In oduc ion
Odou gene a ion is one o he mos ele an ai
quali y issues o con ined li es ock ope a ions. Al hough
odou exposu e has been adi ionally conside ed only
a nuisance p oblem, i is now accep ed ha i can also
impai heal h h ough di ec i i a ion o psychopa ho-
logic mechanisms (Shus e man, 1999; Schi man &
Williams, 2005). Fo his eason, in ecen yea s in en-
si e esea ch has been conduc ed o assess and con ol
odou s emi ed om li es ock acili ies. The e is also
a endency o es ablish s ic e egula ions o imp o e
ai quali y in he su oundings o li es ock acili ies
(Nicell, 2009).
Odou nuisances, howe e , cons i u e a conce n o
e y complex na u e, in compa ison wi h o he ai qua-
li y issues. Assessing odou s is condi ioned by he
subjec i e cha ac e o nuisances and he in insic a-
iabili y o odou emission and dispe sion p ocesses.
Thus, measu ing odou s, de eloping odou dispe sion
models and e alua ing aba emen s a egies ha e been
adi ionally challenging asks o a me s and esea -
che s. Much esea ch has been conduc ed so a in ela-
ion o odou measu emen s and he applica ion o odou
dispe sion models (Yu e al., 2010). Also, a wide num-
be o odou aba emen echniques ha e been cha ac e-
ized (e.g. Powe s, 1999). Howe e , ou cu en know-
ledge seems o be s ill limi ed o de ini i ely sol e
some odou p oblems o li es ock acili ies.
The objec i e o his s udy is o c i ically e iew he
s a e o knowledge on odou mi iga ion echniques in
li es ock housing. Fi s ly, he complex na u e o li-
es ock odou s is b ie ly e iewed. Then, we analyze
he mos ele an odou con ol echnologies, hei
S a egies o con ol odou s in li es ock acili ies: a c i ical e iew
Y. Ubeda1, P. A. Lopez-Jimenez2, J. Nicolas3and S. Cal e 1*
1 Ins i u e o Animal Science and Technology. Uni e si a Poli ècnica de Valencia. Camino de Ve a, s/n.
46022 Valencia, Spain
2 Depa men o Hyd aulic and En i onmen al Enginee ing. Uni e si a Poli ècnica de Valencia.
Camino de Ve a, s/n. 46022 Valencia, Spain
3 En i onmen al Moni o ing. Uni e si y o Liège. A da. Longwy, 185. B 6700 A lon, Belgium
Abs ac
Odou s gene a ed in li es ock buildings cons i u e one o he mos ele an ai quali y issues o in ensi e li es ock
p oduc ion. Reducing nuisance episodes ela ed o odou exposu e is he e o e essen ial o a sus ainable li es ock
p oduc ion. In his s udy, he s a e-o - he-a on odou mi iga ion echniques in li es ock housing is c i ically e iewed.
Scien i ic ad ances in he las decade a e e ised and esea ch needs a e also iden i ied. The complex na u e o li es ock
odou s is i s ly e iewed and examined. Then, he mos ele an odou con ol s a egies a e analyzed in e ms o
p esen knowledge and u u e needs. The s a egies conside ed a e: nu i ional s a egies, manu e addi i es, building
design, ai il a ion, manu e co e s, manu e ea men sys ems and windb eaks. Finally, u u e esea ch needs and
p io i ies when es ablishing mi iga ion echniques a e iden i ied. Despi e impo an ecen ad ances, he e a e s ill
some challenges o scien is s, p oduce s and egula o s, pa icula ly ela ed o ield e alua ion o odou s. The e o e,
o con ol li es ock odou s e ec i ely, using s anda dized ield assessmen echniques will be equi ed. Also,
in es iga ing measu emen and model e o s may be use ul o be e unde s and he limi a ions o he cu en me hods,
as well as o iden i y esea ch p io i ies.
Addi ional key wo ds: odou emission; odou dispe sion; odou mi iga ion; nuisance; ol ac ome y.
* Co esponding au ho : [email p o ec ed].es
Recei ed: 11-03-13. Accep ed: 08-11-13.
This wo k has one Supplemen a y Table ha does no appea in he p in ed a icle bu ha accompanies he pape online.
Abb e ia ions used: CP (c ude p o ein); EF (emission ac o ); FC ( e men able ca bohyd a e); FIDOL ( equency-in ensi y-du a-
ion-o ensi eness-loca ion); VFA ( ola ile a y acid).
Ins i u o Nacional de In es igación y Tecnología Ag a ia y Alimen a ia (INIA) Spanish Jou nal o Ag icul u al Resea ch 2013 11(4): 1004-1015
A ailable online a www.inia.es/sja ISSN: 1695-971-X
h p://dx.doi.o g/10.5424/sja /2013114-4180 eISSN: 2171-9292
s eng hs and weakness and hei e iciency on odou
po en ial educ ion. Finally, u u e esea ch needs and
p io i ies a e p oposed o es ablish e ec i e mi iga ion
s a egies o li es ock odou s.
A complex nuisance p oblem
The complex na u e o li es ock odou s
An odou can be de ined as a human sensa ion ha
occu s when ai bo ne chemical subs ances, called
odo an s, s imula e senso y ecep o s in he nasal
ca i y (Schi man e al., 2001). Li es ock odou s a e
composed o a complex mix u e o compounds, which
a ies be ween animal ypes. As an example, app oxi-
ma ely 330 di e en odo ous compounds ha e been
iden i ied in swine p oduc ion (Schi man e al., 2001),
whe eas 110 compounds we e ound in dai y acili ies
(Filipy e al., 2006).
Li es ock odou s a e mainly gene a ed by he mi-
c obial decomposi ion o o ganic ma e con ained in
he diges i e ac o animals and in hei manu e,
unde anae obic condi ions. Al hough odou s can also
be o igina ed om o he sou ces (e.g. om he skin o
he eed), s udies conduc ed in his sense sugges ha
animals hemsel es cons i u e a mino sou ce o odou
i compa ed wi h manu e (Ve does & Ogink, 1997; Kai
e al., 2006). Impo an sou ces o li es ock odou s a e
ela ed o animal houses, manu e s o age acili ies and
ag icul u al applica ion o manu e, bu he ela i e odou
load o each sou ce is no well de e mined so a .
Odou o ma ion, concen a ion and emissions om
li es ock acili ies depend on many ac o s, which a e
summa ized in Fig. 1. Odou gene a ion is in insically de-
e mined by he animals hemsel es, hei ood and ma-
nagemen sys em o hei manu e. I may also be a ec-
ed by daily and seasonal a ia ions, depending on cli-
ma e and animal ac i i y. Finally, he amoun o odou
emi ed o he a mosphe e is de e mined by he housing
en ila ion a e and he exhaus odou concen a ion.
A e iew o odou emission ac o s is shown in
Suppl. Table 1 [pd online]. Al hough a majo pa o
s udies on odou emissions ha e ocused on he measu-
emen o odou emission a es, uni s used in he li e a-
u e a e no always homogeneous. This he e ogenei y
and he complexi y o odou measu emen s con ibu e
o make compa isons among s udies mo e di icul
(Gay e al., 2003).
Odou nuisances
The p ocesses by which odou s a e o med, eleased
o ai , dispe sed in he a mosphe e, pe cei ed by
indi iduals and cause nuisance in a popula ion a e
complex no ully unde s ood. Van Ha e eld (2001)
de ined some essen ial wo ds o a sound scien i ic
S a egies o con ol odou s in li es ock acili ies: a c i ical e iew 1005
Figu e 1. O e iew o sou ces and ele an ac o s a ec ing odou concen a ion and emission om li es ock houses. VFA: ola-
ile a y acid. Sou ce: Adap ed om Le e al. (2005).
Pa icula e ma e
Tempe a u e
Humidi y
Ai eloci y
Ai exchange a e
Feed and wa e in ake
Feed composi ion:
– P o ein con en
– Aminoacid composi ion
– Non-s a ch polysaccha ides
Species
Age
Numbe
Geno ype
Heal h
Beha iou
Remo al equency
Emi ing a ea
Manu e collec ion sys em
Physicochemical composi ion
Bedding ma e ial
Ven ila ion ai low
Odou concen a ion
Odou composi ion: VFA,
indoles, phenoles, ska oles,
sulphu -con aining compounds
Feed Animal Manu e
Odou
o ma ion
Hyd olisis and
e men a ion unde
anae obic condi ions
En i onmen al
condi ions
Emission
discussion. So, “annoyance” can be de ined as a se o
complex human eac ions esul ing om an immedia e
exposu e o an ambien s esso (e.g. an odou ). On he
con a y, “nuisance” is caused by epea ed e en s o
annoyance o e an ex ended pe iod o ime, which
leads o modi ied o al e ed beha iou and can ha e a
de imen al e ec on well-being and heal h. The e o e,
he annoyance po en ial is an a ibu e o a speci-
ic odou o mix u e o odo an s, whe eas nuisance po-
en ial is a much b oade concep ha desc ibes he p o-
babili y o nuisance occu ence in a pa icula loca ion.
Human esponses o odou s, howe e , a e also highly
a iable, and mus be unde s ood as a combina ion o
i e in e ela ed componen s, known as a whole as
FIDOL (Nicell, 2009). The FIDOL componen s e e
o he F equency (how o en), In ensi y (how s ong),
Du a ion (how long), O ensi eness (how unpleasan ),
and he Loca ion (sensi i i y o neighbou s wi h
ega ds o li es ock ope a ion). Since hese compo-
nen s a e di icul o moni o , some coun ies (e.g.
Ge many, The Ne he lands, Swi ze land, Aus ia, Bel-
gium and Canada) ha e de eloped land use planning
guidelines based on minimum sepa a ion dis ances
be ween li es ock uni s and esiden ial a eas. This
se back dis ance is calcula ed conside ing ou main
ac o s, acco ding o he ollowing gene al equa ion
(Nicolas e al., 2008):
[1]
whe e he se back dis ance (D) is calcula ed as a unc-
ion o he ollowing ac o s: he dispe sion condi ions
( D), ecep o cha ac e is ics ( R), animal species ( A)
and echnical ac o s such as aba emen s a egies ( T).
The equa ion also conside s he a m size (N) and a
i ing ac o o eal a m condi ions (α).
Odou measu emen
Odou measu emen echniques a ise om he un-
damen al p emise ha odou s mus i s be measu ed
objec i ely and ep oducibly measu ed be o e hey can
be e ec i ely subjec ed o egula ion and be o e he
e ec i eness o odou con ol echnologies can be
assessed (Nicell, 2009). Despi e ecen ad ances, ob-
aining p ecise odou measu emen s emains an elusi e
a ge o esea che s and egula o s.
The only s anda dized app oach which is in e na-
ionally accep ed in odou measu emen is he dynamic
ol ac ome y (CEN, 2003). This echnique de e mines
odou concen a ions using he dilu ion- o- h eshold
p inciple, bu s ill poses some challenges o measu-
emen s in ield condi ions (Smi h e al., 2007). Odou
concen a ions a e di ec ly ela ed o odou in ensi y,
bu his ela ionship is no s aigh o wa d because
in ensi y e e s o an indi idual’s pe cep ion o odou
s eng h (Nicell, 2009). Mo e speci ic in o ma ion on
he FIDOL componen s ela ed wi h odou nuisances
can be ob ained only wi h al e na i e me hods, which
a p esen a e no s anda dized. I would be he e o e
con enien o no malize ield assessmen echniques
a an in e na ional le el. In his sense, he Sni ing
Team Me hod o plume measu emen s such as hose
es ablished by he Ge man VDI 3940 could be mo e
ealis ic o e alua e he impac o li es ock odou
sou ces, which a e by na u e a iable and discon i-
nuous in ime (Nicolas e al., 2008).
Ob aining objec i e odou indica o s seems c ucial
o iden i y e ec i e mi iga ion s a egies. To his aim,
he ela ionship be ween odou pe cep ion and che-
mical compounds has been subjec o in ense esea ch.
This is a complex ask because analy ical echniques
may ail o cha ac e ize he syne gic e ec s among
odo an s. In addi ion, pa icula e ma e could play an
impo an ole in odou pe cep ion (Bo che , 2001;
Nicell, 2009). Con a ily, some gases such as NH3and
SH2a e odou cons i uen s, bu hey canno be easily
used as odou indica o s, since hei odou de ec ion
is ela i ely high (Smee s e al., 2007; Blanes-Vidal e
al., 2009a) and hei emission p ocess may di e om
he elease pa hways o mos odo an s (Le e al., 2005;
Blanes-Vidal e al., 2009a). Recen s udies ha e achie ed
high ela ionships (R2~ 90%) be ween ol ac ome ic
measu es and analy ic analyses using gas ch oma o-
g aphy – mass spec ome y (Blanes-Vidal e al.,
2009a; Zhang e al., 2010). Howe e , odo an s may
di e conside ably among li es ock species, and he e-
o e using a gene alized analy ical measu emen me hod
o li es ock odou s seems a he momen no easible.
Odou dispe sion modelling
Fig. 2 summa izes he main ac o s which de e mine
odou dispe sion om li es ock acili ies. Wea he
condi ions (mainly wind speed and di ec ion, and
a mosphe ic s abili y) cons i u e he main ac o de e -
mining odou dispe sion. Fu he mo e, o he ac o s
such as ege a ion and opog aphy also in luence in a
ele an way.
D=α D RN A T
1006 Y. Ubeda e al. / Span J Ag ic Res (2013) 11(4): 1004-1015
Acco ding o Smi h (1993), he dispe sion o li e-
s ock odou s di e s om o he a mosphe ic pollu an s
because o impo an pa icula i ies o odou sou ces,
he na u e o odou s and he ecep o cha ac e is ics.
In con as o indus ial sou ces, li es ock odou sou -
ces usually co e a la ge a ea a o nea g ound le el
and he plume ise is no mally i ele an . Fu he mo e,
in li es ock buildings odou s a e emi ed om ope-
nings o ans in walls and oo s, o ming complica ed
s uc u es which a e di icul o model (Yu e al., 2010).
Model alida ion is also complica ed because o he
challenges o odou measu emen s, as well as he spa-
ial and empo al a iabili y in emission a es. Finally,
ecep o s may be ela i ely close o he sou ce o
emissions, and in his case con en ional dispe sion
models a e no eliable. Fo all hese easons, speci ic
odou dispe sion models a e necessa y.
In a ecen e iew on li es ock odou dispe sion
modelling, he majo esea ch gaps o esea ch we e
examined (Yu e al., 2010). Apa om he pa icula-
i ies o odou dispe sion indica ed abo e, hese
au ho s ques ioned he adi ional use o Pasquill-
Gi o d coe icien s in he Gaussian dispe sion models.
A mosphe ic s abili y has a la ge in luence on he
dispe sion esul s, bu i seems oo simplis ic o
desc ibe i using he Pasquill’s s abili y classi ica ion
scheme. Finally, Yu e al. (2010) iden i ied ha he
main d awback o mos models is he long- ime
in eg a ion pe iods, no mally om 10 o 60 minu es.
Using hese ime in eg a ion pe iods, sho - ime
concen a ion luc ua ions a e usually igno ed by
dispe sion models. Howe e , sho - ime luc ua ions
may in luence conside ably he nuisance po en ial
(Nicell, 2009) and he e o e should be conside ed
when p edic ing he odou plume (Sykes & Gab uk,
1997; Mussio e al., 2001).
In ecen yea s, ad ances in compu a ion ha e allowed
he de elopmen and use o nume ical dispe sion mo-
dels (Lin e al., 2009; Hong e al., 2011). Howe e , a
majo challenge o odou modelling emains o be he
S a egies o con ol odou s in li es ock acili ies: a c i ical e iew 1007
Figu e 2. Elemen s a ec ing odou dispe sion p ocess in li es ock con ining ope a ions. The odou plume unde h ee hypo he i-
cal si ua ions (A, B and C) illus a es he a iabili y o odou exposu e as a unc ion o wea he condi ions, opog aphy, ege a ion
and loca ion.
Wea he
condi ions
Dis ance
Si ua ion A
Si ua ion B
Si ua ion C
O ien a ion
F equency
in ensi y
du a ion
Loca ion
Topog aphy
Vege a ion
co e
p ope alida ion be ween modelled da a and eal
nuisance pe cei ed by he popula ion.
Aba emen and con ol s a egies
in li es ock housing
O e iew o odou aba emen s a egies
A wide a ie y o odou p e en ion and con ol s a-
egies ha e been s udied in ecen yea s. Fo e e y odou
con ol s a egy, i is necessa y o conside he cos s
and he desi ed mi iga ion le el, as well as he applica-
bili y o he o e all a m managemen (Powe s, 1999;
Ullman e al., 2004). Also, i mus be accep ed ha only
a pa ial educ ion o odou s can be achie ed (Nahm,
2003). Th ee main ways a e possible o minimize odou
impac om li es ock houses: educing odou o ma-
ion, using end o pipe echniques and enhancing dis-
pe sion. Odou o ma ion can be educed by means o
die a y manipula ion, addi i es, low-emission li es ock
housing and manu e managemen sys ems. Howe e ,
he e ec i eness o hese s a egies may di e o
di e en animal species. End-o -pipe echniques, such
as ai sc ubbing, and manu e co e s ha e p o ed o be
e y e ec i e o educe odou emission. I is also
possible o p omo e he dispe sion o odou s in he
a m su oundings o educe he nuisance po en ial a
sensi i e a eas.
Die a y manipula ion
Despi e being ela i ely inexpensi e, die a y
s a egies in li es ock p oduc ion may achie e impo -
an en i onmen al bene i s. I has been demons a ed
ha educing c ude p o ein (CP) can e ec i ely educe
he p opo ion o exc e ed ni ogen, which is associa ed
o lowe ammonia emissions, no only a he housing
le el, bu also du ing manu e s o age and land appli-
ca ion o manu e (Hayes e al., 2004; Le e al., 2007).
Howe e , he cause and e ec ela ionship be ween
eed cha ac e is ics and he exc e ion o odo ous com-
pounds is no so e iden . Thus, he e is no ag eemen
abou he e ec o low-p o ein die s on odou compound
p o ile.
Some s udies such as hose conduc ed by Hobbs e
al. (1996) and Ke e al. (2006), showed a dec ease
o odo an concen a ions in g owing and inishing
pigs when using low-CP die s wi h amino acid supple-
men a ion. Feeding pigs wi h low c ude p o ein die s
educed odou concen a ion om 30 o 80%, acco ding
o Hayes e al. (2004) and Le e al. (2007). On he o he
hand, some au ho s epo ed ha odou concen a ion
and o ensi eness inc eased when low-CP die s supple-
men ed wi h syn he ic amino acids we e used (O o e
al., 2003; O’Connell e al., 2006). Finally, o he s udies
could no ind di e ences in odou composi ion and
magni ude when low-CP die s we e used (Su on e al.,
1999; Cla k e al., 2005; Leek e al., 2007).
Some s udies ha e e idenced he in luence o he
en e ic mic obial communi y on he exc e ion o odo ous
subs ances. O’Shea e al. (2011) ound ha chi osan
inclusion in die s inhibi ed lac obacilli popula ions
and his was associa ed o inc eased En e obac e-
iaceae popula ions and odou emissions om manu e.
This sugges s ha lac ic-acid bac e ia may play an
impo an ole in mi iga ing manu e odou emissions.
Mc Alpine e al. (2012) ound ha he inclusion o
xilanase (an enzyme which deg ade be a-xylan in o
xylose) e ec i ely educed manu e odou emissions.
Howe e , he inclusion o a p o ease did no in luence
odou emissions. Also, g ow h-p omo ing subs ances
help o educe odou emissions om pig slu y in a 53-
56% (Nahm, 2002). Howe e , as indica ed by McC o y
& Hobbs (2001) diges i e addi i es do no cons i u e
an al e na i e un il a ho ough unde s anding o mi-
c obial p ocesses in li es ock was es is achie ed and
he e o e mo e esea ch is s ill needed on he e ec s
and modes o ac ion o speci ic mic oo ganisms and
enzymes.
The use o e men able ca bohyd a es (FC) is e ec-
i e o educe ammonia ola iliza ion, bu hey may
also a ec he odou emission p o ile (Le e al., 2005).
The inc ease o eed FC s imula es mic obial ac i i y
in animal gu and in he manu e, shi ing he ni ogen
balance om u ine o aeces (Su on e al., 1999; Cla k
e al., 2005). I has been widely demons a ed ha FC
inco po a ed in o pig die s inc eases he ola ile a y
acid (VFA) con en in manu e (Cla k e al., 2005; Ke
e al., 2006; O’Connell e al., 2006), bu i emains
unclea whe he he odou p o ile is a ec ed. Whe eas
Lynch e al. (2008) ob ained a 41% inc ease o odou
emissions when suga bee pulp was added o pig die s,
a non-signi ican e ec o FC was ound by Cla k e
al. (2005) and Le e al. (2007). As acknowledged by
Leek e al. (2007) and Le e al. (2008), he balance
be ween die a y FC and CP plays an impo an ole on
odou p oduc ion and emission. Howe e , his ela-
ionship mus be u he explo ed.
1008 Y. Ubeda e al. / Span J Ag ic Res (2013) 11(4): 1004-1015

Manu e addi i es
Manu e addi i es a e po en ially e ec i e ools o
educe a mosphe ic emissions om li es ock p oduc-
ion, pa icula ly odou s and ammonia. To be use ul,
hese addi i es mus be sa e in he en i onmen , in-
expensi e and easy o apply (Va el, 2002). These
p ope ies a e app ecia ed by manu ac u e s and a -
me s, bu in some cases he comme cial con iden iali y
may in ol e a lack o s anda d, independen es s.
McC o y & Hobbs (2001) e iewed he use o manu e
addi i es ega ding ammonia and odou educ ion.
They concluded ha only sho - e m odou con ol can
be achie ed using masking, disin ec ing, and oxidizing
agen s. F equen eapplica ion o addi i es is he e o e
equi ed o main ain an accep able odou educ ion.
Wheele e al. (2011) classi ied manu e amend-
men s in o i e ca ego ies: mic obial, chemical, disin-
ec an , masking and adso ben s. As indica ed by
Mackie e al. (1998), li es ock was es cons i u e a
dynamic en i onmen in which ae obic and anae obic
mic obial eac ions occu . As a esul o hese eac-
ions, VFAs a e o med, mos o which a e o ensi e
odo an s. The e o e, manu e addi i es co esponding
on he i s h ee ca ego ies abo e men ioned ocus on
inhibi ing some o hese mic obial p ocesses. Acco -
ding o Va el (2002) an i-mic obial plan -de i ed oils
may play a ole in inhibi ing odou s. Howe e , Amon
e al. (1997) ound no signi ican e ec o using a
manu e addi i e based on an ex ac o Yucca shidige a,
and simila esul s we e ob ained by Wheele e al.
(2011) o o he addi i es. Also, masking agen s
(essen ial oils) and adso ben s (zeoli es) ha e been
epo ed o ha e limi ed odou educ ion po en ial
(Amon e al., 1997; Wheele e al., 2011).
Animal housing
Animal housing and managemen sys ems in luen-
ce he emission o odou s. Howe e , in con as o he
cu en ly well de ined “low-ammonia emission”
housing sys ems, i is di icul o dis inguish “low-odou
emission” housing sys ems. The eason o his is he
la ge a iabili y wi hin housing sys ems (Mol & Ogink,
2004). Gene ally, low-ammonia emission housing
sys ems also educe odou o ma ion, bu his ela ion
is no always s aigh o wa d.
In pig p oduc ion, educing he su ace con ac
be ween slu y and he ai has been demons a ed o
be e ec i e o educe no only ammonia, bu also odou
emissions by up o 50% (Ogink & Koe kamp, 2001).
These sys ems include pa ial sla ed loo s, iangula -
shaped gu e s and equen slu y emo al by lushing.
I is gene ally accep ed ha odo ous compounds a e
mainly p oduced when animal was es a e subjec ed o
anae obic condi ions (Mackie e al., 1998). The e o e,
educing mois u e con en o manu e is e ec i e o e-
duce odou p oduc ion. This can be achie ed by using
bedding ma e ials wi h a p ope managemen (O’Neill
& Phillips, 1991). Con a ily o ammonia emissions,
speci ic esea ch ega ding he e ec o bedding ma e-
ial on odou gene a ion is sca ce, and con adic o y
esul s ha e been ob ained o pig and cow p oduc ion
(Ngwabie e al., 2010; Wang e al., 2011). Fo laying
hens hose sys ems including equen emo al, d ying
o mixing up wi h li e in ol ed ele an odou e-
duc ions wi h espec o he con en ional, long e m
manu e s o age (Ogink & Koe kamp, 2001). Finally,
in b oile s, a p ope egula ion o d inke s and e ige-
a ion ogge s is e ec i e o con ol li e mois u e.
Es ablishing p ope en ila ion lows can also con i-
bu e by elimina ing he excess o wa e and educe
odou gene a ion (Ullman e al., 2004).
Ai cleaning sys ems
Ai cleaning sys ems such as bio il e s, sc ubbe s
and bio ickling il e s ha e been de eloped in he las
decades o emo e ai bo ne pollu an s om li es ock
acili ies. In hese sys ems he exhaus ai is o ced o
pass h ough one o mo e se s o we packing ma e ial
in which ce ain pollu an s a e e ained and elimina ed.
Despi e hei high in es men and unc ion cos s, hey
a e e y e ec i e o emo e pollu an s and hei cha-
ac e iza ion is ela i ely easy in compa ison wi h o he
odou mi iga ion echniques. Howe e , hese sys ems
canno be applied in na u ally en ila ed buildings.
The exhaus ai o con ined li es ock buildings has
no mally high concen a ions o ammonia, which is
ola ilized om he b eakdown o u ea and o he ni-
ogen compounds o u ine and aeces. To emo e he
ammonia om he ai , chemical sc ubbe s ha e been
designed, which use acid solu ion. Melse & Ogink
(2005) epo ed an a e age ammonia emo al e icien-
cy o 96%, and acco ding o Ogink & Aa nink (2007)
hey can also emo e pa icula e ma e by up o 90%.
Howe e , hese sys ems a e ela i ely ine icien o
emo e odou s ( ypically abou 30%) because only
S a egies o con ol odou s in li es ock acili ies: a c i ical e iew 1009
soluble compounds a e emo ed, which does no inclu-
de many odo an s (Melse & Ogink, 2005). Recen
s udies ha e sugges ed ha he addi ion o an o ganic
sol en o he wa e phase could inc ease he a aila-
bili y o odou componen s o he bac e ial popula ion,
enhancing he biodeg ada ion o odou (Melse e al.,
2009). Bio ickling il e s, despi e he lowe ammonia
e iciency, a e on a e age mo e e ec i e o educe
odou s han chemical sc ubbe s (Melse e al., 2009).
Bio il a ion is he mos e ec i e end-o -pipe ech-
nique o educe odou s. When he ai passes h ough a
we o ganic packing ma e ial, odou s a e i s e ained
in he ma e ial su ace and hen decomposed by mi-
c oo ganisms (Re ah & Mo gan-Sagas ume, 2005).
The epo ed e iciency lies wi hin he ange om 80%
o 99%, depending on he packing ma e ial, i s mois u-
e con en and he emp y bed e en ion ime (Chen &
Ho , 2009). To ob ain maximum odou and ammonia
educ ions, hese sys ems should be ins alled a e a
chemical sc ubbe , hus emo ing NH3and odou s in
wo sepa a e s ages (KTBL, 2006).
Manu e s o age and ea men
Manu e s o age and ea men is conside ed a signi-
ican sou ce o odou emissions in li es ock acili ies.
Howe e , he ele ance o his sou ce in compa ison
wi h li es ock houses and land applica ion is no well
quan i ied in li e a u e.
Among he a ailable echniques o odou con ol
in manu e s o age acili ies, he use o co e s o educe
gaseous emissions has been widely s udied in ecen
yea s (Vande Zaag e al., 2008). These au ho s classi y
co e s acco ding o hei o igin. Co e s o na u al o i-
gin include na u ally occu ing c us s, s aw and o he
c op esidues, woodchips and sawdus , expanded clay,
pe li e, ege able oils and ae a ion oam. Syn he ic co-
e s include pe meable co e s (plas ic g anules, ubbe
g anules, hyd ophobic powde ) and impe meable
co e s such as plas ic ilms. Finally, composi e co e s
combine he bes aspec s di e en ma e ials. The use
o co e s is a ac i e because o hei low cos compa-
ed o o he aba emen s a egies.
Acco ding o he e ision conduc ed by Vande Zaag
e al. (2008), a e age odou educ ion o di e en
co e s anges be ween 40% and 90%. Se e al s udies
(Hudson e al., 2008; Blanes-Vidal e al., 2009b)
suppo he idea ha he main mechanism o odou
educ ion is ha co e s ac as a physical ba ie
obs uc ing he ee exchange o ola ile compounds
om he unde lying liquid o he a mosphe e. Mo e-
o e , hese s udies also indica e ha na u al co e s may
also educe odou s as a esul o a bio il a ion ac ion
o he co e i sel .
Howe e , u he esea ch seems necessa y o o e -
come wo main gaps o knowledge on he use o co e s.
On he one hand, he c oss e ec o di e en co e
ma e ials on g eenhouse gas emissions should be be e
cha ac e ized. On he o he hand, he o e all pe o -
mance o co e s should be es ed unde a wide a ie y
o condi ions de i ed om di e en manu e ypes,
clima e condi ions o co e ageing. The use o co e s
may be o highes in e es in hose egions whe e la ge
lagoons a e used (i.e. in ensi e pig a ming in Sou he n
Eu ope and he USA). Main enance o hese co e s
may be a c i ical aspec o hese co e s, acco ding o
he es s made by Aguila e al. (2012) o pe meable
and impe meable co e s.
O he manu e ea men s, despi e no being speci i-
cally designed o aba e odou s, may lead o odou
emission educ ion i hey al e he anae obic con-
di ions o elimina e he p ecu so s o odo ous com-
pounds. Solid-liquid sepa a ion can educe odou
emission, bo h as a s and-alone echnique (Zhang &
Wes e man, 1997) o combined wi h anae obic diges-
ion (Hansen e al., 2006). Howe e , i can only be
conside ed a mi iga ion echnique i he sepa a ion
p ocess can emo e he ines ac ion o solids (pa i-
cles smalle han 75 µm) o which VFAs a e a ached
(Ndegwa e al., 2002).
The ae obic ea men oxidizes manu e o ganic
ma e ials in o s able p oduc s by ae obic bac e ia
(Wes e man & Zhang, 1997). This p ocess s abilizes
he manu e and does no allow he accumula ion o
VFAs and o he odo an s. When he was e is s abilized,
i can be s o ed o a long pe iod wi hou emi ing
ele an odou s. In his echnique, he main decision
is o balance he need o a minimum ae a ion ime wi h
he inc easing cos o long ae a ion imes (Wes e man
& Zhang, 1997; Zhang e al., 2004).
In con as o he ae obic ea men , anae obic diges-
ion p omo es he p oduc ion o VFA as a subs a e o
me hane and ca bon dioxide p oduc ion. Because he
deg ada ion o VFAs is enhanced du ing his p ocess,
he odou elease po en ial o he diges a e du ing
subsequen s o age and land applica ion is lowe han
he undiges ed ma e ials (Hansen e al., 2006). Consi-
de ing he low odou emission po en ial o diges ed
ma e ials, he managemen o undiges ed ma e ials
1010 Y. Ubeda e al. / Span J Ag ic Res (2013) 11(4): 1004-1015
(slu ies and co-subs a es) becomes c ucial o comple e
an e ec i e odou mi iga ion s a egy in he a m.
Windb eaks
I has long been demons a ed ha windb eaks al e
he ai u bulence (Segine , 1975), bu hei e ec i-
eness o enhance odou dispe sion and educe nuisan-
ces has no been s udied un il he las decade. Wind-
b eaks and shel e bel s a ound li es ock uni s a e
no mally ege a ion sys ems ha edi ec wind and
educe wind speed. This e ec on wind modi ies
en i onmen al condi ions upwind and downwind shel-
e ed zones, and hus changes he dispe sion o odou s
(Tyndall & Colle i, 2007). Windb eaks no only
enhance dispe sion by p omo ing ai u bulence, hey
also se e as a il a ion ba ie whe e pa icula e ma e
and odou s a e pa ly e ained. A wind-b eak posi io-
ned nea an odou sou ce can educe he downwind
leng h o he odou dispe sion plume, as e idenced by
ield measu emen s and model simula ions (Lin e al.,
2006). They a e also applicable a easonable cos s
(Tyndall & G ala, 2009).
Quan i ying he odou mi iga ion po en ial o wind-
b eaks is ex emely complica ed, and depends on shel-
e bel cha ac e is ics and wea he condi ions. This has
been s udied using nume ical models (Lin e al., 2007;
2009) o scaled wind unnel es s (Ikeguchi e al.,
2003). Odou s a e be e dispe sed using dense and
high windb eaks, loca ed nea he odou emi ing sou ce
(Lin e al., 2007).
The po en ial educ ion o odou dispe sion by wind-
b eaks is e iden and, conside ing i s low implemen a-
ion cos , his echnique can be ecommended o educe
odou nuisances. Howe e , s anda dizing his echni-
que in p ac ice is challenging. The e is s ill a lack o
scien i ic knowledge measu e in p ac ice how he spe-
ci ic en i onmen al condi ions a e a ec ing he wide
ange o possible windb eak ypes and disposi ions.
Resea ch needs and u u e p io i ies
Recen esea ch on odou science in li es ock p o-
duc ion has signi ican ly imp o ed ou knowledge on
odou na u e, measu emen echniques, dispe sion
modelling, and mi iga ion echniques. I is ema kable
ha he ange o a ailable mi iga ion echniques is
nowadays no signi ican ly di e en om hose p opo-
sed a numbe o yea s ago (O’Neill & Phillips, 1991;
Powe s, 1999). As i is now accep ed, hese au ho s also
conside ed he ele ance o eeding s a egies, li e-
s ock housing, ai il e ing, addi i es, manu e co e s,
manu e managemen sys ems and windb eaks, among
o he s. Many o hese aba emen echniques we e p i-
ma ily de eloped o educe ammonia emissions. How-
e e , esea ch so a has gi en us an insigh in o he
undamen als and po en ials o hose echniques o
aba e odou s. The combina ion o mo e accu a e mea-
su emen me hods and compu e ad ances has p o-
ided he oppo uni y o quan i y he po en ial odou
mi iga ion o di e en s a egies and o assess he
nuisance po en ial in a m su oundings using nume i-
cal dispe sion models. Howe e , e o s a e equi ed
o o e come some aspec s o which scien i ic know-
ledge is s ill incomple e, such as odou measu emen s
and e o analysis.
Despi e he ad ances in odou science, odou mea-
su emen s ill poses a challenge o esea che s.
Simila o o he a mosphe ic pollu an s o ag icul u al
o igin, odou emissions a e highly a iable and in many
cases di icul o ace because o he di use na u e o
hei sou ces. In con as o o he a mosphe ic pollu-
an s, which can be analy ically de e mined wi h p eci-
sion, he subjec i e componen o odou pe cep ion
makes p og ess mo e di icul . The ela ionship among
odo an subs ances, odou concen a ion and odou
in ensi y is now be e unde s ood, bu measu emen
e o s a e s ill oo la ge o de ec ela i ely small e ec s
o aba emen echniques (Clan on e al., 1999; Boeke
& Haas, 2007; Banhazi e al., 2009). I is also s ill
necessa y o quan i y mo e p ecisely and a easonable
cos s he o he componen s o nuisance po en ial, na-
mely equency, du a ion and o ensi eness. I is easo-
nable ha adop ing s anda dized ield ol ac ome y
echniques would allow ob aining be e es ima ions
o he odou impac in he su oundings o di use
sou ces. In his sense, adop ing an in e na ionally s an-
da dized ield assessmen me hod seems an essen ial
equi emen o adop a common s a egy ( o example
a he Eu opean Union le el) o aba e odou nuisances.
Quan i ying e o s o odou es ima ions may be o
highes in e es o scien is s and policy make s. To
his aim, unce ain y analysis can be pe o med acco -
ding o he concep s and p ocedu es de ined by he
Guide o he exp ession o unce ain y in measu emen
(ISO, 1995). Al hough o odou emissions such an
analysis is a p esen missing, po en ial unce ain y
sou ces o odou impac assessmen a e ou lined in
S a egies o con ol odou s in li es ock acili ies: a c i ical e iew 1011
Fig. 3. As an example, Boeke & Haas (2007) ound
ha lowe and uppe limi s o measu emen unce -
ain y, exp essed as a pe cen age o he odou concen-
a ion, we e 25% and 400% espec i ely. Ob iously,
his le el o unce ain y makes di icul es ablishing
compa isons among al e na i es o educe odou
emissions a a m le el.
Apa om measu ing odou concen a ions, e-
sea che s ind o he wo impo an sou ces o unce -
ain y when de e mining odou emissions om li e-
s ock buildings. The i s sou ce is he in insic
a iabili y o odou emissions as a unc ion o in e e-
la ed ac o s such as ai empe a u e and manu e mana-
gemen , among o he s. Because o his a iabili y i is
complica ed o ob ain a ep esen a i e ai sample,
which leads o impo an sampling e o s. The second
sou ce o unce ain y is he measu emen o en ila ion
a es. In mechanically en ila ed buildings his unce -
ain y has been epo ed o be a bes 5-10% o he
measu ed en ila ion, bu in na u ally en ila ed buil-
dings measu emen e o s may be conside ably highe
(Van Buggenhou e al., 2009). Ve y open, na u ally
en ila ed li es ock houses a e cu en ly an in e es ing
al e na i e agains in ensi ely con olled buildings,
pa icula ly in ca le and pig buildings. Howe e , in
hese sys ems measu ing en ila ion lows and odou
emission a es is ex emely unce ain, and he e o e i
is a challenge o esea che s o cha ac e ize hese sys-
ems in e ms o odou p oduc ion.
When de e mining odou nuisance po en ial using
dispe sion modelling, he co esponding modelling
e o s a e added o he a o emen ioned odou emission
unce ain y. Howe e , he con ibu ion o each indi i-
dual unce ain y sou ce o he inal e o o modelled
nuisance po en ials is o he momen unknown. Quan-
i ying he unce ain y o modelled odou nuisance po-
en ials and de e mining he con ibu ions o each
indi idual sou ce would con ibu e o es ablish esea ch
p io i ies conduc ing o educe he mos ele an e o s.
This would also undoub edly lead o a be e unde -
s anding o he p oblem by esea che s, a me s and
policy make s.
Conclusions
The ange o a ailable mi iga ion echniques is
nowadays simila o hose p oposed a numbe o yea s
ago. Howe e , ecen esea ch on li es ock odou s has
signi ican ly imp o ed ou knowledge on odou na u e,
measu emen echniques, dispe sion modelling, and
mi iga ion echniques. Accep ed odou aba emen s a-
egies a a m le el a e: eeding s a egies, li es ock
housing, ai il e ing, diges i e and manu e addi i es,
manu e co e s, manu e managemen sys ems and
windb eaks. Al hough hese echniques a e known o
yea s, esea ch so a has gi en us an insigh in o he
undamen als and po en ials o hose echniques.
Despi e his inc easing knowledge o odou aba emen
s a egies, hei e ec i e implemen a ion a a m le el
needs a de ini e commi men o a me s and egula-
o s. Resea ch also indica es ha odou p oblems mus
1012 Y. Ubeda e al. / Span J Ag ic Res (2013) 11(4): 1004-1015
Figu e 3. O e iew o unce ain y sou ces in he de e mina ion o odou impac s.
Odou
sou ce
E o
concen a ion
Ven ila ion
a e
Va iabili y
and sampling
Model e o s
Me e eological a ia ion
Dispe sion
Odou emission
Recep o s
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Odou impac