ORIGINAL RESEARCH Effects of Different Bedding Mterils on the Behvior of Horses Housed in Single Stlls Hnn Werhhn, MSc, Engel F. Hessel, PD Dr, Irene Bchhusen, MSc, nd Hermn F.A. Vn den Weghe, Prof Dr Ir ABSTRACT The effects of three different edding mterils (strw, wood shvings, nd strw pellets) on the ehvior of six wrmlood horses (four mres, two of them with fols) housed in single stlls were nlyzed. Ech mteril ws used for 2 weeks in three consecutive runs. The ehvior of the horses ws videotped nd nlyzed on the first nd lst 3 dys for ech edding lterntive in the lst of the three runs. The time udgets for the ehviors including stnding, eting, lying, occuption with edding mteril, nd other were generted. Compred with strw pellets nd wood shvings, the ppliction of strw edding led to significntly higher frequency nd longer durtion of occuption with edding mteril nd in turn, shorter frctions of stnding nd other ehviors. The totl durtion of lying ws significntly longer on strw thn on strw pellets. Strw pellets resulted in the lest men recumency durtion per occurrence of this ehvior. Becuse occuption is one of the importnt functions tht edding mteril is supposed to fulfill, we concluded tht in regrd to horse ehvior, strw edding ws the est mong the three mterils nlyzed. Further investigtions with more homogeneous group of pronds re necessry to verify the oserved ehviorl rections. Keywords: Horse; Bedding mteril; Behvior; Single stlls INTRODUCTION In Germny, most riding horses re housed in single stlls. 1 In this housing system, nimls re directly sujected to the influences of the stle environment for the mjor prt of the dy (often up to 23 hours). In ddition to other fctors, the edding mteril hs decisive influence on the stle environment. The functions of the edding mteril From the Division of Process Engineering, Deprtment of Animl Sciences, Georg August University of Goettingen, Vecht, Germny. Reprint requests: Hnn Werhhn, MSc., Division of Process Engineering, Universitetsstr. 7, D-49377 Vecht, Germny 0737-0806/$ - see front mtter Ó 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.jevs.2010.07.005 include the sorption of excrement, protection from mechnicl insult, cushioning the horse s legs ginst concussion, therml isoltion, prevention of drft, improvement of skid nd slip resistnce, nd the occuption of the horses. 2 Preference reserch conducted y Hunter nd Houpt 3 reveled tht horses fvor lying down in res hving edding mteril s compred with res without it. Therefore, dry nd soft floor seems to hve positive influence on horse welfre. Moreover, edding mteril influences the development of noxious gses nd dusts significntly, nd consequently, the ir qulity within stle. It is well-known tht contmintion of the stle ir cn cuse severe respirtory diseses, 4,5 nd tht indequtely mintined edding mteril cn led to hoof prolems such s thrush. 6 However, few investigtions hve een conducted on how nd to wht extent the type of edding influences horse ehvior. McGreevy et l 7 reported tht edding mterils other thn strw increse the risk of norml ehvior. Another study 8 reported tht horses kept on strw edding spend more time lying in lterl recument position. This is importnt for complete sleeping cycle nd the essentil deep sleep phse showing rpid-eye-movement (REM)-sleep phses. 9 Housing systems re supposed to provide conditions tht help mintin nturl ehvior s much s possile. The comprison etween the ehvior of horses in the wild nd domesticted horses in housing system gives n indiction of the niml welfre inherent in system. 10 In Germny, the most commonly used edding mterils for horses housed in single stlls re strw (whet nd rley) nd wood shvings. Strw is comprtively low-priced nd esy to uy in les of different sizes. Its sorent chrcteristics re good nd it cn e disposed off esily. Its disdvntges include dust exposure nd the fct tht it cn hror spores (considerle qulity differences in different tches). Wood shvings re often used s n lterntive for strw. Becuse of the stndrdized processing methods used to mnufcture wood shvings, they re of consistent qulity, more sorent, less dusty, nd hror conspicuously fewer llergens thn strw. However, shvings re more expensive nd more difficult to dispose off. Another mteril with similr chrcteristics to wood shvings is strw pellets, which hve the dvntge tht it cn e esily disposed off. 11 Journl of Equine Veterinry Science Vol 30, No 8 (2010) 425
426 H Werhhn et l Vol 30, No 8 (2010) For keeping the edding clen nd dry, different types of mucking out regimes re commonly used. Crrying out complete mucking on dily sis is lor intensive nd involves high mteril consumption. One wy to sve time nd reduce mteril consumption is to remove only the feces on dily sis. This method hs een recommended, for exmple, for wood shvings nd strw pellets y the mnufcturers. For the most lor-sving regime, only new mteril is dded on dily sis nd complete mucking out tkes plce in intervls of severl weeks. 12 The present investigtion is sed on the results tht originted from n experiment the min focus of which ws on the effect of populr edding mterils on the stle climte. 13,14 Our ojective ws to determine whether nd to wht extent the edding mteril ffects the ehvior of horses housed in single stlls. MATERIALS AND METHODS Loction of the Study The reserch project ws undertken in stle in Löningen (county of Cloppenurg, Lower Sxony, Germny) in the period etween Jnury 26 nd Septemer 4, 2006. Four wrmlood mres (two of them with fols) were housed in single stlls within the stle. Figure 1 shows the lyout of the stle. The four windows were lwys kept closed; one of the doors ws kept hlf open nd the other completely open. The single stlls were seprted y stone wlls (height ¼ 1.3 m), with wooden section (height ¼ 1.2 m) plced on the upper surfce of the wlls. In the direction of the isle, the wll consisted of 0.8-m stone wll with 1.4-m wooden pneling on top. Stlls 1, 3, nd 4 hd spces in their wooden wlls, which llowed the horses to look into the isle. These horses were lso fed (hy) from the isle. The horses in stll 2 were fed inside the stll. Ech stll ws equipped with feeders for concentrtes nd utomtic drinking troughs. Animls A 7-yer-old wrmlood mre (dm, D1) with fol (F1) ws housed in stll 1. Stll 2 housed 6-yer-old wrmlood mre (D2) with fol (F2), stll 3 housed 5-yerold riding horse (wrmlood mre; R1), nd stll 4 n 18-yer-old riding horse (wrmlood mre; R2). The height of the dult horses rnged etween 1.65 nd 1.70 m. The dms weighed out 650 kg, the riding horses out 600 kg, nd the fols out 230 kg. Bedding Mterils nd Feed The two most common edding mterils in Germny were selected for this study: whet strw (unchffed, length 20e30 cm, dry mtter content 89%, wter inding cpcity 321%) nd dust-free wood shvings (spruce wood; Goldspn, Brndenurg Com., Goldenstedt, Germny; dry mtter content, Figure 1. Pln of the stle. 86%; wter inding cpcity, 316%). Additionlly, use of whet strw pellets (strw ground nd mde into pellets; Bioln, RWZ Rhein-Min Com., Cologne, Germny; dry mtter content, 87%; wter inding cpcity, 419%) s edding mteril ws lso investigted, s it is known to cuse prticulrly smll mounts of dust 13 nd mmoni emissions 14 under environmentlly-controlled conditions. Further informtion on the edding mterils investigted y Fleming et l hs een previously pulished. 14 On dily sis, the horses were fed with hy (6 kg/ [mre nd dy]), pellets (3 kg/[mre nd dy]), nd ots (1 kg/[mre nd dy]) once t 8 AM nd then gin t 6 PM. The pellets (Dery Zucht Dery Spezilfutter Com., Germny) contined 12.5 MJ metolic engery (ME)/kg nd 15% crude protein (CP). The ots contined 11.5 MJ ME/kg nd 8.5% CP. Hy (8 MJ ME/kg nd 5.4% CP) ws plced inside the stll for D2 nd on the floor of the isle for the remining three horses. The feed qulity nd type remined constnt over the course of the experiments. The fols were nursed y their dms. Wter ws ville t ll times. Mesurement Techniques Four video cmers (Pnsonic CCTV WV-BP 310), ech with n infrred light source, were fixed on top of the wooden pneling t the ck of the stlls to record the ehvior of the horses. A long time recorder (Time Lpse Video Recorder AG-6040, Pnsonic), multiplexer (Video Multiplexer WJ-FS 116, Pnsonic), nd monitor screen to control the records were plced in room outside the stle. Experimentl Design The sic study ws split into three runs, ech run lsting for 6 weeks. The ehvior mesurements were recorded
H Werhhn et l Vol 30, No 8 (2010) 427 in the lst run, y which time the horses were lredy used to the chnge of edding mteril. In ech run, the edding mterils were used for 2 weeks. In this study, when strw ws used (etween August 9 nd 21, 2006), it ws necessry to dd new mteril dily 12 ; 11 kg of strw per stll ws strewn on dily sis in this study. Following the mnufcturers instructions, the edding mde of strw pellets (etween July 26 nd August 6, 2006) ws kept out 5 cm deep nd the edding of wood shvings (etween August 23 nd Septemer 4, 2008) out 25 cm deep. The mnufcturers lso suggest dding new mteril in intervls of 2 weeks; therefore, no new mteril ws dded within the 2 weeks of the experiment. The totl mount of edding mteril plced in the four stlls ws s follows: strw, 225 kg in stlls 1 nd 2, 150 kg in stlls 3 nd 4 (plus 11 kg dily); strw pellets 33 kg in stlls 1 nd 2, 22 kg in stlls 3 nd 4; shvings 150 kg in stlls 1 nd 2, 120 kg in stlls 3 nd 4. The ehvior of the horses ws oserved nd nlyzed continuously y n individul on the first (period 1) nd lst 3 dys (period 2) of ech edding lterntive in the lst of the three runs (6 dys for ech of the three edding lterntives for six horses, 108 dt sets in totl). Becuse the horses spent 6 to 7 hours dy out t the psture, the ehviorl oservtions for ech horse were crried out dily for 15 hours (6 PMe11 AM). The oservtions were noted when the horses returned to the stle from the psture. The frequency, men durtion per ppernce, nd totl durtion within 15 hours were documented for ech ehvior type. The 20 oserved ehvior types were grouped into the following five ctegories: eting (including eting hy nd concentrtes), stnding (including dozing nd wtching with their hed out), lying (including sternl recumency nd lterl recumency), occuption with edding mteril (including eting, nuzzling, nd investigting the mteril), nd other (including ehviors of short durtion nd/or little frequency; eg, locomotion, drinking, rolling, nd grooming). Sttisticl Anlysis The sttisticl evlution of the dt ws crried out with the softwre progrm SAS 9.1 (SAS Inst. Inc, Cry, NC, USA). The following ehvior dt hd to e logrithmiclly trnsformed into Gussin distriution: frequency of occuption with edding, lying, sternl recumency, nd lterl recumency; men durtion of eting, stnding, occuption with edding nd lterl recumency; nd totl durtion of occuption with edding, nd lterl recumency. The nlysis of vrince ws computed using the GLM procedure with the significnce level t P.05. Proility vlues etween.05 nd.1 were noted s tendencies (t-test). For ll ehviors, the fixed effects of the edding lterntive (strw pellets, strw, nd wood shvings), the shvings strw strw pellets oservtion period (period 1 ¼ dys 1e3; period 2 ¼ dys 11e13), nd the horse were considered. Additionlly, for the two ehviors stnding nd occuption with edding, the interctions etween the edding lterntive nd the horse nd etween the edding lterntive nd the oservtion period were lso considered. Moreover, for the ehvior lying, the fixed effect of the oservtion dy (within the period) nd the interctions etween edding lterntive nd horse, edding lterntive nd oservtion period, oservtion period nd horse, edding lterntive nd oservtion dy, were lso tken into ccount. RESULTS 15,08 15,51 16,27 27,1 27,98 25,61 eting lying stnding occuption other 38,8 32,48 14,96 40,52 7,52 11,5 9,07 6,63 10,97 0% 20% 40% 60% 80% 100% Figure 2. Determined time udgets of the ehvior inside the stll sudivided ccording to edding mterils (oservtion period 15 hours; n ¼ 108;, ¼ lest squres mens within ehvior with different letters re significntly different [P <.05]). Time Budgets For the dily oservtion time of 15 hours, the time udgets for the totl durtion of the five min ehvior groupsdstnding, eting, lying, occuption with edding, nd otherdwere generted (men vlues of ll horses nd oservtion dys; Fig. 2, Tle 1). The edding mteril hd significnt influence on the frequency, men durtion per ppernce, nd totl durtion of occuption with edding (P <.0001). In ll cses, compred with other mterils, the horses spent more time occupying strw edding thn on the other mterils. In contrst, the ehvior stnding ws performed in lower frequency nd in shorter totl durtion (P <.0001). Strw edding lso cused significntly longer totl durtion of lying thn strw pellets (P ¼.0094; Tle 1). Influence of the Individul Horse Ech horse hd highly significnt influence on ll the oserved ehviors with respect to frequency, men durtion per ppernce, nd totl durtion (P <.0001). Figure 3 presents this influence using the exmple of totl durtion of the ehvior occuption with edding. D2 spent the longest time occupied with the edding nd the two fols spent more time occupied with the edding thn the riding
428 H Werhhn et l Vol 30, No 8 (2010) Tle 1. Totl durtion, frequency, nd men durtion of the ehviors stnding, eting, lying, nd occuption sudivided ccording to edding mterils (n ¼ 108) Stnding Eting Lying Occuption n LSM SE LSM SE LSM SE LSM SE Totl durtion (hrs) Strw pellets 36 6.08 0.14 2.44 0.10 3.84 0.09 0.99 0.11 Strw 36 4.87 0.14 2.33 0.10 4.20 0.09 2.24 0.11 Shvings 36 5.82 0.14 2.26 0.10 4.06, 0.09 1.13 0.11 Frequency Strw pellets 36 37.75 1.41 21.72 1.01 22.47 0.91 15.31 1.12 Strw 36 30.00 1.41 19.44 1.01 22.00 0.91 24.25 1.12 Shvings 36 37.89 1.41 19.42 1.01 21.11 0.91 17.11 1.12 Men durtion (mins) Strw pellets 36 10.75 0.47 7.19 0.45 11.62 0.61 3.47 0.23 Strw 36 10.27, 0.47 7.40 0.45 13.58 0.61 5.65 0.23 Shvings 36 9.73 0.47 7.78 0.45 13.06 0.61 3.35 0.23 n, numer of vlues; LSM, lest squres mens; SE, stndrd error., Lest squres mens within vrile with unlike superscripts re significntly different (P <.05). horses nd D1. All the horses showed the longest time occupied on strw edding; in three of the cses it ws significntly different from the other two mterils (P <.05) nd in one cse, it ws significntly longer thn on strw pellets (P ¼.0312). No significnt differences etween the edding mterils could e found in D2 nd F2 (Tle 2). These horses were fed hy inside their stll. Influence of the Oservtion Period on the Time Spent Lying In some cses, the oservtion period influenced the ehvior lying either in tendency or significntly. In Tle 3, the ehvior lying in periods 1 nd 2 is presented, sudivided into sternl nd lterl recumency on the sis of type of edding mteril. When the edding consisted of wood shvings, the phses spent lying in sternl recumency in period 1 were significntly shorter thn in period 2 (P ¼.0464). The results from the other two mterils reported the sme tendency ut they were not sttisticlly significnt. In contrst, the phses spent lying in lterl recumency in period 1 were significntly longer thn in period 2. These results were lso not sttisticlly significnt, ut tendencies could e recognized for strw (P ¼.0620) nd strw pellets (P ¼.0792). In most cses, the phses of sternl recumency re clerly longer thn phses in lterl recumency. No differences could e found in totl durtion nd frequency of lying etween periods 1 nd 2 (Tle 3). DISCUSSION When kept on strw edding, the horses spent the mximum time with the ehvior occuption with edding minutes 250 200 150 100 50 0 c n.s. dm 1 dm 2 riding horse 1 strw pellets strw shvings riding horse 2 fol 1 fol 2 Figure 3. Lest squres mens nd stndrd error of totl durtion of occuption with edding sudivided ccording to horses nd edding mterils (oservtion period 15 hours; n ¼ 108; n.s. ¼ not significnt;,, c ¼ lest squres mens within horse with different letters re significntly different [P <.05]). nd the shortest with the ehvior stnding. It is known tht horses in the wild re occupied with finding feed for out 60% of the dy. 10,15 In contrst, horses housed in stles usully spend lot more time stnding without occuption (upto 65%) nd only out 15% of the dy eting. 15 This sitution cn led to the development of stereotypic ehvior. 7 Providing horses with possiility to occupy themselves with edding mteril should hve n importnt influence on how niml-friendly the housing system is. 2 On the sis of this, compred with wood shvings nd strw pellets, strw s edding mteril seems to meet the requirements of the horses in terms of occuption n.s.
H Werhhn et l Vol 30, No 8 (2010) 429 Tle 2. Totl durtion, frequency, nd men durtion of the ehvior occuption with edding sudivided ccording to edding mterils nd horses (n ¼ 108) Totl durtion (hrs) Frequency Men durtion (mins) n LSM SE LSM SE LSM SE Dm 1 Strw pellets 6 0.65 0.27 14.17, 2.74 2.46 0.56 Strw 6 1.12 0.27 18.66 2.74 3.46 0.56 Shvings 6 0.25 c 0.27 9.83, 2.74 1.33 c 0.56 Dm 2 Strw pellets 6 1.99 0.27 19.00 2.74 6.71 0.56 Strw 6 3.58 0.27 24.33 2.74 8.48 0.56 Shvings 6 2.40 0.27 17.33 2.74 8.09 0.56 Riding horse 1 Strw pellets 6 0.26 0.27 9.00 2.74 1.48 0.56 Strw 6 1.70 0.27 20.00 2.74 5.22 0.56 Shvings 6 0.26 0.27 9.33 2.74 1.65 0.56 Riding horse 2 Strw pellets 6 0.35 0.27 8.00 2.74 2.47 0.56 Strw 6 2.40 0.27 20.00 2.74 7.09 0.56 Shvings 6 0.24 0.27 9.00 2.74 1.61 c 0.56 Fol 1 Strw pellets 6 1.35 0.27 20.17 2.74 3.91 0.56 Strw 6 2.50 0.27 27.17 2.74 5.82 0.56 Shvings 6 1.59, 0.27 26.33 2.74 3.37 0.56 Fol 2 Strw pellets 6 1.38 0.27 21.50 2.74 3.78 0.56 Strw 6 2.17 0.27 35.33 2.74 3.81 0.56 Shvings 6 2.02 0.27 30.83 2.74 4.05 0.56 n, numer of vlues; LSM, lest squres mens; SE, stndrd error.,,c Lest squres mens within the horse with unlike superscripts re significntly different (P <.05). most suitly nd in turn improves their welfre. These findings concur with the results from study y Mills et l 16 regrding preferences etween edding mterils in Thoroughred horses. On the sis of the fct tht horses lso et some edding mteril while they re occupied with it, the present study proves the hypothesis tht time spent stnding is reduced when horses in single stlls spend more time eting. 17 In comprison, Mills nd McDonnell reported tht the time spent lying is not influenced y the time spent eting. 17 In generl, this hypothesis cn lso e supported y the present results, even though the strw edding led to 3% increse in lying ehvior thn strw pellets. This might indicte tht eddings mde of strw pellets re less comfortle thn strw nd even wood shvings. In fct, the strw pellet mttress ws (in dherence to the mnufcturers instructions) only 5-cm deep. Possily, this depth is not enough to crete comfortle ed for the horses. In contrst to the present study nd Mills nd McDonnell, 17 Fder 18 oserved more occurrence of the lying ehvior on shvings thn on strw in open housing systems nd less lying when horses were fed dditionl roughge. Considerle differences were oserved etween the individul horses. This result ws expected ecuse the group ws smll nd very heterogeneous with respect to ge (fols, dults etween 5 nd 18 yers) nd physiologicl condition (dms, fols, nd riding horses). All the horses spent most of their time occupied with edding mde of strw. However, for D2 nd F2, the time spent occupied with edding ws not significntly different etween the mterils. This ltter result ws considered to e ecuse of the fct tht these horses (living in stll 2) were fed with hy within their stll, wheres ll the other horses hd their hy plced in the isle. Becuse of the presence of the hy within the stll, there ws mixing of the feed nd edding. Therefore, when the horses re provided with their rtion within their stlls (s ws the cse in this study), the ehvior occuption with edding is prolonged ecuse the horses hve to serch for its of hy
430 H Werhhn et l Vol 30, No 8 (2010) Tle 3. Totl durtion, frequency, nd men durtion of the ehvior lying sudivided ccording to sternl, lterl, nd totl recumency, edding mterils, nd periods (n ¼ 108) Totl durtion (hrs) Frequency Men Durtion (mins) n LSM SE LSM SE LSM SE Sternl recumency Strw pellets Period 1 18 2.61 0.12 13.44 0.68 12.75 0.92 Period 2 18 2.83 0.12 14.06 0.68 13.65 0.92 Strw Period 1 18 3.08 0.12 13.83 0.68 14.94 0.92 Period 2 18 3.06 0.12 13.11 0.68 16.79 0.92 Shvings Period 1 18 2.91 0.12 13.50 0.68 14.76 0.92 Period 2 18 3.14 0.12 12.39 0.68 17.40 0.92 Lterl recumency Strw pellets Period 1 18 1.19 0.08 8.28 0.64 6.14 0.52 Period 2 18 1.05 0.08 9.17 0.64 4.74 0.52 Strw Period 1 18 1.26 0.08 9.17 0.64 5.99 0.52 Period 2 18 0.99 0.08 7.89 0.64 4.55 0.52 Shvings Period 1 18 1.19 0.08 8.44 0.64 5.98 0.52 Period 2 18 0.89 0.08 7.89 0.64 5.35 0.52 Totl recumency Strw pellets Period 1 18 3.80 0.13 21.72 1.29 11.61 0.88 Period 2 18 3.88 0.13 23.22 1.29 11.62 0.88 Strw Period 1 18 4.34 0.13 23.00 1.29 12.89 0.88 Period 2 18 4.06 0.13 21.00 1.29 14.27 0.88 Shvings Period 1 18 4.10 0.13 21.94 1.29 12.90 0.88 Period 2 18 4.03 0.13 20.28 1.29 14.31 0.88 n, numer of vlues; LSM, lest squres mens; SE, stndrd error., Lest squres mens within ehvior nd mteril with unlike superscripts re significntly different (P <.05). within the edding. In contrst, only minor differences in occuption would e expected if the horse s roughge rtion ws fed d liitum. Among the fols, the time spent eing occupied with edding did not differ s much etween the mterils s compred with the dult horses (prt from D2). They proly spent more time exploring their environment in generl thn the dult horses ecuse of their nturl curiosity t tht ge. When horses re occupied with edding, they hve their hed fcing downwrd. This position is the physiologic posture for more thn hlf of the dy in the wild 2 nd for tht reson is considered to e positive for horse welfre. The differences etween periods 1 nd 2 in men durtion per lying down episode reported only tendencies, nd therefore did not llow cler interprettion. We hypothesized tht the totl time spent lying would e shorter in period 1 thn in period 2 ecuse horses need to get used to chnged environmentdin this cse edding mterildefore they perform norml lying ehvior. 19,20 However, we did not otin this expected result. No significnt difference or tendency in totl recumency etween periods 1 nd 2 ws reported. However, when the men durtion of recumency ws divided into sternl nd lterl recumency, some differences etween period 1 nd 2 could e registered (Tle 3). To explin this oservtion further investigtions re necessry ecuse the differences re still not quite cler. Pedersen et l 8 oserved tht horses kept on strw edding spent three times more time in lterl recumency thn those kept on wood shvings. Our
H Werhhn et l Vol 30, No 8 (2010) 431 studies could not confirm these results ecuse no differences in time spent in lterl recument position were detected etween the strw edding nd the other mterils. In conclusion, the results of this study show tht edding mteril does influence horse ehvior in occuption with edding, stnding, nd lying. On the sis of the longest time spent occupied, strw seems to support the welfre of the horse etter thn wood shvings or strw pellets. Becuse of the highly significnt influence of ech horse, further investigtions with lrger nd more heterogeneous horse group re necessry to verify the oserved rections. Becuse providing roughge d liitum to horses housed in single stlls is not lwys possile, it is dviseddwith regrd to the ehvior of the horsedto plce the rtioned diet inside the stll, therey enling n extension of their time spent occupied. REFERENCES 1. Korries OC. Untersuchung pferdehltender Betriee in Niederschsen. Bewertung unter dem Aspekt der Tiergerechtheit ei Trennung in verschiedene Nutzungsgruppen und Bechtung hltungsedingter Schäden [PhD thesis]. Hnover, Germny: University of Veterinry Medicine; 2003. 2. Zeitler-Feicht MH, Bohnet W, Düe M, Esser E, Frnzky A, Pollmnn U. Positionsppier zu den Leitlinien zur Beurteilung von Pferdehltungen unter Tierschutzgesichtspunkten. Brmsche, Germny: Areitskreis Pferde of Tierärztliche Vereinigung für Tierschutz e.v (TVT); 2005. 3. Hunter L, Houpt KA. Bedding mteril preferences of ponies. J Anim Sci 1989;67:1986e1991. 4. Gerer V, Roinson NE, Luethi S, Mrti E, Wmpfler B, Stru R. Airwy inflmmtion nd mucus in two ge groups of symptomtic well-performing sport horses. Equine Vet J 2003;35:491e495. 5. Dunle AP, Dodd VA. A mechnicl ventiltion system for horse stles to control respirle dust. Ir Vet J 1999;52:257e262. 6. Billings LD. Methods for eddings livestock nd treting sludge. US Ptent 4,788,936 Decemer 6, 1988. 7. McGreevy PD, Cripps PJ, French NP, Green LE, Nicol CJ. Mngement fctors ssocited with stereotypic nd redirected ehviour in the thoroughred horse. Equine Vet J 1995;27:82e83. 8. Pedersen GR, Sondergrd E, Ldewig J. The influence of edding on the time horses spend recument. J Equine Vet Sci 2004;24: 153e158. 9. Dllire A. Rest ehvior. Equine Prct 1986;2:591e607. 10. Zeitler-Feicht MH. Hnduch Pferdeverhlten. Ursche, Therpie und Prophylxe von Prolemverhlten. Stuttgrt (Hohenheim), Germny: Eugen Ulmer GmH & Co; 2008. ISBN 978-3800155798. 11. Aspinll V. The complete textook of veterinry nursing. Edinurgh, United Kingdom: Butterworth Heinemnn; 2006. ISBN 978-0-7506-8847-5. 12. Pirkelmnn H. Pferdehltung: Verhlten, Areitswirtschft, Ställe, Fütterung und Krnkheiten, 2nd ed. Stuttgrt, Germny: Eugen Ulmer GmH & Co; 1991. 13. Fleming K, Hessel EF, Vn den Weghe HFA. Genertion of irorne prticles from different edding mterils used for horse keeping. J Equine Vet Sci 2008;28:408e418. 14. Fleming K, Hessel EF, Vn den Weghe HFA. Evlution of fctors influencing the genertion of mmoni in different edding mterils used for horse keeping. J Equine Vet Sci 2008;28:223e231. 15. Duncn P. Time-udgets of Cmrgue horses. Behviour 1980;72: 26e49. 16. Mills DS, Eckley S, Cooper JJ. Thoroughred edding preferences, ssocited ehviour differences nd their implictions for equine welfre. Anim Sci 2000;70:95e106. 17. Mills DS, McDonnell SM. The domestic horse. The evolution, development nd mngement of its ehviour. Cmridge, United Kingdom: University Press; 2005. 18. Fder C. Ausscheide- und Ruheverhlten von Pferden in Offenlufstllund Boxenhltung [PhD thesis]. Munich, Germny: Technicl University of Munich; 2002. 19. Ruckeusch Y. The hypnogrm s n index of dpttion of frm nimls to chnges in their environment. Appl Anim Ethol 1975;2: 3e18. 20. Rymgle P, Ldewig J. Lying ehvior in horses in reltion to ox size. J Equine Vet Sci 2006;26:11e17.