Directory UMM :Data Elmu:jurnal:A:Applied Animal Behaviour Science:Vol70.Issue2.2000:
Applied Animal Behaviour Science 70 (2000) 99±114
Dimensions of maternal behaviour characteristics in
domestic and wilddomestic crossbred sows
Marek SÏpinkaa,*, Gudrun Illmanna, Francien de Jongeb,
Maria Anderssonc, Teun Schuurmand, Per Jensenc
a
Group of Ethology, Research Institute of Animal Production, CZ-104 01 Prague-UhrÏÂõneÏves, Czech Republic
b
Department of Ecological Agriculture and Society, Wageningen University and Research Centre,
Haarweg 333, 6709 RZ Wageningen, Netherlands
c
Department of Animal Environment and Health, Faculty of Veterinary Medicine, Section of Ethology,
Swedish University of Agricultural Sciences, POB 234, S-532 23 Skara, Sweden
d
Human and Animal Physiology Group, Wageningen Institute of Animal Sciences, Wageningen University,
Haarweg 10, 6709 PJ Wageningen, Netherlands
Accepted 29 May 2000
Abstract
We examined the maternal behaviour of seven domestic and seven wilddomestic primiparous
sows during 10 days post partum to investigate two questions: (1) Did maternal behaviour change
during domestication? (2) Can the interindividual variability of maternal behaviour be subsumed
into a few dimensions of maternal temperament? We recorded: (a) willingness to leave the nest for
food on Day 2; (b) reaction to a playback of squeezed piglet distress vocalisation on Day 2; (c)
spontaneous nursing behaviour and spontaneous lying-down behaviour on Day 5 (from an overnight
video recording); (d) reactions to playbacks of various piglet distress vocalisations on Day 6 and (e)
reactions to a human in the `nest' with piglets on Day 9. Moreover, data on baseline cortisol saliva
concentration and its increase during a brief transportation period and novel environment challenge
at the age of 5 months were available. Crossbred sows did not differ from domestic ones in any
aspect of maternal behaviour except for a higher tendency to terminate ®nal massage during
nursings and a higher frequency of changing posture from lying to standing and back during the
night. Factor analysis (based on correlation matrix of 11 behaviour and cortisol variables calculated
for all 14 sows after removing the effect of breed) indicated that 82% of the variability in the data
could be explained by three factors: ®rst, `calmness' on which low night time frequency of major
posture changes, carefulness of lying-down behaviour and high propensity to remain in nursing
position after milk ejection loaded positively while cortisol concentrations during challenge loaded
negatively; second, `protectiveness' with high loadings of the reaction scores to the playbacks of
piglet distress calls and the human presence near the piglets; and third, `nursing activity' which was
*
Corresponding author. Tel.: 420-2-6771-0713; fax: 420-2-6771-0779.
E-mail address: [email protected] (M. SÏpinka).
0168-1591/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 1 6 8 - 1 5 9 1 ( 0 0 ) 0 0 1 5 1 - 9
100
M. SÏpinka et al. / Applied Animal Behaviour Science 70 (2000) 99±114
strongly positively associated with nursing frequency, and negatively with the proportion of
nutritive nursings and baseline cortisol values. The results indicate that most aspects of pig maternal
behaviour have not been signi®cantly changed by domestication and that substantial variability in
maternal behaviour exists between sows, perhaps in the form of several behaviour characteristics
which encompass both behaviour and endocrine pro®les of the sows. # 2000 Elsevier Science B.V.
All rights reserved.
Keywords: Maternal behaviour; Pigs; Domestication; Nursing; Cortisol; Vocalisation; Temperament
1. Introduction
Maternal behaviour is important for pig husbandry since it partly determines mortality
and growth of the piglets. About 15% of the live born piglets die before weaning (McKay,
1993; Blackshaw et al., 1994), and among them 70±80% is attributable to the sow
behaviour, directly or indirectly. During the ®rst day of life, piglets get trapped under
the sow while she is lying-down or rolling from her belly to her side (Dyck and Swiestra,
1987; Weary et al., 1996a; Herskin et al., 1998). Individual dams differ in the frequency of
postural changes, and in how often they change posture in a way that is dangerous for the
piglets (i.e. ¯opping straight down to one side versus descending to lying posture in a
vertical plane; lying down when piglets are nearby). Even after a piglet is trapped, the sow's
behaviour is important. Just 20% of piglets trapped under the sow's body are actually
crushed. If a trapped piglet starts screaming, the sow may stand up immediately and release
it. In cases when the sow stood up within 1 min, only 5% of piglets died; in contrast, 67%
of the piglets trapped for longer than 4 min were lost (Weary et al., 1996a). Two aspects of
the sow's behaviour, thus, affect the probability of crushing: ®rst, the sow's general
restlessness and her lying-down behaviour; second, the sow's individual reactivity to a
screaming piglet (Wechsler and Hegglin, 1997).
Another problem in piglet production is low milk intake in some piglets or in whole
litters which results in low or too variable weaning weights. This may even lead to piglet
losses, either directly due to starvation or indirectly due to the weak piglets being crushed
by the sow (Hutson et al., 1993; Weary et al., 1996b). Low frequency of nursings (SÏpinka
et al., 1997; SÏpinka et al., 1999), and a high proportion of non-nutritive nursings (nursings
without milk ejection, CastreÂn et al., 1989; Illmann and Madlafousek, 1995; Illmann et al.,
1999) are probably the aspects of nursing behaviour which can most signi®cantly reduce
milk intake. A tendency to terminate the udder massage by the piglets soon after milk
ejection might also suppress future milk production in the glands, although the evidence is
equivocal (Algers and Jensen, 1991; SÏpinka and Algers, 1995; Jensen et al., 1998; Illmann
et al., 1998).
These undesired aspects in the maternal behaviour of domestic sows may have arisen
during the process of domestication, especially during the intense selective breeding
regimes prevalent in last few decades. Information about whether this was the case can be
useful in judging the likelihood that maternal characteristics of sows could be improved
through selective breeding programmes. The present study was conducted in order to
assess whether sows carrying different proportions of genes from domestic and wild boar
M. SÏpinka et al. / Applied Animal Behaviour Science 70 (2000) 99±114
101
stock vary in biologically signi®cant aspects of maternal behaviour. In order to answer this
question, we collected data on maternal behaviour in seven domestic and seven crossbred
wilddomestic primiparous sows. During the data analysis, we found that the breeding
effect could explain only a small proportion of the variation in the data. Therefore,
we investigated the interindividual variation through a post-hoc correlational and factor
analysis. We focused on questions of how various aspects of maternal behaviour
relate to each other and whether they could be subsumed into a few `maternal behaviour
traits'.
2. Methods
2.1. Animals
We used 14 primiparous sows which were born to YorkshireDutch Landrace mothers.
Seven of them were sired by various Yorkshire fathers (`domestic' sows) and seven by one
male wild boar (`crossbred' sows). The sows were born and reared in the outdoor housing
system described below. At the age of 20±21 months, all experimental sows were
inseminated with Great Yorkshire sperm. Hence, the offspring interacting with the
experimental mothers in the current study were either 100% domestic or 25% wild boar.
2.2. Housing conditions
The experiment was carried out at the Wageningen Agricultural University, The
Netherlands in April±June 1997. All sows were loose housed during pregnancy. Two
days before the scheduled farrowing induction, the sows were locked in half-covered
concrete-¯oored rectangular outdoor pens (2.2 m4.5 m). About 5 kg of straw was
provided in the covered half of the farrowing pen, the open half was provided with
drinking nipples for both the sows and the piglets and also served as dunging area. At the
back of the farrowing pens, half-open doors allowed behavioural observations, without
disturbances to sow or litter. At 8 a.m. and 1:30 p.m., sows were allowed to leave the pens in
order to feed in separate feeding crates positioned about 20 m from the pens. Sows which
were to be tested in the same batch (see below) were not housed in adjacent pens in order to
reduce the possibility of habituation to acoustic stimuli in the playbacks tests.
2.3. Procedure
2.3.1. Farrowing and cross-fostering
In order to enable early and balanced cross-fostering between litters, farrowings were
induced on about Day 112 of pregnancy by a prostaglandin analogue (PGF2a) injection.
The induction was scheduled in four batches of four, four, four and two sows. All sows in a
batch farrowed within a time period of 24 h (Day 0). Within 36 h after parturition
(Day 0 or 1), all piglets were weighed, ear tagged and cross-fostered within each batch.
The newly composed litters were balanced with respect to litter size, number of piglets
of each genotype (pure domestic or 25% wild boar), average piglet weight and sex
102
M. SÏpinka et al. / Applied Animal Behaviour Science 70 (2000) 99±114
ratio (in that order of priority). The resulting litter sizes varied between seven and
nine piglets among which two±four piglets were the sow's own progeny while the rest
originated from the other litters in the batch. Mortality of the piglets was assessed by
noting any losses occurring between cross-fostering and video recording 4 days later (see
below).
2.3.2. Nest-leaving and playback experiment on Day 2
On Day 2 after parturition (Day 2), each sow was tested for her willingness to leave the
nest and the young for food and also for her reactivity to squeezed piglet distress
vocalisation. At the time of the morning feeding, the non-tested sows were ®rst allowed
to feed in a normal way. After they were locked back again in their farrowing pens, the pen
of the ®rst sow to be tested was opened and the latency of her emergence from the
farrowing pen was noted. If she did not leave the pen within 5 min, the gate was closed and
latency was set equal to 300 s. We then waited for the moment when the sow was lying
down in the farrowing pen for the ®rst time. When her body touched the ground, a 30 s
recording of piglet distress vocalisation was played (at about natural volume) from a
loudspeaker through an expanded-metal-covered opening in the outer wall of the farrowing
pen. The recording was the vocalisation of a 2-days-old piglet, unrelated to any animal in
the experiment. During the recording, vocalisations were stimulated by restraining the
piglet on the ground by an experimenter using both hands. The reaction of the sow to the
playback was video recorded and later scored using the following scale: 0 Ð no reaction,
1 Ð head movement, 2 Ð body movement, 3 Ð sits, 4 Ð stands up, 5 Ð makes contact
with the expanded metal covering the loudspeaker, 6 Ð bites or paws at the expanded
metal. Two extra points were added if the sow stood up within 5 s since the beginning of the
playback or one point if she did so within 30 s. After the testing of the ®rst sow was
®nished, we continued with testing of the next sow until all sows from a batch (up to four)
were tested. The same vocal stimulus was used for all sows.
2.3.3. Undisturbed nursing behaviour
During the night between Days 4 and 5 (or between Days 5 and 6) post partum, each sow
was video recorded either between 18:00 and 24:00 or between 00:00 and 06:00 h while
there were no people present near the animal facilities. The videotapes were later analysed
to quantify the following parameters of the undisturbed nursing behaviour: intervals
between nursings, proportion non-nutritive nursings, duration of pre-ejection and postejection udder massage, and proportion of nursings terminated by the sow. Non-nutritive
nursings (nursings without milk ejection) were identi®ed by the absence of synchronised
rapid sucking activity of the litter (Illmann and Madlafousek, 1995). A nursing was
classi®ed as terminated by the sow if she rolled over onto her belly or stood up while some
of the piglets were still active at the udder.
2.3.4. Undisturbed lying-down behaviour
The videotaped six night time hours of undisturbed behaviour were also used to assess
the frequency and carefulness of the sows' lying-down behaviour. Each occurrence of the
sow's descent from a standing to a lying posture was counted and given a carefulness score
as follows: one point for snif®ng the ¯oor before lying-down, one point for rooting, one
M. SÏpinka et al. / Applied Animal Behaviour Science 70 (2000) 99±114
103
point if the sow descended in a vertical plane (as opposed to ¯opping over to one side),
one point if there were, at that moment, no piglets near her on the side on which she lay
down.
2.3.5. Playback experiment on Day 5 or 6
These tests were conducted on Day 5 or 6 post partum either in the morning or in the
afternoon. The behaviour of the sow was videotaped in her pen while she was subjected to
three different tests of her reactivity to piglet distress vocalisations. The tests were:
Trapped piglet call ± A 35 s playback of a piglet's distress vocalisation which had been
recorded as described in the section on playback experiment on Day 2. However, different
recordings were used from those on Day 2. The playback was started while the sow was
descending to a lying posture at the moment her body touched the ground.
Isolated piglet call ± A 60 s playback of a piglet's grunting and squeaking which had been
recorded when a 7-day old piglet had been isolated from her mother and littermates. The
playback was started at any moment between 20 and 35 min after the last milk ejection
when both the sow and the litter was resting.
Teat fighting calls ± A 50 s playback of loud vocalisations recorded while two piglets had
been fighting for a teat during nursing. The playback was started during a nursing about
15 s after the pre-ejection udder massage by the piglets had begun.
Each of the three tests was repeated twice using vocalisations from different piglets to
those used for the playback stimuli. Hence, each sow was presented with a total of six
playback stimuli during the experimental session. The playbacks were always separated by
at least 15 min. The order of the tests was variable in individual sows as it was dependent on
the spontaneous nursing and resting behaviour of the animals. The behavioural reactions of
the sow were scored using the same scale as in the playback experiment on Day 2. A
preliminary analysis showed that the scores from the three types of tests were highly
intercorrelated and displayed similar results in the domestic-crossbred comparison. Therefore, the score reactions from the six tests (reactions to trapped-piglet, isolated-piglet and
teat-®ghting calls, each tested twice) were combined into a ®nal score.
2.3.6. The human-in-the-nest test
On Day 8 or 9 post partum, the response of the sow to a human being present near her
piglets was tested. First, the non-tested sows were allowed to feed in a normal way. After
they were locked back again in their farrowing pens, the ®rst sow to be tested was allowed
to leave the pen, enter the feeding crate and was locked there for 10 min while she was
feeding. In the meanwhile, an experimenter entered the pen with her piglets, closed the bar
gate behind him/her and stood quietly about 1 m behind the bars of the pen gate. The sow
was released from the feeding pen and once she approached her pen, her behaviour was
scored. Every 20 s for 5 min, we recorded her location, using instantaneous sampling, as
follows: nose contact with the bar gate Ð 2 points, within 1 m in front of the gate Ð 1
point, other place Ð 0 points. We also scored the average frequency of her calls during each
20 s period, using the following scale: frequent vocalisation (approx. >1 call/s) Ð 2 points,
moderate vocalisation (
Dimensions of maternal behaviour characteristics in
domestic and wilddomestic crossbred sows
Marek SÏpinkaa,*, Gudrun Illmanna, Francien de Jongeb,
Maria Anderssonc, Teun Schuurmand, Per Jensenc
a
Group of Ethology, Research Institute of Animal Production, CZ-104 01 Prague-UhrÏÂõneÏves, Czech Republic
b
Department of Ecological Agriculture and Society, Wageningen University and Research Centre,
Haarweg 333, 6709 RZ Wageningen, Netherlands
c
Department of Animal Environment and Health, Faculty of Veterinary Medicine, Section of Ethology,
Swedish University of Agricultural Sciences, POB 234, S-532 23 Skara, Sweden
d
Human and Animal Physiology Group, Wageningen Institute of Animal Sciences, Wageningen University,
Haarweg 10, 6709 PJ Wageningen, Netherlands
Accepted 29 May 2000
Abstract
We examined the maternal behaviour of seven domestic and seven wilddomestic primiparous
sows during 10 days post partum to investigate two questions: (1) Did maternal behaviour change
during domestication? (2) Can the interindividual variability of maternal behaviour be subsumed
into a few dimensions of maternal temperament? We recorded: (a) willingness to leave the nest for
food on Day 2; (b) reaction to a playback of squeezed piglet distress vocalisation on Day 2; (c)
spontaneous nursing behaviour and spontaneous lying-down behaviour on Day 5 (from an overnight
video recording); (d) reactions to playbacks of various piglet distress vocalisations on Day 6 and (e)
reactions to a human in the `nest' with piglets on Day 9. Moreover, data on baseline cortisol saliva
concentration and its increase during a brief transportation period and novel environment challenge
at the age of 5 months were available. Crossbred sows did not differ from domestic ones in any
aspect of maternal behaviour except for a higher tendency to terminate ®nal massage during
nursings and a higher frequency of changing posture from lying to standing and back during the
night. Factor analysis (based on correlation matrix of 11 behaviour and cortisol variables calculated
for all 14 sows after removing the effect of breed) indicated that 82% of the variability in the data
could be explained by three factors: ®rst, `calmness' on which low night time frequency of major
posture changes, carefulness of lying-down behaviour and high propensity to remain in nursing
position after milk ejection loaded positively while cortisol concentrations during challenge loaded
negatively; second, `protectiveness' with high loadings of the reaction scores to the playbacks of
piglet distress calls and the human presence near the piglets; and third, `nursing activity' which was
*
Corresponding author. Tel.: 420-2-6771-0713; fax: 420-2-6771-0779.
E-mail address: [email protected] (M. SÏpinka).
0168-1591/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 1 6 8 - 1 5 9 1 ( 0 0 ) 0 0 1 5 1 - 9
100
M. SÏpinka et al. / Applied Animal Behaviour Science 70 (2000) 99±114
strongly positively associated with nursing frequency, and negatively with the proportion of
nutritive nursings and baseline cortisol values. The results indicate that most aspects of pig maternal
behaviour have not been signi®cantly changed by domestication and that substantial variability in
maternal behaviour exists between sows, perhaps in the form of several behaviour characteristics
which encompass both behaviour and endocrine pro®les of the sows. # 2000 Elsevier Science B.V.
All rights reserved.
Keywords: Maternal behaviour; Pigs; Domestication; Nursing; Cortisol; Vocalisation; Temperament
1. Introduction
Maternal behaviour is important for pig husbandry since it partly determines mortality
and growth of the piglets. About 15% of the live born piglets die before weaning (McKay,
1993; Blackshaw et al., 1994), and among them 70±80% is attributable to the sow
behaviour, directly or indirectly. During the ®rst day of life, piglets get trapped under
the sow while she is lying-down or rolling from her belly to her side (Dyck and Swiestra,
1987; Weary et al., 1996a; Herskin et al., 1998). Individual dams differ in the frequency of
postural changes, and in how often they change posture in a way that is dangerous for the
piglets (i.e. ¯opping straight down to one side versus descending to lying posture in a
vertical plane; lying down when piglets are nearby). Even after a piglet is trapped, the sow's
behaviour is important. Just 20% of piglets trapped under the sow's body are actually
crushed. If a trapped piglet starts screaming, the sow may stand up immediately and release
it. In cases when the sow stood up within 1 min, only 5% of piglets died; in contrast, 67%
of the piglets trapped for longer than 4 min were lost (Weary et al., 1996a). Two aspects of
the sow's behaviour, thus, affect the probability of crushing: ®rst, the sow's general
restlessness and her lying-down behaviour; second, the sow's individual reactivity to a
screaming piglet (Wechsler and Hegglin, 1997).
Another problem in piglet production is low milk intake in some piglets or in whole
litters which results in low or too variable weaning weights. This may even lead to piglet
losses, either directly due to starvation or indirectly due to the weak piglets being crushed
by the sow (Hutson et al., 1993; Weary et al., 1996b). Low frequency of nursings (SÏpinka
et al., 1997; SÏpinka et al., 1999), and a high proportion of non-nutritive nursings (nursings
without milk ejection, CastreÂn et al., 1989; Illmann and Madlafousek, 1995; Illmann et al.,
1999) are probably the aspects of nursing behaviour which can most signi®cantly reduce
milk intake. A tendency to terminate the udder massage by the piglets soon after milk
ejection might also suppress future milk production in the glands, although the evidence is
equivocal (Algers and Jensen, 1991; SÏpinka and Algers, 1995; Jensen et al., 1998; Illmann
et al., 1998).
These undesired aspects in the maternal behaviour of domestic sows may have arisen
during the process of domestication, especially during the intense selective breeding
regimes prevalent in last few decades. Information about whether this was the case can be
useful in judging the likelihood that maternal characteristics of sows could be improved
through selective breeding programmes. The present study was conducted in order to
assess whether sows carrying different proportions of genes from domestic and wild boar
M. SÏpinka et al. / Applied Animal Behaviour Science 70 (2000) 99±114
101
stock vary in biologically signi®cant aspects of maternal behaviour. In order to answer this
question, we collected data on maternal behaviour in seven domestic and seven crossbred
wilddomestic primiparous sows. During the data analysis, we found that the breeding
effect could explain only a small proportion of the variation in the data. Therefore,
we investigated the interindividual variation through a post-hoc correlational and factor
analysis. We focused on questions of how various aspects of maternal behaviour
relate to each other and whether they could be subsumed into a few `maternal behaviour
traits'.
2. Methods
2.1. Animals
We used 14 primiparous sows which were born to YorkshireDutch Landrace mothers.
Seven of them were sired by various Yorkshire fathers (`domestic' sows) and seven by one
male wild boar (`crossbred' sows). The sows were born and reared in the outdoor housing
system described below. At the age of 20±21 months, all experimental sows were
inseminated with Great Yorkshire sperm. Hence, the offspring interacting with the
experimental mothers in the current study were either 100% domestic or 25% wild boar.
2.2. Housing conditions
The experiment was carried out at the Wageningen Agricultural University, The
Netherlands in April±June 1997. All sows were loose housed during pregnancy. Two
days before the scheduled farrowing induction, the sows were locked in half-covered
concrete-¯oored rectangular outdoor pens (2.2 m4.5 m). About 5 kg of straw was
provided in the covered half of the farrowing pen, the open half was provided with
drinking nipples for both the sows and the piglets and also served as dunging area. At the
back of the farrowing pens, half-open doors allowed behavioural observations, without
disturbances to sow or litter. At 8 a.m. and 1:30 p.m., sows were allowed to leave the pens in
order to feed in separate feeding crates positioned about 20 m from the pens. Sows which
were to be tested in the same batch (see below) were not housed in adjacent pens in order to
reduce the possibility of habituation to acoustic stimuli in the playbacks tests.
2.3. Procedure
2.3.1. Farrowing and cross-fostering
In order to enable early and balanced cross-fostering between litters, farrowings were
induced on about Day 112 of pregnancy by a prostaglandin analogue (PGF2a) injection.
The induction was scheduled in four batches of four, four, four and two sows. All sows in a
batch farrowed within a time period of 24 h (Day 0). Within 36 h after parturition
(Day 0 or 1), all piglets were weighed, ear tagged and cross-fostered within each batch.
The newly composed litters were balanced with respect to litter size, number of piglets
of each genotype (pure domestic or 25% wild boar), average piglet weight and sex
102
M. SÏpinka et al. / Applied Animal Behaviour Science 70 (2000) 99±114
ratio (in that order of priority). The resulting litter sizes varied between seven and
nine piglets among which two±four piglets were the sow's own progeny while the rest
originated from the other litters in the batch. Mortality of the piglets was assessed by
noting any losses occurring between cross-fostering and video recording 4 days later (see
below).
2.3.2. Nest-leaving and playback experiment on Day 2
On Day 2 after parturition (Day 2), each sow was tested for her willingness to leave the
nest and the young for food and also for her reactivity to squeezed piglet distress
vocalisation. At the time of the morning feeding, the non-tested sows were ®rst allowed
to feed in a normal way. After they were locked back again in their farrowing pens, the pen
of the ®rst sow to be tested was opened and the latency of her emergence from the
farrowing pen was noted. If she did not leave the pen within 5 min, the gate was closed and
latency was set equal to 300 s. We then waited for the moment when the sow was lying
down in the farrowing pen for the ®rst time. When her body touched the ground, a 30 s
recording of piglet distress vocalisation was played (at about natural volume) from a
loudspeaker through an expanded-metal-covered opening in the outer wall of the farrowing
pen. The recording was the vocalisation of a 2-days-old piglet, unrelated to any animal in
the experiment. During the recording, vocalisations were stimulated by restraining the
piglet on the ground by an experimenter using both hands. The reaction of the sow to the
playback was video recorded and later scored using the following scale: 0 Ð no reaction,
1 Ð head movement, 2 Ð body movement, 3 Ð sits, 4 Ð stands up, 5 Ð makes contact
with the expanded metal covering the loudspeaker, 6 Ð bites or paws at the expanded
metal. Two extra points were added if the sow stood up within 5 s since the beginning of the
playback or one point if she did so within 30 s. After the testing of the ®rst sow was
®nished, we continued with testing of the next sow until all sows from a batch (up to four)
were tested. The same vocal stimulus was used for all sows.
2.3.3. Undisturbed nursing behaviour
During the night between Days 4 and 5 (or between Days 5 and 6) post partum, each sow
was video recorded either between 18:00 and 24:00 or between 00:00 and 06:00 h while
there were no people present near the animal facilities. The videotapes were later analysed
to quantify the following parameters of the undisturbed nursing behaviour: intervals
between nursings, proportion non-nutritive nursings, duration of pre-ejection and postejection udder massage, and proportion of nursings terminated by the sow. Non-nutritive
nursings (nursings without milk ejection) were identi®ed by the absence of synchronised
rapid sucking activity of the litter (Illmann and Madlafousek, 1995). A nursing was
classi®ed as terminated by the sow if she rolled over onto her belly or stood up while some
of the piglets were still active at the udder.
2.3.4. Undisturbed lying-down behaviour
The videotaped six night time hours of undisturbed behaviour were also used to assess
the frequency and carefulness of the sows' lying-down behaviour. Each occurrence of the
sow's descent from a standing to a lying posture was counted and given a carefulness score
as follows: one point for snif®ng the ¯oor before lying-down, one point for rooting, one
M. SÏpinka et al. / Applied Animal Behaviour Science 70 (2000) 99±114
103
point if the sow descended in a vertical plane (as opposed to ¯opping over to one side),
one point if there were, at that moment, no piglets near her on the side on which she lay
down.
2.3.5. Playback experiment on Day 5 or 6
These tests were conducted on Day 5 or 6 post partum either in the morning or in the
afternoon. The behaviour of the sow was videotaped in her pen while she was subjected to
three different tests of her reactivity to piglet distress vocalisations. The tests were:
Trapped piglet call ± A 35 s playback of a piglet's distress vocalisation which had been
recorded as described in the section on playback experiment on Day 2. However, different
recordings were used from those on Day 2. The playback was started while the sow was
descending to a lying posture at the moment her body touched the ground.
Isolated piglet call ± A 60 s playback of a piglet's grunting and squeaking which had been
recorded when a 7-day old piglet had been isolated from her mother and littermates. The
playback was started at any moment between 20 and 35 min after the last milk ejection
when both the sow and the litter was resting.
Teat fighting calls ± A 50 s playback of loud vocalisations recorded while two piglets had
been fighting for a teat during nursing. The playback was started during a nursing about
15 s after the pre-ejection udder massage by the piglets had begun.
Each of the three tests was repeated twice using vocalisations from different piglets to
those used for the playback stimuli. Hence, each sow was presented with a total of six
playback stimuli during the experimental session. The playbacks were always separated by
at least 15 min. The order of the tests was variable in individual sows as it was dependent on
the spontaneous nursing and resting behaviour of the animals. The behavioural reactions of
the sow were scored using the same scale as in the playback experiment on Day 2. A
preliminary analysis showed that the scores from the three types of tests were highly
intercorrelated and displayed similar results in the domestic-crossbred comparison. Therefore, the score reactions from the six tests (reactions to trapped-piglet, isolated-piglet and
teat-®ghting calls, each tested twice) were combined into a ®nal score.
2.3.6. The human-in-the-nest test
On Day 8 or 9 post partum, the response of the sow to a human being present near her
piglets was tested. First, the non-tested sows were allowed to feed in a normal way. After
they were locked back again in their farrowing pens, the ®rst sow to be tested was allowed
to leave the pen, enter the feeding crate and was locked there for 10 min while she was
feeding. In the meanwhile, an experimenter entered the pen with her piglets, closed the bar
gate behind him/her and stood quietly about 1 m behind the bars of the pen gate. The sow
was released from the feeding pen and once she approached her pen, her behaviour was
scored. Every 20 s for 5 min, we recorded her location, using instantaneous sampling, as
follows: nose contact with the bar gate Ð 2 points, within 1 m in front of the gate Ð 1
point, other place Ð 0 points. We also scored the average frequency of her calls during each
20 s period, using the following scale: frequent vocalisation (approx. >1 call/s) Ð 2 points,
moderate vocalisation (