Effects of late introduction of sows to two farrowing environments on the progress of farrowing and...

L. J. Pedersen and T. Jensenfarrowing and maternal behavior

Effects of late introduction of sows to two farrowing environments on the progress of

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Running head: Introduction of sows to farrowing pens 1

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Effects of late introduction of sows to two farrowing environments on the progress of farrowing 3

and maternal behavior. 4

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L. J. Pedersen1 and T. Jensen. 6

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Institute of Animal Health, Welfare and Nutrition., Faculty of Agricultural Sciences, University of 8

Aarhus, 8830 Tjele, Denmark. 9

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1Corresponding author: [email protected] 12

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Page 1 of 31 Journal of Animal Science

Published Online First on May 9, 2008 as doi:10.2527/jas.2007-0749 by guest on October 13, 2011jas.fass.orgDownloaded from


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ABSTRACT: To evaluate the effect of late introduction to farrowing pens on the progress of farrowing 15

and maternal behavior, 20 primiparous and 20 multiparous sows were allocated randomly to 1 of 2 16

treatments 1) early introduction to pen (EP, n = 20) and 2) late introduction to pen (LP, n = 20). To 17

evaluate the difference between loose housed sows and crated sows when introduced late to the 18

farrowing environment a third treatment was included 3) late introduction to farrowing crate (LC, n =19

20). Sow behavior and piglet birth intervals were recorded using video recordings from 16 h before the 20

birth of the first piglet (BFP) until 48 h after BFP. Behavioral data were analyzed using Proc Mixed in 21

SAS whereas the percentage of stillborn piglets as well as the response of the sow to piglet scream was 22

analyzed using Proc Genmod in SAS. Before farrowing (16 h to 3 h before BFP) sows introduced late 23

to pens had more postural changes per hour than sows introduced early to pens (LP = 12.7, EP = 8.9; P24

= 0.04), whereas there were no differences between sows introduced late to crates and sows introduced 25

late to pens (LC = 14.2, LP = 12.7; P = 0.53). Inter-birth interval (P = 0.04), variation in the inter-birth 26

interval (P = 0.01), and percentage of stillborn piglets (P = 0.003) were affected by an interaction 27

between parity and treatment. In multiparous sows there were no differences between treatments (P >28

0.18) either in the progress of farrowing or in the percentage of stillborn piglets. For primiparous sows, 29

there were no differences (P > 0.22) between sows that were introduced late to pens and sows that were 30

introduced early to pens. Primiparous sows that were introduced late to crates compared to pens had 31

longer inter-birth intervals (LC = 29 ± 4.9 min, LP = 16 ± 2.9 min; P = 0.02), a greater variation of 32

these intervals (LC = 35 ± 8.3 min, LP = 16 ± 3.6 min; P = 0.006), and a greater percentage of stillborn 33

piglets (LC = 21 %; 95 % confidence interval ranging 14 to 30 %, LP = 5 %; 95 % confidence interval 34

ranging 2 to 12 %; P = 0.004). After farrowing, neither postural changes, time spent in lateral lying, 35

Page 2 of 31Journal of Animal Science



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number of near crushing situations, nor the response to piglet scream test were affected by treatment (P36

> 0.09). When sows and gilts were introduced late to farrowing pens, neither progress of farrowing nor 37

maternal behavior of importance for piglet crushing were influenced. However, crating primiparous 38

sows that were introduced late to the farrowing environment compared to pen housing had detrimental 39

effects on the progress of farrowing and the percentage of still born piglets. 40

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Keywords: environment, farrowing pens, maternal behavior, sows, stillborn piglets 42

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INTRODUCTION 44

In intensive pig production sows are often moved to the farrowing unit close to the time of farrowing. 45

This is due to a combination of an increased weaning age and increased litter size leading to more use 46

of foster sows that nurse 2 litters in succession. Thus some farrowing crates are occupied for a longer 47

period and consequently there will not be room for the next batch of sows. To move sows immediately 48

before farrowing may be stressful, with potential negative effects on the progress of farrowing and 49

maternal behavior (Lawrence et al., 1997). Because maternal behavior and neonatal piglet viability is 50

considered of great importance for early piglet survival when sows are kept loose, the production 51

success may be particularly sensitive to such management procedures in loose-housed sows. When kept 52

under natural conditions, sows will seek isolation and initiate nest-building 2 to 3 d before farrowing 53

(Jensen, 1986). Thus sows introduced late to the farrowing housing begin seeking isolation while still 54

in the gestation unit. The lack of an outlet for this strong motivation may also constitute a stressor, 55

interfering with aspects of maternal behavior of importance for early piglet survival such as nesting 56

behavior and carefulness when lying down (Andersen et al., 2005; Pedersen et al., 2006). Present 57

knowledge indicates that moving sows shortly before farrowing may interfere with the progress of 58




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farrowing and other aspects of maternal behavior thereby reducing piglet survival. Such a 59

relationship may particularly be important when sows are housed loose in pens where the impact of 60

piglet viability and maternal behavior on piglet survival seems greater. The aim of the present study 61

was 1) to investigate the effect of late introduction to farrowing pens on the progress of farrowing and 62

maternal behavior and 2) to evaluate differences between penned and crated sows in maternal 63

behaviors. 64

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MATERIALS AND METHODS 66

Animals, Housing and Treatment 67

All procedures involving animals were approved by the Danish Animal Experiments Inspectorate in 68

accordance with the Danish Ministry of Justice Law no. 382 (June 10, 1987) and Acts 333 (May 19, 69

1990), 726 (September 9, 1993) and 1016 (December 12, 2001). 70

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Sixty sows (Landrace x Yorkshire) were used in a randomized complete block design with 2 blocks. In 72

block 1 the sows were primiparous and in block 2 the sows were multiparous (2.2 ± 1.1 litters, mean ±73

SD). Within blocks sows were randomly distributed to 3 times of introduction to the farrowing unit. To 74

evaluate the effect of late introduction to farrowing pens on the progress of farrowing and maternal 75

behavior, 20 primiparous and 20 multiparous sows were allocated randomly to 1 of 2 treatments 1) 76

early introduction to pen (EP; n = 20) and 2) late introduction to pen (LP; n = 20). To evaluate the 77

difference between loose-housed sows and crated sows when introduced late to the farrowing 78

environment a third treatment was included 3) late introduction to farrowing crate (LC; n = 20). In the 79

late introduction to crates and pens, sows were moved from the gestation pen to the farrowing 80




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environment on d 114 of pregnancy while in the early introduction to pens the sows were moved from 81

the gestation pen to the farrowing pen on d 95 of pregnancy, except the first 6 sows that were moved on 82

d 105 of pregnancy. The reason for changing the day of introduction from d 105 to d 95 was that it 83

allowed for additional sampling of the time taken to adjust to the new environment (data not reported 84

here). Initial analysis showed no differences in any response variables between the 2 d of introduction. 85

Thus the 2 treatments were treated as 1 throughout the paper. 86

87

The experiment was conducted run from February to October 2005 at the experimental herd of 88

Research Center Foulum. Sows were walked a distance of 100 m from the gestation unit to the 89

farrowing unit in batches of 6 sows approximately weekly. They were moved between 1000 and 1100. 90

Each farrowing unit comprised between 20 and 28 farrowing pens or crates in an environmentally 91

controlled building. The room temperature was kept constant around 20°C throughout the experiment. 92

Farrowing pens for loose-housed sows (Figure 1) measured 2.7 m x 3.2 m and were divided into a 93

resting area (2.7 m x 1.5 m) with concrete floor and an activity area with slatted floor (2.7 m x 1.7 m). 94

A moulded piglet box of plastic with an integral plastic flooring measuring 1 m in length x 0.5 m in 95

width x 0.45 m in height was situated in the center of the pen. The box had a single opening of 31 cm x 96

33 cm facing towards the resting area of the pen and an infrared heating lamp was connected to each 97

box. The day before expected farrowing the piglet box was filled with a 10 cm layer of chopped straw 98

and the heating lamp was turned on. At the back wall of the resting area a 2.5 m long farrowing rail of 99

galvanized iron (4 cm in diameter) was positioned 15 cm from the wall and 22 cm above the floor. The 100

back wall and the sidewalls were made of solid plastic. The front wall that was facing the alley from 101

where the sows were fed and inspected consisted of iron tubes. The feed trough, a water nipple with an 102




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open water bowl below, and a straw rack were positioned in the front of the pen. Pens for crated sows 103

(Figure 1) consisted of a total area measuring 2.35 m in length and 2 m in width. Two thirds of the 104

floor was concrete whereas the remaining third at the hind part of the sow had slatted metal floor. 105

Within a pen the sow was crated by spindle tubing. The crates measured 2 m in length and were 106

adjustable in width from 0.65 cm to 0.80 cm. 107

108

During gestation (from 4 wk after mating) all sows were housed in dynamic groups of 30 to 35 sows 109

with a space allowance of approximately 3 m2 per sow and with access to 1 electronic sow feeding 110

station per pen. Primiparous sows and multiparous sows were kept separate in different groups. Pens 111

were divided into a resting area with concrete floor and an activity area with slatted floor also made of 112

concrete. The feeding station was placed in the slatted floor area. Sows got a daily ration of 2.6 kg feed 113

containing 7.62 MJ net energy/kg. The feeding cycle started at 0500 and access to the feeding station 114

was closed during nighttime from 0900 to 0500. Approximately 200 g chopped straw per sow was 115

delivered daily by hand in the solid concrete area. 116

117

In the farrowing units sows were fed twice daily with a standard sow meal containing 8.40 MJ net 118

energy/kg. Before farrowing sows were fed a ration of 2.6 kg daily and after farrowing the sows feed 119

ration was gradually increased over the next 2 wk until sows were fed ad libitum. In the farrowing pens 120

long straw was available ad libitum from a straw rack. Crated sows got approximately 500 g long straw 121

twice daily delivered in front of their feed trough. If soiled, the pen was cleaned once daily, but fresh 122

straw was left untouched. During the previous farrowing and lactation all multiparous sows had been 123

housed in the same type of pen or crate as the experimental housing. Thus older multiparous sows may 124

have had experience with both types of farrowing housing. 125




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Behavioral Observations and Tests 127

A digital video camera (TVCCD-14IR, Monacor, Bremen, Germany) connected to a standard PC was 128

placed above each pen/crate. Recordings were carried out from d 114 of pregnancy until 48 h after the 129

birth of first piglet (BFP) using a digital surveillance system (MSH-Video, M.Shafro & Co., Riga, 130

Latvia). The time of birth of each individual piglet was recorded and the mean birth interval as well as 131

the variation (calculated as SD) in the birth intervals within each litter was calculated. Nest building 132

behavior was observed from 16 h before BFP until 8 h after. The duration of nest building within each 133

hour was recorded (for the applied definition of nest building see Table 1). The number of postural 134

changes per hour, defined as the number of shifts between the 4 postures (lateral lying, sternal lying, 135

sitting, and standing and walking combined) in Table 1 and the duration of lateral lying per hour were 136

observed from 16 h before, and 48 h after, BFP. Initial data inspection showed that around 80 % of the 137

sows (both crated and penned) did not show extensive nest building earlier than 16 h before BFP. Very 138

little nest building behavior was observed after BFP and therefore only the last 16 h before BFP was 139

included when analyzing the duration of nest building behavior. The 16 h were divided into 2 periods: 140

P1 was 16 h to 3 h before BFP and P2 was 2 h before BFP until BFP. After BFP the 48 h observations 141

of postural changes and lateral lying were divided into 2 periods: P3 was 0 to 8 h after BFP and P4 was 142

9 to 48 h after BFP. 143

144

From BFP until 48 h after, the total number of incidents, where piglets were either crushed or at risk of 145

being crushed (defined as a piglet being trapped underneath the sow’s body but surviving, or the piglet 146

being hit, and knocked out of the way by the sow during a postural change (Marchant et al., 2001) was 147

observed. 148




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149

Between 18 and 36 h after BFP the sow’s response to the playback sound of a screaming piglet was 150

tested (Thodberg et al., 1998). The test was repeated at 4 d after farrowing. The scream of an alien 151

piglet that was held by a person who firmly pressed the body of the piglet was recorded on a tape 152

recorder (AV30 MkII, Dan-sound Educational, Denmark) and a standardized 2-min sequence was used 153

during testing. The playback recorder was placed on the roof of the piglet box in the pens and on the 154

bars at the back of the crates. The test was not started until at least 5 min after a nursing bout. The 155

observer remotely switched on the playback recorder while the sow was lying laterally. Sow behavior 156

was observed from a remote video. The sound of the screaming piglet was played until the sow was 157

standing up or for a maximum of 2 min. The latency until the sow responded either by rolling over to 158

sternal lying, by sitting, or standing up was recorded during the test. 159

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Other Recordings 161

The length of pregnancy was recorded by calculating the number of days from first insemination until 162

the day of BFP. The total number of piglets born was counted and all dead piglets were necropsied to 163

count the number of stillborn piglets and the number of crushed piglets. A piglet was categorized as 164

being stillborn when the piglet had not been breathing and a piglet was defined as crushed when 165

traumas were visible as internal or external lacerations (for methodology see Damm et al., 2005b). 166

167

Statistical Analysis 168

The following basic generalized linear model was used to analyze data: 169

Model (1): Yijk =µ + αi + βj + αβij + Xijk + εijk 170




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In model (1) µijk is the expected value of the response variable, αi is the effect of the ith treatment (LC, 171

LP, EP), βj is the effect of the jth parity (primiparous sows, multiparous sows), Xijk is the number of 172

total piglets born in the kth sow, and ε is the error term. The experimental unit for treatment and parity 173

effects was sows. 174

175

In the analysis of the length of gestation, the average inter-birth interval as well as the variation in the 176

inter-birth interval, the total number of near-crushing situations, the number of postural changes per 177

hour, the time spent in lateral lying per hour and the duration of nest building behavior per hour, the 178

response value Yijk was normally distributed with N(µijk,σ2). Proc Mixed in SAS (SAS Inst. Inc, Cary, 179

NC) version 9.1 was used to analyze these data. 180

181

For time spent nest building the basic model (1) was extended to include periods (P1 and P2) as a fixed 182

effect and sows as a normally distributed random effect against which the effects of treatment and 183

parity were tested. A similar model was used when analyzing the number of postural chances and time 184

spent in lateral lying, where data from 16 h before BFP until 48 h after BFP was used. In conjunction 185

with P1 and P2 two additional periods were included in the fixed period effect, P3 and P4. 186

187

Data on mortality were not normally distributed and were thus analyzed in a generalized linear model 188

for Poisson distributed data ( McCullagh and Nelder, 1989) using the Proc Genmod in SAS. Therefore, 189

when analyzing data on mortality (still born, crushed and dead of liveborn), Yijk was set to logit (Pijk)190

where Pijk is the expected number of dead piglets in the ijkth litter. The response value Yijk was 191




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approximately binominal distributed with Bin(Pijk, Nijk), where Nijk is the number of total piglets born 192

in the ijkth litter. Due to a tendency for over dispersion, the PSCALE option in Proc Genmod in SAS. 193

194

In analysis of the piglet scream test it turned out that more than 40 % of the sows did not respond to the 195

test. Therefore data were dichotomized into two categories: sows that responded within 2 min and sows 196

that did not. When analyzing the probability that sows were responding to the piglet scream test on d 1 197

and d 4, Yijk was set to logit (Pijk), where Pijk is the expected probability of sows responding in the 198

piglet scream test. The observed response of the sow to the piglet scream test in the ijkth litter is Yijk ∼199

Bin (Pijk). 200

201

Pairwise comparisons of treatment effects for each parity class were made using the contrast statement 202

in the respective procedures of SAS. Estimated LS means ± SE are shown in the text, figures, and 203

tables for the normally distributed data whereas data on mortality and responsiveness to the piglet 204

scream test is shown as LS means with 95 % confidence intervals. 205

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RESULTS 207

Two primiparous sows on the LP treatment and 1 primiparous sow on the LC treatment were omitted 208

from the analysis, due to various technical problems with the video recordings of these animals. 209

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Farrowing 211

Length of gestation was affected by parity (P = 0.03), with longer gestation length for primiparous 212

sows than for multiparous sows. There was no effect of treatment (P = 0.20) on length of gestation 213

(Table 2). 214

215

The mean inter-birth-interval (IBI) was affected by an interaction between treatment and parity (P =216

0.04). The IBI was not different between the EP sows and the LP sows either in primiparous (P = 0.83) 217

or in multiparous sows (P = 0.35). In contrast, the IBI of primiparous sows was longer in the LC sows 218

than in the LP sows (P = 0.02), whereas there was no difference (P = 0.27) in the IBI between the 219

multiparous LC and LP sows (Table 2). Furthermore the IBI increased with increasing number of total 220

piglets born (F1,50 = 4.7, P = 0.03). There were no differences in IBI between primiparous and 221

multiparous sows either in LC sows (P = 0.14), LP sows (P = 0.09) or EP sows (P = 0.40). 222

223

A similar interaction between treatment and parity was found for the variation in the IBIs (P = 0.01). 224

The variation in the IBI was greater for the primiparous LC sows than for the primiparous LP (P =225

0.006) whereas there was no difference (P = 0.18) between multiparous LC sows and multiparous LP 226

sows (Table 2). The primiparous LC sows had a greater variation than multiparous LC sows (P = 0.06) 227

whereas primiparous LP sows had less variation in IBI than multiparous LP sows (P = 0.03; Table 2). 228

Also the percentage of stillborn piglets was affected by the same interaction (P = 0.003), in that 229

primiparous LC sows had greater percentage of stillborn piglets than primiparous LP sows (P = 0.004). 230

There was no difference between LC and LP sows (P = 0.26) and between LP and EP sows (P = 0.60) 231

for the multiparous sows. Primiparous LC sows also had greater percentage of stillborn piglets than 232

multiparous LC sows (P < 0.001). The back transformed estimated mean percentages of stillborn 233




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piglets are shown in Table 2 along with the significances level of the chi-square test of the contrasts 234

between the treatments within parity class and between parity class within treatment (Table 2). Using 235

these estimates the odds ratio of giving birth to a stillborn piglet in primiparous LC sows was 236

calculated to be 5 times greater than for primiparous LP sows (95 % confidence interval was ranging 237

1.6 to 14.7; X2 = 8, P = 0.004). The odds ratio for primiparous LP sows was not different from that of 238

primiparous EP sows (2.7 with a 95 % confidence interval ranging 0.5 to 13.0) (P = 0.20). Treatments 239

were not different in the percentage of crushed piglets (P = 0.68) or in the percentage of liveborn 240

piglets that died (P = 0.28; Table 2). 241

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Nesting Behavior and Postural Changes 243

The time spent nest building tended to be different between treatments (F2,53 = 2.6, P = 0.08). However, 244

the EP and LP sows (LP = 101 ± 48 s/h, EP = 142 ± 50 s/h; P = 0.50) were not different and neither 245

were the LP and LC sows (LC = 46 ± 17 s/h, LP = 101 ± 48 s/h; P = 0.13). Time spent nest building 246

was influenced by an interaction between period and parity (P = 0.002) in that primiparous sows and 247

multiparous sows spent an equal amount of time nest building during P1 (primiparous = 221 ± 84 s/h; 248

multiparous = 387 ± 140 s/h) whereas primiparous sows spent less time nest building than multiparous 249

sows during P2 (primiparous = 7 ± 3 s/h, multiparous = 92 ± 33 s/h; P = 0.002). 250

251

The number of postural changes was affected by an interaction between period and treatment (P =252

0.02). During P1 and P2, respectively, EP sows had less postural changes than LP sows (P = 0.04 and 253

P = 0.12), whereas EP sows and LP sows did not differ (P > 0.40) during P3 and P4. There were no 254




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differences (P > 0.33) between LP and LC sows in the number of postural changes during any of the 255

periods (Figure 2). 256

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Time spent lying lateral was not affected by treatment (P = 0.68). Time spent lying lateral was 258

influenced by an interaction between period and parity (P = 0.002). Primiparous sows compared to 259

multiparous sows spent more time in lateral lying during P1 (primiparous = 1,138 ± 127 s/h-1,260

multiparous = 762 ± 121 s/h-1; P = 0.03) and P2 (primiparous = 2601 ± 127 s/h, multiparous = 1,856 ±261

121 s/h; P = 0.001) whereas there were no difference in P3 (primiparous = 3,241 ± 127 s/h; 262

multiparous = 3,220 ± 121 s/h) and P4 (primiparous = 2,873 ± 127 s/h; multiparous = 2,658 ± 121 s/h). 263

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Near-Crushing Incidents and Odds Ratio for Responding to the Sound of a Screaming Piglet 265

The number of near-crushing incidents was affected by parity (P = 0.03) and total number of piglets 266

born (P = 0.03). Primiparous sows had more near-crushing situations during the 48-h observation 267

period than multiparous sows (2.25 ± 1.37 vs. 0.69 ± 0.74) and the number of near crushing situations 268

increased with increasing number of total piglets born (estimated regression coefficient = 0.11 ± 0.05). 269

The number of near-crushing situations tended to differ between treatments (P = 0.08), in that LC sows 270

tended to have fewer near-crushing situations than LP (LC = 0.52 ± 0.71, LP = 1.82 ± 1.35; P = 0.08). 271

Crushing incidences were not different for LP and EP sows (LP = 1.82 ± 1.35, EP = 2.04 ± 1.40). 272

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The odds ratio for sows to respond to the sound of a screaming piglet did not differ between treatments 274

and between parity on d 1 or d 4. On d 1, 59 % responded to the scream test whereas on d 4, 56 %275

responded. 276




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DISCUSSION 278

Effects during the Nest Building Phase 279

Results showed that introducing sows to farrowing pens close to the time of farrowing increased the 280

number of postural changes but had no influence on the time spent nest building. This may indicate that 281

while the motivation to nest build is unaffected by the late move, the sows were still responding to the 282

new environment by general restlessness. Restlessness was not further increased in crated sows 283

introduced late compared to penned sows introduced late. Earlier studies have shown that being crated 284

compared to being penned on introduction to the farrowing unit increases restlessness during the nest 285

building phase (Jarvis et al., 2001) and induces increased HPA–axis activity (Cronin et al., 1991; 286

Lawrence et al., 1994; Jarvis et al., 1997, 2001). It is thus surprising that we did not find a similar effect 287

of crating in the present study. The effect on restlessness of introducing the sow late to the farrowing 288

unit may be greater than the effect of crating. 289

290

Even though crated sows performed a similar number of postural changes they tended to perform less 291

nest building behavior than penned sows moved late. An effect of environment on nesting behavior has 292

been found in several earlier studies (Thodberg et al., 2002; Damm et al., 2003 Jarvis et al., 2001) 293

where sows in farrowing pens spent more time nest building than sows in farrowing crates. In addition, 294

the nature and the amounts of substrate directed behavior differ between the housing systems (Jarvis et 295

al., 2001). Primiparous sows in the present experiment appeared to start their nest building later than 296

multiparous sows, which has also been found in earlier studies (Jarvis et al., 2001; Thodberg et al., 297

2002). 298

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Effects on the Progress of Farrowing and Stillborn Piglets 300

Being introduced late to pens did not influence the progress of farrowing, and the percentage of 301

stillborn and crushed piglets either in primiparous sows or multiparous sows. This indicated that the 302

stress of being introduced to a novel environment in itself is not large enough to interfere with the 303

progress of farrowing. 304

305

In contrast, crating sows compared to penning them upon late introduction affected both the progress of 306

farrowing and the number of stillborn piglets. The effect was however only present in the primiparous 307

sows. Several authors have shown that crating of primiparous sows is stressfull and induces changes in 308

the HPA-axis during the peri-parturient period even when the sows were introduced 5 d before 309

expected farrowing (Lawrence et al., 1994; Jarvis et al, 1997, 2001). An additional activation of the 310

HPA-axis and or increased opioid secretion caused by the stress of being crated in primiparous sows 311

may contribute to the longer IBI, increased variation in the IBIs and greater percentage of stillborn 312

piglets seen in the present study. Effects of crating primiparous sows on the progress of farrowing and 313

the percentage of stillborn piglets, are likely to be the combined effects of the novelty of confinement 314

(Cronin et al., 1991; Lawrence et al., 1994), restriction of the highly motivated nest-building behavior 315

(Lawrence et al., 1994) and farrowing in a novel environment (Lawrence et al., 1992). It seems less 316

likely that being in a crate during farrowing in itself is stressful because neither Gilbert et al. (1997) nor 317

Jarvis et al. (1998) found any effect of crating on the HPA- axis activity during farrowing. This is 318

possibly due to the fact that sows spent the majority of farrowing lying still anyway. Another 319

explanation may be, that the natural physiological increase in cortisol is so high during farrowing that it 320

overrides any additional stress increased elevation of cortisol. 321

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The difference between the crated primiparous sows and the crated multiparous sows in the progress of 323

farrowing and the percentage of stillborn piglets, that were not evident in the penned sows, further 324

strengthens the importance of the novelty of confinement. Primiparous sows were crated for the first 325

time in their life when introduced to the farrowing crate and they may thus respond stronger to the 326

stress of crating due to lack of experience with such a restrictive environment. This is supported by 327

Jarvis et al. (2002) and Thodberg et al. (2002) who found that sows in their second parity showed some 328

signs of adaptation to crating in response to previous experience, in both nest building behavior and 329

progress of farrowing. 330

331

A change in the housing method from the gestation period to the farrowing period has been shown to 332

affect both the peri-parturient behavior (Beattie et al., 1995; Harris and Gonyou, 1998; Boyle et al., 333

2000, 2002) and the percentage of stillborn piglets (Cronin et al. 1996). This supports the concept that 334

the novelty of being crated for the first time in the farrowing unit is stressful to an extent that it affects 335

both behavior and the birth process. The difference in the percentage of stillborn piglets for the 336

primiparous sows moved late to crates compared to the primiparous sows moved late to pens was 337

greater in the present study than what was found by Cronin et al. (1996) where primiparous sows were 338

moved earlier to either crates or pens. Beside the more long lasting negative effect of crating on the 339

birth process (Biensen et al., 1996; Cronin et al., 1996) there may be an additive effect of the novelty of 340

crating. 341

342

Due to the current EU legislation the use of confinement during gestation will be banned from 2014. 343

However, crating is still allowed and widely used during farrowing. Seen in the light of the negative 344

effect this shift in housing system has on the progress of farrowing and the percentage of stillborn 345




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piglets as emphasized by both the present and previous studies it would be beneficial to hasten 346

development of farrowing pens for loose sows. 347

348

Effects on Posture and Maternal Behavior after Birth 349

The majority of crushing and death in general occur within the first 1 to 2 d of the piglets’ life. During 350

the first 8 h after BFP the sows are mainly in lateral lying (Pedersen et al., 2003). Because crushing 351

occurs during postural changes, a high level of restlessness during this particular period may constitute 352

a potential risk situation for newborn piglets (Damm et al., 2005a,b). However, late introduction to the 353

farrowing pens did not increase restlessness during this period, or during the next 9 to 48 h, indicating 354

that sows were not influenced by the late introduction to an extent that increase restlessness. 355

356

The number of postural changes seems important for piglets’ risk of being crushed. In addition, it may 357

be equally important that the sow perform pre-lying behavior that effectively clusters the piglets before 358

the sow lies down. Such behaviors have been shown to reduce the number of near crushing situations 359

(Marchant et al., 2001). Sows that are disturbed for example due to novelty of the environment or due 360

to restriction in their movement may be less attentive during lying down and the risk of near crushing 361

situations may thus be greater. The present study did, however not find increased number of near 362

crushing situations in the late introduced sows compared to the early introduced sows indicating that 363

sows readily adapted to the new environment. Penned sows tended to have more near-crushing 364

incidents than crated sows, however without a parallel increase in percentage of piglets that died from 365

crushing. This may indicate that even though the crate helps reduce the number of near crushing 366

situations it may not effectively reduce the risk of crushing. Weber et al. (2007) found in a large survey 367

on crated and penned sows that a greater percentage of piglets died from crushing in penned sows than 368




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in crated sows, whereas the total mortality did not differ between the 2 systems. Perhaps weak piglets 369

are more easily crushed in a pen than in a crate because weak piglets are unable to respond properly to 370

pre-lying behavior. On the other hand weak piglets may die from other causes such as hypothermia, 371

lack of milk or disease in a crate system. Even though primiparous and multiparous sows had the same 372

number of postural changes after BFP, the primiparous sows had more near-crushing incidents than 373

multiparous sows. An explanation for this could be that primiparous sows are less experienced in 374

performing pre-lying behavior and in clustering the piglets before lying down. However this has never 375

been studied in detail. 376

377

Even though both a large number of postural changes and a large number of near crushing situations 378

may be considered a risk to piglet survival, data on crushing does not always support this (Pedersen et 379

al., 2006). How the sow responds when a piglet is trapped underneath it may be equally important. A 380

trapped piglet will scream if possible and it will have a better chance to escape if the sow responds to 381

its scream by changing posture than if the sow remains lying (Weschler and Hegglin, 1997). Previous 382

research has shown much variability in the way sows respond to the scream of a trapped piglet 383

(Grandinson et al., 2003). Although the trait seems slightly heritable (Grandinson et al., 2003), 384

environmental disturbances may also affect the response. For example novelty of the environment may 385

take the sows attention away from the newborn piglets or make them more responsive. However, no 386

such effects were found in the present study by the late introduction to pens. 387

388

The present study showed that sows introduced late to farrowing pens did not respond to the new 389

environment to an extent that affected the progress of farrowing and behaviors of importance for piglet 390

survival. Therefore, late introduction to the farrowing environment does not seem to be a problem 391




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19

when sows are housed in farrowing pens on introduction. In contrast, late introduction to crates 392

compared to pens severely affected the progress of farrowing and the percentage of stillborn piglets in 393

primiparous sows. Whether this effect was due to the novelty of crating or crating in itself cannot be 394

verified from the present study because no sows were introduced early to crates. 395

396

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475Table 1. Ethogram for the behavioral elements observed from 16 h before birth of

first piglet (BFP) until 48 h after BFP

Behavior Description

Lateral lying Sow is lying on the side with one shoulder touching the floor.

Sternal lying Sow is lying on the belly without a shoulder touching the floor.

Sitting Both feet on the sow’s front legs as well as the sow’s posterior

are touching the floor.

Standing/walking Sow stands on all four legs.

Nest building Sow stands on all four legs engaged in either of the following

behaviors: Rooting (repeated snout movements on the floor with

or without straw), pawing, carrying straw in the mouth and

arranging straw in the nest (up and down head movements

directed towards straw on the ground or in a pile).

476




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477

Table 2. Progress of farrowing and mortality for primiparous and multiparous sows moved day 114 of

pregnancy to pens (LP) or crate (LC) or moved day 109 of pregnancy to pens (EP) for farrowing

Primi parous sows Multi parous sows

Treatments

(n)

LC

(9)

LP

(8)

EP

(10)

LC

(10)

LP

(10)

EP

(10)

Length of

gestation, d1

117.5 ± 0.4 116.3 ± 0.4 117.3 ± 0.4 115.8 ± 0.4 116.3 ± 0.4 116.8 ± 0.4

Inter-birth

interval, min1

29 ± 4.9 a 16 ± 2.9b 17 ± 2.7b 21 ± 3.4 b 27 ± 4.3 b 22 ± 3.6 b

Variation in the

inter-birth

interval, min1

35 ± 8.3ax 16 ± 3.6 bx 18 ± 4.2b 22 ± 5.1 by 26 ± 6.9by 26 ± 6.1 b

Total piglets

born2

13.4 ±3.8 13.3 ±3.6 14.5 ± 2.7 16.5 ± 2.27 15.8 ±2.8 15.3 ±2.3

Stillborn ,% 3 21 (14 to 30)ax 5 (2 to 12)b 2 (1 to 7)b 4 (2 to 8) by 7 (4 to 13)b 5 (2 to12) b

Total dead of

liveborn,% 3

6 (2 to 18) 19 (9 to 34) 18 (9 to 32) 14 (6 to 30) 18(9 to 35) 22 (12 to36)

Crushed,% 3 5 (1 to 15) 15 (7 to 29) 12 (5 to 24) 4 (1 to 17) 8 (3 to 23) 13 (6 to 25)

a,b Row values within parity with different superscripts differ (P < 0.05). x,y Row values within treatment different superscripts differ (P < 0.05). 1 Lsmeans (± SE). 2 The number given is the raw mean ± std because no statistical calculation was carried out. 3 The estimated mean as percentage of total born piglets with the 95 % confidence interval shown in bracket.

478




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Figure 1. Schematic drawing and picture of the farrowing environment for (A) sows in pens and (B) 479

sows in crates 480

481




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482A)

B)

483

Straw rack

Feed for sow

Water for sow and piglets

Feed for piglets

Creep area

3,27 m

2,68 m

Straw rack

Feed for sow

Water for sow and piglets

Feed for piglets

Creep area

3,27 m

2,68 m 2,35 m

0,60 m

2,00 m0,83 m0,65 m

Feed for piglets

Creep area

0,70 m

Heat lamp

Water for piglets

0,5 m

Feed for sow

2,35 m

0,60 m

2,00 m0,83 m0,65 m

Feed for piglets

Creep area

0,70 m

Heat lamp

Water for piglets

0,5 m

2,35 m

0,60 m

2,00 m0,83 m0,65 m

Feed for piglets

Creep area

0,70 m

Heat lamp

Water for piglets

0,5 m

Feed for sow

Figure 1 E-2007-0749




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Figure 2. The number of postural changes per h in different periods relative to the birth of the first 484

piglet (BFP) for sows moved d 114 to farrowing crates (LC), sows moved d 114 to farrowing pens (LP) 485

and sows moved d 95 to farrowing pens (EP). a,b Means with different superscript indicate significant 486

difference between columns within periods (P < 0.05)487

488

489

490

491

492

493

494

495

496

497

498

499

500

501

502

503

504

505

506




29

29

507

508

509

510

511

512

513

514

515

516

517

518

519

520

521

522




30

30

523

524

525

526

527

528

529

530

531

532

533

534

535

536

537

538

02468

1012

141618

16 to 3hbefore BFP

2 to 1h beforeBFP

0 to 8h afterBFP

9 to 48h afterBFP

Num

ber/h LC

LP

EP

a

ab a

b

ab




31

31

539

540

541

542

543

544

545

546

547

548

549

550

551

552

Figure 2 E-2007-0749




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