of the floor (m2), and t was the
duration of the sampling period (h). The total emission for the
period (mg of [N]) was determined as [TAN] � V, and total NH3
emission for the duration of the experiment (120-h) was
derived by summing emissions for each sampling period.
The fluxes of N2O, CH4 and CO2 were measured directly via
a sampling point located immediately before and after each
chamber (see Fig. 1), with a trace gas analyser (TGA) (1412
Photoacoustic Field Gas-Monitor, Innova AirTech Instru-
ments, Ballerup, Denmark). The TGA was used in similar
conditions as those described by Pereira et al. (2011). The
detection limits of the TGA were 0.03, 0.40 and 1.50 ppm for
N2O, CH4 and CO2, respectively. The concentrations of these
three gases weremeasured (with the TGA) in each chamber at
0, 0.5, 1-h, and then every 2-h over the first 12-h, and then
every 6-h until 120-h. Cumulative emissions of each GHG gas
(N2O, CO2 or CH4) were estimated by averaging the flux
between two sampling occasions and multiplying by the time
interval between sampling occasions. Cumulative GHG emis-
sionswere expressed as CO2-equivalents using the conversion
. CH
4eCem
issions
aCum
ulativeCem
issions
Fluxes
P0e120
b%TotalC
**
**
NS
*NS
NS
NS
NS
***
***
***
***
***
NS
tylevel.
b i o s y s t em s e n g i n e e r i n g 1 1 2 ( 2 0 1 2 ) 1 3 8e1 5 0142
factors of 298 and 25 for N2O and CH4, respectively (Forster
et al., 2007).
2.4. Statistical analysis
Analysis of variance (ANOVA) was conducted using STATIS-
TIX 7.0 (Analytical Software, Tallahassee, FL, USA) to test the
effects of the treatments considering the time after excreta
deposition as a split factor over the two experimental factors
(dairy cattle excreta characteristics and temperature). Tukey
tests were carried out for comparison of means between
treatments and their interactions (temperature � time after
excreta deposition, excreta type � time after excreta depo-
sition and temperature � excreta type). The relationship
between cumulative emission and temperature for the three
excreta types was established using regression analysis (i.e.
fitting exponential, logarithmic and polynomial equations).
Table
3e
Analysisofvariance
testsforgase
ousN
andCem
issionsfrom
excreta
depositedonasim
ulatedco
ncrete
floor
Factor
NH
3eN
emissions
N2OeN
em
issions
aCumulativeN
emissions
CO
2eCem
issions
Fluxes
P0e120
Fluxes
P0e120
b%TotalN
Fluxes
P0e120
PTem
peratu
re(A
)**
***
NS
NS
***
***
PExcreta
type(B)
*****
***
**
**
A�
BNS
***
NS
NS
NS
NS
NS
PTim
eafterdeposition(C)
*****
***
**
A�
C**
***
***
**
B�
C***
***
***
***
NS,*,**
and***meanth
atth
efactororinteractioneffectswere,resp
ectively,notsignifica
ntorsignifica
ntatth
e0.05,0.01and0.001pro
babili
aCumulativegase
ousN
(NH
3þ
N2O)orC(CO
2þ
CH
4)emissions,
resp
ectively.
bPercentageofeach
gasemittedrelatively
toth
etotalN
orCapplied(urineþ
faece
s).
3. Results and discussion
3.1. Urease activity and excreta properties
The urease activity did not differ significantly (P > 0.05)
between the concrete floors of the nine chambers, with
a mean value of 1.4 � 0.02 g [NHþ4eN] m�2 h�1. The relatively
high value for urease activity (>1.0 g [NHþ4eN] m�2 h�1)
implied this should not limit NH3 volatilization from the
liquid emitting layer deposited to the concrete floors (Braam
& Swierstra, 1999).
For practical reasons, the subsamples of urine and faeces
were immediately frozen after collection in containers
embedded in ice in order to preserveN (Knowlton et al., 2010).
Then, before running each laboratory experiment, these
subsamples of urine and faeces were thawed and the
temperature elevated to the trial temperature level (5, 15, 25
or 35 �C). Urea hydrolysis is catalysed by the enzyme urease,
present in faeces and on fouled concrete floor surfaces
(Braam&Swierstra, 1999), and a great increase in NH3 release
occurs betweenpH7.0 and 10 at high temperatures (10e30 �C)(Hartung & Phillips, 1994; Hristov et al., 2011). Since the urine
and faeces samples were collected separately and thawed in
closed PVC flasks, the urea hydrolysis, and any significant
potential gas loss, would have been avoided during this
period (Elzing & Monteny, 1997).
3.2. Nitrogen emissions
3.2.1. Ammonia emissionsFluxes of NH3 for the excreta from the three dairy cattle types
were significantly affected (P< 0.01) by temperature and time
after deposition (Table 3). At 5 �C, emission rate peaked
between 3 and 6-h. For the remaining temperatures (15, 25
and 35 �C), the emission rate peak occurred between 1 and 3-
h. Following these emission rate peaks, there was a progres-
sive reduction in NH3 fluxes until the end of the experiment
(120-h) for all temperatures. Elzing and Monteny (1997) also
observed peak emission rates between 1 and 5-h after urine
application to a slatted floor, indicating that urea hydrolysis
occurred in the first hours after excreta deposition. Muck
b i o s y s t em s e ng i n e e r i n g 1 1 2 ( 2 0 1 2 ) 1 3 8e1 5 0 143
(1982) reported that more than 95% of urea decomposition
from cattle urine deposited on a floor should occur within 6-h
at 30 �C. At all temperatures, the fluxes of NH3 from excreta of
heifers and dry cowswere not significantly different (P> 0.05).
Relative to excreta of heifers and dry cows, the NH3 fluxes
from excreta of lactating cows were significantly higher
(P < 0.05) at all temperatures (Fig. 2aec).
The effect of temperature on the increase in NH3 emissions
indicates that the temperature had a marked influence on
formation of NHþ4 in aqueous phase and release of NH3 to
gaseous phase (Ni, 1999). Firstly, NHþ4 production depends on
urease activity, urease being abundant in faeces and on fouled
concrete floors. Urease activity is affected by temperature,
being reduced at temperatures lower than 10 �C and increased
between 10 and 40 �C (Sommer et al., 2006), but there was no
evidence that urease activity was limiting in our study.
Secondly, NH3 release depends on the following parameters:
convective mass transfer coefficient, concentration of NH3 in
the gaseous phase at the excreta surface and concentration of
NH3 gas in the free air stream (Ni, 1999). Increasing tempera-
ture influences the NHþ4 /NH3(aq) equilibrium and the disso-
ciation coefficient determining the equilibrium of NH3(aq) to
NH3(g) (Sommer et al., 2006). This temperature effect on
emissions from excreta has also been reported by Van der
Stelt, Temminghoff, Van Vliet, and Van Riemsdijk (2007),
and from urine puddles by Cortus et al. (2008) who observed
a 2-fold increase in NH3 volatilization when temperature
increased from 10 to 20 �C. The sensitivity of volatilization to
temperature has been shown to be greater at higher temper-
atures (Rong, Nielsen, & Zhang, 2009).
0
100
200
300
400
500
600
0 12 24 36 48
0 12 24 36 48
mg
NH
3-N
m-2
h-1
mg
NH
3-N
m-2
h-1
b DR
0
100
200
300
400
500
600
0 12 24 36 48 60 72 84 96 108 120
a HEIFERS
0
1
2
0 12 24 36 48 60 72 84 96 108 120
Time after deposition, h
mg
N2O
-N m
-2 h
-1
5 ºC 15 ºC 25 ºC 35 ºC
d
0
1
2
Time after
mg
N2O
-N m
-2 h
-1
5 ºC 15 ºC
e
Fig. 2 e Average gas fluxes of NH3 (aec) and N2O (def) following
represent standard error of the mean (N [ 3).
Cumulative NH3 emissions increased significantly
(P < 0.05) with increasing temperature, being significantly
higher (P < 0.05) at 35 �C than at all other temperatures. An
increase in temperature from 5 to 15 �C, or 25 to 35 �C, resultedin an increase in cumulative NH3 emissions of about 55%,
while a temperature increase from 15 to 25 �C resulted in an
increase in emission of ca. 25%. However, an increase in
temperature from 5 to 25 �C, or 15 to 35 �C, led to an increase in
cumulative NH3 emissions of ca. 75 and 95%, respectively.
Cumulative NH3 emissions, expressed as percentage of the
ureaeN content of the applied urine, ranged between 49 and
189%, being less than 100% for temperatures below15 �C (Table
2 and Fig. 3def). Ammonia emissions primarily arise from the
urea content of the urine, with some contribution from other
organic N compounds in the urine, while emissions from
faeces are normally considered to be negligible. However, at
the higher temperatures, degradation of the other organic N
compounds in the urine and mineralization of faecal N would
becomemore important as sources ofNH3 emission (Bussink&
Oenema, 1998). TheureaeNcontent of urinewasmuchgreater
for lactating dairy cows than for dry cows or heifers, both in
absolute terms and also when expressed as a percentage of
urine total N (94% compared to 73%, respectively; Table 2). The
percentage of total N applied to the chamber as ureaeN was
less than 50% for the excreta fromheifers and dry cows and ca.
69% for lactating dairy cows. Our results are comparable with
data reported in previous studies (Misselbrook et al., 2005;
Muck & Richards, 1983; Whitehead & Raistrick, 1993); these
authors also referred to NH3 emissions from other organic N
compounds presents in urine and faeces. Hence, we conclude
60 72 84 96 108 120
60 72 84 96 108 120 0 12 24 36 48 60 72 84 96 108 120
Y COWS
deposition, h
25 ºC 35 ºC
0
100
200
300
400
500
600
0 12 24 36 48 60 72 84 96 108 120
mg
NH
3-N
m-2
h-1
c LACTATING COWS
0
1
2
Time after deposition, h
mg
N2O
-N m
-2 h
-1
5 ºC 15 ºC 25 ºC 35 ºC
f
the excreta deposition on concrete floors. Vertical bars
0
20
40
60
80
100
0 12 24 36 48 60 72 84 96 108 120
% t
otal
N a
pplie
d
aHEIFERS
0
20
40
60
80
100
0 12 24 36 48 60 72 84 96 108 120
% t
otal
N a
pplie
d
bDRY COWS
0
25
50
75
100
125
150
175
200
Time after deposition, h
% u
rea-
N a
ppli
ed
5 ºC 15 ºC 25 ºC 35 ºC
d
0
25
50
75
100
125
150
175
200
Time after deposition, h
% u
rea-
N a
ppli
ed
5 ºC 15 ºC 25 ºC 35 ºC
e
0
20
40
60
80
100
0 12 24 36 48 60 72 84 96 108 120
0 12 24 36 48 60 72 84 96 108 1200 12 24 36 48 60 72 84 96 108 1200 12 24 36 48 60 72 84 96 108 120
% t
otal
N a
pplie
d
cLACTATING COWS
0
25
50
75
100
125
150
175
200
Time after deposition, h
% u
rea-
N a
ppli
ed
5 ºC 15 ºC 25 ºC 35 ºC
f
Fig. 3 e Cumulative N (NH3 D N2O) emissions from excreta (urine D faeces) deposited on a simulated concrete floor,
expressed as a percentage of the applied total N (aec) and ureaeN (def). Vertical bars represent standard error of the mean
(N [ 3).
b i o s y s t em s e n g i n e e r i n g 1 1 2 ( 2 0 1 2 ) 1 3 8e1 5 0144
that, considering the time after excreta deposition in concrete
floors, organic N compounds other than urea were also
responsible for NH3 emission in this study, particularly at
temperatures �15 �C.Cumulative NH3 emissions from excreta of heifers and dry
cows did not differ significantly (P > 0.05), but were signifi-
cantly lower (P < 0.05) than emissions from excreta of
lactating cows. Mean cumulative NH3 emissions across the
three excreta types, expressed as a percentage of total N
deposited, were 29, 43 and 51% at temperatures of 5, 15 and
25 �C, respectively. At 35 �C, the cumulative NH3 emissions
represented 75% of total N deposited for excreta of heifers and
dry cows and 92% of total N deposited for lactating cows (Table
2 and Fig. 4a). The lower cumulative NH3 emissions from
excreta of heifers or dry cows as compared to excreta of
lactating cows were related to the higher ureaeN content in
urine of lactating cows (Table 2). These differences in N
excretion can be explained by the higher CP content in diet
supplied to lactating cows as compared to the other two cattle
types (Table 1). Feeding metabolic protein in excess of
requirements leads to a reduction in the N use efficiency by
the lactating cows, resulting in a major loss of N as urea
through urine (Monteny, Smits, van Duinkerken, Mollenhorst,
& de Boer, 2002; Sommer et al., 2006). Previous studies
(Arriaga, Salcedo, Martınez-Suller, Calsamiglia, & Merino,
2010; Powell, Broderick, & Misselbrook, 2008) performed in
tie-stall cattle houses showed that reducing the dietary CP
content results in lower NH3 emissions, in agreement with our
results.
3.2.2. Nitrous oxide emissionsFluxes of N2O ranged between 0 and 1.6 mg [N2OeN] m�2 h�1
over the 120-h measurement period. There was no significant
effect of temperature and a small, but significant, effect of
time after deposition (Table 3), with fluxes of N2O from the
three types of excreta increasing slightly over the 120-h of
experiment at all temperatures, except for excreta of heifers
for which the emission peaked within 1-h after deposition at
temperatures of 15, 25 and 35 �C (Fig. 2def).
In our study N2O emissions were very low (Fig. 2def and
Fig. 4b), accounting for ca. 2e4% of cumulative gaseous N
(NH3 þ N2O) emissions. This is in agreement with previous
studies where low N2O emissions from concrete areas of
animal houses (Adviento-Borbe et al., 2010; Ngwabie,
Jeppsson, Nimmermark, Swensson, & Gustafsson, 2009;
Samer et al., 2012) and outdoor yards (Ellis et al., 2001;
Misselbrook et al., 2001) with liquid systems of manure
management have been reported.
Cumulative N2O emissions were not significantly different
(P > 0.05) between temperatures, although numerically
slightly higher at 35 �C. Our results are in agreement with
Arriaga et al. (2010) which didn’t find a positive relationship
between N2O emission and temperature (4e29 �C) in tie-stall
floors, and also with Adviento-Borbe et al. (2010) who found
relatively constant N2O emissions at temperatures between
�5 and 32 �C in freestall cattle houses. The lack of a temper-
ature effect on N2O emissions, and the low observed emission
rates in our study, could be explained by: (i) the low nitrifica-
tion rates because the absence and/or slow growth of
y = 1096.4e0.0316x
R2 = 0.97
y = 2113.4e0.0322x
R2 = 0.95
y = 1.13e0.03x
R2 = 0.95
0
2
4
6
8
0 10 20 30 40
a
y = 119.57x0.07
R2 = 0.42
y = 72.30x0.11
R2 = 0.56
y = 0.08x2 - 2.93x + 58.04
R2 = 0.990
50
100
150
200
0 10 20 30 40
Temperature (ºC)
Cum
ulat
ive
N2O
-N e
mis
sion
(mg
m-2
)
Heifers Dry cows Lactating cows
b
y = 16.14e0.02x
R2 = 0.96
y = 9.32e0.03x
R2 = 0.89
y = 7.79e0.03x
R2 = 0.96
0
10
20
30
40
0 10 20 30 40
Cum
ulat
ive
CO
2-C
em
issi
on (g
m-2
)
c
y = -0.12x2 + 4.99x - 25.36
R2 = 0.73
y = -0.04x2 + 2.57x - 14.29
R2 = 0.82
y = -0.05x2 + 2.12x - 11.67
R2 = 0.540
10
20
30
40
0 10 20 30 40
Temperature (ºC)
Cum
ulat
ive
CH
4-C
em
issi
on (g
m-2
)
Cum
ulat
ive
NH
3-N
em
issi
on (g
m-2
)
Heifers Dry cows Lactating cows
d
Fig. 4 e Relationship between cumulative emissions (NH3, N2O, CO2 and CH4) and temperature for the three excreta types
deposited on a simulated concrete floor (N [ 3).
b i o s y s t em s e ng i n e e r i n g 1 1 2 ( 2 0 1 2 ) 1 3 8e1 5 0 145
nitrobacters in excreta; (ii) the absence of NO�3 in excreta
(Table 2) providing no substrate for denitrification; (iii) the
high NH3 emissions at higher temperatures reducing the
availability of NHþ4 for nitrification and consequently resulting
in smaller N2O emissions from both nitrification and
denitrification.
At each temperature, cumulative N2O emissions from the
three types of excreta differed significantly (P < 0.05),
following the order: lactating cows > dry cows > heifers
(Fig. 4b). Similarly, Kulling et al. (2001) observed lower N2O
emissions from manure of cattle that have been fed with
lower dietary CP content. Cumulative N2O emissions for
excreta of these three types of dairy cattle ranged between 1
and 2% of total N deposited. Higher N2O emissions from
excreta of lactating cows might be explained by the higher
NHþ4 and NH3 contents in the emitting layer, these N forms
being more available for nitrification, and potentially denitri-
fication in anaerobic microsites.
3.2.3. Total N emissionsThere was a significant effect of temperature and excreta type
cumulative gaseous N emissions (NH3 þ N2O), expressed as
a percentage of total N deposited (urine þ faeces) to the
concrete floor (Table 3). Despite there being less total N
deposited in the excreta treatments of heifers and dry cows
than lactating cows (ca. 62%), cumulative N emissions were
not significantly different (P > 0.05) at 5, 15 and 25 �C.However, at 35 �C cumulative N emissions were significantly
higher (P < 0.05) from excreta of lactating cows (Fig. 3aec).
When expressed as a percentage of urine ureaeN content,
gaseous N emissions increased significantly (P < 0.05) with
increasing temperature and at 15 �C emissions exceeded 100%
of the ureaeN content. Such N emissions, expressed as
percentage of the amount of ureaeN in urine, were signifi-
cantly higher (P< 0.05) from excreta of heifers, followed by dry
cows, due the ureaeN content in these two excreta types
being, respectively, only 34 and 47% compared to that of
lactating cows (Fig. 3def).
The fact that our study has shown that gaseous N emis-
sions exceeded 100% of the ureaeN content at temperatures
�15 �C (Fig. 3def), suggest the need to identify the main
organic N compounds present in urine and faeces that
contribute to gaseous N emissions (NH3, N2O and perhaps NO)
from concrete areas of animal houses at higher temperatures
and how thesemay be controlled in order to reduce emissions
in countries with hotter climates.
b i o s y s t em s e n g i n e e r i n g 1 1 2 ( 2 0 1 2 ) 1 3 8e1 5 0146
3.3. Carbon emissions
3.3.1. Carbon dioxide emissionsTherewere significant effects of temperature and excreta type
on CO2 fluxes (Table 3). For all excreta types emission peaked
in the first 6-h after excreta deposition. Carbon dioxide
emission over the first 6-h increased significantly (P > 0.05)
with increasing temperature. After 6-h, CO2 fluxes decreased
progressively in most treatments until the end of the experi-
ment. In addition, at all temperatures and in most measure-
ment periods, the fluxes of CO2 were not significant different
(P> 0.05) between the excreta of heifers and dry cows butwere
slightly lower compared to that of lactating cows (Fig. 5aec).
The increase in temperature from 5 to 15 �C, or 25 to 35 �C,increased cumulative CO2 emissions by ca. 45%, while from 15
to 25 �C cumulative emissions increased by 10%. Increasing
temperature from 5 to 25 �C, or 15 to 35 �C, led to an increase in
the cumulative CO2 emissions of ca. 65%, and a temperature
increase from 5 to 35 �C increased emission by 140%. No
significant differences (P > 0.05) in cumulative (120-h) CO2
emissions were found between temperatures 5, 15 and 25 �C,which were all significantly lower (P < 0.05) than at 35 �C.Emissions of CO2 derive from the aerobic decomposition of
organic compounds (Møller, Sommer, & Ahring, 2004) and
from bacterial respiration in faeces.
Cumulative CO2 emissions from excreta of heifers and dry
cows were not significantly different (P > 0.05), but those from
excreta of lactating cowswere significantly higher (P< 0.05) than
for theother twodairycattle types (Fig.4c). Inaddition,ourresults
showed that cumulative CO2 emissions, as percentage of total C
0
1
2
3
0 12 24 36 48 60 72 84 96 108 120
g C
O2-
C m
-2 h
-1
a HEIFERS
0
1
2
3
0 12 24 36 48
g C
O2-
C m
-2 h
-1
b DRY
0
100
200
300
400
500
0 12 24 36 48 60 72 84 96 108 120
Time after deposition, h
mg
CH
4-C
m-2
h-1
mg
CH
4-C
m-2
h-1
5 ºC 15 ºC 25 ºC 35 ºC
d
0
100
200
300
400
500
0 12 24 36 48
Time after
5 ºC 15 ºC
e
Fig. 5 e Average gas fluxes of CO2 (aec) and CH4 (def) following
represent standard error of the mean (N [ 3).
deposited in floors, were significantly greater from excreta of
lactating cows than from heifers and dry cows (Fig. 4c). This is
most likely because of the greater ureaeN content in excreta of
lactating cows, resulting in higher CO2 emissions through urea
hydrolysis from this excreta type (Ni et al., 1999).
3.3.2. Methane emissionsThe fluxes of CH4 were significantly influenced (P < 0.05) by
temperature, but not by excreta type (Table 3). Fluxes of CH4
were below our detection limit at 5 �C and highest at 25 �C,compared to all other temperatures. Generally, CH4 fluxes
peaked at two important periods over the 120-h of measure-
ment, namely immediately after excreta deposition (for 25
and 35 �C) and between 6 and 24 h after excreta deposition (for
15 and 25 �C) (Fig. 5def). The existence of high fluxes of CH4 at
the beginning of the experiment (Fig. 5def) could be explained
by the release of the CH4 dissolved in the excreta (Fangueiro,
Coutinho, Chadwick, Moreira, & Trindade, 2008; Wulf,
Maeting, & Clemens, 2002). Later emissions of CH4 would
have been generated under the anaerobic conditions in the
base of the emitting layer of excreta (Ellis et al., 2001;
Misselbrook et al., 2001), starting from the volatile fatty acids
produced through microbiological decomposition of the
organic C compounds (Møller et al., 2004).
The cumulative CH4 emissions did not differ significantly
(P > 0.05) at 15 and 35 �C, but were significantly lower (P < 0.05)
than at 25 �C. From 15 to 25 �C there was a significant increase
(P< 0.05) in cumulativeCH4 emissions, but emissionswere lower
at35 �C.CumulativeCH4emissionsat5and35 �Crepresentedless
than 9% of cumulative C (CO2 þ CH4) emissions, while at 15 and
60 72 84 96 108 120
COWS
mg
CH
4-C
m-2
h-1
60 72 84 96 108 120
deposition, h
25 ºC 35 ºC
0
1
2
3
0 12 24 36 48 60 72 84 96 108 120
g C
O2-
C m
-2 h
-1
c LACTATING COWS
0
100
200
300
400
500
0 12 24 36 48 60 72 84 96 108 120
Time after deposition, h
5 ºC 15 ºC 25 ºC 35 ºC
f
the excreta deposition on concrete floors. Vertical bars
0
20
40
60
80
0 12 24 36 48 60 72 84 96 108 120
% t
otal
C a
pplie
d
HEIFERS
0
20
40
60
80
0 12 24 36 48 60 72 84 96 108 120
% t
otal
C a
pplie
d
DRY COWS
0
20
40
60
80
0 12 24 36 48 60 72 84 96 108 120
Time after deposition, h
% t
otal
C a
pplie
d
5 ºC 15 ºC 25 ºC 35 ºC
LACTATING COWS
Fig. 6 e Cumulative C (CO2 D CH4) emissions from excreta
(urine D faeces) deposited on a simulated concrete floor,
expressed as a percentage of total C applied in the faeces.
Vertical bars represent standard error of the mean (N [ 3).
b i o s y s t em s e ng i n e e r i n g 1 1 2 ( 2 0 1 2 ) 1 3 8e1 5 0 147
25 �Cwere between 11 and 69%. In our study, the absence of CH4
emissionsat5 �C(i.e.belowourdetectionlimit)couldberelatedto
the low activity ofmethanogenic bacteria at temperatures below
10 �C (Sommer, Petersen,&Møller, 2004). Increasing temperature
from 5 to 25 �C leads to an increase inmethanogenesis (Kashyap
etal., 2003), corroboratingwithour results. Theunexpectedly low
CH4emissionsat35 �Cinourstudy(Fig.5def)areprobablyrelated
to an absence of anaerobic conditions due the drying of the
emitting layer. There could also have been inhibition of meth-
anogenesis due the presence of high amounts of NH3/NHþ4
(Angelidaki, Ellegaard, &Ahring, 1993) thatwere produced at this
temperature.
There were no significant differences (P > 0.05) in cumu-
lative CH4 emissions from excreta of the three types of dairy
cattle for all temperatures except at 25 �C, in which CH4
emissions from excreta of lactating cows were significantly
lower (P < 0.05) (Fig. 4d). The higher CH4 emissions from
excreta of heifers and dry cows (Fig. 4d)were probably because
of the higher fibre content of the diet (Table 1), leading to
a higher content of volatile fatty acids in faeces and, conse-
quently, higher CH4 emissions (Cardenas et al., 2007; Mathot,
Decruyenaere, Stilmant, & Lambert, 2012).
3.3.3. Total C emissionsThere was a significant effect of temperature, but not of
excreta type on total C (CO2 þ CH4) emissions (Table 3). The
total amount of C lost as CO2 and CH4 emissions did not differ
significantly (P < 0.05) at 5, 15 and 35 �C, but were significantly
higher (P < 0.05) at 25 �C (Fig. 6).
3.4. Greenhouse gas emissions
Since CO2 emitted frommanuremanagement is considered as
natural recycling and not accounted as a GHG in IPCC or
CORINIAIR inventory methodologies, the CO2 emissions
obtained in this study will have no practical impact on GHG
emissions from commercial dairy cattle houses. The GHG
(N2O and CH4) emissions, expressed as CO2-equivalents, were
significantly influenced (P < 0.05) by temperature, but not by
excreta type (Table 4). Cumulative GHG emissions, expressed
as CO2-equivalents, were less than 0.4 kg CO2-equivalentsm�2
for temperatures of 5, 15 and 35 �C, but were significantly
higher (by 130%) at 25 �C. At 5 �C, N2O was the main contrib-
utor to total GHG emissions, while at 15 and 25 �C CH4 was the
main contributor. At 35 �C, the two GHGs contributed in
similar proportions. There was no significant difference
(P > 0.05) between excreta type in terms of the contribution of
N2O to total GHG emission at 5, 15 and 35 �C, while the
contribution of CH4 was not significantly different (P > 0.05) at
5 and 35 �C. The contribution of CH4 from excreta of lactating
cows was significantly lower (P < 0.05) than from excreta of
heifers or dry cows at 15 and 25 �C (Table 4).
3.5. Implications of temperature and dairy cattle excretacharacteristics on gaseous emissions
This study was carried out under laboratory conditions and
caution must be exercised if extrapolating to real conditions.
However, the results from this study showed that potential
NH3 emissions from cattle excreta on concrete floors
increased significantly with increasing temperature. There-
fore we might expect high NH3 emissions from concrete areas
of cattle houses and outdoor yards in dairy regions and/or
countries with hotter climates. At all the tested temperatures,
our results showed that potential NH3 emissions from excreta
of lactating cowswere higher relative to excreta of heifers and
dry cows. Consequently, it is important that such differences
are considered in National inventories for accurate estimates
of NH3 emissions. However, results from our laboratory study
need to be validated at full scale before they can be used for
deriving emission factors for use in National inventory
compilation.
Our results suggest that total potential GHG emissions (N2O
and CH4) will be higher in temperate climates than in cold or
hot climates. Implications for GHG emissions from excreta
deposited on concrete floors are small due the lower N2O and
CH4 emissions (Adviento-Borbe et al., 2010; Misselbrook et al.,
2001; Pereira et al., 2011). Hence, temperature effects might be
Table 4 e Cumulative greenhouse gas emissions from excreta deposited on a simulated concrete floor (N [ 3).
Treatments Temp. (�C) GHG emissions
ag CO2-eq m�2 bN2O (%) bCH4 (%)
Heifers 5 44 (13) 100 (0) 0 (0)
Dry cows 5 84 (5) 100 (0) 0 (0)
Lactating cows 5 127 (3) 100 (0) 0 (0)
Heifers 15 400 (21) 8 (6) 92 (6)
Dry cows 15 323 (42) 32 (8) 68 (8)
Lactating cows 15 233 (24) 66 (9) 34 (9)
Heifers 25 1042 (242) 3 (4) 97 (4)
Dry cows 25 995 (20) 9 (1) 91 (1)
Lactating cows 25 656 (123) 21 (5) 79 (5)
Heifers 35 115 (6) 49 (8) 51 (8)
Dry cows 35 179 (6) 62 (3) 38 (3)
Lactating cows 35 222 (19) 68 (2) 32 (2)
PTemp. * * *
PExcreta NS * *
PTemp. � Excreta NS * *
Values between parentheses represent standard error of the mean.
NS and * mean that the factor or interaction effects were, respectively, not significant or significant at the 0.05 probability level.
a Cumulative (120-h) GHG emissions expressed in CO2-equivalents m�2.
b Percentage of N2O and CH4 emitted relatively to the total emission of GHG, respectively.
b i o s y s t em s e n g i n e e r i n g 1 1 2 ( 2 0 1 2 ) 1 3 8e1 5 0148
more important on emissions (CH4 in particular) from
concrete slurry pits (Møller et al., 2004; Sommer et al., 2004)
located under slatted areas and inside the cattle houses.
National emission factors for housing systems should
therefore be established as a function of temperature in order
to distinguish dairy regions with different climates. In addi-
tion, since temperature is probably the most important factor
controlling gaseous emissions (Adviento-Borbe et al., 2010;
Cortus et al., 2008; Elzing &Monteny, 1997; Hartung & Phillips,
1994; Hristov et al., 2011; Ni, 1999; Rong et al., 2009; Samer
et al., 2012; Sommer et al., 2006; Van der Stelt et al., 2007), an
increase in gaseous emissions due to global warmingmight be
expected in the future, creating great challenges for animal
production and the sustainability of livestock systems,
particularly in countries with hotter climates such as the
Mediterranean (Nardone, Ronchi, Ranieri, & Bernabucci, 2010).
Further studies are required to accurately quantify and
suggest mitigation methods for gaseous emissions from dairy
cattle housing in hotter climates.
4. Conclusions
Increasing temperature (from 5 to 35 �C) significantly
increased NH3 emissions from dairy cattle excreta deposited
on concrete floors. At temperature values �15 �C, cumulative
(120-h) NH3 emissions accounted for more than 100% of the
ureaeN content in urine for all three excreta types, showing
that other organic N compounds of the urine and faeces were
also an important source of NH3. Ammonia emissions from
excreta from lactating cows were significantly higher than
excreta from dry cows and heifers. Cumulative GHG emis-
sions (as CO2-equivalents) were significantly higher at 25 �Cthan at all other temperatures, but were not significantly
different between the three excreta types.
The results suggest that potential NH3 emissions from
concrete floors of cattle housing could be particularly impor-
tant in hotter climate areas, such as theMediterranean region.
We conclude that temperature had a more significant influ-
ence on potential NH3 and GHG emissions and excreta char-
acteristics of dairy cattle had more effect on N2O emissions.
Acknowledgements
This study was supported by a grant (SFRH/BD/32267/2006) to
the first author from the Portuguese Foundation for Science
and Technology (FCT, Portugal). We thank Dr. A. M. D. Sil-
vestre and Dr. J. Louzada for statistical advice as well as the
reviewers of the first draft of this submission for their
constructive suggestions.
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