Reducing respiratory health risks to horses and workers: A comparison of two stall bedding materials

Animals 2015,5, 965-977; doi:10.3390/ani5040394 OPEN ACCESS animals ISSN 2076-2615 www.mdpi.com/jou nal/animals A icle Reducing Respi a o y Heal h Risks o Ho ses and Wo ke s: A Compa ison o Two S all Bedding Ma e ials Ma kku Saas amoinen 1,*, Susanna Sä kijä i 1and Seppo Hyyppä 2 1Na u al Resou ces Ins i u e Finland (Luke), Opis on ie 10 a 1, 32100 Ypäjä, Finland; E-Mail: [email p o ec ed] 2Ypäjä Equine College, Opis on ie 9, 32100 Ypäjä, Finland; E-Mail: Seppo.hyyppa@he osopis o. i *Au ho o whom co espondence should be add essed; E-Mail: [email p o ec ed]; Tel.: +358-29-532-6509. Academic Edi o : Ki illy Thompson Recei ed: 14 July 2015 / Accep ed: 29 Sep embe 2015 / Published: 8 Oc obe 2015 Simple Summa y: In his s udy, he e ec o wood sha ings and pea was examined on s able ai quali y and heal h o ho ses and s able wo ke s. The ammonia le el in he boxes in which pea was used as bedding was non-exis en o e y low. The espi a o y symp oms in ho ses inc eased ega dless o he bedding ma e ial a he beginning o he s udy. The heal h s a us o he ho ses on pea bedding e u ned o he ini ial le el in he end o he ial bu ho ses in s alls bedded wi h wood sha ings con inued o be symp oma ic. The hoo es o he ho ses in s alls wi h pea bedding had a be e mois u e con en . The esul s sugges ha pea is a be e bedding ma e ial o ho ses and people wo king o isi ing ho se s ables han wood sha ings. Abs ac : S able ai quali y and he choice o bedding ma e ial a e an impo an heal h issue bo h in ho ses and people wo king o isi ing ho se s ables. Risks o impai ed espi a o y heal h a e hose ha can especially be a oided by imp o ing ai quali y in he s able. The choice o bedding ma e ial is pa icula ly impo an in cold clima e condi ions; whe e ho ses a e kep mos o he day and yea indoo s h oughou hei li e. This s udy examined he e ec o wo bedding ma e ials; wood sha ings and pea ; on s able ai quali y and heal h o ho ses. Ammonia and dus le els we e also measu ed o assess condi ions in he s able. Ammonia was no de ec ed o was a e y low le els (<0.25 ppm) in he boxes in which pea was used as bedding; bu i s concen a ion was clea ly highe (1.5–7.0 ppm) in s alls wi h wood sha ings as bedding. Pe sonal measu emen s o wo ke s e ealed qui e high ammonia exposu e (5.9 ppm8h) in he boxes in which wood sha ings we e used; bu no exposu e was Animals 2015,5966 obse ed in s alls bedded wi h pea . The espi a o y symp oms in ho ses inc eased ega dless o he bedding ma e ial a he beginning o he s udy. The heal h s a us o he ho ses in he pea bedding g oup e u ned o he ini ial le el in he end o he ial bu ho ses bedded wi h wood sha ings con inued o be symp oma ic. The hoo es o he ho ses wi h pea bedding had a be e mois u e con en han hose o he ho ses bedded wi h wood sha ings. The esul s sugges ha pea is a be e bedding ma e ial o ho ses han wood sha ings ega ding he heal h o bo h ho ses and s able wo ke s. Keywo ds: bedding ma e ial; espi a o y heal h; pea ; wood sha ing 1. In oduc ion The s alls o ho ses a e bedded o abso b u ine, mois u e, and gases and o inc ease he com o , heal h, and well-being o he ho ses. In addi ion, a la ge numbe o people a e engaged in he ho se indus y as aine s, ide s, s able wo ke s, a ie s, and o he oles wo king o isi ing s ables o many hou s daily, and being subjec ed o he in luences o he s able en i onmen . Mos o hem a e young people, o example iding school pupils. Ho ses in no he n clima ic condi ions (e.g., in he No dic coun ies and Canada) a e exe cised ou doo s usually o 1 o 2 h and spend, consequen ly, he majo pa o he day (o en up o 23 h) indoo s. Because o his, s able ai quali y is o conside able impo ance. Fu he mo e, aining and acing in cold wea he condi ions expose he ulne able espi a o y sys em o heal h p oblems, inc easing in lamma o y cells in he lungs [1]. As a consequence, espi a o y diso de s a e common p oblems, and espi a o y alle gy is commonly diagnosed as a condi ion a ec ing he equine lung. When he condi ion becomes p o ac ed i is e e ed o as ch onic obs uc i e pulmona y disease (COPD) o hea es (o RAO, ecu en ai way obs uc ion), an animal model o as hma. Anecdo al epo s sugges ha he condi ion is a e in clima es whe e animals a e ou side all yea a ound bu is common in clima es whe e ho ses a e s abled indoo s [2]. Clinical signs in ho ses wi h his ch onic lung disease include poo a hle ic pe o mance, ch onic couching, pu ulen nasal discha ge, and ul ima ely di icul ies in b ea hing [2,3]. People wo king in and isi ing ho se s ables may also be exposed o he e ec s o he s able ai . Causes o ch onic ai way disease bo h in ho ses and humans usually in ol e exposu e o excessi e concen a ions o ai bo ne dus , molds, i uses, bac e ia, spo es, ae oalle gens, and endo oxins which mos ly o igina e om bedding and eed [4–7]. Fu he mo e, he inhala ion o gaseous i i an s such as ammonia may ini ia e ai way obs uc ion and exace ba e o p olong he clinical signs o COPD in a ec ed ho ses [2] as well as humans [3]. The e ec o bedding ma e ial on he quali y o s able ai , bo h on s able dus and he ammonia concen a ion, is signi ican [8]. The a ious o ms o bedding in a s able and e en he di e ences in beddings be ween boxes wi hin a s able [8] in luence he s able dus and gas loads, and consequen ly he isk o ai way heal h o bo h ho ses and humans. Cu en ly, se e al ma e ials a e a ailable o he bedding o boxes in ho se s ables. The mos common bedding ma e ials a e wood sha ings, saw dus , s aw, and pea . Many o he ma e ials a e also used as bedding, including p ocessed (pelle ed) wooden ma e ials and (pelle ed, chopped) s aw om di e en Animals 2015,5967 plan s. In addi ion, sh edded o cu pape and some plan ma e ials (by-p oduc s), as well as woodchips a e used. Each o hese has indi idual p ope ies, including ad an ages and disad an ages [9]. S all ma s a e also a ailable, bu hey a e usually used oge he wi h bedding because o he binding o u ine. I has also been epo ed ha ho ses p e e bedding ma e ial o lying down as compa ed wi h a eas wi hou i [10]. Fac o s conside ed when selec ing bedding a e i s a ailabili y, cos , cleanness ( ee om dus and o eign ma e ial) and i s e ec on s able ai quali y. The bedding ma e ial should also be easy and ligh o handle, o a oid excessi e physical exe ion in s able wo ke s. F om he poin o iew o ho ses’ heal h and well-being, good bedding c ea es a laye o insula ion be ween he ho se and cold loo , pads he ha d su ace, p e en s b uised knees, elbows, hocks and hips, and keeps he ho se clean. The bedding ma e ial also a ec s he beha io o ho ses [11–13], o example he incidence o s e eo ypic beha iou . In addi ion, good bedding ma e ial has a be e po en ial o be e-used e.g., in a ming and ho icul u e [14,15]. The objec i e o his s udy was o examine he e ec s o wo di e en bedding ma e ials, wood sha ings and pea , on he heal h o ho ses. This issue was e alua ed on he basis o espi a o y and o e all heal h and quali y o hoo es, and by measu ing s able ai quali y. 2. Ma e ials and Me hods The expe imen was conduc ed in he acili ies o MTT Ag i ood Resea ch Finland (MTT, cu en ly Na u al Resou ces Ins i u e Finland Luke) in he sou h wes e n pa o Finland (la i ude 60˝) unde au umn/ea ly win e (Oc obe o Decembe ) clima ic condi ions. The du a ion o he expe imen was 84 days. Twel e Finnho se b ood ma es ( ou o which we e p egnan ) aged be ween 5 and 17 yea s we e housed in box s ables in indi idual s alls (3 m ˆ3 m), di ided in o sepa a e sec ions o he s able acco ding o he bedding ma e ial (pea ; wood sha ings). The s able sec ions we e o he same size and had an iden ical mechanical en ila ion sys em. The ho ses we e held on pas u e om he beginning o June o he middle o Sep embe . The wo bedding ma e ials we e selec ed because hey a e he mos common ma e ials used o bedding in Finland. They bo h ha e a low con en o ha m ul componen s when manu ac u ed, selec ed and s o ed p ope ly. Pea is a ou ed as a bedding ma e ial because o i s good p ope ies in soil imp o emen and good compos ing abili y, as well as i s supe io capaci y o bind ammonia and luid [13,16,17] compa ed o o he ma e ials. Bo h bedding ma e ials we e manu ac u ed o use as beddings in ho se s alls; pea by Vapo L d. (Jy äskylä, Finland) and wood sha ings by Jou senon pu upaali L d. (Jou seno, Finland). The ho ses we e exe cised daily in paddocks in g oups o ou hou s, and o one hou by iding o d i ing du ing he cou se o he expe imen . The s alls we e manually cleaned by he same pe son be ween 8 and 12 am when he ho ses we e in ou doo paddocks. All eces and we ma e ial we e emo ed and new bedding ma e ial was added. The dep h o he bedding was abou 10 cm. All emo ed and added bedding ma e ials we e measu ed by hei olume. The ho ses we e indi idually ed acco ding o hei needs h ee imes pe day (mo ning, noon, e ening) wi h silage/haylage (DM 26.6%–6.9%) and pelle ed compounded eed (DM 88%) (Suomen Rehu L d., Tu ku, Finland) o minimize he elease o ai bo ne pa icles om he eeds. The die was Animals 2015,5968 balanced o p o ein (ni ogen) in ake o a oid ni ogen los in u ine and, hus, o minimize he ammonia in he s able. The o age was p oduced by MTT and i s e men a ion and hygienic quali y ul illed he c i e ia o good quali y haylage and silage [18]. The o age was placed on he loo . Ou doo empe a u es and wea he condi ions we e eco ded daily a 8:00 am. The a e age ou doo empe a u es in Oc obe , No embe and Decembe , espec i ely, we e ´1.7 ˝C (´10 o 2 ˝C), ´3.8 ˝C (´14 o 3 ˝C) and ´6.6 ˝C (´20 o 0 ˝C). Acco ding o he s a is ics o he Finnish Me eo ological Ins i u e he empe a u es in Decembe we e qui e no mal, bu in No embe he daily empe a u es we e highly a iable, and in Oc obe he empe a u es we e excep ionally low. The s able empe a u es and humidi y, as well as ammonia and ca bon dioxide le els and amoun o dus , we e measu ed daily in bo h s able sec ions. Me hane (day 0) and hyd ogen sulphide (days 0 and 42) con en s we e measu ed, bu because o unde ec able alues he measu ing was no con inued. Gases concen a ions we e measu ed a a heigh o 120 cm om he g ound using an Accu o gas de ec ion pump which d aws ai h ough sampling ubes (D äge Sa e y AG, Lübeck, Ge many). The measu emen s we e ca ied ou a 6:00 am in h ee boxes o each s able sec ion; om he middle o he box a he le el o he muzzle o he ho se. Dus was con inuously collec ed in o dus cases ha we e i ed in emp y boxes in bo h s able sec ions a he le el o 40 cm om he g ound. Exposu e o he s able wo ke s o ammonia was e alua ed wi h pe sonal measu emen s using sampling ubes a ached o he lapel o he pe son (D äge Sa e y AG, Ge many) in he middle and a he end o he expe imen du ing he cleaning o he s alls. The measu emen esul was con e ed o co espond o an exposu e pe iod o eigh hou s (HTP8h) [19]. HTP alue is he concen a ion ha is ha m ul o people. A espi a o y endoscopic examina ion was pe o med h ee imes du ing he s udy (days 0, 42 and 84), including examina ion o he e hmoidal egion, pha yngeal openings o gu u al pouches, so pala e, la ynx, and achea (symp oms = 1; no symp oms = 0). T acheob onchial aspi a es we e d awn du ing he endoscopy and cy ological and bac e iological (neu ophil cells) e alua ion was ca ied ou . The classi ica ion o he neu ophil cells in b onchoal eola smea samples was as ollows: none o some single cells (´); single cells and ew small pool o cells (+); se e al la ge pools o cells (++); abundan pools o cells (+++); and an ex eme abundance o cells (++++). Blood analyses, ecal analyses and hoo quali y e alua ion we e used as measu es o heal h and well-being o he ho ses. These samples we e aken wi h he same in e al as he endoscopic examina ion. In addi ion, ec al body empe a u e was measu ed and, hea a e (wi h s e hoscope) and espi a ion a e ia auscul a ion we e eco ded by a e e ina ian esea che . Blood samples we e collec ed om he jugula ein, and he blood analysis consis ed o hemoglobin, haema oc i , se um u ea, i on, p o ein, and di e en ial cell coun . Bac e iology, pa asi es, and he pH o aeces we e de e mined. The quali y o hoo es was assessed om he d y ma e con en o hoo ho n. The hoo ho n samples we e collec ed om he hoo es o on legs when he ho ses we e in shoeing. All samples we e analyzed in he clinical labo a o y o MTT. The expe imen al design was a andomized block design wi h epea ed measu emen s. A e he i s endoscopy, he ho ses we e o med in o pai s based on hei symp oma ic simila i y. The wo ho ses o each pai we e hen andomly allo ed o di e en bedding ma e ial g oups (pea bedding o wood sha ing bedding). The p ocedu e was epea ed un il all ho ses we e di ided in he wo g oups. The Animals 2015,5969 in o ma ion om he i s endoscopy was excluded om he da a because i was included in he animal pai - a iable in he model. The da a (samples om ho ses) we e analyzed using he MIXED p ocedu e o he SAS sys em wi h he ollowing s a is ical model: Yijk =µ+ pi+ bj+(pˆb)ij + k+(pˆ )jk + (bˆ )jk + eijk, whe e Yijk is he obse a ion, µis he o e all mean, piis he andom e ec o i h animal pai (i= 1 . . . 6), bjis he ixed e ec o j h bedding ma e ial (j= 1 . . . 2), kis he ixed e ec o he ime pe iod (k= 2 o 3), and eijk is he no mally dis ibu ed e o wi h a mean o 0 and a iance δ2. Te ms (pˆb)ij, (pˆ )jk and (bˆ )jk a e compound e ec s o ac o s. The bes i ing co a iance s uc u e o epea ed measu emen s was selec ed on he basis o he Akaike in o ma ion c i e ion. The di e ences we e es ed wi h Tukey’s es . Ca ego ical a iables (neu ophil cells in acheal mucus) and 0/1- a iables we e no es ed s a is ically, bu we e p esen ed desc ip i ely, because o he small numbe o obse a ions and hei subjec i e sco ing making hem less in o ma i e. In animal handling and sample collec ion, he Eu opean Union ecommenda ion di ec i es (1999/575/EU) and na ional animal wel a e and e hical legisla ion se by he Minis y o Ag icul u e and Fo es y o Finland we e ollowed ca e ully. The expe imen al p ocedu es we e e alua ed and app o ed by The Animal Ca e Commi ee o MTT be o e he s udy was s a ed. The endoscopic examina ion was ca ied ou and all samples om he ho ses we e collec ed by a e e ina ian esea che . 3. Resul s and Discussion 3.1. Ai Quali y The a e age empe a u es in he s able sec ions (pea bedding s. wood sha ing bedding) in Oc obe , No embe and Decembe , espec i ely, we e 9.2 s. 10.3 ˝C, 9.4 s. 9.4 ˝C, and 8.0 s. 8.0 ˝C. These empe a u es a e wi hin he a ge indoo empe a u e ange (8–12 ˝C) in ho se s ables in Finland [20]. The a e age mois u e con en o he s able ai (pea s. wood sha ings) was 54.3% s. 54.6%, 56.0% s. 57.6% and 53.0% s. 58.6% in he co esponding mon hs. Du ing he lowes ou doo empe a u es he mois u e con en s we e na u ally a he lowes le els (38% o 44%). The mois u e o he s able ai o igina es om ho ses’ espi a ion, u ine, eces and d inking and washing wa e . Excessi ely high empe a u es and mois u e may inc ease he elease o ammonia om he bedding [21]. The bedding ma e ial nume ically in luenced he ammonia con en o he s able ai (Table 1). Measu emen s we made ea ly in he mo ning be o e any o he ac i i y in he s ables. Thus, he ammonia concen a ions ep esen he si ua ion a i s wo s a e he nigh . The ammonia le el in he middle o he boxes in which pea was used as bedding was non-exis en o e y low (<0.25 ppm). Howe e , he ammonia concen a ion in he s alls wi h wood sha ings as bedding was nume ically (6–8 imes) highe (1.5–7.0 ppm) and a he highes close o le els (10 ppm) conside ed ha m ul [22]. The ammonia le els obse ed in he p esen s udy we e lowe han ecen ly epo ed gas le els in he mo ning in s ables wi h bedding consis ing o pine wood sha ing [23], bu unde wa me condi ions (summe , in No h Dako a, US). Ammonia in he s able o igina es om u ine. The u ina y p oduc ion depends he die (N-in ake) and wa e in ake. Bo h u ina y p oduc ion and N-losses inc ease wi h inc easing N-in ake [24]. In he p esen s udy he die was indi idually balanced o p o ein (N) in ake, and exc e ion o N was no ob iously e y high. The e we e no di e ences in ammonia concen a ions in he s alls o ho ses on pea bedding (0–0.25 ppm) because o he supe io ammonia abso p ion capaci y o pea . Conce ning he Animals 2015,5970 ho ses on wood sha ings bedding he ammonia con en a ied be ween he ho ses (s alls) and measu ing da es om 1.5 o 7.0 ppm. Table 1. Gas concen a ions in he s able ai . Wood Sha ing Bedding Pea Bedding Day 0 Ammonia 0.5 ppm 0 ppm Ca bon dioxide 650 ppm 500 ppm Hyd ogen sulphide 0 ppm 0 ppm Me hane 0 ppm 0 ppm Day 42 Ammonia 1.5–7.0 ppm 0–0.25 ppm Ca bon dioxide 500 ppm 700 ppm Hyd ogen sulphide 0 ppm 0 ppm Day 84 Ammonia 4.0–7.0 ppm 0–0.25 ppm Ca bon dioxide 700 ppm 600 ppm The amoun o dus collec ed was small o bo h bedding ypes, and no majo di e ences we e obse ed in dus measu emen s be ween he bedding ma e ials. Bo h bedding ma e ials we e specially manu ac u ed o use in ho se s alls. The ca bon dioxide alues we e lowe han he uppe accep able limi alues o ho ses (3000 ppm) and o humans (1000 ppm) [3]. Ca bon dioxide le els we e simila in bo h s able sec ions. The bedding ma e ials also a ec ed he en i onmen o he people wo king in he s ables. Pe sonal measu emen s o he ammonium exposu e o he wo ke s e ealed was highe (5.9 ppm8h) in he boxes in which wood sha ings we e used. No exposu e was obse ed in s alls bedded wi h pea . This is impo an o conside , because wo ke s can spend a conside able amoun o ime each day in he s ables. In his s udy i ook abou 13 min o clean one box. Acco ding o p e ious s udies, eeding and handling o eed ake abou 5 o 7 min pe ho se pe day [25,26], and cleaning he s alls (mucking ou , eplacemen o bedding ma e ials) akes app oxima ely 10 min pe ho se daily i no machine y is used [25–27]. The uppe limi o HTP8h is, howe e , as high as 20 ppm [19]. S udies on pea as a bedding ma e ial a e sca ce. Ai aksinen e al. [17] and Nikama e al. [15] ha e epo ed a supe io abili y o pea bedding o bind ammonia, which is based on i s low pH alue. The pH alue o he pea o bedding (Vapo L d.) used in he p esen s udy was 4.0. The pH alue o wood sha ings used he e was no a ailable, bu acco ding o a s udy he pH o wood sha ings is highe (pH 5.5) han ha o pea [28]. Pea ended o c ea e a be e s able en i onmen han pelle ed sawdus due o highe abso p ion o ammonia and lowe le els ola ile o ganic compounds [3], bu no di e ences be ween he bedding ma e ials we e obse ed ega ding he amoun o dus . Howe e , depending on i s o igin, pea has been shown o a y widely in dus iness and hygienic quali y [17]. Acco ding o se e al o he s udies, he ype o he bedding ma e ial has a conside able e ec on s able dus , ammonia, bac e ia, and endo oxin concen a ions in ho se s alls [4,7,23,29–31]. Animals 2015,5971 Fleming e al. [7] obse ed ha he gaseous ammonia concen a ion was lowes when s aw pelle s we e used. The o de based on ammonia concen a ions among he s udied bedding ma e ials in hei s udy was s aw pelle s, linen, hemp, wood sha ings, pape cu ings, and whea s aw. In a s udy by Ga lipp e al. [31] ammonia emissions om wood sha ings we e conside ably lowe han om s aw. In some s udies mucking ou and handling o bedding ma e ials in luenced he dus and gas (ammonia) emissions in he s able [7,30,32]. In he p esen s udy, he ammonia con en o he s able ai was highe when wood sha ings we e used, and du ing mucking exposu e o ammonia occu ed only in s alls bedded wi h wood sha ings, esul ing om he supe io ammonia binding capaci y o pea . Pelle ing o he bedding ma e ial educes he gene a ion o ai bo ne pa icles by he bedding ma e ial [33]. Fleming e al. [30] ound he lowes pa icle gene a ion wi h s aw pelle s. In hei wo s udies [7,30] hey concluded ha s aw pelle s may p omo e an imp o emen in he s able clima e in ela ion o ai bo ne pa icle o ma ion, ammonia binding and ammonia ans o ma ion. Pelle ed newspape also appea s o ha e a good po en ial as a bedding ma e ial o ho ses [33]. In one s udy [34] he esea che s obse ed ha he gene a ion o ai bo ne pa icles in s aw, wood sha ings, lax, and hemp can be educed wi h a sepa a ion echnology. They also ound ha he gene a ion o pa icles inc eased du ing he s o age o he bedding. P ope en ila ion is impo an o emo e mois u e, gases, and dus and o he pa icles om he s able. Howe e , in many cases he en ila ion o s ables does no p o ide adequa e exchange o esh ai . Thus, he quali y and p ope ies o he bedding ma e ial a e o conside able impo ance. 3.2. Ho se Heal h The i s endoscopic examina ion a he beginning o he expe imen e ealed ha 4 o he 12 ho ses had espi a o y symp oms (+ . . . +++). Thus, mo ing he ho ses om pas u e o indoo housing in he middle o Sep embe ( wo weeks be o e beginning o he s udy) appea ed o expose he ho ses o espi a o y disease because o he ai quali y o he s able. In a Swedish s udy he highes dus measu emen s we e obse ed in win e when he s able doo s we e closed [3]. Sligh ly inc eased ai bo ne bac e ia le els we e also obse ed in s ables in Sep embe compa ed o o he seasons in ha s udy. In he p esen s udy he equency o espi a o y symp oms inc eased in bo h g oups du ing he i s hal o he s udy pe iod, bu hen dec eased in he ho ses bedded wi h pea such ha he numbe o ho ses wi h symp oms in his g oup was he same a he beginning and end o he expe imen . In he ho ses bedded wi h wood sha ings he numbe o symp oma ic ho ses emained la ge han a he beginning, being wice o ha compa ed o he ho ses wi h pea bedding (Table 2). Thus, he pea bedding seemed o be a be e bedding choice han wood sha ings ega ding he heal h o espi a o y ac . The numbe o neu ophil cells did no di e be ween he g oups (da a no shown). The acheob onchial aspi a es ob ained du ing endoscopy con ained ei he sca ce o mode a e numbe s o neu ophils (pea bedding: ´. . . ++; wood sha ings bedding: 0 . . . +++). An ele a ed numbe o neu ophils o he de ec ion o Cu schman’s spi als is sugges ed o co ela e wi h CODP symp oms [35]. One o he ho ses bedded wi h wood sha ings had a high neu ophil pe cen age and also spi als in i s sample a he second and hi d samplings, and was he e o e diagnosed as a CODP ho se a ha ime. Animals 2015,5972 Table 2. Symp oma ic ho ses based on endoscopy examina ion. Wood Sha ing Bedding Ho se Day 0 Day 42 Day 84 1111 2000 3001 4111 5010 6011 Ho ses wi h symp oms 2 4 4 To al symp oma ic du ing he expe imen 10 Pea bedding Ho se Day 0 Day 42 Day 84 7010 8111 9010 10 0 1 1 11 0 0 0 12 1 0 0 Ho ses wi h symp oms 2 4 2 To al symp oma ic du ing he expe imen 8 The e we e no s a is ically signi ican di e ences in blood pa ame e s o he ho ses be ween he pea bedding and wood sha ing bedding g oups (da a no shown). The pa ame e s in all ho ses we e wi hin he ange o e e ence alues. The bedding did no a ec he espi a ion o hea a e o he ho ses (da a no shown). The mic o lo a o eces was also una ec ed by he bedding, which is in ag eemen wi h Tanne e al. [4] and Hübine e [36]. The pH alue was somewha lowe (p= 0.01) in he ho ses wi h pea bedding (6.78) han in hose bedded wi h wood sha ings (7.08) a he end o he expe imen (day 84), and he colou o hei eces was da ke , which was ob iously a esul o obse ed ea ing pea in small amoun s. Hübine e [36] ound no e ec o bedding ma e ial (wood sha ings o pea ) on he aecal pH. The mois u e con en o he hoo ho n a he end o he s udy was highe (p< 0.05) in he ho ses bedded wi h pea (32.6%) compa ed o he ho ses wi h wood sha ings as bedding (30.5%). In he middle o he s udy he di e ence was no s a is ically signi ican (pea 34.2%, wood sha ings 33.2%). D yness o he hoo es can cause p oblems when he na u al elas ici y and oughness is los [37]. The weakening o he hoo mechanism can lead o hoo c acks and impose an addi ional s ain on he legs. Tanne e al. [38] ound ha he hoo es we e d ye and mo e caked when phone book pape was used as a bedding ma e ial han in ho ses bedded on sawdus . The esul s suppo ed by li e a u e [17,30] sugges ha bedding ma e ials ha e he po en ial o a ec s able ai condi ions and animal heal h and wel a e. Howe e , in some s udies, no di e ences ha e been Animals 2015,5973 obse ed. Fo example Tanne e al. [38] ound no di e ence in he espi a o y heal h o ho ses when bedded wi h ei he sawdus o (sh edded and milled) phonebook pape . Howe e , he choice o bedding ma e ial is especially impo an in cold clima ic condi ions, which o ces ho ses o be kep indoo s o a la ge pa o he yea . Al hough he e appea s o be clea di e ences in he p ope ies and in luences be ween a ious bedding ma e ials and ypes, he quali y and o igin o a pa icula bedding is impo an ega ding he ai bo ne dus concen a ions o igina ing om he bedding ma e ial [17,30,39], and s able owne s and manage s should hus also pay pa icula a en ion o his issue when selec ing bedding ma e ials. Ho ses appea o ha e indi idual p e e ences o bedding ma e ial, and no signi ican o e all p e e ence o example o ei he wood sha ings o s aw was obse ed [12]. We han e al. [13] also ound indi idual di e ences, bu he ho ses gene ally p e e ed s aw. The au ho s concluded ha on he basis o he longes ime being occupied, s aw seems o suppo he wel a e o he ho se be e han wood sha ings o s aw pelle s. 3.3. Consump ion o he Bedding Ma e ials The consump ion o bedding ma e ials di e ed conside ably. The consump ion o pea was 59% o ha o wood sha ings (by olume), ob iously due o i s supe io abili y o bind liquids. This a ec s he cos o bedding as well as he need o s o age o bo h bedding ma e ial and manu e, hus in luencing he cons uc ion cos s o he acili ies. 3.4. Gene al Discussion An issue o inc easing impo ance is he in luence o manu e on en i onmen , which means ha he amoun o manu e p oduced should be minimal and ha i should be easily used as a e ilize o in soil imp o emen [14,15], o e en as a sou ce o ene gy, o example in me hane p oduc ion [40]. Rapid compos ing and a good abili y o bind and ans e ni ogen a e impo an p ope ies o pea bedding eques ed by a me s and o he use s o manu e. Poeplau e al. [41] epo ed posi i e ends in o ganic ca bon s o age in Swedish ag icul u al soils due o inc eased ho se indus y and ho se manu e use in ag icul u e du ing he pas wo decades. I is also impo an ha he bedding ma e ial can be easily handled in he s able, which is in luenced, o example, by how i is packed, o how much i is consumed daily. Pea is a good al e na i e o bedding ma e ial in hose coun ies whe e i is p oduced o ag icul u al/ho icul u al o ene gy use, o example in he No dic and Bal ic coun ies, Russia, Poland e c. Howe e , i is impo an o conside ha ag icul u al pea soils should be managed sus ainably and ha cul u al and socio-economical aspec s o pea lands a e aken in o accoun [42]. In many o he coun ies, such as in The Ne he lands and Ge many, he pe cen age o emaining p is ine mi es is small [43]. The ba e y o me hods used o moni o indoo ai quali y and animal heal h in he s able was limi ed in he p esen s udy. In addi ion, ou doo exe cise o he ho ses makes his issue complica ed o in es iga e, ega dless o he me hods applied. Ho ses also indi idually di e in hei sensi i i y o exposu e o en i onmen al ac o s, i.e., hei gene ic p edisposi ion o example, o RAO [44]. On he o he hand, many s udies ega ding ai way heal h ha e been ield s udies wi hou a con olled o