Behaviour of growing pigs kept in pens with outdoor runs

Livestock Production Science 69 (2001) 265–278 www.elsevier.com / locate / livprodsci

Behaviour of growing pigs kept in pens with outdoor runs II. Temperature regulatory behaviour, comfort behaviour and dunging preferences a, a b A.W. Olsen *, L. Dybkjær , H.B. Simonsen a

Danish Institute of Agricultural Sciences, Department of Animal Health and Welfare, Research Centre Foulum, P.O. Box 50, 8830 Tjele, Denmark b ˚ The Royal Veterinary and Agricultural University, Department of Animal Science and Health, Grønnegardsvej 8, DK-1870 Frederiksberg C, Denmark Received 28 March 2000; received in revised form 1 August 2000; accepted 22 January 2001

Abstract The aim of this study was to examine the temperature regulatory behaviour, comfort behaviour, and dunging preferences of growing pigs when housed in a barn with outdoor runs. Seven replicates, each consisting of 96 pigs of 10 weeks of age, were randomly distributed to eight experimental pens with outdoor runs, each provided with a wallow. The pigs were subjected to three environmental factors that might influence their behaviour: the side of the building (north / south), access to an outdoor shelter (6), and roughage (6). The pigs used the wallow for lying and oral behaviour within the whole temperature range (24 to 1 248C), but the duration of these behavioural patterns increased when the temperature exceeded 158C. The pigs placed the majority (more than 75%) of their dung in the outdoor runs — about 50% in the wallow. The pigs excreted away from the roughage and their lying area, and shade, provided on the south side of the building, was found to increase dung placed outside the building. The side of the building (north / south), roughage, and shelter are factors considered to be important to both the pigs’ temperature regulation and to where the pigs place their dung.  2001 Elsevier Science B.V. All rights reserved. Keywords: Pig-behaviour; Wallow; Outdoor runs; Shelter; Straw; Temperature; Straw-flow

1. Introduction One of the objectives of organic farming in Denmark is to consider the physiological and the behavioural needs of the animals (BØJ, 1994). *Corresponding author. Tel.: 145-89-991-368; fax: 145-89991-500. E-mail address: [email protected] (A.W. Olsen).

Therefore, organically raised pigs in Denmark have to be kept outside, but growing pigs may be kept indoors if they have free access to roughage and an outdoor area (BØJ, 1994). However, no rules apply with regard to concern for the pigs’ ability to regulate their body temperature. On cold days, lying in straw (Fraser, 1985), lying in sternal recumbency, and / or huddling (Geers et al., 1987) may be the pigs’ ways of staying warm. Solid

0301-6226 / 01 / $ – see front matter  2001 Elsevier Science B.V. All rights reserved. PII: S0301-6226( 01 )00173-7

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floors are about 3–58C warmer than slatted floors (Randall et al., 1983) and a bedding of 20–25 mm straw maintains a temperature about 7–88C warmer than concrete slats (Verstegen and van der Hel, 1974), and on deep-straw the temperature increment would be even larger (Mount, 1975). However, because pigs are not able to sweat, they are considered to be more sensitive to hot than cold conditions (Ingram, 1965). On hot days they may cool themselves by going into a wallow or under water sprinklers (Heitman et al., 1962), and they may seek protection from the sun in the shade (Heitman et al., 1962; Blackshaw and Blackshaw, 1994) when such facilities are available. They can also increase their heat loss by moving away from hot places to a cooler floor or a place with higher air velocity, changing their lying posture from belly to side, or by avoiding having body contacts with other pigs (Geers et al., 1986). On hot days they attempt to lie in a damp place or wallow, or even bathe in a standing position, as they do in natural conditions (van Putten, 1978). Rolling from side to side in the wallow or damp place (van Putten, 1978), the moist upper side will be cooled by evaporative heat loss (Ingram, 1965). However, wallowing is not only performed on hot days but also on cooler days, suggesting that wallowing also plays a role in skin and hair care (van Putten, 1978). After wallowing, pigs perform other types of comfort behaviour; Sambraus (1981) reported that sows shake themselves, and then rub their sides and back. Pigs are also able to rub their hindquarters by sitting down and moving forward and backward (van Putten, 1978). Usually, pig barns are not provided with wallows or sprinklers, and the pigs have to find other ways of cooling. Water dispensers be can used as showers, by splashing water out of the drinking bowl, by pressing the backs to the valve, or biting the valve and letting the water pass the mouth and wetting the floor (van Putten, 1978). Normally, pigs attempt to urinate and defecate furthest away from their resting area (Whatson, 1978; Baxter, 1984; Stolba and Wood-Gush, 1989). However, heat can make the pigs defecate and urinate on solid-floored areas of the pen in attempt to wallow in their own dung and urine (Geers et al., 1988). For other reasons, such behaviour is inappropriate as it causes poor hygiene in

the pen, increases odours and gases in the barn, and increases the labour for the farmer (Randall et al., 1983; Geers et al., 1988). Therefore, apart from giving the pigs ample straw to keep warm, when designing pig-barns it is also important to provide them with facilities that allow them to cool themselves on hot days. To meet the pigs’ needs for temperature regulatory behaviours and to avoid the consequences of them fouling the pen, knowledge of pigs’ dunging behaviour has to be taken into consideration when designing pig units. Many causes for pigs’ dunging preferences have been suggested over the years. Fritschen (1975) suggested that pigs preferred to dung in draughty, damp and open areas. Another common thought is that pigs prefer to dung in well-illuminated areas (Randall et al., 1983). Randall et al. (1983) observed more soiling on cold than warmer floors, and Hacker et al. (1994) found that pigs defecated more in the ‘wrong’ areas of the pen with increasing age and size of the pigs suggesting increased crowding as the cause. Hacker et al. (1994) also stated that pigs drink, urinate and defecate in a close sequence, and suggested that placing the drinker away from the sleeping area would keep that part of the pen clean. However, Stolba and WoodGush (1989) showed that pigs in a seminatural environment prefer to dung away from their sleeping area, which was also found in indoor housed pigs (Whatson, 1978; Baxter, 1984). To make it possible for the pigs to regulate their body temperature on hot as well as cold days, and to allow them to structure their environment in a hygienic manner, we designed a barn with different activity / temperature zones and floor types. The indoor area consisted of deep straw, straw-flow (Bruce, 1990) and slats. The outdoor runs included wallows, slats and concrete floors. The objectives of this study were, in this complex environment, to study the effect of three environmental factors — the side of the building (north / south), access to a shadegiving shelter (6), and roughage (6) — on the pigs’ dunging, comfort and temperature regulatory behaviour. Most of these behavioural patterns are hypothesised to depend on climatic conditions, shade, and the north vs. the south side of the building. Consequently, in this paper, special emphasis is put on these parameters.

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2. Materials and methods The procedure for behavioural observations, animals, housing and management used in the present investigation are described in detailed by Olsen (2000), but are outlined briefly here. The behaviour activities presented in this paper differ from those in the preceding paper (Olsen, 2000), and will be described in details. Seven replicates, each consisting of ninety-six pigs of 10 weeks of age were randomly distributed to eight experimental pens with outdoor runs: four at the south side of the building and four at the north side. Indoors pens consisted of a deep bedded straw area, a straw-flow area (Bruce, 1990) and slats. The outdoor runs were all provided with wallows and consisted of the following: shelter area (half of the runs were provided with shelters), a wallow (all runs), roughage trough (half of the runs were provided with roughage ad libitum) and the remaining outdoor area (all runs). The outdoor runs were cleaned once a day, the pigs were fed indoors ad libitum with cereal feed. More details on the animals used for the investigation, their housing and management are described in Olsen (2000).

2.1. Treatments and design The treatments were: (1) shelter (partial coverage) in the outdoor run, and (2) free access to roughage (wholecrop silage of barley and pears (Hordeum vulgare and Pisum sativum ssp. arvense)) in the outdoor run. As the two treatments may counteract with the side of the building (north vs. south), the two treatments were distributed as a 2 3 2 design within each side of the building (north / south). Moreover, we hypothesise that the pigs’ behavioural temperature regulatory activities are affected mainly by shelter, side of building and the climatic conditions. Therefore, in this paper, the side of the building is examined as a treatment. The shelter was made from a sheet of plywood (2.2 3 1.4 m) placed at the pen-fixtures 1.1 m above floor level at the end of the run closest to the building wall (measuring 2.2 m across the run and 1.5 m into the run). Due to the orientation of the building, the shelters on the north side of the building were overshadowed by the building itself in

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the morning and did not provide shade until in the afternoon. At the south side of the building, the shelters provided shade all day, but to a varying degree. Roughage was given in a trough (2.2 m long 3 0.4 m wide 3 0.2 m deep) placed on the ground in the outdoor run furthest away from the building. To prevent rain and snow from falling into the troughs, they were covered by a length of plywood at about 1 m above floor level.

2.2. Behavioural measurements Ninety-six outdoor raised pigs were moved into the eight experimental pens (i.e. 12 pigs per pen) at about 10 weeks of age (mean 5 68.6 days, S.D. 5 5.0). The adaptation period was 2 weeks before the observations began at week 3, and were repeated at weeks 5, 7, 9, 11 and 12. In each of these weeks, the observations were carried out on 2 successive days between 08:00 and 16:00. All 96 pigs were observed during these 2 days; 24 pigs each morning and afternoon. Two persons observed the same animal simultaneously; one person observed the current focal pig when outdoors, and the other person observed the current pig when it was indoors. In advance, the start positions (outdoor / indoor) of the two observers were determined randomly. The observers changed positions each day at noon after having observed 24 pigs (day 1) and again after observing 72 pigs (day 2); by the end of each 2-day observation period all 96 pigs had been observed, and the observations were distributed equally between observers indoor and outdoor on mornings and afternoons. The observation order for pigs and pens was determined randomly in advance. In each randomly chosen pen, each of three randomly chosen pigs was observed for 5 min by use of all-occurrence sampling. However, if the pig to be observed was not active, the next randomly listed pig was chosen for the observation (Dybkjær, 1992). Between each 5min observation period, a scan was made to determine the pigs’ locations in the different areas of the pen and outdoor run. The areas were defined as: indoor; deep-straw, straw-flow, straw-flow when facing the self-feeder, and slats, outdoor; wallow, shelter area, facing the roughage trough, and the

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remaining outdoor area. An overview of the barn can be seen in Olsen (2000). Handheld computers (Psion Organizer II and Psion Work About from Psion PLC (www.psion.com)) were used for data collection. Definitions of the pigs’ behaviours used for this paper are shown in Table 1.

2.3. Climatic measurements Dry bulb temperature (8C) and humidity (%) were automatically logged indoors and outdoors. During the scans, the observer located outdoors recorded the weather conditions; rain, snow, wind, overcast or sunshine (for each recording; yes / no).

2.4. Statistical analyses Because the pen was the experimental unit, penmeans were calculated on the basis of the 12 pigmeans per pen for each behavioural measurement (Table 1). All continuous variables were analysed by

mixed linear models using PROC MIXED with RANDOM statement of SAS (SAS Institute, 1995). Class variables were replicate (1–7), observation week (repeated measures; 1–6), pen (1–8), side of the building (North / South), roughage (6) and shelter (6). The model statement included roughage (df 5 1), shelter (df 5 1), side of the building (df 5 1) and week (df 5 5) as general fixed effects, and interactions between these variables if P , 0.05. Random variables included pen and replicate and all interactions in which they took part. Outdoor temperature (min: 2 4.48C, max: 1 23.78C), outdoor humidity (min: 56.8%, max: 99.3%), number of sun recordings (min: 0, max: 12), number of rain recordings (min: 0, max: 12) and number of wind recordings (min: 0, max: 12) were included if P , 0.05. Among all the climatic recordings, the abovementioned climatic variables were selected for the mixed linear analysis as described below. Snowfall was recorded only twice during the whole data collection period and was, therefore, excluded from the analyses. The number of overcast recordings

Table 1 Definitions of behaviour and postures Behaviours and postures

Description

Drinking

Snout in the drinking bowl and sounds comes from the activated water nipple Head inside the self-feeder, or chewing while moving head away from the feeder Lying in a wet area and wriggling the body The pig shakes its body The pig moves its body up and down against pen hardware The pig is sitting on the floor while sliding its hindquarters forwards and backwards against the floor The pig’s snout is in contact with the wallow water while moving its snout with forwards and backwards pointed movements, or only with forward pointed movements The pig lifts its head from the wallow water while chewing The pig’s snout is placed in the wallow water while bubbles comes from the water, but no rooting is performed The pig’s snout is placed in the wallow water, but no rooting or bubbles is made

Eating / chewing feed Wriggling Shaking Rubbing trunk Rubbing hindquarters Rooting in wallow water

Chewing wallow water Making bubbles in wallow Snout passive in wallow water Defecating Urinating Lateral recumbency Sternal recumbency Lying in contact General activity Sitting Standing / walking

Lying on the left or right side with all four legs visible The pigs lie on its belly, and less than four legs are visible Lying while a part of the trunk touches another pigs trunk Not lying with its eyes closed The pig sits with its front-legs stretch

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were also excluded as it were opposite to sunshine (recorded as ‘yes’ every time sunshine was recorded as ‘no’, and vice versa). The decision about what other climatic variables to include in the mixed linear analysis were made after subjecting all the remaining variables to correlation analysis. Indoor temperature and humidity showed high correlation with outdoor temperature and humidity, respectively (R S .0.9, P50.0001 for both) and, therefore, only the outdoor temperature and humidity were used in the mixed linear analyses. The five remaining climatic variables were then subjected to a principal component analysis to see if a further reduction in the climatic variables could be made. That was not the case, and all five remaining climatic conditions (outdoor temperature and outdoor humidity, number of sun recordings, number of rain recordings and number of wind recordings) were included in the mixed linear model analyses when P,0.05. When P,0.05, the relationship was investigated further by means of partial correlation analyses on pen level, adjusted for the effects of replicate, side of building, shelter and roughage. Parametric (Pearson) correlation analysis was used for the continuous variables (temperature and humidity), and Spearman correlation analysis for the ordinal variables (weather recordings). To meet the requirements of variance stability some of the dependent variables were ARCSIN transformed (inverse squared sine transformation). With regards to the oral activities directed towards the wallow water, too many zero-observations gave non-normal distribution, and therefore the nonparametric Wilcoxon rank sum test (Cody and Smith, 1991) was used to analyse these variables. Results of the oral behaviour directed to the wallows from the non-parametric statistics are given in ordinary means and standard derivations, but all other results are given in least square means and standard errors printed in PROC MIXED when using the LSMEAN statement. If transformed, LS-means and their S.E. were back-transformed using the approximations presented in Jørgensen and Pedersen (1998).

3. Results In Tables 2–5 fixed effects are shown when P, 0.05. Correlation coefficients with climatic effects

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are shown when both the mixed model and the following partial correlation analysis gave P,0.05 as shown in Tables 2–4, whereas no such effects showed up for the variables in Table 5. The percentages of the pigs located in the different areas of the pen and outdoor run are shown in Table 2. The majority (mean 85%) were located indoors during day-time hours where the behavioural observations were carried out, while 15% were located outdoors. On average, 64% of the pigs were located in the deep-straw area. At the north side of the building, a larger percentage of the pigs were in the straw-flow area facing the self-feeder compared to those housed at the south side of the building (P, 0.05). However, the side of the building did not affect time spent eating (mean5497.8 s / h, S.D.5 327.3) or food consumption (daily mean528.5 kg per pen, S.D.51.3; see Olsen, 2000). When the pigs were housed on the south side of the building and had access to roughage, a higher percentage were facing the roughage trough compared to those not having access to roughage, independently of the side of the building (P,0.05). The percentages of pigs located in the different areas of the pen and outdoor runs were also affected by temperature, humidity and sunshine (Table 2). Temperature and sunshine (the number of sun recordings) were the only two climatic conditions affecting the overall percentage of pigs being indoors and outdoors (P,0.05); a positive correlation was found for the percentage of pigs outdoors (P,0.01). Temperature also affected the percentage of pigs located in seven of the eight pen areas (P,0.05). Temperature correlated positively with the percentage of pigs located in the straw-flow, in the shelter area, wallow, facing roughage trough, and in the remaining outdoor area (P,0.01 for all). Temperature correlated negatively with the percentage of pigs on straw-flow facing the self-feeder and the percentage in the deep-straw (P,0.01). Humidity was found to affect the percentage of pigs facing the self-feeder and the percentage located in deep-straw (P,0.05); positive correlations were found for both variables (P,0.01). Sunshine (number of sun recordings) affected the number of pigs facing the roughage trough and percentage in the shelter area (P,0.05); positive correlations were found for both variables (P,0.01).

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Table 2 Percentage of the pigs located in the different areas of the pen and outdoor run; data are overall mean (S.D.), least-square means (LS-means) and S.E. for fixed effects when P,0.05, and correlation coefficients when P,0.05 Area

Overall mean (S.D.)

Deep straw

63.7 (0.14)

Straw-flow Facing the self-feeder

12.4 (9.1) 7.2 (3.0)

Indoor slats Shelter area

2.0 (1.5) 2.7 (3.6)

Wallow Facing roughage trough

2.3 (3.2) 3.7 (4.8)

Remaining outdoor area Total indoor

6.6 (4.8) 85.0 (9.6)

Total outdoor

15.0 (12.6)

Fixed effects LS-means

N: 7.6 b , S: 6.9 a

N2r: 3.1 b , N1r: 4.2 bc S2r: 2.1 a , S1r: 5.3 c

S.E.

0.2

1.0

Correlation coefficients d Temp: R P 5 20.75 Humid: R S 50.44 Temp: R P 50.67 Temp: R P 5 20.38 Humid: R P 50.36 Temp: R P 50.33 Sun: R S 50.23 Temp: R P 50.35 Temp: R P 50.27 Sun: R S 50.35 Temp: R P 50.42 Temp: R P 5 20.58 Sun: R S 5 20.30 Temp: R P 50.50 Sun: R S 50.33

a,b,c

Values with different superscripts are different at P,0.05. Results of partial correlation analysis when both PROC MIXED and the following correlation analysis gave P,0.05; R S , Spearman correlation coefficients; R P , Pearson Correlation coefficients; Temp, temperature (8C); sun, number of sun recordings. Abbreviations: N, north side of building, S, south side of building; 1r, 1 roughage, 2r, 2roughage. d

Table 3 shows the duration of comfort and temperature regulatory behaviour. Rubbing trunk was performed longer when pigs had access to shelter compared to pigs not having access to shelter (P, 0.05). Access to shelter also increased the duration of lying in sternal recumbency with body contact and total duration of sternal recumbency compared to the pigs without access to shelter (P,0.05 for both). When housed at the south side of the building, the pigs spent more time chewing wallow water and making bubbles in wallow water compared to those housed at the north side (P,0.05 for both). Pigs that had access to roughage spent less time standing / walking compared to non-roughage pigs at the north side of the building (P,0.05). Comfort and temperature regulatory behaviour were also affected by temperature, humidity, sunshine, and a single effect of wind was also found (Table 3). In Olsen (2000), we showed that oral behaviour towards wallow water was positively correlated with temperature. This behaviour consisted of rooting, chewing, making bubbles and having the snout passive in the wallow water, which, in this paper, we analysed separately to extract more

detailed information on this relationship. The pigs held their snout passive in the wallow water on average 3.6 s / h (S.D.511.3), which was not affected by either climatic conditions, shelter, or side of building (P.0.05), but rooting in wallow water correlated positively with temperature (P,0.01). Making bubbles in wallow water correlated positively with both temperature and the number of sun recordings, whereas it correlated negatively with humidity (P,0.01 for all). Temperature affected the comfort behaviour of ‘rubbing trunk’ and ‘rubbing hindquarters’, and they were both positively correlated with temperature (P,0.01 for both). ‘Wriggling’ (mean50.4 s / h, S.D.52.2) and ‘shaking’ (mean52.2, S.D.54.1) were not affected by any climatic condition. As mentioned in Olsen (2000) we found no effect on the time the pigs spent drinking (on average 39.7 s / h, S.D.537.4). The duration of the majority of the lying postures was affected by temperature (Table 3); positive correlations were found between temperature and total duration of lying, duration of lying without having body contact, duration of sternal recumbency without body contact, and lateral recumbency with-

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Table 3 Durations of behaviour (s / h); data are overall mean (S.D.), least-square means (LS-means) and S.E. for fixed effects when P,0.05, and correlation coefficients when P,0.05 Behaviour

Overall mean

Fixed effect LS-mean

Rubbing trunk Rubbing hindquarters d Rooting in wallow water d Chewing wallow water d Making bubbles in wallow water d

6.3 0.1 3.2 6.7 3.2

2s: 5.06 a , s: 7.61 b ,

0.75

N:4.74 a , S: 8.67 b N: 1.92 a , S: 4.42 b

2.01 1.19

Lateral recumbency without body contact Total lateral recumbency Sternal recumbency with body contact Sternal recumbency without body contact Total sternal recumbency Lying without body contact

301.4 (323.7) 785. 0 (506.9) 618.1 (398.4) 501.9 (363.9) 1119.9. (446.0) 803.2 (517.9)

Total lying

1904.9 (591.0)

Standing / walking

1515.2 (582.7)

(10.1) (0.6) (16.4) (26.2) (16.1)

S.E.

2s: 571.8 a , 1s: 664.3 b

57.1

2s: 1065 a , 1s: 1175 b

65.0

N2r: 1641,7 b , N1r: 1429.7 a S2r: 1521.1 ab , S1r: 1468.5 a

Correlation coefficients c Temp: R P 50.26 Temp: R S 50.26 Temp: R S 50.25 Temp: R S 50.24 Humid: R S 5 20.27 Sun: R S 50.26 Temp: R P 50.44 Humid: R P 5 20.21 Temp: R P 5 20.32 Temp: R P 50.58 Temp: R P 50.62 Humid: R P 5 20.41 Wind: R S 5 20.20 Temp: R P 50.32 Humid: R P 5 20.21

91.3

a,b

Values with different superscripts are different at P,0.05. Results of partial correlation analysis when both PROC MIXED and the following correlation analysis gave P,0.05; R S , Spearman correlation coefficients; R P , Pearson correlation coefficients; Temp, temperature (8C); Sun, number of sun recordings. d Fixed effects are analysed by Wilcoxon sum rank test and Spearman correlations are made. Abbreviations: N, north side of building; S, south side of building; 1s, 1shelter; 2s, 2shelter; 1r, 1 roughage; 2r, 2roughage. c

out body contact (P,0.01 for all). The total duration of lateral recumbency was the only lying posture that we found to be negatively correlated with temperature (P,0.01). Humidity was found to affect total duration of lying, duration of lying without body contact, and total duration of sternal recumbency (P,0.05 for all); all three variables were negatively correlated with humidity (P,0.01 for all). Lying without body contact was the only lying posture affected by wind (P,0.05), and we found them to be negatively correlated (P,0.01). Four postures were not affected by any climatic conditions (P. 0.05); duration of lateral recumbency with body contact (mean5483.6 s / h, S.D.5402.6), lying with body contact (mean51101.7 s / h, S.D.5539.9), sitting (mean5117.9 s / h, S.D.5105.9) and standing / walking (P.0.05 for all). The pigs’ general activity was not affected by climatic conditions (mean5 2170.8 s / h, S.D.5531.1). The duration of different lying postures in different areas of the pen and outdoor run are shown in

Table 4. Fixed effects are not shown in the table as only one was found. Pigs with access to shelter at the south side of the building increased the duration of lying laterally without body contact in the shelter area (LS-mean (S.E.): 16.4 (4.0)) compared to all other pigs (North2shelter57.3 (4.0), North1 shelter51.1 (4.0), South2shelter53.3 (4.0); P, 0.05). The climatic conditions influenced most of the variables shown in Table 4. Duration of lying laterally or sternally in deep-straw was influenced by temperature (P,0.05 for all); lying with body contact laterally or sternally correlated negatively with temperature (P,0.01 for both), whereas lying sternally without body contact correlated positively with temperature (P,0.01). The duration of all four different ways of lying at the straw-flow area was also affected by temperature (P,0.05), and all four lying postures correlated positively with temperature (P,0.01 for all). No pigs were observed lying on the indoor slats. In the shelter area, lying sternally

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Table 4 Duration of lateral and sternal recumbency with and without body contact to another pig in different areas of the pen and outdoor run. Data are overall mean (S.D.) and correlation coefficients when P,0.05 Area

Lying posture

Overall mean

Correlation coefficients a

Deep-straw

Lateral1 Lateral2 Sternal1 Sternal2

372.7 (367.9) 211.8 (247.8) 501.4 (413.1) 308.0 (261.0)

Temp: R P 5 20.30

Straw-flow

Lateral1 Lateral2 Sternal1 Sternal2

82.4 60.0 58.1 94.2

Temp: Temp: Temp: Temp:

Shelter area

Lateral1 Lateral2 Sternal1 Sternal2

2.6 (23.0) 7.0 (39.1) 9.2 (50.1) 24.0 (77.5)

Temp: R P 50.34 Sun: R S 50.21 Temp: R P 50.30, sun: R S 50.29

Lateral1 Lateral2 Sternal1 Sternal2

1.2 (15.3) 6.5 (35.7) 17.3 (75.1) 29.1 (90.2)

Temp: R P 50.20 Temp: R P 50.28 Temp: R P 50.32

Lateral1 Lateral2 Sternal1 Sternal2

24.7 16.1 32.0 46.5

Temp: R P 50.24 Temp: R P 50.29 Temp: R P 50.36, wind: R S 5 20.28 Temp: R P 50.33

Wallow

Remaining outdoor area

(184.4) (146.6) (111.3) (146.4)

(100.1) (60.5) (90.3) (113.9)

Temp: R P 5 20.52 Temp: R P 50.32 R P 50.35 R P 50.31 R P 50.27 R P 50.30

a

Results of partial correlation analysis when both PROC MIXED and the following correlation analysis gave P,0.05; R S , Spearman correlation coefficients; R P , Pearson Correlation coefficients. Temp, temperature (8C); Sun, number of sun recordings.

with body contact was affected by the number of sun recordings (P,0.05), and a positive correlation was found (P,0.01). Duration of lying laterally or sternally in the shelter area without body contact were both affected by temperature (P,0.05), and duration of sternal posture was also affected by the number of sun recordings (P,0.05 for all); only positive correlations emerged (P,0.01). No pigs were observed lying in the roughage trough. Lying laterally in the wallow with body contact was only done for about 3 s / h and was not affected by any treatment or climatic condition (P.0.05). However, the three lying postures in the wallow (sternally with or without body contact, and laterally without body contact) were affected by temperature (P,0.05), and these three variables correlated positively with temperature (P,0.01). In the remaining outdoor area, the duration of all four different lying postures was affected by temperature (P,0.05), and only positive correlations emerged (P,0.01). Lying sternally with body contact was also affected by the number of

wind recordings (P,0.05) and a negative correlation emerged (P,0.01). The percentage of all urinations and defecations in the different areas of the pen and outdoor run are shown in Table 5. No effect of climatic conditions emerged. The majority of the outdoor urinations and defecations were placed in the wallow, and more than 75% of all urinations and defecations were placed outdoors. The percentage of urinations and defecations placed outdoors were affected by a combination of shelter and side of building. When pigs were housed on the south side of the building, access to shelter in the outdoor run appeared to decrease the percentage of defecation and urination placed indoors. When housed on the south side of the building and not having access to shelter, the pigs defecated more inside the building compared to those on both sides of the building having access to shelter. Consequently, the south-side, non-shelter pigs also defecated less outside the building compared to shelter-pigs on the same side of the building

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Table 5 Percentage of all urinations and defecations in different areas of the pen and outdoor run. Data are overall mean (S.D.), and least-square means (LS-means) and S.E. for fixed effects when P,0.05 Overall mean Urinations Deep-straw Straw-flow

3.1 (15.2) 11.9 (27.3)

Indoor slats Shelter area Wallow When facing roughage trough Remaining outdoor area Total indoors Total outdoors

9.9 (26.3) 9.6 (24.7) 49.6 (44.1) 5.5 (20.5) 10.3 (25.9) 24.9 (37.0) 75.1 (37.1)

Defecations Deep-straw Straw-flow Indoor slats Shelter area Wallow When facing roughage trough Remaining outdoor area Total indoors Total outdoors

2.8 (15.9) 3.9 (17.3) 4.8 (18.3) 11.3 (26.6) 44.4 (43.3) 9.8 (25.7) 23.9 (26.3) 11.6 (28.3) 88.5 (28.3)

Fixed effects LS-mean

S.E.

2s: 18.4 b , 1s:7.2 a 2sN: 13.0 a , 2sS: 23.7 b , 1sN: 9.6 a , 1sS: 4.8 a 2sN: 3.3 a , 2sS: 6.7 a , 1sN: 14.8 b , 1sS: 8.3 ab 2s: 7.8 a , 1s: 15.4 b

4.0 4.9 3.1 3.1

2rN: 8.7 b , 2rS: 3.6 ab , 1rN: 2.0 a , 1rS: 5.1 ab 2r: 17.1 b , 1r: 8.7 a 2sN: 22.3 a , 2sS: 34.6 b , 1sN: 24.9 ab , 1sS: 16.5 a 2sN: 77.7 ab , 2sS: 65.4 a , 1sN: 75.1 ab , 1sS: 83.5 b

2.7 2.9 6.2 6.4

N: 0.9 a , S: 5.6 b

2.1

2sN: 5.0 a , 2sS: 17.5 b , 1sN:18.6 b , 1sS: 11.0 ab

4.4

2r: 14.3 b , 1r: 5.4 a

3.7

2sN:12.1 ab , 2sS: 22.4 b , 1sN: 14.7 a , 1sS: 7.5 a 2sN: 87.9 b , 2sS: 77.6 a , 1sN: 85.4 ab , 1sS: 92.5 b

5.4 5.5

a,b Values with different superscripts are different at P,0.05. Abbreviations: N, north side of building; S, south side of building; 1s, 1shelter; 2s, 2shelter; 1r, 1roughage; 2r, 2roughage.

and those on the north side not having access to shelter (P,0.05). Moreover, the south-side, nonshelter pigs urinated more frequent inside the building compared to shelter-pigs on the same side of the building and non-shelter pigs on the north side (P, 0.05). These pigs also urinated less outside the building compared to shelter pigs on the same side of the building (P,0.05), and urinated more frequently on the straw-flow compared to all other pigs (P, 0.05). The percentage of defecations placed in the shelter area decreased when the pigs had no access to shelter at the north side of the building compared to shelter-pigs on the same side (P,0.05), and compared to non-shelter-pigs on the south side of the building (P,0.05). The shelter-pigs housed at the north side of the building urinated more frequently in the straw-flow area compared to non-shelter pigs independently of the side of the building (P,0.05). Pigs with access to roughage placed their dung and urine closer to the building wall compared to the non-roughage pigs: they defecated less frequently when facing the roughage trough (P,0.05) and

urinated less frequently in the remaining outdoor area (P,0.05). The roughage-pigs housed at the north side of the building also urinated less frequently when facing the roughage trough compared to non-roughage pigs on the same side (P,0.05), whereas there was no difference within the south side of the building. Pigs housed on the south side defecated more frequently in the deep straw compared to pigs housed on the north side of the building (P,0.05). From observation week 3–12, the percentage of defecations placed outdoors increased from 76 to 92%; the percentage in week 3–7 were statistically lower than in week 9–12 (P,0.05). We found no effect of shelter or side of building on the frequency of the pigs’ postural changes. However, temperature was found to affect the number of times the pigs changed their lying postures in the wallow, in the shelter area, and in general regardless of the area in the pen (P,0.01 for all). Temperature also affected the number of times they changed any posture (including sitting and standing / walking) in the wallow and in total regardless of pen

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Fig. 1. Temperature, duration of lying in the wallow (squares) and standing / walking / sitting in the wallow (triangles) (s per h).

area (P,0.01 for both). Partial correlation analysis showed positive correlations between temperature and all the above-mentioned variables; R P varied between 0.33 and 0.41 (P,0.01 for all). Moreover, the recordings of sunshine was found to influence the number of posture changes in the shelter area (P, 0.01), and a positive correlation emerged (R P 50.23, P,0.01). Fig. 1 shows the duration of lying in the wallow and walking / standing / sitting in the wallow. The durations of the pigs’ walking / standing / sitting in the wallow remained almost constant within the temperature range, but the duration of lying in the wallow increased when the temperature exceeded| 148C.

4. Discussion The pigs were not subjected to extreme temperatures, as the range during the 2 years of data collection was from 24 to 1248C. Only 5% of the observations were carried out when temperature exceeded 188C and only 10% when the temperature

was lower than 08C. However, the majority of the pigs’ temperature regulatory and comfort behaviour was affected by climatic conditions. We found relationships between some of the climatic conditions and pigs’ oral behaviour towards the wallow water (see also Olsen, 2000), as well as the duration of different lying postures in different areas of the pens and outdoor runs. Rooting in wallow water and making bubbles in wallow water were found to increase with increasing temperature. Moreover, making bubbles and chewing wallow water were performed for longer periods on the south side of the building than on the north side, indicating that these three kind of behavioural activities change gradually with increasing temperature from being explorative to being temperature regulatory behaviour. However the duration of holding the snout passively in wallow water was not influenced by temperature, shelter, or side of building, suggesting that this behaviour is mainly a explorative / foraging activity within the temperature range investigated. The summed duration of these four types of behavioural activities towards the wallow water increased when the temperature exceeded 158C (Olsen,

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2000), and we suggest this temperature as the point where the behaviour gradually changes towards temperature regulatory associated behaviour. Similarly, in outdoor raised pigs, Andresen and Redbo (1999) found increased rooting in the wallow from about 208C. The duration walking / standing / sitting in the wallow remained almost constant within the temperature range, but the duration of lying in the wallow increased from about 148C (Fig. 1). This might suggest that the pigs’ use of the wallow to increasing their heat loss begin gradually at about 148C. However, in outdoor kept pigs, wallows are reported to be used regularly when temperature exceed 18–198C (Sambraus, 1981; Stolba and Wood-Gush, 1989). Even though the duration of lying in the wallow increased at approximately 148C, the pigs actually lay in the wallow within the whole temperature range, even at temperatures below 08C —but not for very long. This supports the suggestion that wallowing may play a role in pigs’ skin and hair care (van Putten, 1978). Also the duration of rubbing trunk and hindquarters increased with increasing temperatures supporting the fact that these behavioural comfort activities are related to the temperature regulatory behaviours (Sambraus, 1981). However, we found that access to shelter increased the duration of rubbing trunk. This is opposite of what we expected and no obvious explanation is apparent. In agreement with others (Riskowski et al., 1990; Geers et al., 1986), we found that increasing temperature appeared to increase lying without body contact and to decrease lying sternally with body contact; lying sternally while huddling is one of the pig’s ways of staying warm (Riskowski et al., 1990). The total duration of lying in sternal recumbency and the duration of lying in sternal recumbency with body contact appeared to increase when the pigs had access to shelter; probably because the shelter may increase the radiant cooling (see Baxter, 1984). Lying without body contact is a way to increase the body heat loss (Baxter, 1984). Moreover, we found this posture to be negatively correlated with the number of wind recordings; probably as increasing air movement increases the body heat loss by convection (Baxter, 1984). Not surprisingly, lying in deep straw with body contact was negatively correlated with temperature,

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as tucking into straw together with other pigs is an effective way to stay warm (Geers et al., 1986), whereas the duration of lying in deep-straw without body contact, and lying in all the other areas were positively correlated with temperature. These findings may suggest that lying with body contact in deep-straw is a significant way of staying warm, whereas lying in other areas of the pen and outdoor run are ways to increase heat-loss from the body. The effectiveness, however, depends on the posture of the pigs (lateral / sternal6body contact) and the thermal conductivity of the floor (material, wet / dry) (Baxter, 1984). The more recordings of sunshine, the higher percentage of the pigs lay in all areas other than the deep-straw area, i.e. they sought protection from the sun along the building wall (or under the shelter) and they increased the duration of cooling their snout by making bubbles in the wallow. The number of sun recordings was also correlated positively with duration of facing the roughage trough; probably because the pigs’ heads were then in shade of the sheet of plywood preventing rain and snow from falling into the trough. Of course the shade effect would be greatest on the south side of the building. On that side of the building, the roughage-pigs actually a spent longer time in that position compared to nonroughage pigs (regardless of side of the building), probably because of the pleasant combination of roughage and shade. Humidity was negatively correlated with the duration of lying and the duration of making bubbles in wallow water suggesting that increasing humidity increased behaviour to keep warm, whereas decreasing humidity increased behaviour to cool the pigs. However, we did not find any effects of the number of rain recordings on the pigs’ behaviours. Most frequently the pigs were located indoors (85%) in the deep straw area (60%), however, for several reasons the outdoor area increased the quality of the pen environment. The pigs had more choices of where to place their dung. About 3% of the all urinations and defecations were placed in the deep straw; more than 75% of the urinations and defecations were placed outdoors; about 50% in the wallow. The frequent use of the outdoor area for dunging gave a good air quality inside the barn (Møller and Olsen, 1999) to the benefit of both the

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pigs and the farmer. Furthermore, access to roughage in the outdoor run decreased oral behaviours towards pigs and pen hardware (Olsen, 2000). The fact that the pigs placed the majority of the dung outside the building and only about 3% in the deep-straw area may support the suggestion that pigs prefer to dung in light and draughty areas (Randall et al., 1983) and away from their sleeping area (Stolba and Wood-Gush, 1989). Furthermore, the frequent excretion in the wallow supports the suggestion of Fritschen (1975), that pigs prefer to excrete in wet areas. In sows, Sambraus (1981) found that defecation and urination was done before wallowing, but he found only a few cases of defecating and urinating in the wallow. Hacker et al. (1994) stated that pigs drink, urinate and defecate in a close sequence. In the present study, however, the pigs used the wallow for different type of oral behaviour, but we did not observe any drinking activity from the wallow. A higher percentage of the defecations was placed in the deep-straw (about 6%) when the pigs were housed on the south side of the building compared to when they were housed on the north side (about 1%). Within the south side of the building, access to shelter considerably reduced the percentage of the urinations placed at the straw-flow (from about 24 to 5%) and the overall percentage of the indoor urinations (from about 35 to 17%) and defecations (from about 22 to 8%). Therefore, providing shade when the pigs are housed on the south side of a building might make the pigs avoid dunging in their indoor area, thereby maintaining a healthier and more pleasant air to the benefit of both pigs and farmer. We found that the pigs preferred not to defecate and urinate close to the roughage. Because of the so-called ‘unstable posture’ during excretion (Randall et al., 1983), pigs do not prefer to dung in busy areas (Baxter, 1982). Aarnik et al. (1997) suggested that this is the reason why pigs keep their dung away from their food. The pigs do use a bent posture during defecations and urination, keeping their foreand hind-legs closer together than when either standing or walking. However, in this study, the majority of the dung was placed in one single area — the wallow — the most slippery place in the whole pen. Moreover, slats are often more slippery than straw-strewn concrete floors. Pigs usually walk carefully on slats, but mostly they use the place to

dung. Therefore, if an ‘unstable posture’ is the reason why pigs keep their dung way from the feed, they would probably not use the slats (or the wallow in this study) for defecation either. We suggest that the pigs prefer to keep the feed free from dung much the same as they prefer to keep the lying area free from dung (Stolba and Wood-Gush, 1989). From a management point of view, this knowledge can be used to arrange the pens in such a way that pigs prefer to dung in the areas that are most convenient for the farmer. Dunging on the concrete areas has been observed to increase during the growing period (Hacker et al., 1994; Aarnik et al., 1997) with increased crowding as the suggested reason. However, in the present investigation, where the pigs had outdoor runs and ample space, this was not the case. In contrast, we found that the pigs increasingly defecated and urinated outside the building during the growing period. This suggests that fouling on the concrete floor in pig-barns can most likely be avoided by the provision of outdoor runs, thereby decreasing the task of cleaning floors and, thereby improving the air quality inside the barn. Except from the duration of lying in the deep straw area, the duration of lying in the different areas of the pen and outdoor areas correlated positively with temperature. Also, a higher percentage of pigs were located in these areas when the temperature increased. Less use of the straw-area and more use of the concrete areas and slats with increased temperature are also reported by others (van Putten, 1978; Fraser, 1985; Geers et al., 1986), and is considered to be one type of temperature regulatory behaviour. In the present study, we found a higher percentage of pigs located outside the building when the sun was shining, but they sought protection from the sun along the building wall (or under the covering). More pigs were also facing the roughage trough when the sun was shining, probably because the pigs’ heads then were in shade from the protective sheet of plywood. The shade effect was, of course, greatest on the south side of the building where more pigs were found when they had access to roughage probably because of the pleasant combination of roughage and shade. Humidity correlated positively with the percentage of pigs located in the deep straw, indicating that increasing humidity may increase the

A.W. Olsen et al. / Livestock Production Science 69 (2001) 265 – 278

behaviour to keep warm, and decreasing humidity increase behavioural cooling activities. However, we did not find any effects of the number of rain recordings on pigs’ behaviour. Furthermore, no effects of the climatic conditions on pigs’ excretory behaviour was found, probably because the pigs were not subjected to extremes of temperatures.

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and Centre for Applied Ethics, University of British Columbia, Canada. The technical assistance of P.M. Hagelskjær, M. Levring, L. Jensen and E.L. Decker, Danish Institute of Agricultural Sciences, is gratefully acknowledged. We also thank Hans Kier’s Fund, The Danish Society for Animal Protection, and the Danish Research Centre for Organic farming for contributing to the financing of this study.

5. Conclusion References Pigs’ temperature regulatory and comfort behaviour was found to be dependent on temperature. The pigs used the wallow for lying within the whole temperature range from 24 to 1248C, but the duration of oral activities towards the wallow and the duration of lying in the wallow increased when temperature exceeded approximately 158C. Consequently, we suggest that these types of behaviour are temperature regulatory activities at higher temperatures, but exploratory / foraging, and skin- and hair caring activities, at lower temperatures. The majority of the dung — more than 75% — was placed in the outdoor runs, which increased significantly during the growing period (from 76 to 92%). The pigs kept the dung away from the roughage and lying area, and they placed about 50% of their dung in the wallow. This supports the theory that pigs prefer to dung in light, draughty and wet places, and that they keep their dung away from their nest and food. Shade provided on the south side of the building was found to increase dung placed outside the building. Consequently, from a management and health perspective, north vs. south side of the building, roughage, and a shade-giving shelter are important considerations in where pigs place their dung and should be considered when designing finishing units.

Acknowledgements We thank the following for their advice: Dr. H.B. Simonsen, Department of Animal Science and Animal Health, The Royal Danish Veterinary and Agricultural University; Dr. E.-M. Vestergaard, Department of Animal Health and Welfare, Danish Institute of Agricultural Sciences; Dr. David Fraser, Animal Welfare Program, Faculty of Agricultural Sciences

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