The effect of group-housing with free-farrowing pens on reproductive traits and the behaviour of low-risk and high-risk crushing sows

Applied Animal Behaviour Science 211 (2019) 33–40

Contents lists available at ScienceDirect

Applied Animal Behaviour Science journal homepage: www.elsevier.com/locate/applanim

The effect of group-housing with free-farrowing pens on reproductive traits and the behaviour of low-risk and high-risk crushing sows

T

⁎

C.G.E. Grimberg-Henricia, , K. Büttnera, R.Y. Lohmeiera, O. Burfeindb, J. Krietera a b

Institute of Animal Breeding and Husbandry, Christian-Albrechts-University, Olshausenstr. 40, D-24098 Kiel, Germany Chamber of Agriculture of Schleswig-Holstein, Gutshof 1, D-24327 Blekendorf, Germany

A R T I C LE I N FO

A B S T R A C T

Keywords: Group housing system Free-farrowing pens Piglet mortality Low-risk and high-risk crushing sows

Free-farrowing systems and group-housing systems for lactating sows are sensitive systems and require an optimal interaction of different environmental factors to be successful. The aim of the present study was to compare sows’ reproductive traits during lactation in two group-housing systems (GH; GHbig: n = 40; GHsmall: n = 40) and in a single-housing system (SH; n = 63). The two GH systems differed in size (GHbig: 8.3 m2 / sow; GHsmall: 7.1 m2 / sow). The GH sows were separated into free-farrowing pens from three days ante partum until six days post partum. For the remaining time, the sows and piglets were allowed to run together in the whole GH system. Data were collected in four batches with 20 GH sows (GHbig: n = 10; GHsmall: n = 10) and 16 SH sows in each housing system. Regarding the reproductive traits, sows of both GH systems had significantly more total piglet losses (e.g. crushing, underweight, runt) and crushed more piglets during lactation compared to the SH sows (p < 0.05). In addition, the GHsmall sows had higher total piglet losses and crushed more piglets compared to the GHbig sows (p < 0.05). Besides the reproductive traits, the lying down and rolling behaviour of both highrisk crushing sows (HRC; ≥35% crushed piglets; n = 10) and low-risk crushing sows (LRC;≤20% crushed piglets; n = 10) in the GH system were investigated in the first 72 h post partum to obtain more information about critical situations of piglets being crushed. HRC and LRC sows did not differ in their frequency of lying down movements. However, HRC and LRC sows performed more lying down movements by using the pen walls, which has been described as the safest way to prevent crushing. With regard to rolling movements, HRC sows rolled more frequently and performed significantly more 180° rolling movements from one side to the other side (p < 0.05) and 90° rolling movements ‘onto belly’ from the side onto the belly (p < 0.05). Furthermore, piglets of HRC sows were significantly less active during postural changes (p < 0.05). In conclusion, the safety of the piglets with regard to higher pre-weaning mortality was reduced in the GH systems with the free-farrowing pens. In addition, the pen size of the free-farrowing pens of the GH systems had an influence on the total piglet losses. More piglet losses were documented for sows in smaller free-farrowing pens. Additionally, the detailed observation of HRC and LRC sows within the same housing system showed high variation in their maternal behaviour and in their postural changes in free-farrowing pens. Especially HRC sows performed more rolling movements compared to LRC sows.

1. Introduction A group-housing system for lactating sows offers the sows and piglets a more natural rhythm ante partum and post partum (Jensen, 1986), a stronger sow-piglet relation (Arey and Sancha, 1996; Grimberg-Henrici et al., 2016) and a more gentle weaning procedure due to fewer and less intensive fights between the piglets (Bohnenkamp et al., 2013b). Besides these positive effects of a group-housing system during lactation, pre-weaning piglet mortality remains a critical economical and ethical issue. Free-farrowing pens within group-housing

⁎

systems offer sows and their piglets even more contact and freedom of movement. However, piglet mortality rates range from 11 to 34% (Pedersen et al., 1998; Weber, 2000; Marchant et al., 2001; Andersen et al., 2007; Baxter et al., 2015) in free-farrowing pens. Piglets are most vulnerable to crushing in the first 24 h post partum and 50% of crushed piglets are documented in the first two days after birth (Marchant et al., 2001; Kilbride et al., 2012). The pre-weaning mortality of piglets due to crushing is a multifactorial problem. The probability of a piglet being crushed is associated with the health of the piglet (Marchant et al., 2001; Pedersen

Corresponding author. E-mail address: [email protected] (C.G.E. Grimberg-Henrici).

https://doi.org/10.1016/j.applanim.2018.12.001 Received 2 July 2018; Received in revised form 26 November 2018; Accepted 3 December 2018 Available online 05 December 2018 0168-1591/ © 2018 Elsevier B.V. All rights reserved.

Applied Animal Behaviour Science 211 (2019) 33–40

C.G.E. Grimberg-Henrici et al.

8.3 m2 and each sow from the GHsmall system 7.1 m2 including the individual space in the free-farrowing pen and the running area. The sows with their litters were separated into the free-farrowing pens from three days ante partum until six days post partum. After six days post partum, the gates of the pens were opened, and all sows and piglets were allowed to mix. Sows in the GH system were fed electronically in the pens with an ad libitum commercial meal. Ad libitum feeding has been found to prevent aggression between sows (Barnett et al., 1994). Thus, ad libitum feeding was a required management action in the GH system because a sow’s aggression in a group and its restlessness are major disruptive factors, and interest of each other’s feed between sows is a common reason for aggression (Csermely and Wood-Gush, 1987). In GH systems, in which the sows had the possibility to separate during feeding and to not be disturbed by other sows, no ad libitum feeding is required, as shown in the studies of Bohnenkamp et al. (2013c) and Grimberg-Henrici et al. (2016). Drinking nipples for the piglets and the sows were available in each pen. A separate feeding area for the creep diet for the piglets was provided in the running area. Sows in the SH system were fixed permanently in farrowing crates (2.0 m × 2.6 m) and were fed electronically with a commercial meal, which increased constantly during lactation to a maximum of 7.5 kg per day. SH pens had water-heated piglet resting areas (0.6 m2) with heating lamps and, in addition, manipulable material (plastic balls and wood) was made available. The floor in these pens was a plastic, slatted floor with an iron, slatted floor part in the lying area of the sows. Sows and piglets shared a drinking trough. Creep feed was provided in feeding bowls for the piglets. All litters were standardised to 14 piglets for each sow until two days post partum. Because of large litter sizes cross-fostering was the exception within the treatment groups. Moreover, if a cross-fostered piglet died, this loss was assigned to the foster mother. Surplus piglets moved out the experiment and were raised by artificial nurses or foster sows, which were not part of this study. Piglets heavier than the mean weight within the litter were chosen randomly to be taken away from their biological mother. This procedure is in accordance with the methods of Phillips et al. (2014). Moreover, boars were not castrated and all piglets of batches 2 and 4 were not tail-docked. The piglets were weaned on average 26 ± 1 days post partum. During gestation, all sows were housed in a dynamic group with electronic feeding stations and were randomly moved to the GH or SH system, respectively, one week before the calculated farrowing date. The average number of parities of the GH sows were 4.27 ± 0.26 and of the SH sows 3.90 ± 0.31. Lights were switched on at 6 a.m. and off at 8 pm.

et al., 2011), the litter size relating to lower individual birth weights (Milligan et al., 2002), maternal performance (Marchant et al., 2001; Andersen et al., 2005; Burri et al., 2009; Wischner et al., 2009) and the condition and age of the sow (Weary et al., 1998). In addition, piglet mortality is influenced by pen design (Weary et al., 1996a; Herskin et al., 1998; Weary et al., 1998), the expertise of the sow with alternative farrowing systems (Marchant et al., 2000), the expertise of the stockpersons (Li et al., 2010) and the lying down and rolling behaviour of the sow, as reviewed by Damm et al. (2005). Especially the lying down and rolling behaviour of the sows has a great influence on the number of crushed piglets. Some studies have reported high numbers of crushed piglets during lying down movements (Weary et al., 1998; Marchant et al., 2001). In turn, other studies have documented more crushed piglets during rolling movements (Weary et al., 1996a, 1998; Danholt et al., 2011). Moreover, several studies have described pre-lying behaviour, which has a positive effect on the number of crushed piglets (Schmid, 1991; Marchant et al., 2001). However, no studies have observed pre-rolling behaviour, which makes rolling movements extremely dangerous for piglets, as reviewed by Damm et al. (2005). In addition, pen design has an influence on these types of behaviour. For example, fewer piglets are crushed when sows use the pen walls during lying down (Marchant et al., 2001), and related thereto, sloped walls are shown to be very useful in reducing crushing (Marchant et al., 2001). Furthermore, sows roll less on concrete floors compared to plastic floors (Weary et al., 1998). Softer floor types such as sand and straw are said to reduce the number of crushed piglets, however, the frequency of rolling movements is not reduced (Herskin et al., 1998). In light of this, the objective of the present study was to investigate differences in pre-weaning piglet mortality between group-housed and single-housed sows. Two different sizes of free-farrowing pens within a group-housing system were tested with regard to differences in piglet mortality rates. Reproductive traits and piglet losses were documented in detail during lactation. In addition, sows with few crushed piglets (LRC) and sows with many crushed piglets (HRC) in free-farrowing pens were observed with regard to their lying down and rolling behaviour 72 h post partum to obtain more information about critical situations of piglets being crushed. 2. Material and methods 2.1. Animals and housing The study was conducted on the Futterkamp agricultural research farm of the Chamber of Agriculture of Schleswig-Holstein over a period from April 2016 until January 2017. A total of 143 cross-bred (Large White × Landrace) nulliparous and multiparous sows and their piglets (Pietrain x (Large White × Landrace)) were observed during lactation in a group-housing system (GH; GHbig: n = 40; GHsmall: n = 40) and in a conventional single-housing system (SH; n = 63). Data were collected in four batches with 20 sows in the GH system and 16 sows in the SH system per batch. Multiparous sows, which were assigned to the GH system, were housed before in a SH system. The GH systems differed in size but had an identical design (Fig. 1). Ten sows were housed together in both GH systems. Each sow had a free-farrowing pen (GHbig: 2.2 m × 2.6 m; GHsmall: 2.2 m x 2.4 m) provided with an embedded and covered piglet nest (1.7 m2) with a rubber floor and a heating lamp. The pens had a straw rack and anti-crush rails along the pen walls. Furthermore, in the free-farrowing pen, half of the floor was a plastic, slatted floor and the other half a concrete, slatted floor. Manipulable material (plastic balls) was also available to the sows and the piglets. All pens had an entrance for the sows and a separated entrance for the piglets to a shared running area (GHbig: 2.5 m × 12.0 m; GHsmall: 2.5 m x 11.0 m), which was also equipped with anti-crush rails along the walls. The floor of the running area was a concrete, slatted floor. Each sow from the GHbig system had in total

2.2. Reproductive traits The reproductive traits of the sows were documented as the number of live-born piglets, stillborn piglets, total piglet losses and individual weights of the piglets one day after birth. Piglet losses were recorded during the whole lactation period regarding cause, date, weight of the piglet and location of the dead piglet. Total piglet losses included piglets that were crushed and piglets that had died due to other causes (e.g. underweight, runt, splay legs). The documentation of the piglet losses were conducted visually by well-trained caretakers. 2.3. Video analysis All sows were videotaped during their time in the farrowing stables. Video cameras (Axis M3024LVE, 5 frames/s) were positioned above each pen to obtain a complete overview. In the free-farrowing pens, high numbers of crushed piglets were documented in the first days after birth. Sows with low and sows with high piglet motility rates due to crushing were analysed to obtain information on dangerous situations for piglets of being crushed and to find differences in sows’ and piglets’ behaviour. The sows were observed continuously in the first 72 h post partum based on Philipps et al. (2014). The borders for high-risk and 34

Applied Animal Behaviour Science 211 (2019) 33–40

C.G.E. Grimberg-Henrici et al.

Fig. 1. A schematic view of the group-housing system and single-housing system (2.0 m × 2.6 m). Two different variants of a group-housing system were tested with ten individual pens numbered from one to ten (GHbig: 2.2 m × 2.6 m; GHsmall: 2.2 m × 2.4 m) and a shared running area (GHbig: 2.5 m × 12.0 m; GHsmall: 2.5 m × 11.0 m).

when the sow made a postural change. Therefore, the frequencies of the lying down and rolling movements of the sows, the frequency of the position of the piglets at the moment when the sow was lying down or rolling and the number of crushed piglets during these postural changes were recorded (Table 1).

Table 1 Ethogram for behavioural observations of lying down and rolling movements of the sows and piglets’ positions in the first 72 h post partum (modified according to Wischner et al., (2010)). Parameter

Description Sows

Crushing Lying down Lying down using pen walls Lying down without using pen walls Rolling

180˚ rolling (side-side) 90˚ rolling ‘onto side’ (belly-side) 90˚ rolling ‘onto belly’ (side-belly)

2.4. Statistical analysis

No movement of trapped piglet after a change in the posture of the sows. From a standing or sitting posture in a ventral, sternal or lateral recumbency. From a standing or sitting posture in a ventral, sternal or lateral recumbency by leaning on a pen wall to lie down. From a standing or sitting posture in a ventral, sternal or lateral recumbency by lying down freely without using a pen wall. Postural changes in a lying posture from one lateral position to another lateral position (side-to-side) or from a ventral or sternal position to a lateral position (bellyto-side). Postural changes in a lying posture from one lateral position to another lateral position (side-to-side). Postural changes in a lying posture from a ventral or sternal position to a lateral position (belly-to-side). Postural changes in a lying posture from lateral position to a ventral or sternal position (side-to-belly).

All data were analysed with the statistical software SAS® 9.4 (SAS Institute Inc., 2008). Fixed effects were added in a stepwise manner to the model. The Akaike’s information criteria corrected (AICC) and the Bayesian information criteria (BIC) were used to compare the different models. The model with the smallest AICC and BIC values was chosen. The residuals were tested for normal distribution. 2.4.1. Reproductive traits The normally distributed data of the reproductive traits as the number of piglets born alive, the birth weight of the piglets and the weight of dead piglets (except stillborn piglets) were analysed with the MIXED procedure. The data of the number of stillborn piglets was analysed with the GLIMMIX procedure with a Poisson-distribution using the log-link function. The models included the fixed effects housing system (GHbig, GHsmall, SH), batch (B1-B4), parity class (Class 1: 1; Class 2: 2–4; Class 3: ≥5), the interaction between housing system and batch and the interaction between housing system and parity class. The interactions were removed from the model if no significant effects were found. The sow was added to the model of birth weight and the weight of dead piglets as a random effect nested in the housing system. The significance of differences in the least square means was adjusted by the Bonferroni-correction. The number of total piglet losses and the number of crushed piglets were analysed with the GLIMMIX procedure with a binomial-distribution using the logit-link function. The model included the fixed effects housing system (GH, SH), batch (B1-B4), parity class (Class 1: 1; Class 2: 2–4; Class 3: ≥5), the interaction between housing system and batch and the interaction between housing system and parity class. The interactions were removed from the model if no significant effects were found. The sow was added to the model as a random effect nested in the housing system. The significance of differences in the least square means was adjusted by the Bonferroni-correction. In addition, the course of the number of crushed piglets was analysed. Therefore, the number of crushed piglets for the three time periods (1: birth to day two (Birth-Day2); 2: day three to day five (Day3-Day5); 3: equal to or greater than day six (> Day6)) was analysed with the GLIMMIX procedure with a Poisson-distribution using the log-link function. The model included the fixed effects housing system (GHbig, GHsmall, SH), batch (B1-B4), parity class (Class 1: 1; Class

Piglets Position ‘nest’ Position ‘near sow’ Position ‘active’ Position ‘non-synchronous’

At least 70% of the piglets were resting in the piglet nest during postural change of the sow. At least 70% of the piglets were active near the sow or resting near the sow during postural change of the sow. At least 70% of the piglets were walking or running around in the pen during postural change of the sow. At least 70% of the piglets did not perform the same behaviour during postural change of the sow.

low-risk crushing sows were calculated with UNIVARIATE in the statistical software SAS® 9.4 (SAS Institute Inc., 2008) to determinate the quantiles of the 25%, with low and high numbers of crushed piglets respectively. On the basis of this calculation and with regard to almost equal distribution of the number of parities of the sows, ten GH sows were selected with piglet crushing mortality rates equal to or less than 20% – which corresponds to one to three crushed piglets (low-risk crushing (LRC) sows) – and ten GH sows with piglet crushing mortality rates equal to or greater than 35% – which corresponds to seven to ten crushed piglets (high-risk crushing (HRC) sows). The video recordings were analysed with the Behavioural Observation Research Interactive Software (BORIS version 4.1.4) and an event sampling method was used by scoring the sow and the position of the piglets at the moment 35

Applied Animal Behaviour Science 211 (2019) 33–40

C.G.E. Grimberg-Henrici et al.

2: 2–4; Class 3: ≥5), time period of crushing (Birth-Day2, Day3Day5, > Day6) and the interaction between housing system and time period of crushing. The sow was added to the model as a random effect nested in the housing system. The significance of differences in the least square means was adjusted by the Bonferroni-correction. 2.4.2. Video analysis The number of live-born piglets and the birth weight of the piglets were analysed with the MIXED procedure. The models included the fixed effects group (LRC, HRC), parity class (Class 1: 1; Class 2: 2–4; Class 3: ≥5) and the interaction between group and parity class. The interaction was removed from the model if no significant effects were found. In addition, the random effect of the sow nested in the group was added to the model of the birth weight of the piglets. The significance of differences in the least square means was adjusted by the Bonferronicorrection. The number of crushed piglets regarding the lying down and rolling movements during the first 72 h post partum were analysed with the GLIMMIX procedure with a Poisson-distribution using the log-link function. The models included the fixed effects group (LRC, HRC), parity class (Class 1: 1; Class 2: 2–4; Class 3: ≥5) and the interaction between group and parity class. The interaction was removed from the model if no significant effects were found. In addition, the covariable number of live-born piglets of the sows was included in the model. The significance of differences in the least square means was adjusted by the Bonferroni-correction. The data of the sows’ and piglets’ behaviour from the video analysis were analysed with a multivariate variance analysis using the GLM procedure and the MANOVA statement. The model included the dependent variables of the total frequency of lying down movements of the sows during the first 72 h post partum, the total frequency of rolling movements of the sows during the first 72 h post partum and the total frequency of piglet positions during postural changes of the sow. The independent variables were group (LRC, HRC) and parity class (Class 1: 1; Class 2: 2–4; Class 3: ≥5). The number of live-born piglets was added to the model as a linear continuous variable. The significance of differences in the least square means was adjusted with the Bonferronicorrection.

Fig. 2. LSMeans with standard error of the time course of the number of crushed piglets for the interaction between housing systems (group-housing system (GHbig, GHsmall); single-housing system (SH)) and time period of crushing (Birth-Day2, Day3-Day5, < Day6).

compared to the dead piglets of the SH sows over all batches (GHbig: B1: 1.46 kg ± 0.14; B2: 1.53 kg ± 0.13; B3: 1.37 kg ± 0.11; B4: 1.07 kg ± 0.14 vs. GHsmall: B1: 1.10 kg ± 0.12; B2: 1.29 kg ± 0.11; B3: 1.32 kg ± 0.12; B4: 1.48 kg ± 0.12 vs. SH: B1: 1.23 kg ± 0.13; B2: 1.11 kg ± 0.13; B3: 0.95 kg ± 0.13; B4: 0.97 kg ± 0.11; F6,83.6 = 2.34, p = 0.0388). Other causes that led to piglet mortality such as underweight, runt, splay legs etc. were higher for SH sows compared to sows from both GH systems (GHbig: 3.99% ± 0.89 vs. GHsmall: 5.45% ± 1.07 vs. SH: 11.0% ± 1.36; F2,185.9 = 11.85, p < 0.0001). The number of stillborn piglets fluctuated across the batches (GHbig: B1: 0.59 ± 0.24; B2: 1.27 ± 0.35; B3: 1.54 ± 0.40; B4: 2.93 ± 0.70 vs. GHsmall: B1: 2.38 ± 0.52; B2: 1.29 ± 0.35; B3: 1.08 ± 0.31; B4: 1.43 ± 0.39 vs. SH: B1: 1.08 ± 0.26; B2: 1.15 ± 0.27; B3: 2.11 ± 0.39; B4: 0.91 ± 0.23; F6,126 = 2.51, p = 0.0453), however, it did not differ statistically between the GH and the SH sows.

3. Results 3.1. Reproductive traits

3.1.2. Parity classes Sows from the parity class 3 gave birth to significantly fewer piglets compared to sows from the parity classes 1 and 2 (Class 1: 18.1 ± 0.67 vs. Class 2: 17.6 ± 0.44 vs. Class 3: 16.5 ± 0.42; F2,136 = 3.00, p = 0.0533). In addition, sows from the parity class 3 had significantly more stillborn piglets compared to sows from the parity classes 1 and 2 (Class 1: 0.88 ± 0.20 vs. Class 2: 1.49 ± 0.17 vs. Class 3: 1.88 ± 0.19; F2,126 = 4.75, p = 0.0102). Furthermore, sows from all parity classes differed significantly from each other regarding the birth weight of their piglets (Class 1: 1.10 kg ± 0.04 vs. Class 2: 1.25 kg ± 0.03 vs. Class 3: 1.29 kg ± 0.02; F2,132 = 8.26, p = 0.0004). The three parity classes did not differ regarding their total piglet losses (Class 1: 25.7% ± 2.88 vs. Class 2: 27.9% ± 1.95 vs. Class 3: 26.9% ± 1.85; F2,143.4 = 0.21, p = 0.8144) and the number of crushed piglets (Class 1: 13.7% ± 2.13 vs. Class 2: 20.2% ± 1.72 vs. Class 3: 17.8% ± 1.57; F2,131.2 = 2.46, p = 0.0889).

3.1.1. Housing system In the present study, 17.4 ± 0.50 piglets were born alive per sow and the birth weight of the piglets was on average 1.21 kg ± 0.02 for all housing systems. With regard to piglet losses of live-born piglets, sows from the GH systems had significantly higher total piglet losses during lactation compared to the SH sows (GHbig: 28.3% ± 2.36 vs. GHsmall: 35.9% ± 2.56 vs. SH: 19.0% ± 1.56; F 2,139.4 = 16.69, p < 0.0001). Furthermore, sows from GHsmall had significantly more total piglet losses compared to sows from GHbig. In addition, sows from both GH systems crushed significantly more piglets compared to the SH sows (GHbig: 23.1% ± 2.17 vs. GHsmall: 28.0% ± 2.38 vs. SH: 7.00% ± 0.88; F2,136.3 = 49.78, p < 0.0001). Fig. 2 demonstrates the course of the crushed piglets of the different housing systems during lactation. 65.3% of the piglets were crushed during birth and the first two days post partum. 23.1% of the crushed piglets were found dead between days three and five post partum. The running area was opened for the GH sows and their piglets at day six of lactation. 11.6% of the crushed piglets were found after opening the pens. Sows from both GH systems crushed significantly more piglets during birth and at days one and two post partum compared to the SH sows. However, the sows did not differ statistically between the housing systems regarding their number of crushed piglets after day two post partum. Furthermore, the dead piglets of sows from both GH systems were significantly heavier

3.2. Video analysis 3.2.1. Low-risk and high-risk crushing sows Table 2 shows the reproductive and behavioural differences between LRC and HRC sows and their piglets. LRC and HRC sows did not differ significantly regarding their number of parities. Furthermore, HRC sows gave birth to significantly more live-born piglets compared to 36

Applied Animal Behaviour Science 211 (2019) 33–40

C.G.E. Grimberg-Henrici et al.

Table 2 LSMeans with standard error of the reproductive traits and of lying down and rolling frequencies in the first 72 h post partum of low-risk crushing (LRC) and high-risk crushing (HRC) sows housed in the group-housing systems (GHbig, GHsmall), and LSMeans with standard error of the percentages of piglets’ positions (%) during lying down and rolling behaviour. Parameter

Low-risk crushing (LRC) sows (n = 10)

High-risk crushing (HRC) sows (n = 10)

Number of parities Piglets born alive Birth weight Crushed piglets lying down Crushed piglets rolling

4.20a ± 0.86 14.0a ± 0.73 1.37c ± 0.06 0.63a ± 0.26 0.44a ± 0.21

3.70a ± 0.86 16.2b ± 0.68 1.23d ± 0.05 1.79b ± 0.46 3.32b ± 0.65

Lying down Lying down using pen walls Lying down without using pen walls

28.4a ± 3.82 8.10a ± 3.00

24.5a ± 3.61 11.2a ± 2.84

Rolling 180˚ rolling (side-side) 90˚ rolling ‘onto side’ (belly-side) 90˚ rolling ‘onto belly’ (side-belly) Piglets’ position Piglet position ‘nest’ Piglet position ‘near sow’ Piglet position ‘active’ Piglet position ‘non-synchronous’

0.23a ± 1.96 13.8a ± 4.79 8.66a ± 4.29

25.5a ± 5.05 29.0a ± 5.45 33.6a ± 3.56 11.8a ± 2.20

Table 3 LSMeans with standard error of the reproductive traits and of lying down and rolling frequencies in the first 72 h post partum of the sows from three parity classes (Class 1: 1; Class 2: 2–4; Class 3: ≥5) housed in the group-housing systems (GHbig, GHsmall), and LSMeans with standard error of the percentage of the piglets’ positions (%) during lying down and rolling behaviour. Parameter

Parity class 2 (n = 5)

Parity class 3 (n = 8)

Piglets born alive Birth weight Crushed piglets lying down Crushed piglets rolling

17.0a ± 0.80 1.19a ± 0.06 0.61a ± 0.25 1.86a ± 0.61

14.7ab ± 1.00 1.36a ± 0.08 0.84ab ± 0.37 1.46a ± 0.48

13.7b ± 0.76 1.36a ± 0.06 2.33b ± 0.64 0.68a ± 0.29

Lying down Lying down using pen walls Lying down without using pen walls

25.1a ± 4.56 9.67a ± 3.58

27.0a ± 5.00 9.65a ± 3.93

27.3a ± 4.14 9.64a ± 3.25

6.95a ± 2.34 22.0a ± 5.72

4.10a ± 2.57 19.0a ± 6.27

3.35a ± 2.12 10.3a ± 5.19

24.9c ± 5.12

16.5cd ± 5.61

6.75d ± 4.64

14.0c ± 6.01 47.7a ± 6.50 28.4a ± 4.25 9.83a ± 2.62

27.0cd ± 6.60 26.7a ± 7.12 31.9a ± 4.66 14.4a ± 2.87

Rolling 180˚ rolling (side-side) 90˚ rolling ‘onto side’ (bellyside) 90˚ rolling ‘onto belly’ (sidebelly)

9.37b ± 1.85 20.5a ± 4.53 23.5b ± 4.05

Piglet position Piglet position ‘nest’ Piglet position ‘near sow’ Piglet position ‘active’ Piglet position ‘nonsynchronous’

26.3a ± 4.76 39.5a ± 5.14 21.7b ± 3.36 12.6a ± 2.07

36.7d ± 5.45 28.3a ± 5.98 22.6a ± 3.85 12.4a ± 2.37

a−b

Significant differences between the sows from the three parity classes (p < 0.05). c–d Marginal differences between the sows from the three parity classes (p < 0.10).

a−b c–d

Parity class 1 (n = 7)

Significant differences between the LRC and HRC sows (p < 0.05). Marginal differences between the LRC and HRC sows (p < 0.10).

LRC sows (LRC: 14.0 ± 0.73 vs. HRC: 16.2 ± 0.68; F1,16 = 4.74, p = 0.0447) and the piglets of HRC sows were marginally lighter compared to piglets of LRC sows (LRC: 1.37 ± 0.06 vs. HRC: 1.23 ± 0.05; F1,16 = 3.09, p = 0.0980). The first 72 h post partum video analysis detected 72.8% of the total number of crushed piglets during lactation of these sows. Furthermore, HRC sows crushed significantly more piglets during lying down (LRC: 0.63 ± 0.26 vs. HRC: 1.79 ± 0.46; F1,15 = 5.26, p = 0.0366) and rolling movements (LRC: 0.44 ± 0.21 vs. HRC: 3.32 ± 0.65; F1,15 = 14.63, p = 0.0017) compared to LRC sows. The two groups did not differ in the frequency of lying down movements with using the pen walls (LRC: 28.4 ± 3.82 vs. HRC: 24.5 ± 3.61; F1,15 = 0.50, p = 0.4923) and without using the pen walls (LRC: 8.10 ± 3.00 vs. HRC: 11.2 ± 2.84; F1,15 = 0.49, p = 0.4936). However, the sows of both groups lay down more frequently using a pen wall compared to those which lay down without using a pen wall. With regard to rolling movements, HRC sows performed significantly more 180° rolling movements (LRC: 0.23 ± 1.96 vs. HRC: 9.37 ± 1.85; F1,15 = 9.98, p = 0.0065) and 90° rolling movements ‘onto belly’ compared to LRC sows during the first 72 h after birth (LRC: 8.66 ± 4.29 vs. HRC: 23.5 ± 4.05; F1,15 = 5.48, p = 0.0335). However, the two groups did not differ with regard to their frequency of 90° rolling movements ‘onto side’ (LRC: 13.8 ± 4.79 vs. HRC: 20.5 ± 4.53; F1,15 = 0.91, p = 0.3552). With regard to the piglets’ position, piglets of HRC sows were significantly less active during postural changes of the sows (LRC: 21.7% ± 3.36 vs. HRC: 33.6% ± 3.56; F1,15 = 5.14, p = 0.0386).

13.7 ± 0.76; F2,16 = 4.77, p = 0.0238). However, the birth weight of the piglets did not differ significantly between the three parity classes (Class 1: 1.19 kg ± 0.06 vs. Class 2: 1.36 kg ± 0.08 vs. Class 3: 1.36 kg ± 0.06; F2,16 = 2.25, p = 0.1374). Moreover, sows from the parity class 1 crushed significantly fewer piglets during lying down movements compared to sows from the parity class 3 (Class 1: 0.61 ± 0.25 vs. Class 2: 0.84 ± 0.37 vs. Class 3: 2.33 ± 0.64; F2,15 = 3.87, p = 0.0443). The sows of the three parity classes did not differ with regard to the number of crushed piglets during rolling movements (Class 1: 1.86 ± 0.61 vs. Class 2: 1.46 ± 0.48 vs. Class 3: 0.68 ± 0.29; F2,15 = 1.91, p = 0.1829). The sows of the three parity classes showed no differences in lying down behaviour and the use (Class 1: 25.1 ± 4.56 vs. Class 2: 27.0 ± 5.00 vs. Class 3: 27.3 ± 4.14; F2,15 = 0.06, p = 0.9453) or non-use (Class 1: 9.67 ± 3.58 vs. Class 2: 9.65 ± 3.93 vs. Class 3: 9.64 ± 3.25; F2,15 = 0.00, p = 1.000) of the pen walls when lying down. With regard to rolling behaviour, sows from the parity class 1 performed marginally more 90° rolling movements ‘onto belly’ compared to sows from the parity class 3 (Class 1: 24.9 ± 5.12 vs. Class 2: 16.5 ± 5.61 vs. Class 3: 6.75 ± 4.64; F2,15 = 3.00, p = 0.0799). The sows from the three parity classes did not differ in the frequency of 90° rolling movements ‘onto side’ (Class 1: 22.0 ± 5.72 vs. Class 2: 19.0 ± 6.27 vs. Class 3: 10.3 ± 5.19; F2,15 = 1.11, p = 0.3563) and 180° rolling movements (Class 1: 6.95 ± 2.34 vs. Class 2: 4.10 ± 2.57 vs. Class 3: 3.35 ± 2.12; F2,15 = 0.59, p = 0.5661). With regard to the piglets’ position during postural changes, piglets of sows from the parity class 1 were in the nest less frequently compared to piglets of sows from parity class 3 (Class 1: 14.0% ± 6.01 vs. Class 2: 27.0% ± 6.60 vs. Class 3: 36.7% ± 5.45; F2,15 = 0.59, p = 0.0632).

3.2.2. Parity classes Table 3 shows the reproductive and behavioural performances of the sows from the three parity classes. Sows from the parity class 1 gave birth to significantly more piglets compared to sows from the parity class 3 (Class 1: 17.0 ± 0.80 vs. Class 2: 14.7 ± 1.00 vs. Class 3: 37

Applied Animal Behaviour Science 211 (2019) 33–40

C.G.E. Grimberg-Henrici et al.

4. Discussion

and thus more frequently present during postural changes of the sow, which for the piglets increase the risk of being crushed. Moreover, the pen design can have an influence on the pre-weaning piglet mortality and on risky postural movements of the sows. Environmental stimuli (sand and straw) which increased nest-building behaviour and the comfort of the sow showed a positive effect on piglet mortality and maternal performance (Herskin et al., 1998). Furthermore, Damm et al. (2006) found that sows preferred to use walls with anti-crush rails for lying down less often and to use plain or sloped walls more often. In the present study, GHsmall sows were housed in freefarrowing pens of a size of 5.2 m2 and had significantly more total piglet losses and number of crushed piglets compared to GHbig sows which were housed in pens of a size of 6.2 m2. Weber et al. (2009) did not report significant effects of the pen size on piglet losses. However, they detected a slight tendency that sows in smaller pens had more total piglet losses and crushed more piglets. They suggest a minimum pen size of 5 m2. However, Baxter et al. (2015) found that piglet mortality increased significantly if sows were housed in free-farrowing pens larger than 9.7 m2 compared to sows in smaller free-farrowing pens of 7.9 m2. An explanation for the higher piglet mortality in larger pens was that the sows had more floor space where they could lie down and roll without coming into contact with supportive structures such as anticrush rails. It is important to note that previous housing conditions can influence the behaviour of the sows (Cronin et al., 1996; Weng et al., 2009). However, with regard to the selection of the sows in the present study, no differences were found between gilts and multiparous sows considering their total piglet losses and number of crushed piglets. The multiparous sows which were tested in the GH system with the freefarrowing pens were housed in a SH system with permanent confinement in crates. For example Damm et al. (2005) reviewed that crates can control and support the sows in their lying down and rolling behaviour by slowing down these movements. Thus, multiparous sows could be used to this supportive environment. The present study was conducted under practical conditions and for that reason also multiparous sows were used, however, for future research it would be interesting to use only gilts and to observe their reproductive and behavioural performances over several lactation to evaluate free-farrowing systems.

4.1. Reproductive traits In the present study, 65% of the crushed piglets were documented at birth and the first two days of lactation. This is in line with results of Kilbride et al. (2012) and Marchant et al. (2001), who observed 50% of the crushed piglets in the first two days after birth. In addition, the course of the number of the crushed piglets during lactation is in accordance to the results of Marchant et al. (2000). Furthermore, the GH sows had significantly higher total piglet losses and number of crushed piglets compared to the SH sows. These results are comparable with other studies which investigated sows in free-farrowing systems compared to sows kept in crates (Marchant et al., 2001; Hales et al., 2014; van Nieuwamerongen et al., 2015). In free-farrowing systems sows are not fixed in crates ante partum, during farrowing and post partum. This situation was applicable to the GH sows in this study when the sows were enclosed in their pens until six days post partum. The high mortality rates of live-born piglets for the GH sows in the present study correspond with results of other studies on free-farrowing systems which have reported mortality rates between 22–34 % (Pedersen et al., 1998; Marchant et al., 2001). However, other studies have reported lower piglet mortality rates of around 11–18 % of sows in free-farrowing systems (Cronin et al., 2000; Weber, 2000; Baxter et al., 2015). In these studies, the free-farrowing pens were divided into a lying area for the sow near the piglet nest, a dunging and a feeding area (Cronin et al., 2000; Weber, 2000; Baxter et al., 2015). These functional areas in the free-farrowing pens were possibly missing in the pens of the present study. In addition, in studies which found low piglet mortality rates in the free-farrowing pens the number of live-born piglets was on average 11–12 piglets, whereas, sows in the present study gave birth to 17 piglets on average. Several studies have found that the number of liveborn piglets and piglet mortality is positively correlated (Roehe and Kalm, 2000; Weber et al., 2009; Pedersen et al., 2011). Moreover, the individual birth weights decrease if the number of live-born piglets increases (Roehe and Kalm, 2000; Wolf et al., 2008). However, an optimal birth weight is important for piglet survival and vitality (Baxter et al., 2008). More vital piglets and thus more reactive piglets would be beneficial to possibly reduce piglet mortality especially in free-farrowing systems. In the study of van Nieuwamgerongen et al. (2015), the total piglet losses during lactation of GH sows were 3.22 piglets per sows and for SH sows 1.52 piglets per sows. In this study, the litters were also standardised to 14 piglets per sow. However, the number of live-born piglets was 15 piglets per sow on average compared to 17 piglets per sow in the present study. Furthermore, in the present study, piglet mortality was twice that high compared to the results of van Nieuwamgerongen et al. (2015). Thus, lower numbers of live-born piglets seemed to have an effect on the piglet mortality despite litter equalisation. Besides, sows from both GH systems and the SH sows differed statistically with regard to mortality rates of piglets that died for other causes such as being underweight and runt. Weber et al. (2007); Verhovsek et al. (2007) and van Nieuwamgerongen et al. (2015) reported also significantly higher numbers of piglets of crated sows having died due to other causes compared to sows from free-farrowing systems. One possible explanation for this observation was that the piglets scored as underweight and as runts in a SH system died in a freefarrowing pen due to crushing and thus crushing was documented as the cause of death instead of being underweight and runt. Furthermore in the present study, the weight of the dead piglets was significantly higher for piglets of the GH sows compared to the SH sows. With regard to the results that sows from both GH systems crushed a higher number of piglets compared to SH sows, Weary et al. (1998) also observed a greater number of smaller, crushed piglets at birth and a greater number of larger, crushed piglets were documented on days 2 and 3 post partum. These piglets were possibly more active at the udder

4.2. Video analysis 4.2.1. Low-risk and high-risk crushing sows In the first 72 h post partum, 73% of the total number of crushed piglets during lactation were detected by observing the behaviour of the sow continuously. It can be evaluated that this period of time gives a valid overview of the behavioural differences of these sows regarding high-risks and low-risks for crushing. In the present study, HRC sows had on average two live-born piglets more compared to LRC sows. However, the difference of crushed piglets of four piglets was even higher than the difference of live-born piglets. In our study, we found high differences in the number of crushed piglets of sows housed in the same free-farrowing pen. That is why we looked more in detail on differences of these sows within this research population. The sows were chosen with consideration of the number of parities. That HRC and LRC sows differed in their number of live-born piglets was one finding of many. In addition, piglets of HRC sows were slightly lighter at birth. This is in line with results of Phillipps et al. (2014). They also observed HRC and LRC sows in free-farrowing pens and found larger litters with lighter piglets for HRC sows. Andersen et al. (2005) also found larger litters for HRC sows. Several studies have indicated that larger litters are correlated with higher piglet mortality, because in larger litters decreases the individual birth weight of the piglets and thus the vitality of the piglets (Roehe and Kalm, 2000; Weber et al., 2009; Pedersen et al., 2011; Phillips et al., 2014). Due to the larger litter size and with the slightly lower birth weights of the 38

Applied Animal Behaviour Science 211 (2019) 33–40

C.G.E. Grimberg-Henrici et al.

be away from the sows is found to start around two days after birth (Hrupka et al., 1998; Berg et al., 2006). However, the first days are the most critical time for crushing as shown in the present study. Hrupka et al. (2000) showed that physical contact in a cold environment is more attractive to piglets than loneliness in a warm environment. Furthermore, Vasdal et al. (2010) tested different types of piglet creep areas to increase the time of the piglets in the nest. However, soft bedding material and improved thermal comfort did not attract the piglets to the nest more. In a semi-natural environment, piglets will spend 90% of their time in the first two days post partum together with the sow in the nest to develop the sow-piglet relationship (Stanged and Jensen, 1991) and to obtain warmth, milk and protection against predators (Weary et al., 1996b). However, this natural need of the piglets to be near the sow is a high-risk factor in being crushed in pig husbandry.

piglets, HRC sows had possibly a higher risk to crush piglets compared to LRC sows. Although litter equalisation was done until 2 days post partum in the present study, the larger litter sizes could be influence the sow’s behaviour. However, for further research it would be useful to balance both groups also for the number of live-born piglets. However, we corrected afterwards our behavioural findings of the present study for this effect by including the covariable number of live-born piglets in the model. To ensure data comparability we orientated towards the studies of Andersen et al. (2005) and Phillips et al. (2014) that also investigated reproductive and behavioural differences of high-risk and low-risk crushing sows without balancing the two groups with regard to their litter size. Moreover, the number of crushed piglets was higher during rolling movements of the sows compared to the documented number of crushed piglets during lying down movements. Several studies have differed in their documentation of the incidence of crushed piglets during postural changes with some having reported a high incidence of crushed piglets caused by rolling movements of the sows (Weary et al., 1996a, 1998; Danholt et al., 2011). Others in contrast have described a higher number of crushed piglets during lying down movements (Weary et al., 1998; Marchant et al., 2001). With regard to lying down movements, it can be assumed that LRC sows performed these movements more carefully compared to HRC sows, because no differences were found in the frequency of lying down movements between these two groups. Burri et al. (2009) also observed lower piglet mortality rates for sows which were more careful during lying down movements and gathered their piglets on one side of their body before lying down. The pre-lying behaviour of the sows was also described by Schmid (1991) as rooting and pawing to wake up the piglets, moving around, gathering of all piglets on one side and lying down on the opposite side of the piglets. It has also been said that prelying behaviour has a positive effect on the number of crushed piglets (Schmid, 1991; Marchant et al., 2001). In the present study, piglets of LRC sows were more active during postural changes compared to piglets of HRC sows due to possibly better performed pre-lying behaviour. Moreover, a positive finding in the present study was that the sows used the pen walls more frequently while lying down, which is the safest way to prevent crushing according to Marchant et al. (2001). An important difference in the present study between HRC and LRC sows was the frequency of rolling movements. HRC sows performed significantly more 180° rolling movements from one side to the other side and 90° rolling movements ‘onto belly’ from the side to the belly. One main problem as reviewed by Damm et al. (2005) is that sows have no behavioural patterns to introduce rolling movements such as the prelying behaviour to wake up the piglets to reduce the risk of being crushed. Weary et al. (1996a) showed that rolling movements performed more slowly resulted in lower numbers of crushed piglets. In addition, piglets of LRC sows were more active during rolling movements, which possibly indicates more communication between LRC sows and their piglets during rolling compared to HRC sows and their piglets. However, the restriction of rolling movements could be contrary to the natural behaviour of the sows since rolling from the side onto the belly (90° rolling ‘onto belly’) is part of the gradual weaning process to terminate nursing (Jensen, 1988). Studies have found that environmental influences can decrease the risk of being crushed during rolling movements. Weary et al. (1998) reported that sows rolled less frequently on concrete floors compared to sows on plastic floors. Herskin et al. (1998) found that straw and sand bedding can reduce the risk of crushing compared to a concrete floor, although no differences in the frequency of rolling movements were described. Thus, softer types of floors seem to be less dangerous. Another approach to reduce crushing could be a higher acceptance of piglets to rest in the piglet nest. Marchant et al. (2001) concluded that high mortality rates due to crushing are caused because piglets rest near the sow most of the time and have reduced agility after birth. However, the motivation of the piglets to use the piglet nest and thus to

4.2.2. Parity classes During the first 72 h post partum, fewer numbers of crushed piglets were documented for gilts during lying down movements. A reason for more piglet losses due to crushing by older sows could be the bigger size of the sows. Marchant et al. (2000) also found that the piglet mortality of live-born piglets was significantly associated with the number of parities and the body length of the sows. Moreover, the comparison of the three parity classes of the sows resulted in some evidence that older sows are possibly more experienced regarding their maternal abilities compared to younger sows during postural changes. Piglets of older sows were in the nest more frequently and away from the sow during postural changes compared to piglets of gilts, which probably indicates a better communication between the sow and their piglets (Schmid, 1991; Burri et al., 2009). Furthermore, gilts performed rolling movements from the side to the belly more often compared to older sows. These rolling movements are used by the sows to terminate the suckling behaviour of the piglets (Jensen, 1988). Bohnenkamp et al. (2013a) observed that gilts weaned their piglets earlier compared to older sows. 5. Conclusion The present study analysed different environmental factors that provide more information on pre-weaning mortality. Freedom of the sows reduced the safety of the piglets as shown by the higher piglet mortality in the free-farrowing pens. Moreover, the pen size had an influence on the piglet losses, which increased in smaller free-farrowing pens. Moreover, the detailed observation of LRC and HRC sows within the same housing system showed high variation in their maternal behaviour and in their postural changes in free-farrowing pens. HRC sows performed more rolling movements and their piglets were less active during postural changes that possibly indicates a lower level of communication between the sows and their piglets. In addition, there is some evidence that gilts and older sows differ in their maternal behaviour with regard to investment and communication. Conflict of interest None. Acknowledgments The project was supported by funds of the German Government’s Special Purpose Fund held at Lantwirtschaftliche Rentenbank. References Andersen, I.L., Berg, S., Bøe, K.E., 2005. Crushing of piglets by the mother sow (Sus scrofa) - purely accidental or a poor mother? Appl. Anim. Behav. Sci. 93, 229–243. Andersen, I.L., Tajet, G.M., Haukvik, I.A., Kongsrud, S., Bøe, K.E., 2007. Relationship

39

Applied Animal Behaviour Science 211 (2019) 33–40

C.G.E. Grimberg-Henrici et al.

A cohort study of preweaning piglet mortality and farrowing accommodation on 112 commercial pig farms in England. Prev. Vet. Med. 104, 281–291. Li, Y.Z., Johnston, L., Hilbrands, A., 2010. Pre-weaning mortality of piglets in a bedded group-farrowing system. J. Swine Health Prod. 18. Marchant, J.N., Rudd, A.R., Mendl, M.T., Broom, D.M., Meredith, M.J., Corning, S., Simmins, P.H., 2000. Alternative and conventional farrowing systems. Vet. Rec. 147, 214. Marchant, J.N., Broom, D.M., Corning, S., 2001. The influence of sow behaviour on piglet mortality due to crushing in an open farrowing system. Anim. Sci. 72, 19–28. Milligan, B.N., Fraser, D., Kramer, D.L., 2002. Within-litter birth weight variation in the domestic pig and its relation to pre-weaning survival, weight gain, and variation in weaning weights. Livest. Prod. Sci. 76, 181–191. Pedersen, B.K., Jensen, K.H., Nielsen, N.P., 1998. Farrowing Systems for the Future. Agris. Pedersen, L.J., Berg, P., Jørgensen, G., Andersen, I.L., 2011. Neonatal piglet traits of importance for survival in crates and indoor pens. J. Anim. Sci. 89, 1207–1218. Phillips, C.E., Farmer, C., Anderson, J.E., Johnston, L.J., Shurson, G.C., Deen, J., Keisler, D.H., Conner, A.M., Li, Y.Z., 2014. Preweaning mortality in group-housed lactating sows: hormonal differences between high risk and low risk sows. J. Anim. Sci. 92, 2603–2611. Roehe, R., Kalm, E., 2000. Estimation of genetic and environmental risk factors associated with pre-weaning mortality in piglets using generalized linear mixed models. Anim. Sci. 70, 227–240. SAS Institute Inc, 2008. User’s Guide (release 9.4). Cary, North Carolina, USA. . Schmid, H., 1991. Natürliche Verhaltenssicherungen der Hausschweine (Sus scrofa) gegen das Erdrücken der Ferkel durch die Muttersau und die Auswirkungen haltungsbedingter Störungen (Doctoral dissertation). Stanged, G., Jensen, P., 1991. Behaviour of semi-naturally kept sows and piglets (except suckling) during 10 days postpartum. Appl. Anim. Behav. Sci. 31, 211–227. Vasdal, G., Glærum, M., Melišová, M., Bøe, K.E., Broom, D.M., Andersen, I.L., 2010. Increasing the piglet’s use of the creep area-A battle against biology? Appl. Anim. Behav. Sci. 125, 96–102. Verhovsek, D., Troxler, J., Baumgartner, J., 2007. Peripartal behaviour and teat lesions of sows in farrowing crates and in a loose-housing system. Anim Welfare 16, 273. van Nieuwamerongen, S.E., Soede, N.M., van der Peet-Schwering, C.M.C., Kemp, B., Bolhuis, J.E., 2015. Development of piglets raised in a new multi-litter housing system vs. conventional single-litter housing until 9 weeks of age. J. Anim. Sci. 93, 5442–5454. Weary, D.M., Pajor, E.A., Fraser, D., Honkanen, A.-M., 1996a. Sow body movements that crush piglets: a comparison between two types of farrowing accommodation. Appl. Anim. Behav. Sci. 49, 149–158. Weary, D.M., Pajor, E.A., Thompson, B.K., Fraser, D., 1996b. Risky behaviour by piglets: a trade off between feeding and risk of mortality by maternal crushing? Anim. Behav. 51, 619–624. Weary, D.M., Phillips, P.A., Pajor, E.A., Fraser, D., Thompson, B.K., 1998. Crushing of piglets by sows: effects of litter features, pen features and sow behaviour. Appl. Anim. Behav. Sci. 61, 103–111. Weber, R., 2000. Alternative housing systems for farrowing and lactating sows. Publ. Eur. Assoc. Anim. Prod. 102, 109–116. Weber, R., Keil, N.M., Fehr, M., Horat, R., 2007. Piglet mortality on farms using farrowing systems with or without crates. Anim. Welf. 16, 277–279. Weber, R., Keil, N.M., Fehr, M., Horat, R., 2009. Factors affecting piglet mortality in loose farrowing systems on commercial farms. Livest. Sci. 124, 216–222. Weng, R.C., Edwards, S.A., Hsia, L.C., 2009. Effect of individual, group or ESF housing in pregnancy and individual or group housing in lactation on sow behavior. Asian-Aust. J. Anim. Sci. 22, 1574–1580. Wischner, D., Kemper, N., Krieter, J., 2009. Nest-building behaviour in sows and consequences for pig husbandry. Livest. Sci. 124, 1–8. Wischner, D., Kemper, N., Stamer, E., Hellbrügge, B., Presuhn, U., Krieter, J., 2010. Prelying behaviour patterns in confined sows and their effects on crushing of piglets. Appl. Anim. Behav. Sci. 122 (1), 21–27. Wolf, J., Žáková, E., Groeneveld, E., 2008. Within-litter variation of birth weight in hyperprolific Czech Large White sows and its relation to litter size traits, stillborn piglets and losses until weaning. Livest. Sci. 115, 195–205.

between postnatal piglet mortality, environmental factors and management around farrowing in herds with loose-housed, lactating sows. Acta Agric. Scand. A 57, 38–45. Arey, D.S., Sancha, E.S., 1996. Behaviour and productivity of sows and piglets in a family system and in farrowing crates. Appl. Anim. Behav. Sci. 50, 135–145. Barnett, J.L., Cronin, G.M., McCallum, T.H., Newman, E.A., 1994. Effects of food and time of day on aggression when grouping unfamiliar adult pigs. Appl. Anim. Behav. Sci. 39, 339–347. Baxter, E.M., Jarvis, S., D’eath, R.B., Ross, D.W., Robson, S.K., Farish, M., Nevison, I.M., Lawrence, A.B., Edwards, S.A., 2008. Investigating the behavioural and physiological indicators of neonatal survival in pigs. Theriogenology 69, 773–783. Baxter, E.M., Adeleye, O.O., Jack, M.C., Farish, M., Ison, S.H., Edwards, S.A., 2015. Achieving optimum performance in a loose-housed farrowing system for sows: the effects of space and temperature. Appl. Anim. Behav. Sci. 169, 9–16. Berg, S., Andersen, I.L., Tajet, G.M., Haukvik, I.A., Kongsrud, S., Bøe, K.E., 2006. Piglet use of the creep area and piglet mortality-effects of closing the piglets inside the creep area during sow feeding time in pens for individually loose-housed sows. Anim. Sci. 82, 277–281. Bohnenkamp, A.-L., Meyer, C., Müller, K., Krieter, J., 2013a. Group housing with electronically controlled crates for lactating sows. Effect on farrowing, suckling and activity behavior of sows and piglets. Appl. Anim. Behav. Sci. 145, 37–43. Bohnenkamp, A.L., Traulsen, I., Meyer, C., Müller, K., Krieter, J., 2013b. Comparison of growth performance and agonistic interaction in weaned piglets of different weight classes from farrowing systems with group or single housing. Animal 7, 309–315. Bohnenkamp, A.L., Traulsen, I., Meyer, C., Müller, K., Krieter, J., 2013c. Group housing for lactating sows with electronically controlled crates: 1. Reproductive traits, body condition, and feed intake. J. Anim. Sci. 91, 3413–3419. Burri, M., Wechsler, B., Gygax, L., Weber, R., 2009. Influence of straw length, sow behaviour and room temperature on the incidence of dangerous situations for piglets in a loose farrowing system. Appl. Anim. Behav. Sci. 117, 181–189. Cronin, G.M., Simpson, G.J., Hemsworth, P.H., 1996. The effects of the gestation and farrowing environments on sow and piglet behaviour and piglet survival and growth in early lactation. Appl. Anim. Behav. Sci. 46, 175–192. Cronin, G.M., Lefébure, B., McClintock, S., 2000. A comparison of piglet production and survival in the Werribee Farrowing Pen and conventional farrowing crates at a commercial farm. Aust. J. Exp. Agric. 40, 17–23. Csermely, D., Wood-Gush, D.G.M., 1987. Different methods of grouping and their effects on the agonistic behaviour of sows. Appl. Anim. Behav. Sci. 18, 389. Damm, B.I., Forkman, B., Pedersen, L.J., 2005. Lying down and rolling behaviour in sows in relation to piglet crushing. Appl. Anim. Behav. Sci. 90, 3–20. Damm, B.I., Moustsen, V., Jørgensen, E., Pedersen, L.J., Heiskanen, T., Forkman, B., 2006. Sow preferences for walls to lean against when lying down. Appl. Anim. Behav. Sci. 99, 53–63. Danholt, L., Moustsen, V.A., Nielsen, M.B.F., Kristensen, A.R., 2011. Rolling behaviour of sows in relation to piglet crushing on sloped versus level floor pens. Livest. Sci. 141, 59–68. Grimberg-Henrici, C.G.E., Büttner, K., Meyer, C., Krieter, J., 2016. Does housing influence maternal behaviour in sows? Appl. Anim. Behav. Sci. 180, 26–34. Hales, J., Moustsen, V.A., Nielsen, M.B.F., Hansen, C.F., 2014. Higher preweaning mortality in free farrowing pens compared with farrowing crates in three commercial pig farms. Animal 8, 113–120. Herskin, M.S., Jensen, K.H., Thodberg, K., 1998. Influence of environmental stimuli on maternal behaviour related to bonding, reactivity and crushing of piglets in domestic sows. Appl. Anim. Behav. Sci. 58, 241–254. Hrupka, B.J., Leibbrandt, V.D., Crenshaw, T.D., Benevenga, N.J., 1998. The effect of farrowing crate heat lamp location on sow and pig patterns of lying and pig survival. J. Anim. Sci. 76, 2995–3002. Hrupka, B.J., Leibbrandt, V.D., Crenshaw, T.D., Benevenga, N.J., 2000. The effect of thermal environment and age on neonatal pig behavior. J. Anim. Sci. 78, 583–591. Jensen, P., 1986. Observations on the maternal behaviour of free-ranging domestic pigs. Appl. Anim. Behav. Sci. 16, 131–142. Jensen, P., 1988. Maternal behaviour and mother-young interactions during lactation in free-ranging domestic pigs. Appl. Anim. Behav. Sci. 20, 297–308. Kilbride, A.L., Mendl, M., Statham, P., Held, S., Harris, M., Cooper, S., Green, L.E., 2012.

40