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A comparison of postural changes and maternal responsiveness during early lactation in Landrace and Minpig sows
Applied Animal Behaviour Science 131 (2011) 40–47
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A comparison of postural changes and maternal responsiveness during early lactation in Landrace and Minpig sows夽 Shi-quan Cui a , Dong-hua Chen a , Jian-hong Li a , Xiang Li a , Guo-an Yin b , Jun Bao b,∗ a b
School of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, PR China School of Animal Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, PR China
a r t i c l e
i n f o
Article history: Accepted 20 January 2011 Available online 20 February 2011 Keywords: Behaviour Postural change Maternal responsiveness Sow Minpig Landrace
a b s t r a c t Maternal behaviour is one of the instinct behaviours associated with offspring survival. Minpig is a local breed in the Northeast of China known for its strong maternal sense. In this study, sows of Minpig (n = 30, parity 2–8) and Landrace (n = 21, parity 2–8) were farrowed in individual pens with access to a yard. Sow behaviour was videotaped for 72 h in the second and third week after parturition. The results showed that the Minpig sows and Landrace sows were different in piglet-crushing behaviour (rolling, lying down from a sitting position or a standing position), lateral recumbency, ventral recumbency, and sitting and nursing behaviour (frequency of nutritive nursing and proportion of nursing terminated by the sow). The Minpig sows lie down at higher frequencies from a standing position, but crushing resulting from this movement in the Minpig sows was much less common than in the Landrace sows with only 10 crushing incidents compared to 32, respectively. Crushing occurred most often when the sows changed from the ventral recumbency position to lateral recumbency. In the present study, the total number of occurrences of piglet crushing by the Minpig sows was significantly lower (P < 0.05) than that of the Landrace ones (17 vs. 74). The results indicate that the Minpig sows provided more chances for piglets to escape successfully when the piglets were trapped by her body, leading to 76.5% of the Minpig piglets successfully escaping compared to 18.9% of the Landrace piglets. To explore the reason behind the above results, the carefulness of the sows during standing-to-lying and the responsiveness of the sows to piglet distress calls were investigated. Compared with the Landrace breed, the Minpig sows scored higher in standing-to-lying carefulness (F¯ Minpig = 2.4994, F¯ Landrace = 2.1238, P < 0.01) and higher in responsiveness to piglet distress calls (F¯ Minpig = 1.7343, F¯ Landrace = 0.294, P < 0.001). In conclusion, the data suggest that the Minpig sows show stronger maternal instincts through their behavioural postures and their carefulness with piglets compared with the Landrace breed, and this difference may play an important role in the further exploitation of local breeds for the swine breeding program in China. © 2011 Elsevier B.V. All rights reserved.
1. Introduction
夽 This study was financially supported by the Scientific Research Foundation of Northeast Agricultural University, PR China. ∗ Corresponding author. Tel.: +86 459 6819002; fax: +86 459 6819015. E-mail address: [email protected] (J. Bao). 0168-1591/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.applanim.2011.01.011
The loss of pre-weaning piglets is an important economic and animal welfare problem in swine production (English and Morrison, 1984). The crushing of piglets by sows is reported to be the major cause of piglet mortality (Dyck and Swierstra, 1987; Svendsen et al., 1986). Therefore, maternal behaviour may be an important factor correlated with the mortality of neonatal piglets (Fraser,
S.-q. Cui et al. / Applied Animal Behaviour Science 131 (2011) 40–47
1990). The posture changes of sows from the standing to the lying down position during the whole lactating period are dangerous for piglet survival (Weary et al., 1998; Marchant et al., 2001; Vieuille et al., 2003) because piglets are often crushed during this process (Edwards et al., 1986; Weary et al., 1996). The sequence of lying down can be divided into five stages (Marchant and Broom, 1996): (1) one of the sow’s front legs kneels onto the floor and then the other follows; (2) the sow may pause shortly before continuing movement; (3) the sow slips forward on its knees by turning to bring one shoulder and the side of the head to rest upon the floor; (4) the sow may pause shortly again before movement continues; and (5) the sow lowers the hindquarters of its body and slides its rear legs by turning until it touches the floor completely. For pregnant sows, stage 1, 3, and 5 took 2, 1, and 2 s, respectively, and stage 2 and 4 took 1 and 2 s, respectively (Harris and Gonyou, 1998). However, the overall time taken to lie down and the time taken in stage 4 could be influenced by type of the pen. For example, stage 4 could take up to 4 s in spacious crates as opposed to 1 s in narrow crates or loosed pens. Two patterns of lying-down behaviour were commonly observed in lactating sows: lying down vertically (the sow lies down on her belly at the end of stage 5) and lying down laterally (the sow lets her hindquarters fall to one side at the end of stage 5). Compared with lying down vertically, lying down laterally is considered more dangerous for the piglets when they are present, especially when the sow lies down by falling on her side (Blackshaw and Hageasø, 1990; Wechsler and Hegglin, 1997). However, pre-lying behaviour such as looking at the piglets, sniffing, or rooting away the piglets can reduce the risk of piglet crushing (Marchant et al., 1996). Generally, sows perform most pre-lying behaviour on the day of parturition because that is when the piglets are most vulnerable (Weary et al., 1996; Marchant et al., 2001). McGlone and Morrow-Tesch (1990) reported that the amount of time sows spent sitting was positively correlated with the number of piglets crushed and that sows that spent more time sitting seemed more likely to crush piglets. Rolling behaviour is also considered as one of the movements dangerous to piglets (Weary et al., 1996; Wechsler and Hegglin, 1997). Sows spend most of the time on lateral recumbency during parturition and the first day post-partum (Petersen et al., 1990; Jarvis et al., 1999; Pedersen et al., 2003; Vieuille et al., 2003); therefore, sows need to roll from one side to the other occasionally for comfort. Additionally, rolling behaviour is also part of the gradual weaning process for the sows (Jensen, 1988; Jensen and Recén, 1989). The danger from movement has been associated not only with the speed and manner in which movements were performed, but also the frequency of movements made by sows. Rolling movements that resulted in the crushing of piglets was often performed much faster than rolls that did not (Weary et al., 1996). Sows that are responsive to piglet distress calls could reduce the risk of piglet-crushing. There were large individual differences in the sows’ responsiveness to piglet distress calls (Hutson et al., 1991, 1993). Some sows were very responsive to the vocalisation of a trapped piglet and would rise or sit to give the piglet a chance for survival, whereas other sows did not react at all (Hutson et al.,
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1991; Cronin and Cropley, 1991). It had been reported that sows showing a strong response to the sound of a screaming piglet seemed to display less risky behaviour around their piglets early post-partum (Thodberg et al., 2002; Wechsler and Hegglin, 1997) and had fewer crushed piglets (Wechsler and Hegglin, 1997). The selective breeding in modern swine production mainly focus on the growth traits of the pig rather than the maternal ability of sows. Actually, the maternal ability is significant in swine production, especially for improving the farming management. Minpig is a local breed in Northeastern China and has been characterised as prolific (14.35 piglets per birth) and a source of good meat and has a strong resistance to poor feed quality and cold climate (Wang et al., 2002). Furthermore, its good maternal temperament is another outstanding characteristic of the Minpig breed. At weaned age 60 days this breed has 11–12 alive piglets per litter, compared to Landrace breed with 9–10 alive piglets per litter at weaning age of 35 days (Wang et al., 2002). This research aims to compare the maternal behaviour of the Minpig sows with that of the Landrace sows and to provide valuable behavioural observations of the local breeds for the purpose of future swine production. 2. Materials and methods 2.1. Animals and housing Thirty Minpig sows and 21 Landrace sows from a commercial farm were used. Sows were multifarious (parity 2–8) and farrowed from June 15 to July 23, 2008. The two breeds of sows were housed separately in two barns. Each barn consisted of 42 individual pens for farrowing and early lactation. The farrowing pens (2.7 m × 2.1 m) were on solid concrete flooring, and no bedding or rails were provided on the floor to protect piglets from being crushed (Fig. 1). The sows were fed twice daily at 06:30 and 15:30 and had free access to fresh water. The sows were allowed to leave their pens to exercise in an open yard for approximately a half hour right before each feeding. No heat lamps were provided for the newborn piglets in the creep area during the summer. Room temperature and humidity ranged from 25 to 32 ◦ C and 45 to 55%, respectively, during the daytime. During the night, the room temperature varied between 18 and 22 ◦ C, and the relative humidity was approximately 35%. The barn was ventilated through a natural ventilation system. 2.2. Behaviour observation and categorisation The behaviours of the sows and their piglets were recorded with a video recording system (JinPeng L4400). Video cameras (Lerong RL-H115) were fixed in the front of the pens. At farrowing, all sows were videotaped for 72 h, starting from the first birth of piglets. The 24 h period following the birth of the first piglet was called day 1 (d1 ) post-partum, the subsequent 24 h period was called day 2 (d2 ) and the following one called day 3 (d3 ). During week 2 and week 3 post-partum, the sows were videotaped twice each week for two consecutive days between 09:30–11:30 and 13:00–15:00. Behaviour data from the video records
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Fig. 1. Diagram of the farrowing pens in this study: (1) resting area for the sow; (2) feeding area; (3) resting area for the piglets, (4) drinkers, (5) the door to a yard.
were analysed, and the various behaviour traits are defined in Table 1. A scoring system was established to assess a sow’s carefulness during the postural change from standing-to-lying. Behavioural criteria of the scoring system included sniffing piglets before lying down, rooting before lying down, descending ventrally (as opposed to flopping over to one side), and lying down when there were no piglets near her on that side (Valros et al., 2003a). During each standing-tolying event, if any one of the behaviours described above was present, the sow would be scored as one, and if not, she would be scored as zero. The carefulness score of a sow ranged from 0 to 4 during each standing-to-lying event. The piglet distress calls from each litter were obtained on the first day after birth by pressing a toe of a newborn piglet without imposing serious injury and recording the sound with a Sound Recording Pen (Sony ICD-SX800).
Each distress call from the piglets was 3–5 s in time-length and a recording of 30 s was obtained by repeatedly recording it. Therefore, each experimental sow had the recording of its own piglet’s call. The recording was played back to the mother immediately after she had finished lying down after feeding. A loudspeaker was placed at the rear of the sows’ hindquarters and the sows’ response to the sound was recorded. The test was carried out on d2 or d3 of the first week after farrowing and once again on the fourth day of week 2 and week 3. The responses to the playback by the sows were scored as follows: 0—No reaction; 1—Head moves; 2—Sits; 3—Stands up; or 4—Makes contact with the loudspeaker. 2.3. Statistical analysis The data were analysed using Microsoft Excel. The state behaviour was presented as a percentage of the total obser-
Table 1 Behavioural parameters and their definitions. Postural parameters General behaviour Lateral recumbency Ventral recumbency Standing or walking Sitting Lateral recumbency-to-other postures Ventral-to-lateral recumbency Sitting-to-lying Standing-to-lying Nursing behaviour Duration of nutritive nursing Frequencies of nutritive nursing Duration of pre-massage Duration of post-massage
Nursing terminated by the sow
Definition Sow’s head, ear, scapular and waist all touching the floor and all four legs visible. Sow’s chest and abdomen touching the floor and front legs stretched or folded under the body. Upright body position on extended legs and legs frozen or moving; includes walking while exhibiting other behaviour. Hind quarter and caudal end touching the floor with hinder legs folded and front legs erect to support the body weight. Posture changing from lateral recumbency to other behaviours including ventral recumbency, sitting and standing. Posture changing from ventral recumbency to lateral recumbency. Posture changing from sitting to lying, including ventral recumbency and lateral recumbency. Postures changing from standing to lying, including ventral recumbency and lateral recumbency. Duration was identified by the rapid suckling of the piglets with milk ejection, calculated by seconds (Gustafsson et al., 1999). Frequency was defined as the number of occurrences of milk ejections of the sow during a definite time (Gustafsson et al., 1999). Pre-massage was considered to start when at least half the litter started to massage the udder and to end once the milk was ejected (Gustafsson et al., 1999). Post-massage was initiated when the milk ejection ended and terminated when at least half the litter stopped massaging the udder. If the sow changed postures such as by rolling over or walking away from the piglets, the post-massage was over. After milk ejection, the suckling of piglets was terminated by a posture change of the sow (Gustafsson et al., 1999).
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Table 2 Numbers of piglets trapped by Minpig and Landrace sows during postural changes. Breeds (n)
Litter size (mean ± s.e.)
Observation periods
Postural changes
Standingto-lying vertically
Minpig (n = 30)
Landrace (n = 21) a
Standingto-lying laterally
No of piglet trapped Ventral-tolateral recumbency
Lateral-toventral recumbency
Sitting-tolying
Lying-tositting
10.5 ± 2.46
d1 d2 d3 Total
1 (1)a 4 (3) 0 5 (4)
2 (1) 1 (0) 2 (2) 5 (3)
3 (2) 4 (4) 0 7 (6)
0 0 0 0
0 0 0 0
0 0 0 0
6 (4) 9 (7) 2 (2) 17 (13)
10.6 ± 2.91
d1 d2 d3 Total
10 (3) 3 (0) 6 (1) 19 (4)
6 (1) 4 (1) 3 (0) 13 (2)
11 (3) 6 (2) 8 (2) 25 (7)
3 (1) 2 4 9 (1)
4 (0) 2 0 6
2 (0) 0 0 2
36 (8) 17 (3) 21 (3) 74 (14)
The number in the brackets represents the number of piglets that successfully escaped from being trapped.
vations, and the event behaviour (such as movements of lateral recumbency-to-other postures, ventral-to-lateral recumbency, and sitting-to-lying and standing-to-lying) was presented as the frequency of the occurrences per hour. A GLM procedure of the SAS statistical software (SAS, Ver 9.0) was used to test the behavioural differences between the two breeds and observations over different times. The model for the behavioural analysis during the first three days after parturition included the following effects: Yijk = + Breedi + Dayj + Breedi × Dayj + eij where is a general mean, Breedi is the fixed effect of the breeds, Dayj is the fixed effect of the observation days (d1 , d 2 , d 3 ) after parturition and Breedi × Dayj is the interaction between the breeds and the observation days. The model for the behavioural analysis during week 2 and week 3 after parturition included the following effects: Yijk = + Breedi + Weekj + Periodk × Breedi × Weekj + Breedi × Periodk + eijk where is a general mean, Breedi is the fixed effect of breeds of sow, Weekj is the fixed effect of the observation week (Week 2 and Week 3) after parturition, Periodk is the fixed effect of the period (09:30–11:30 and 13:00–15:00) during the observation day, Breedi × Weekj is the interaction between the breeds and the observation week and Breedi × Periodk is the interaction between the breeds and the period during the observation day. The carefulness scores of the sows during standingto-lying and the responsiveness of the sows to the piglet distress calls were evaluated by a weighted least square analysis in the CATMOD procedure in SAS. The model is as follows: Yijk = + Bi + Dj + Tk + eijk where Yijk is the total score, is a general mean, Bi is the fixed effect of the breeds, Dj is the fixed effect of the observation time when the behaviour was recorded, Tk is the effect of the number of the occurrences of the different scoring standard and eijk is the residual effect. 3. Results 3.1. Crushing of piglets by sows The average litter size (born alive) for the Minpig sows and the Landrace sows was 10.50 ± 2.46 and 10.62 ± 2.91,
respectively (Table 2). The number of incidences of pigletcrushing by the Minpig sows was lower compared to that by the Landrace sows during the first three days post-partum. Piglet-crushing occurred more often when sows changed from ventral to lateral recumbency than in other postural changes. The Minpig sows showed fewer piglet trappings (17 incidences), which only occurred in the postural changes from standing to lying and from ventral to lateral recumbency, compared to the Landrace sows (74 incidences) that showed piglet trappings in all postural changes (Table 2). Among the piglets trapped by the Minpig sows, 76.5% successfully escaped, while only 18.9% of piglets trapped by the Landrace sows escaped. None of the trapped piglets died throughout the study because of the intensive animal care by farmers.
3.2. Postural behaviour The amount of time that sows spent in lateral recumbency did not differ during the first three days post-partum (Table 3) but significantly decreased with an increase in lactation days after one week postpartum (P < 0.001). The Minpig sows spent more time in lateral behaviour in the first three days post-partum than the Landrace sows (d1 , P = 0.05; d2 , P = 0.01; d3 , P < 0.001). No differences were observed between the two breeds after one week post-partum. The amount of time that sows spent in ventral recumbency showed no difference during the first three days post-partum (P > 0.05) and then increased as lactation progressed after one week (P < 0.001). During the first three days postpartum, the time spent in ventral recumbency by the Minpig sows was less than that by the Landrace sows (P < 0.05). The Landrace sows performed more sitting behaviour than the Minpig sows during the first three days postpartum. Significant differences were only found on the first and the third day post-partum (P < 0.05). There were no differences observed in the time spent on standing between the Minpig and Landrace sows and during the first three days post-partum.
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Table 3 Time budgets for postural changes of Minpig and Landrace sows during early lactation (%). d1
Minpig Landrace P-value
92.1 ± 1.35 88.3a ± 1.35
Ventral recumbency behaviour
Minpig Landrace P-value
2.7x ± 1.05 5.7ay ± 1.05
Sitting behaviour
Minpig Landrace P-value
0.2x ± 0.17 1.4ay ± 0.17
Minpig Landrace P-value
4.8 ± 0.53 4.4 ± 0.53
P-value
91.8x ± 1.35 86.9aby ± 1.35 0.230
91.4x ± 1.35 84.3by ± 1.35
4.3x ± 1.05 7.5aby ± 1.05 0.024
4.4x ± 1.05 9.7by ± 1.05
0.2 ± 0.17 0.5b ± 0.17 0.039
0.2x ± 0.17 0.8by ± 0.17
3.7 ± 0.53 4.9 ± 0.53 0.797
3.9 ± 0.53 5.0 ± 0.53
<0.001
W3
W2 81.6a ± 3.05 78.1a ± 3.83
P-value
52.4b ± 3.10 58.8b ± 3.73
0.674
32.7b ± 2.71 29.3b ± 3.27
0.884
0.5 ± 0.38 1.6 ± 0.46
0.081
14.3bx ± 1.33 10.0by ± 1.60
0.072
<0.001 <0.001
12.4a ± 2.67 16.8a ± 3.35 <0.001
<0.001
0.9 ± 0.37 1.3 ± 0.47 0.913
0.141
4.9a ± 1.31 3.8a ± 1.64 <0.001
Note: Different superscripts in a row indicate significant differences between observation days (a, b: P < 0.05). Different superscripts in a column indicate significant differences between breeds (x, y: P < 0.05). Means and standard errors are shown.
Table 4 Frequencies of postural changes of Minpig and Landrace sows during the first three days in lactation. Postural changes (/h)
Breeds
d1
d2
d3
Frequencies of lateral recumbency-to-other postures
Minpig Landrace P-value
0.61 ± 0.06 0.70a ± 0.06
0.44 ± 0.06 0.44ab ± 0.06 0.001
0.46 ± 0.06 0.54b ± 0.06
Frequencies of ventral-to-lateral recumbency
Minpig Landrace P-value
0.24x ± 0.05 0.48ay ± 0.05
0.26 ± 0.05 0.27a ± 0.05 0.035
Frequencies of sitting-to-lying
Minpig Landrace P-value
0.10x ± 0.05 0.39ay ± 0.05
Frequencies of standing-to-lying
Minpig Landrace P-value
0.59ax ± 0.04 0.36y ± 0.04
P-value
W2
W3
P-value
0.232
0.52a ± 0.09 0.76a ± 0.11 <0.0001
1.01b ± 0.09 1.13b ± 0.11
0.074
0.32 ± 0.05 0.45b ± 0.05
0.001
0.48a ± 0.08 0.62a ± 0.10 0.0004
0.89b ± 0.08 0.88b ± 0.10
0.497
0.10 ± 0.05 0.19 ± 0.05b 0.031
0.04 ± 0.05y 0.21 ± 0.05bx
<0.001
0.20a ± 0.06 0.14 ± 0.07 0.0281
0.42bx ± 0.06 0.18y ± 0.07
0.028
0.40bx ± 0.04 0.24y ± 0.04 0.001
0.38bx ± 0.04 0.25y ± 0.04
<0.001
0.36a ± 0.07 0.24 ± 0.09 <0.001
0.92bx ± 0.07 0.42y ± 0.09
0.001
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Breeds
Lateral recumbency behaviour
Standing behaviour
d3
d2
Behaviour parameters
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3.3. Posture changes The frequency of postural changes from lateral recumbency to other postures (lateral-to-ventral recumbency, lateral recumbency-to-sitting, and lateral recumbency-tostanding) increased after week 1 post partum (Table 4). There were no differences between the Minpig and Landrace sows. The frequency of postural change from ventral-tolateral recumbency in the Minpig sows was lower than in the Landrace sows (P < 0.05) during the first three days postpartum. There were no differences between the two breeds during other observation periods. The Minpig sows and Landrace sows showed an increased frequency of postural change from ventral-to-lateral recumbency during the observation periods (P < 0.05). The Minpig sows had fewer postural changes from sitting-to-lying than the Landrace sows on the first and the third day post-partum (P < 0.05). During week 3 after parturition, the frequency of postural changes from sittingto-lying in the Minpig sows was greater than in the Landrace sows. The Minpig sows performed postural changes from standing-to-lying more often than the Landrace sows during all observation periods except for week 2 post-partum (P < 0.05). 3.4. Nursing behaviour The duration of nutritive nursing was different between week 2 and week 3 post-partum (Table 5) (P < 0.05). The duration of pre- and post-massage did not differ for all observation periods or between the Minpig and Landrace sows. The frequency of nutritive nursing of the Minpig sows was higher than that of the Landrace sows (P < 0.05), but no differences were found between the two periods (week 2 and week 3) post-partum. The proportion of nursings terminated by sows was lower in the Minpig sows than in the Landrace sows during week 2 after parturition (P < 0.05). 3.5. Carefulness of sows during standing-to-lying behaviour Table 6 shows the quantitative results of the carefulness scores of the sows during standing-to-lying. The analysis results of the carefulness score of the sows by the weighted least square method showed that Qw = 5.59 (P > 0.05), which demonstrates a good fit with the model. The independent variables, breeds and observation time, also had statistical significance (P < 0.01). The predicted values from the model in SAS software were presented as follows: F¯ Minpig = mean + differential effects = 2.3116 + 0.1878 = 2.4994;and F¯ Landrace = mean + differential effects = 2.3116 + (−0.1878) = 2.1238. Based on the results above, the fitting prediction results of the carefulness score of the Minpig sows was 2.4994, whereas that of the Landrace sows was 2.1238. The examined results of the differential effects for the observation time were −0.2538, 0.0422, and 0.2116 for d1 , d2 , and d3 ,
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respectively (P < 0.01). The predicted values of d1 , d2 , and d3 were 2.0578, 2.3538, and 2.5232, respectively. Therefore, the sows showed tendencies for higher carefulness during the first three days after parturition. 3.6. Responsiveness of sows to playback of piglet distress calls The quantitative results of the responsiveness of the sows to the playback of piglet distress calls are presented in Table 7. The analysis results of the responsiveness of the sows by the weighted least square method shows that Qw = 0.30 (P > 0.05), which demonstrates a good fit with the model. The independent variable of sow breed also had statistical significance (P < 0.001). The predicted values from the model in SAS software are presented as follows: F¯ Minpig = mean + differential effects = 1.0144 + 0.7199 = 1.7343; F¯ Landrace = mean + differential effects = 1.0144 + (−0.7199) = 0.2945. Based on the results above, the responsiveness value of the Minpig sows (1.7343) was significantly higher than that of the Landrace sows (0.2945). 4. Discussion Sows often spend a long time laterally recumbent and rarely change postures after parturition. This less movement is an important aspect of maternal ability and provides a great benefit to suckling of the newborn piglets. In the present study, the Minpig sows spent a significantly longer time laterally recumbent than the Landrace sows during the first three days post-partum, and there was a lower rate of occurrence of crushing in Minpig sows during the same time. The lateral recumbency behaviour of sows not only permits piglets to move close to the mother’s udder to obtain nutrition by suckling but can also provide a warm and safe environment for piglets (Jarvis et al., 1999; Pedersen et al., 2003). The results of lateral behaviour from this study suggest that the maternal ability of Minpig is better than that of Landrace. The ventral recumbency behaviour of sows during nursing is a signal to refuse nursing (Petherick, 1983; Jensen et al., 1991) and is the main form of the gradual process of weaning. In accordance with this behaviour, in this study, the sows exhibited ventral recumbency behaviour less in the first three days than the second and the third week after parturition. In addition, there were significant differences between the two breeds: the Minpig sows spent less time performing ventral behaviour during the first three days after parturition. The increasing frequency of lateral recumbency-to-other posture changes is another sign to refuse nursing piglets (Valros et al., 2003b). Additionally, biologically, the frequency of nursing terminated by the sows tends to increase during the lactation. However, there was a difference between the breeds in the proportion of nursing terminated by the sow: that of the Minpig sows were significantly lower than that of the Landrace sows during week 2 after parturition. Svendsen et al. (1986) reported that the crushing of piglets occurred most often during the first three days after parturition, especially in
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Table 5 The nursing behaviours of the Minpig and Landrace sows during week 2 and week 3 post-partum. Behavioural parameters
Breeds
W2
Duration of nutritive nursing (s)
Minpig Landrace P-value
14.68a ± 0.26 14.76a ± 0.32
W3
Duration of pre-massage (min)
Minpig Landrace P-value
1.78 ± 0.09 1.98 ± 0.12
Duration of post-massage sow allowed (min)
Minpig Landrace P-value
3.89 ± 0.22 3.58 ± 0.28
Frequencies of nutritive nursing (/h)
Minpig Landrace P-value
1.38x ± 0.03 1.24y ± 0.04
Proportion of nursing terminated by the sow (%)
Minpig Landrace P-value
19.08x ± 3.87 35.42ay ± 4.86
P-value
13.86b ± 0.26 13.78b ± 0.31
0.990
1.87 ± 0.09 1.75 ± 0.11
0.678
3.28 ± 0.22 3.51 ± 0.27
0.868
1.38x ± 0.03 1.14y ± 0.04
<0.001
0.002
0.489
0.175
0.136 46.70 ± 3.93 54.58b ± 4.74
0.006
<0.001
Table 6 Carefulness scores of Minpig and Landrace sows during postural changes from standing to lying. Observation periods
d1
d2
Scores
0
1
2
3
4
Minpig Landrace
0 3
40 40
110 80
86 25
12 0
0
d3 1
1 1
2
18 12
the first 24 h post-partum, which is in agreement with our results. It has been reported that the number of the piglets crushed is positively correlated with the amount of time sows spend sitting (McGlone and Morrow-Tesch, 1990). The result that the Minpig sows spent significantly shorter time than the Landrace sows sitting during the first three days post-partum indicates that the probability of crushing piglets in the Landrace sows is much higher than the Minpig sows when changing postures from sitting to lying. This inference can be verified by another result of this study that showed that the crushing of piglets by the Minpig sows was zero for the first three days after parturition during postures changes from sitting to lying, while the number of occurrences in the Landrace sows was six. Furthermore, the statistical results demonstrate that the Minpig sows showed good maternal ability in several state behaviours such as lateral recumbency, ventral recumbency and sitting behaviour. We found that the frequency of the sows’ standing-tolying behaviour in the first day post-partum was much higher than in the second and the third day in the Minpig sows but not in the Landrace sows, which may be related to the Minpig’s farrowing characteristics. In this study, during the first three days after farrowing, the frequency of standing-to-lying behaviour was significantly higher in the Minpig sows than in the Landrace sows. Fraser (1990) sug-
3
63 48
62 31
4
0
1
2
3
4
16 5
0 0
8 16
47 45
70 32
28 4
gested that the danger of crushing mainly occurred during the posture changes, such as changing from standing to lying or from sitting to lying. If this hypothesis is correct, the Minpig sows should crush more piglets than the Landrace sows. The results of the present study seem to conflict with the hypothesis. Although the Minpig sows performed more standing-to-lying behaviours than the Landrace sows, only 10 incidences were observed for Minpig sows compared with 32 in Landrace sows. Why do the results not support the previous hypothesis? From the behavioural characteristics of the Minpig sows, we found that the Minpig sows root their piglets away before lying down on the floor, unlike the Landrace sows that often flop suddenly straight to one side. Thus in this case, standing-to-lying may not be the critical behaviour for crushing piglets for the Minpig sows. Also, the predictive value of carefulness of the Minpig sows (2.4994) was higher than that of Landrace (2.1238). Thus, we could interpret the reason of why the piglet-crushing number of occurrences was much fewer for the Minpig sows even though they exhibit a higher frequency of standing-to-lying behaviour than the Landrace sows. In addition, piglet crushing was not only related with the frequency of standing-to-lying but also with the frequency of ventral recumbency-to-lateral recumbency and sitting-to-lying behaviour (Fraser, 1990). Therefore, we selected various behaviour parameters to observe, and the
Table 7 Responsiveness scores of Minpig and Landrace sows to piglet distress calls. Observation periods Scores Minpig Landrace
d1
d2
d3
0
1
2
3
4
5
0
1
2
3
4
5
0
1
2
3
4
5
9 17
4 0
3 1
3 1
2 0
2 0
6 9
3 0
2 1
3 0
3 0
1 0
7 10
2 0
1 1
3 0
3 1
1 0
S.-q. Cui et al. / Applied Animal Behaviour Science 131 (2011) 40–47
results of the ventral recumbency-to-lateral recumbency and sitting-to-lying behaviour were in keeping with that of standing-to-lying behaviour. The above results demonstrate that the Minpig sows have a better maternal ability than the Landrace sows. Furthermore, there were large individual differences in the responsiveness of sows to piglet distress calls (Wechsler and Hegglin, 1997). A sow with good maternal abilities was predicted to change postures such as sitting or standing up immediately when a piglet was trapped under her body, which would give the piglet a greater chance of survival. The reaction scores of the sows in the study confirmed this hypothesis. Using the model by the weight least square analysis, the predictive value of responsiveness of the Minpig sows was 1.7343, which was significantly higher than that of Landrace sows (0.2945). This result also explained the reason why Minpig sows had fewer crushing events during the first three days post-partum. When a piglet was crushed under the sow, the rate of escape in the Minpig sows was 76.5%, compared to 18.9% of the Landrace sows. 5. Conclusions In conclusion, Minpig sows have better maternal abilities than Landrace sows when measured by either the behavioural characteristics observed in early lactation or by the predictive values of responsiveness of sows to piglet distress calls. The maternal ability of sows plays an important role in the survival of piglets; therefore, we suggest that the sow’s maternal traits, including some related behaviours, should be considered in breeding selection and that the Minpig breed maybe a good choice for its further exploitation in China’s pig breeding programs. Acknowledgments We would like thank the people who provided on-farm assistance during the experiment. References Blackshaw, J.K., Hageasø, A.M., 1990. Getting-up and lying-down behaviours of loose-housed sows and social contacts between sows and piglets during day1 and day 8 after parturition. Appl. Anim. Behav. Sci. 25, 61–70. Cronin, G.M., Cropley, J.A., 1991. The effect of piglet stimuli on the posture changing behavior of recently farrowed sows. Appl. Anim. Behav. Sci. 30, 167–172. Dyck, G.W., Swierstra, E.E., 1987. Causes of piglet death from birth to weaning. Can. J. Anim. Sci. 67, 543–547. Edwards, S.A., Malkin, S.J., Spechter, H.H., 1986. An analysis of piglet mortality with behavioural observations. Anim. Prod. 42, 470. English, P.R., Morrison, V., 1984. Causes and prevention of piglet mortality. Pig News Inf. 5, 369–376. Fraser, D., 1990. Behavioural perspectives on piglet survival. J. Reprod. Fert. 40 (Suppl.), 370–455. ˇ Gustafsson, M., Jensen, P., de Jonge, F.H., Illmann, G., Spinka, M., 1999. Maternal behaviour of domestic sows and crosses between domestic sows and wild boar. Appl. Anim. Behav. Sci. 65, 29–42.
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Harris, M.J., Gonyou, H.W., 1998. Increasing available space in a farrowing crate does not facilitate postural changes or maternal responses in gilts. Appl. Anim. Behav. Sci. 59, 285–296. Hutson, G.D., Wilkinson, J.L., Luxford, B.G., 1991. The response of lactating sows to tactile, visual and auditory stimuli associated with a model piglet. Appl. Anim. Behav. Sci. 32, 129–137. Hutson, G.D., Price, E.O., Dickenson, L.G., 1993. The effect of playback volume and duration on the response of sows to piglet distress calls. Appl. Anim. Behav. Sci. 37, 31–37. Jarvis, S., McLean, K., Calvert, S.K., Deans, L.A., Chirnside, J., Lawrence, A.B., 1999. The responsiveness of sows to their piglets in relation to the length of parturition and the involvement of endogenous opioids. Appl. Anim. Behav. Sci. 63, 195–207. Jensen, P., 1988. Maternal behaviour and mother–young interactions during lactation in free-ranging domestic pigs. Appl. Anim. Behav. Sci. 20, 297–308. Jensen, P., Recén, B., 1989. When to wean-observations from free ranging domestic pigs. Appl. Anim. Behav. Sci 23, 49–60. Jensen, P., Stangel, G., Algers, B., 1991. Nursing and suckling behaviour of semi-naturally kept pigs during the first 10 days postpartum. Appl. Anim. Behav. Sci 31, 195–210. Marchant, J.N., Broom, D.M., 1996. Factors affecting posture-changing in loose-housed and confined gestating sows. Anim. Prod. 63, 477–485. Marchant, J.N., Broom, D.M., Corning, S., 1996. The effects of sow maternal behaviour on piglet mortality in an open farrowing system. Anim. Sci. 62, 675 (Abstr.). Marchant, J.N., Broom, D.M., Corning, S., 2001. The influence of sows behaviour on piglet mortality due to crushing in an open farrowing system. Anim. Sci. 72, 19–28. McGlone, J.J., Morrow-Tesch, J., 1990. Productivity and behavior of sows in level vs. sloped farrowing pens and crates. J. Anim. Sci. 68, 82–87. Pedersen, L.J., Damm, B.I., Marchant-Forde, J.N., Jensen, K.H., 2003. Effects of feed-back from the nest on maternal responsiveness and postural changes in primiparous sows during the first 24 h after farrowing onset. Appl. Anim. Behav. Sci. 83 (2), 109–124. Petersen, V., Récen, B., Vestergaard, K., 1990. Behaviour of sows and piglets during farrowing under free-range conditions. Appl. Anim. Behav. Sci. 26, 169–179. Petherick, J.C., 1983. A note on nursing termination and resting behaviour of suckling piglets. Appl. Anim. Ethol. 9 (3–4), 359–365. Svendsen, J., Bengtsson, A.C., Svendsen, L.S., 1986. Occurrence and causes of traumatic injures in neonatal pigs. Pig News Inf. 7, 159–170. Thodberg, K., Jensen, K.H., Herskin, M.S., 2002. Nursing behaviour, postpartum activity and reactivity in sows: effect of farrowing environment, previous experience and temperament. Appl. Anim. Behav. Sci. 77, 53–76. ˇ Valros, A., Rundgren, M., Spinka, M., Saloniemi, H., Algers, B., 2003a. Sow activity level, frequency of standing-to-lying posture changes and anti-crushing behavior—within sow-repeatability and interactions with nursing behavior and piglet performance. Appl. Anim. Behav. Sci. 83, 29–40. ˇ Valros, A., Rundgren, M., Spinka, M., Saloniemi, H., Rydhmer, L., Hultén, F., Uvnäs-Moberg, K., Tománek, M., Krejci, P., Algers, B., 2003b. Metabolic state of the sow, nursing behaviour and milk production. Livest. Prod. Sci. 79, 155–167. Vieuille, C., Berger, F., Le Pape, G., Bellanger, D., 2003. Sow behaviour involved in the crushing of piglets in outdoor farrowing huts—a brief report. Appl. Anim. Behav. Sci. 80, 109–115. Weary, D.M., Pajor, E.A., Thompson, B.K., Fraser, D., 1996. Sow body movements that crush piglets: a comparison between two types of farrowing accommodation. Appl. Anim. Behav. Sci. 49, 149–158. Wang, X.B., Wang, Y.B., Zhang, B.R., 2002. Comparison of reproduction performance in Minpig sows and Minpig hybrid sows Heilongjiang. J. Anim. Sci. Vet. Sci. 1, 12–14. 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. Wechsler, B., Hegglin, D., 1997. Individual differences in the behaviour of sows at the nest-site and the crushing of piglets. Appl. Anim. Behav. Sci. 51, 39–49.
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Applied Animal Behaviour Science journal homepage: www.elsevier.com/locate/applanim
A comparison of postural changes and maternal responsiveness during early lactation in Landrace and Minpig sows夽 Shi-quan Cui a , Dong-hua Chen a , Jian-hong Li a , Xiang Li a , Guo-an Yin b , Jun Bao b,∗ a b
School of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, PR China School of Animal Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, PR China
a r t i c l e
i n f o
Article history: Accepted 20 January 2011 Available online 20 February 2011 Keywords: Behaviour Postural change Maternal responsiveness Sow Minpig Landrace
a b s t r a c t Maternal behaviour is one of the instinct behaviours associated with offspring survival. Minpig is a local breed in the Northeast of China known for its strong maternal sense. In this study, sows of Minpig (n = 30, parity 2–8) and Landrace (n = 21, parity 2–8) were farrowed in individual pens with access to a yard. Sow behaviour was videotaped for 72 h in the second and third week after parturition. The results showed that the Minpig sows and Landrace sows were different in piglet-crushing behaviour (rolling, lying down from a sitting position or a standing position), lateral recumbency, ventral recumbency, and sitting and nursing behaviour (frequency of nutritive nursing and proportion of nursing terminated by the sow). The Minpig sows lie down at higher frequencies from a standing position, but crushing resulting from this movement in the Minpig sows was much less common than in the Landrace sows with only 10 crushing incidents compared to 32, respectively. Crushing occurred most often when the sows changed from the ventral recumbency position to lateral recumbency. In the present study, the total number of occurrences of piglet crushing by the Minpig sows was significantly lower (P < 0.05) than that of the Landrace ones (17 vs. 74). The results indicate that the Minpig sows provided more chances for piglets to escape successfully when the piglets were trapped by her body, leading to 76.5% of the Minpig piglets successfully escaping compared to 18.9% of the Landrace piglets. To explore the reason behind the above results, the carefulness of the sows during standing-to-lying and the responsiveness of the sows to piglet distress calls were investigated. Compared with the Landrace breed, the Minpig sows scored higher in standing-to-lying carefulness (F¯ Minpig = 2.4994, F¯ Landrace = 2.1238, P < 0.01) and higher in responsiveness to piglet distress calls (F¯ Minpig = 1.7343, F¯ Landrace = 0.294, P < 0.001). In conclusion, the data suggest that the Minpig sows show stronger maternal instincts through their behavioural postures and their carefulness with piglets compared with the Landrace breed, and this difference may play an important role in the further exploitation of local breeds for the swine breeding program in China. © 2011 Elsevier B.V. All rights reserved.
1. Introduction
夽 This study was financially supported by the Scientific Research Foundation of Northeast Agricultural University, PR China. ∗ Corresponding author. Tel.: +86 459 6819002; fax: +86 459 6819015. E-mail address: [email protected] (J. Bao). 0168-1591/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.applanim.2011.01.011
The loss of pre-weaning piglets is an important economic and animal welfare problem in swine production (English and Morrison, 1984). The crushing of piglets by sows is reported to be the major cause of piglet mortality (Dyck and Swierstra, 1987; Svendsen et al., 1986). Therefore, maternal behaviour may be an important factor correlated with the mortality of neonatal piglets (Fraser,
S.-q. Cui et al. / Applied Animal Behaviour Science 131 (2011) 40–47
1990). The posture changes of sows from the standing to the lying down position during the whole lactating period are dangerous for piglet survival (Weary et al., 1998; Marchant et al., 2001; Vieuille et al., 2003) because piglets are often crushed during this process (Edwards et al., 1986; Weary et al., 1996). The sequence of lying down can be divided into five stages (Marchant and Broom, 1996): (1) one of the sow’s front legs kneels onto the floor and then the other follows; (2) the sow may pause shortly before continuing movement; (3) the sow slips forward on its knees by turning to bring one shoulder and the side of the head to rest upon the floor; (4) the sow may pause shortly again before movement continues; and (5) the sow lowers the hindquarters of its body and slides its rear legs by turning until it touches the floor completely. For pregnant sows, stage 1, 3, and 5 took 2, 1, and 2 s, respectively, and stage 2 and 4 took 1 and 2 s, respectively (Harris and Gonyou, 1998). However, the overall time taken to lie down and the time taken in stage 4 could be influenced by type of the pen. For example, stage 4 could take up to 4 s in spacious crates as opposed to 1 s in narrow crates or loosed pens. Two patterns of lying-down behaviour were commonly observed in lactating sows: lying down vertically (the sow lies down on her belly at the end of stage 5) and lying down laterally (the sow lets her hindquarters fall to one side at the end of stage 5). Compared with lying down vertically, lying down laterally is considered more dangerous for the piglets when they are present, especially when the sow lies down by falling on her side (Blackshaw and Hageasø, 1990; Wechsler and Hegglin, 1997). However, pre-lying behaviour such as looking at the piglets, sniffing, or rooting away the piglets can reduce the risk of piglet crushing (Marchant et al., 1996). Generally, sows perform most pre-lying behaviour on the day of parturition because that is when the piglets are most vulnerable (Weary et al., 1996; Marchant et al., 2001). McGlone and Morrow-Tesch (1990) reported that the amount of time sows spent sitting was positively correlated with the number of piglets crushed and that sows that spent more time sitting seemed more likely to crush piglets. Rolling behaviour is also considered as one of the movements dangerous to piglets (Weary et al., 1996; Wechsler and Hegglin, 1997). Sows spend most of the time on lateral recumbency during parturition and the first day post-partum (Petersen et al., 1990; Jarvis et al., 1999; Pedersen et al., 2003; Vieuille et al., 2003); therefore, sows need to roll from one side to the other occasionally for comfort. Additionally, rolling behaviour is also part of the gradual weaning process for the sows (Jensen, 1988; Jensen and Recén, 1989). The danger from movement has been associated not only with the speed and manner in which movements were performed, but also the frequency of movements made by sows. Rolling movements that resulted in the crushing of piglets was often performed much faster than rolls that did not (Weary et al., 1996). Sows that are responsive to piglet distress calls could reduce the risk of piglet-crushing. There were large individual differences in the sows’ responsiveness to piglet distress calls (Hutson et al., 1991, 1993). Some sows were very responsive to the vocalisation of a trapped piglet and would rise or sit to give the piglet a chance for survival, whereas other sows did not react at all (Hutson et al.,
41
1991; Cronin and Cropley, 1991). It had been reported that sows showing a strong response to the sound of a screaming piglet seemed to display less risky behaviour around their piglets early post-partum (Thodberg et al., 2002; Wechsler and Hegglin, 1997) and had fewer crushed piglets (Wechsler and Hegglin, 1997). The selective breeding in modern swine production mainly focus on the growth traits of the pig rather than the maternal ability of sows. Actually, the maternal ability is significant in swine production, especially for improving the farming management. Minpig is a local breed in Northeastern China and has been characterised as prolific (14.35 piglets per birth) and a source of good meat and has a strong resistance to poor feed quality and cold climate (Wang et al., 2002). Furthermore, its good maternal temperament is another outstanding characteristic of the Minpig breed. At weaned age 60 days this breed has 11–12 alive piglets per litter, compared to Landrace breed with 9–10 alive piglets per litter at weaning age of 35 days (Wang et al., 2002). This research aims to compare the maternal behaviour of the Minpig sows with that of the Landrace sows and to provide valuable behavioural observations of the local breeds for the purpose of future swine production. 2. Materials and methods 2.1. Animals and housing Thirty Minpig sows and 21 Landrace sows from a commercial farm were used. Sows were multifarious (parity 2–8) and farrowed from June 15 to July 23, 2008. The two breeds of sows were housed separately in two barns. Each barn consisted of 42 individual pens for farrowing and early lactation. The farrowing pens (2.7 m × 2.1 m) were on solid concrete flooring, and no bedding or rails were provided on the floor to protect piglets from being crushed (Fig. 1). The sows were fed twice daily at 06:30 and 15:30 and had free access to fresh water. The sows were allowed to leave their pens to exercise in an open yard for approximately a half hour right before each feeding. No heat lamps were provided for the newborn piglets in the creep area during the summer. Room temperature and humidity ranged from 25 to 32 ◦ C and 45 to 55%, respectively, during the daytime. During the night, the room temperature varied between 18 and 22 ◦ C, and the relative humidity was approximately 35%. The barn was ventilated through a natural ventilation system. 2.2. Behaviour observation and categorisation The behaviours of the sows and their piglets were recorded with a video recording system (JinPeng L4400). Video cameras (Lerong RL-H115) were fixed in the front of the pens. At farrowing, all sows were videotaped for 72 h, starting from the first birth of piglets. The 24 h period following the birth of the first piglet was called day 1 (d1 ) post-partum, the subsequent 24 h period was called day 2 (d2 ) and the following one called day 3 (d3 ). During week 2 and week 3 post-partum, the sows were videotaped twice each week for two consecutive days between 09:30–11:30 and 13:00–15:00. Behaviour data from the video records
42
S.-q. Cui et al. / Applied Animal Behaviour Science 131 (2011) 40–47
Fig. 1. Diagram of the farrowing pens in this study: (1) resting area for the sow; (2) feeding area; (3) resting area for the piglets, (4) drinkers, (5) the door to a yard.
were analysed, and the various behaviour traits are defined in Table 1. A scoring system was established to assess a sow’s carefulness during the postural change from standing-to-lying. Behavioural criteria of the scoring system included sniffing piglets before lying down, rooting before lying down, descending ventrally (as opposed to flopping over to one side), and lying down when there were no piglets near her on that side (Valros et al., 2003a). During each standing-tolying event, if any one of the behaviours described above was present, the sow would be scored as one, and if not, she would be scored as zero. The carefulness score of a sow ranged from 0 to 4 during each standing-to-lying event. The piglet distress calls from each litter were obtained on the first day after birth by pressing a toe of a newborn piglet without imposing serious injury and recording the sound with a Sound Recording Pen (Sony ICD-SX800).
Each distress call from the piglets was 3–5 s in time-length and a recording of 30 s was obtained by repeatedly recording it. Therefore, each experimental sow had the recording of its own piglet’s call. The recording was played back to the mother immediately after she had finished lying down after feeding. A loudspeaker was placed at the rear of the sows’ hindquarters and the sows’ response to the sound was recorded. The test was carried out on d2 or d3 of the first week after farrowing and once again on the fourth day of week 2 and week 3. The responses to the playback by the sows were scored as follows: 0—No reaction; 1—Head moves; 2—Sits; 3—Stands up; or 4—Makes contact with the loudspeaker. 2.3. Statistical analysis The data were analysed using Microsoft Excel. The state behaviour was presented as a percentage of the total obser-
Table 1 Behavioural parameters and their definitions. Postural parameters General behaviour Lateral recumbency Ventral recumbency Standing or walking Sitting Lateral recumbency-to-other postures Ventral-to-lateral recumbency Sitting-to-lying Standing-to-lying Nursing behaviour Duration of nutritive nursing Frequencies of nutritive nursing Duration of pre-massage Duration of post-massage
Nursing terminated by the sow
Definition Sow’s head, ear, scapular and waist all touching the floor and all four legs visible. Sow’s chest and abdomen touching the floor and front legs stretched or folded under the body. Upright body position on extended legs and legs frozen or moving; includes walking while exhibiting other behaviour. Hind quarter and caudal end touching the floor with hinder legs folded and front legs erect to support the body weight. Posture changing from lateral recumbency to other behaviours including ventral recumbency, sitting and standing. Posture changing from ventral recumbency to lateral recumbency. Posture changing from sitting to lying, including ventral recumbency and lateral recumbency. Postures changing from standing to lying, including ventral recumbency and lateral recumbency. Duration was identified by the rapid suckling of the piglets with milk ejection, calculated by seconds (Gustafsson et al., 1999). Frequency was defined as the number of occurrences of milk ejections of the sow during a definite time (Gustafsson et al., 1999). Pre-massage was considered to start when at least half the litter started to massage the udder and to end once the milk was ejected (Gustafsson et al., 1999). Post-massage was initiated when the milk ejection ended and terminated when at least half the litter stopped massaging the udder. If the sow changed postures such as by rolling over or walking away from the piglets, the post-massage was over. After milk ejection, the suckling of piglets was terminated by a posture change of the sow (Gustafsson et al., 1999).
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43
Table 2 Numbers of piglets trapped by Minpig and Landrace sows during postural changes. Breeds (n)
Litter size (mean ± s.e.)
Observation periods
Postural changes
Standingto-lying vertically
Minpig (n = 30)
Landrace (n = 21) a
Standingto-lying laterally
No of piglet trapped Ventral-tolateral recumbency
Lateral-toventral recumbency
Sitting-tolying
Lying-tositting
10.5 ± 2.46
d1 d2 d3 Total
1 (1)a 4 (3) 0 5 (4)
2 (1) 1 (0) 2 (2) 5 (3)
3 (2) 4 (4) 0 7 (6)
0 0 0 0
0 0 0 0
0 0 0 0
6 (4) 9 (7) 2 (2) 17 (13)
10.6 ± 2.91
d1 d2 d3 Total
10 (3) 3 (0) 6 (1) 19 (4)
6 (1) 4 (1) 3 (0) 13 (2)
11 (3) 6 (2) 8 (2) 25 (7)
3 (1) 2 4 9 (1)
4 (0) 2 0 6
2 (0) 0 0 2
36 (8) 17 (3) 21 (3) 74 (14)
The number in the brackets represents the number of piglets that successfully escaped from being trapped.
vations, and the event behaviour (such as movements of lateral recumbency-to-other postures, ventral-to-lateral recumbency, and sitting-to-lying and standing-to-lying) was presented as the frequency of the occurrences per hour. A GLM procedure of the SAS statistical software (SAS, Ver 9.0) was used to test the behavioural differences between the two breeds and observations over different times. The model for the behavioural analysis during the first three days after parturition included the following effects: Yijk = + Breedi + Dayj + Breedi × Dayj + eij where is a general mean, Breedi is the fixed effect of the breeds, Dayj is the fixed effect of the observation days (d1 , d 2 , d 3 ) after parturition and Breedi × Dayj is the interaction between the breeds and the observation days. The model for the behavioural analysis during week 2 and week 3 after parturition included the following effects: Yijk = + Breedi + Weekj + Periodk × Breedi × Weekj + Breedi × Periodk + eijk where is a general mean, Breedi is the fixed effect of breeds of sow, Weekj is the fixed effect of the observation week (Week 2 and Week 3) after parturition, Periodk is the fixed effect of the period (09:30–11:30 and 13:00–15:00) during the observation day, Breedi × Weekj is the interaction between the breeds and the observation week and Breedi × Periodk is the interaction between the breeds and the period during the observation day. The carefulness scores of the sows during standingto-lying and the responsiveness of the sows to the piglet distress calls were evaluated by a weighted least square analysis in the CATMOD procedure in SAS. The model is as follows: Yijk = + Bi + Dj + Tk + eijk where Yijk is the total score, is a general mean, Bi is the fixed effect of the breeds, Dj is the fixed effect of the observation time when the behaviour was recorded, Tk is the effect of the number of the occurrences of the different scoring standard and eijk is the residual effect. 3. Results 3.1. Crushing of piglets by sows The average litter size (born alive) for the Minpig sows and the Landrace sows was 10.50 ± 2.46 and 10.62 ± 2.91,
respectively (Table 2). The number of incidences of pigletcrushing by the Minpig sows was lower compared to that by the Landrace sows during the first three days post-partum. Piglet-crushing occurred more often when sows changed from ventral to lateral recumbency than in other postural changes. The Minpig sows showed fewer piglet trappings (17 incidences), which only occurred in the postural changes from standing to lying and from ventral to lateral recumbency, compared to the Landrace sows (74 incidences) that showed piglet trappings in all postural changes (Table 2). Among the piglets trapped by the Minpig sows, 76.5% successfully escaped, while only 18.9% of piglets trapped by the Landrace sows escaped. None of the trapped piglets died throughout the study because of the intensive animal care by farmers.
3.2. Postural behaviour The amount of time that sows spent in lateral recumbency did not differ during the first three days post-partum (Table 3) but significantly decreased with an increase in lactation days after one week postpartum (P < 0.001). The Minpig sows spent more time in lateral behaviour in the first three days post-partum than the Landrace sows (d1 , P = 0.05; d2 , P = 0.01; d3 , P < 0.001). No differences were observed between the two breeds after one week post-partum. The amount of time that sows spent in ventral recumbency showed no difference during the first three days post-partum (P > 0.05) and then increased as lactation progressed after one week (P < 0.001). During the first three days postpartum, the time spent in ventral recumbency by the Minpig sows was less than that by the Landrace sows (P < 0.05). The Landrace sows performed more sitting behaviour than the Minpig sows during the first three days postpartum. Significant differences were only found on the first and the third day post-partum (P < 0.05). There were no differences observed in the time spent on standing between the Minpig and Landrace sows and during the first three days post-partum.
44
Table 3 Time budgets for postural changes of Minpig and Landrace sows during early lactation (%). d1
Minpig Landrace P-value
92.1 ± 1.35 88.3a ± 1.35
Ventral recumbency behaviour
Minpig Landrace P-value
2.7x ± 1.05 5.7ay ± 1.05
Sitting behaviour
Minpig Landrace P-value
0.2x ± 0.17 1.4ay ± 0.17
Minpig Landrace P-value
4.8 ± 0.53 4.4 ± 0.53
P-value
91.8x ± 1.35 86.9aby ± 1.35 0.230
91.4x ± 1.35 84.3by ± 1.35
4.3x ± 1.05 7.5aby ± 1.05 0.024
4.4x ± 1.05 9.7by ± 1.05
0.2 ± 0.17 0.5b ± 0.17 0.039
0.2x ± 0.17 0.8by ± 0.17
3.7 ± 0.53 4.9 ± 0.53 0.797
3.9 ± 0.53 5.0 ± 0.53
<0.001
W3
W2 81.6a ± 3.05 78.1a ± 3.83
P-value
52.4b ± 3.10 58.8b ± 3.73
0.674
32.7b ± 2.71 29.3b ± 3.27
0.884
0.5 ± 0.38 1.6 ± 0.46
0.081
14.3bx ± 1.33 10.0by ± 1.60
0.072
<0.001 <0.001
12.4a ± 2.67 16.8a ± 3.35 <0.001
<0.001
0.9 ± 0.37 1.3 ± 0.47 0.913
0.141
4.9a ± 1.31 3.8a ± 1.64 <0.001
Note: Different superscripts in a row indicate significant differences between observation days (a, b: P < 0.05). Different superscripts in a column indicate significant differences between breeds (x, y: P < 0.05). Means and standard errors are shown.
Table 4 Frequencies of postural changes of Minpig and Landrace sows during the first three days in lactation. Postural changes (/h)
Breeds
d1
d2
d3
Frequencies of lateral recumbency-to-other postures
Minpig Landrace P-value
0.61 ± 0.06 0.70a ± 0.06
0.44 ± 0.06 0.44ab ± 0.06 0.001
0.46 ± 0.06 0.54b ± 0.06
Frequencies of ventral-to-lateral recumbency
Minpig Landrace P-value
0.24x ± 0.05 0.48ay ± 0.05
0.26 ± 0.05 0.27a ± 0.05 0.035
Frequencies of sitting-to-lying
Minpig Landrace P-value
0.10x ± 0.05 0.39ay ± 0.05
Frequencies of standing-to-lying
Minpig Landrace P-value
0.59ax ± 0.04 0.36y ± 0.04
P-value
W2
W3
P-value
0.232
0.52a ± 0.09 0.76a ± 0.11 <0.0001
1.01b ± 0.09 1.13b ± 0.11
0.074
0.32 ± 0.05 0.45b ± 0.05
0.001
0.48a ± 0.08 0.62a ± 0.10 0.0004
0.89b ± 0.08 0.88b ± 0.10
0.497
0.10 ± 0.05 0.19 ± 0.05b 0.031
0.04 ± 0.05y 0.21 ± 0.05bx
<0.001
0.20a ± 0.06 0.14 ± 0.07 0.0281
0.42bx ± 0.06 0.18y ± 0.07
0.028
0.40bx ± 0.04 0.24y ± 0.04 0.001
0.38bx ± 0.04 0.25y ± 0.04
<0.001
0.36a ± 0.07 0.24 ± 0.09 <0.001
0.92bx ± 0.07 0.42y ± 0.09
0.001
S.-q. Cui et al. / Applied Animal Behaviour Science 131 (2011) 40–47
Breeds
Lateral recumbency behaviour
Standing behaviour
d3
d2
Behaviour parameters
S.-q. Cui et al. / Applied Animal Behaviour Science 131 (2011) 40–47
3.3. Posture changes The frequency of postural changes from lateral recumbency to other postures (lateral-to-ventral recumbency, lateral recumbency-to-sitting, and lateral recumbency-tostanding) increased after week 1 post partum (Table 4). There were no differences between the Minpig and Landrace sows. The frequency of postural change from ventral-tolateral recumbency in the Minpig sows was lower than in the Landrace sows (P < 0.05) during the first three days postpartum. There were no differences between the two breeds during other observation periods. The Minpig sows and Landrace sows showed an increased frequency of postural change from ventral-to-lateral recumbency during the observation periods (P < 0.05). The Minpig sows had fewer postural changes from sitting-to-lying than the Landrace sows on the first and the third day post-partum (P < 0.05). During week 3 after parturition, the frequency of postural changes from sittingto-lying in the Minpig sows was greater than in the Landrace sows. The Minpig sows performed postural changes from standing-to-lying more often than the Landrace sows during all observation periods except for week 2 post-partum (P < 0.05). 3.4. Nursing behaviour The duration of nutritive nursing was different between week 2 and week 3 post-partum (Table 5) (P < 0.05). The duration of pre- and post-massage did not differ for all observation periods or between the Minpig and Landrace sows. The frequency of nutritive nursing of the Minpig sows was higher than that of the Landrace sows (P < 0.05), but no differences were found between the two periods (week 2 and week 3) post-partum. The proportion of nursings terminated by sows was lower in the Minpig sows than in the Landrace sows during week 2 after parturition (P < 0.05). 3.5. Carefulness of sows during standing-to-lying behaviour Table 6 shows the quantitative results of the carefulness scores of the sows during standing-to-lying. The analysis results of the carefulness score of the sows by the weighted least square method showed that Qw = 5.59 (P > 0.05), which demonstrates a good fit with the model. The independent variables, breeds and observation time, also had statistical significance (P < 0.01). The predicted values from the model in SAS software were presented as follows: F¯ Minpig = mean + differential effects = 2.3116 + 0.1878 = 2.4994;and F¯ Landrace = mean + differential effects = 2.3116 + (−0.1878) = 2.1238. Based on the results above, the fitting prediction results of the carefulness score of the Minpig sows was 2.4994, whereas that of the Landrace sows was 2.1238. The examined results of the differential effects for the observation time were −0.2538, 0.0422, and 0.2116 for d1 , d2 , and d3 ,
45
respectively (P < 0.01). The predicted values of d1 , d2 , and d3 were 2.0578, 2.3538, and 2.5232, respectively. Therefore, the sows showed tendencies for higher carefulness during the first three days after parturition. 3.6. Responsiveness of sows to playback of piglet distress calls The quantitative results of the responsiveness of the sows to the playback of piglet distress calls are presented in Table 7. The analysis results of the responsiveness of the sows by the weighted least square method shows that Qw = 0.30 (P > 0.05), which demonstrates a good fit with the model. The independent variable of sow breed also had statistical significance (P < 0.001). The predicted values from the model in SAS software are presented as follows: F¯ Minpig = mean + differential effects = 1.0144 + 0.7199 = 1.7343; F¯ Landrace = mean + differential effects = 1.0144 + (−0.7199) = 0.2945. Based on the results above, the responsiveness value of the Minpig sows (1.7343) was significantly higher than that of the Landrace sows (0.2945). 4. Discussion Sows often spend a long time laterally recumbent and rarely change postures after parturition. This less movement is an important aspect of maternal ability and provides a great benefit to suckling of the newborn piglets. In the present study, the Minpig sows spent a significantly longer time laterally recumbent than the Landrace sows during the first three days post-partum, and there was a lower rate of occurrence of crushing in Minpig sows during the same time. The lateral recumbency behaviour of sows not only permits piglets to move close to the mother’s udder to obtain nutrition by suckling but can also provide a warm and safe environment for piglets (Jarvis et al., 1999; Pedersen et al., 2003). The results of lateral behaviour from this study suggest that the maternal ability of Minpig is better than that of Landrace. The ventral recumbency behaviour of sows during nursing is a signal to refuse nursing (Petherick, 1983; Jensen et al., 1991) and is the main form of the gradual process of weaning. In accordance with this behaviour, in this study, the sows exhibited ventral recumbency behaviour less in the first three days than the second and the third week after parturition. In addition, there were significant differences between the two breeds: the Minpig sows spent less time performing ventral behaviour during the first three days after parturition. The increasing frequency of lateral recumbency-to-other posture changes is another sign to refuse nursing piglets (Valros et al., 2003b). Additionally, biologically, the frequency of nursing terminated by the sows tends to increase during the lactation. However, there was a difference between the breeds in the proportion of nursing terminated by the sow: that of the Minpig sows were significantly lower than that of the Landrace sows during week 2 after parturition. Svendsen et al. (1986) reported that the crushing of piglets occurred most often during the first three days after parturition, especially in
46
S.-q. Cui et al. / Applied Animal Behaviour Science 131 (2011) 40–47
Table 5 The nursing behaviours of the Minpig and Landrace sows during week 2 and week 3 post-partum. Behavioural parameters
Breeds
W2
Duration of nutritive nursing (s)
Minpig Landrace P-value
14.68a ± 0.26 14.76a ± 0.32
W3
Duration of pre-massage (min)
Minpig Landrace P-value
1.78 ± 0.09 1.98 ± 0.12
Duration of post-massage sow allowed (min)
Minpig Landrace P-value
3.89 ± 0.22 3.58 ± 0.28
Frequencies of nutritive nursing (/h)
Minpig Landrace P-value
1.38x ± 0.03 1.24y ± 0.04
Proportion of nursing terminated by the sow (%)
Minpig Landrace P-value
19.08x ± 3.87 35.42ay ± 4.86
P-value
13.86b ± 0.26 13.78b ± 0.31
0.990
1.87 ± 0.09 1.75 ± 0.11
0.678
3.28 ± 0.22 3.51 ± 0.27
0.868
1.38x ± 0.03 1.14y ± 0.04
<0.001
0.002
0.489
0.175
0.136 46.70 ± 3.93 54.58b ± 4.74
0.006
<0.001
Table 6 Carefulness scores of Minpig and Landrace sows during postural changes from standing to lying. Observation periods
d1
d2
Scores
0
1
2
3
4
Minpig Landrace
0 3
40 40
110 80
86 25
12 0
0
d3 1
1 1
2
18 12
the first 24 h post-partum, which is in agreement with our results. It has been reported that the number of the piglets crushed is positively correlated with the amount of time sows spend sitting (McGlone and Morrow-Tesch, 1990). The result that the Minpig sows spent significantly shorter time than the Landrace sows sitting during the first three days post-partum indicates that the probability of crushing piglets in the Landrace sows is much higher than the Minpig sows when changing postures from sitting to lying. This inference can be verified by another result of this study that showed that the crushing of piglets by the Minpig sows was zero for the first three days after parturition during postures changes from sitting to lying, while the number of occurrences in the Landrace sows was six. Furthermore, the statistical results demonstrate that the Minpig sows showed good maternal ability in several state behaviours such as lateral recumbency, ventral recumbency and sitting behaviour. We found that the frequency of the sows’ standing-tolying behaviour in the first day post-partum was much higher than in the second and the third day in the Minpig sows but not in the Landrace sows, which may be related to the Minpig’s farrowing characteristics. In this study, during the first three days after farrowing, the frequency of standing-to-lying behaviour was significantly higher in the Minpig sows than in the Landrace sows. Fraser (1990) sug-
3
63 48
62 31
4
0
1
2
3
4
16 5
0 0
8 16
47 45
70 32
28 4
gested that the danger of crushing mainly occurred during the posture changes, such as changing from standing to lying or from sitting to lying. If this hypothesis is correct, the Minpig sows should crush more piglets than the Landrace sows. The results of the present study seem to conflict with the hypothesis. Although the Minpig sows performed more standing-to-lying behaviours than the Landrace sows, only 10 incidences were observed for Minpig sows compared with 32 in Landrace sows. Why do the results not support the previous hypothesis? From the behavioural characteristics of the Minpig sows, we found that the Minpig sows root their piglets away before lying down on the floor, unlike the Landrace sows that often flop suddenly straight to one side. Thus in this case, standing-to-lying may not be the critical behaviour for crushing piglets for the Minpig sows. Also, the predictive value of carefulness of the Minpig sows (2.4994) was higher than that of Landrace (2.1238). Thus, we could interpret the reason of why the piglet-crushing number of occurrences was much fewer for the Minpig sows even though they exhibit a higher frequency of standing-to-lying behaviour than the Landrace sows. In addition, piglet crushing was not only related with the frequency of standing-to-lying but also with the frequency of ventral recumbency-to-lateral recumbency and sitting-to-lying behaviour (Fraser, 1990). Therefore, we selected various behaviour parameters to observe, and the
Table 7 Responsiveness scores of Minpig and Landrace sows to piglet distress calls. Observation periods Scores Minpig Landrace
d1
d2
d3
0
1
2
3
4
5
0
1
2
3
4
5
0
1
2
3
4
5
9 17
4 0
3 1
3 1
2 0
2 0
6 9
3 0
2 1
3 0
3 0
1 0
7 10
2 0
1 1
3 0
3 1
1 0
S.-q. Cui et al. / Applied Animal Behaviour Science 131 (2011) 40–47
results of the ventral recumbency-to-lateral recumbency and sitting-to-lying behaviour were in keeping with that of standing-to-lying behaviour. The above results demonstrate that the Minpig sows have a better maternal ability than the Landrace sows. Furthermore, there were large individual differences in the responsiveness of sows to piglet distress calls (Wechsler and Hegglin, 1997). A sow with good maternal abilities was predicted to change postures such as sitting or standing up immediately when a piglet was trapped under her body, which would give the piglet a greater chance of survival. The reaction scores of the sows in the study confirmed this hypothesis. Using the model by the weight least square analysis, the predictive value of responsiveness of the Minpig sows was 1.7343, which was significantly higher than that of Landrace sows (0.2945). This result also explained the reason why Minpig sows had fewer crushing events during the first three days post-partum. When a piglet was crushed under the sow, the rate of escape in the Minpig sows was 76.5%, compared to 18.9% of the Landrace sows. 5. Conclusions In conclusion, Minpig sows have better maternal abilities than Landrace sows when measured by either the behavioural characteristics observed in early lactation or by the predictive values of responsiveness of sows to piglet distress calls. The maternal ability of sows plays an important role in the survival of piglets; therefore, we suggest that the sow’s maternal traits, including some related behaviours, should be considered in breeding selection and that the Minpig breed maybe a good choice for its further exploitation in China’s pig breeding programs. Acknowledgments We would like thank the people who provided on-farm assistance during the experiment. References Blackshaw, J.K., Hageasø, A.M., 1990. Getting-up and lying-down behaviours of loose-housed sows and social contacts between sows and piglets during day1 and day 8 after parturition. Appl. Anim. Behav. Sci. 25, 61–70. Cronin, G.M., Cropley, J.A., 1991. The effect of piglet stimuli on the posture changing behavior of recently farrowed sows. Appl. Anim. Behav. Sci. 30, 167–172. Dyck, G.W., Swierstra, E.E., 1987. Causes of piglet death from birth to weaning. Can. J. Anim. Sci. 67, 543–547. Edwards, S.A., Malkin, S.J., Spechter, H.H., 1986. An analysis of piglet mortality with behavioural observations. Anim. Prod. 42, 470. English, P.R., Morrison, V., 1984. Causes and prevention of piglet mortality. Pig News Inf. 5, 369–376. Fraser, D., 1990. Behavioural perspectives on piglet survival. J. Reprod. Fert. 40 (Suppl.), 370–455. ˇ Gustafsson, M., Jensen, P., de Jonge, F.H., Illmann, G., Spinka, M., 1999. Maternal behaviour of domestic sows and crosses between domestic sows and wild boar. Appl. Anim. Behav. Sci. 65, 29–42.
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