- Email: [email protected]
What do maternal tests actually test?
Accepted Manuscript Title: What do maternal tests actually test? Authors: C.G.E. Grimberg-Henrici, I. Czycholl, O. Burfeind, J. Krieter PII: DOI: Reference:
S0168-1591(17)30030-8 http://dx.doi.org/doi:10.1016/j.applanim.2017.01.010 APPLAN 4397
To appear in:
APPLAN
Received date: Revised date: Accepted date:
10-10-2016 17-1-2017 22-1-2017
Please cite this article as: Grimberg-Henrici, C.G.E., Czycholl, I., Burfeind, O., Krieter, J., What do maternal tests actually test?.Applied Animal Behaviour Science http://dx.doi.org/10.1016/j.applanim.2017.01.010 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
What do maternal tests actually test? C.G.E. Grimberg-Henricia, I. Czycholla, O. Burfeindb, J. Krietera a
Institute of Animal Breeding and Husbandry, Christian-Albrechts-University,
Olshausenstr. 40, D-24098 Kiel, Germany b
Chamber of Agriculture of Schleswig-Holstein, Gutshof 1, D-24327 Blekendorf, Germany
Corresponding author: Charlotte G. E. Grimberg-Henrici Email: [email protected] Address: Institute of Animal Breeding and Husbandry, Christian-Albrechts-University, Olshausenstr. 40, D-24098 Kiel, Germany Phone: +49 (0)431 8804363 Fax: +49 (0)431 8802588
Highlights
We investigated the maternal behaviour of 47 sows in week 2 and 4 of lactation in five successive tests in the home pen and in a test arena.
Factor analysis extracted five factors by the Kaiser-Guttman criterion, explaining together 89.2 % of the total variance.
The results revealed different underlying maternal factors: communication, contact, care and local attachment.
Factor 1 explains for the largest part of variance and indicates the most important maternal factor, the reaction of sows to their piglets in threatening situations.
ABSTRACT Several studies have used behavioural tests to characterise sows regarding their maternal performance. These studies have always chosen a selection of behavioural tests and the combination of tests varied between the studies. In the present study, 47 sows were tested in week 2 and 4 of lactation in five successive maternal tests, which were conducted in their home pens and in a test arena. The sows’ reaction to piglet stress signals, separation from and reunion with their piglets were tested. The behavioural parameters observed in these maternal tests were examined by means of a factor analysis to identify redundancies in behavioural parameters. Five factors were extracted,
1
explaining together 89.2 % of the total variance, of which Factor 1 explains 33.5 %, Factor 2 18.4 %, Factor 3 14.5 %, Factor 4 12.6 % and Factor 5 10.2 %. The interpretation of the factor loadings revealed four underlying maternal factors: communication, care, contact and local attachment. Communication, thus vocalisation, was extracted by the factor analysis as the most important maternal factor and is used in sows to call their piglets in threatening situations as in the separation test and the piglet scream test. Furthermore, communication plays a role for the maternal contact and care factors. Sows used vocalisation to contact their piglets using nose-to-nose contacts, which were observed in the reunion test and also in the piglet scream test. With regard to the care factor, sows use vocalisation to call their piglets for nursing and to synchronise nursing with other sows. The willingness to stay with their piglets, thus local attachment to their piglets, was shown by sows in the separation and reunion test in the test arena and the piglet scream test. Furthermore, the factor analysis proves that single maternal tests can also combine more than one maternal factor and that the experimental environment in which the tests are placed influences the significance of the tests. The present results demonstrate the complexity and diversity of maternal behaviour.
Keywords Factor analysis; Maternal behaviour; Behavioural testing; Sow
1. INTRODUCTION Piglet performance such as survival and growth is greatly dependent on the quality of maternal behaviour. For instance, sows with lower piglet mortality rates are known to show more maternal behaviour such as more nest building (Andersen et al., 2005), expressing more nose-to-nose contacts with their piglets during posture changes (Andersen et al., 2005) and being more careful when lying down (Burri et al., 2009). Maternal behaviour which leads to decreased piglet mortality and to increased piglet growth is an important breeding goal. Different tests have been used to investigate maternal behaviour. The piglet scream test is a commonly used maternal test in which the reaction of the sow towards a screaming piglet (Grandinson et al., 2003; Løvendahl et al., 2005; Melišová et al., 2014) or a sound (Grandinson et al., 2003) is tested. The piglet handling test is a maternal test related to the piglet scream test, in which the reaction of the sow to the handled piglet is observed (Grandinson et al., 2003; Held et al., 2006). Furthermore, sows are tested in piglet-separation tests to investigate whether they search for their piglets, for example by being more restless and by vocalising more frequently (Andersen et al., 2005; Hellbrügge et al., 2008). A separation test is often followed by a reunion test in which the reactions of the sows are tested when their piglets are returned to them (Pitts et al., 2002; Andersen et al., 2005). Most of the studies which have investigated maternal behaviour have used a selection of these tests. To our knowledge, it has still not been proven which types of maternal behaviour these tests evaluate
2
and what these tests exactly test for. Furthermore, it is not known which combinations of maternal tests and what types of tests are advisable. The aim of this present study was therefore to give new insights into the structure of the maternal behaviour of sows and to obtain more information on the significance of these tests. To do this, sows were tested in week 2 and 4 of lactation in their home pens and in a test arena in a piglet scream test, a separation test and a reunion test. As there are redundancies between the tests, factor analysis was used as a helpful tool to investigate the actual underlying structure of behaviour. This method has been used in animal welfare science, for instance as a tool for lameness detection (Miekley et al., 2013) as well as for the evaluation of emotional states in animals (Temple et al., 2011; Wemelsfelder et al., 2012).
2. MATERIAL AND METHODS 2.1. Animals and housing The study was conducted on Futterkamp, the research farm of the Chamber of Agriculture of Schleswig-Holstein
from
May
2014
until
September
2014.
A
total
of
47
cross-bred
(Large White x Landrace) multiparous sows were tested during lactation in a group-housing system (GH) and in a conventional, single-housing system (SH) with regard to their maternal behaviour (Grimberg-Henrici et al., 2016). The treatment groups were used in a previous study (Grimberg-Henrici et al., 2016). In the present study, the different treatment groups (SH, GH) were not considered for data analysis and thus were summarized as research population. Data were collected in four batches with 12 sows per batch. It was considered that the sows did not differ to a large extent concerning their number of parities within and between the batches. All litters were standardised to 13 piglets for each sow until two days postpartum. In the GH system, six sows were housed together. Each sow had a single pen (1.8 m × 2.6 m) provided with a farrowing crate and electronically controlled gates. In addition, all sows shared a running area (2.4 m × 5.4 m). The sows were only fixed in the farrowing crates from three days antepartum to one day postpartum. A flat barrier prevented the piglets from leaving the single pen, whereas the sow could leave the pen. The barrier was removed five days postpartum and all litters of the six sows had the possibility to mix in the running area. Sows in the SH system were fixed in farrowing crates (2.0 m × 2.6 m). Boars were not castrated and the piglets were weaned on average 27.8 ± 0.15 days postpartum. The farrowing stables had water-heated piglet resting areas (0.6 m2) and manipulable material (e.g. plastic balls) was available for the sows and the piglets. The temperature in the stables varied between 19 and 21 °C. Lights (80 lx) were switched on at 6 am and off at 8 pm. Sows were fed a commercial lactating meal, the amount of which was increased constantly during lactation to a maximum of 7.5 kg per day. The piglets received a commercial creep diet. Sows and piglets shared a drinking bowl and had free access to water. 2.2. Behavioural testing All sows were tested in five different successive tests to investigate their maternal behaviour. For the sequence of testing, which is described below, was chosen for reasons of animal welfare, feasibility and practical relevance. The sows were observed in behavioural tests in week 2 (12.8 ± 0.15 days
3
postpartum) and in week 4 (25.8 ± 0.15 days postpartum) of lactation. The tests were performed in the home pens (HP) of the sows and in a test arena (TA) (Fig. 1). The TA was built to create a test situation for the sows, which was uncoupled from their housing system and, thus, a new environment for all sows. The tests started at 8 am and all sows were tested in a random order. The TA was in a separate room and was 3.9 m x 3.7 m large and the opaque side walls were 1.1 m high. The entrance for the sow was 1.2 m wide and there was a piglet nest in one corner. The nest was 1.5 m x 1.5 m x 2.12 m large and the opaque side walls were 1.1 m high. The front wall of the nest had a door (0.8 m wide and 0.4 m high) and was connected with the inside of the TA. The TA was divided into four parts with four possible locations of the sows. 2.2.1. Separation test in test arena The sow was brought to the TA and had ten minutes to habituate to the new environment. After habituation, the piglets were transported to the TA and were put in the piglet nest. Before transportation, one piglet was separated for the piglet scream test in the TA, which was performed later in the experimental set-up. During the separation test the sow was able to hear and smell her piglets. The separation test started when the first piglet was put in the piglet nest. The sow was observed every ten seconds for a whole observation period of five minutes (31 observations per sow and test) concerning location in the TA (Fig. 1), posture, behaviour and vocalisation (Table 1). The test design was modified according to previous experiments by Pitts et al. (2002) and Andersen et al. (2005). The test was supposed to showed how focused the sow was towards her piglets during separation and investigated the responsiveness of the sow to her piglets. We concentrated on behaviour directed towards the piglets such as vocalisation, occupation with the piglet nest, staying near the piglet nest and stress signals. 2.2.3. Reunion test in test arena After the separation test, the reunion test was performed: the door of the piglet nest was opened to reunite the sow with her piglets. The test started when the door was opened. The piglets were carefully pushed with a broom to leave the nest. When all piglets had left the nest, the door was closed. The reaction of the sow was recorded again every ten seconds for an observation period of five minutes (31 observations per sow and test) with regard to location (Fig. 1), posture, behaviour and vocalisation (Table 1). This test was a modified version of the test by Pitts et al. (2002) and Andersen et al. (2005). In this test the reaction of the sow to her piglets was observed when the piglets were suddenly reunited. Behaviour which focused on the piglets such as nose-to-nose contact with the piglets, running after the piglets, nursing and vocalisation were evaluated as good maternal behaviour. 2.2.3. Piglet scream test in test arena For the piglet scream test, the previously separated piglet was now taken to the TA where the sow with the rest of her piglets was walking around. One experimenter stood outside the TA with the piglet next to the piglet nest (location 1) and motivated the piglet to scream by placing it on its back. The reaction of the sow was observed again every ten seconds for 30 seconds (four observations per sow and test) with regard to location (Fig. 1), posture, behaviour and vocalisation (Table 1). This test was similarly constructed compared to the experiments of Grandinson et al. (2003). It investigated the
4
willingness of the sow to protect her piglets and the reactivity and responsiveness of the sow to a piglet distress call. The behaviour was scored as good maternal behaviour when the sow turned towards her piglet using vocalisation, by staying near the screaming piglet and by coming into contact with her other piglets. 2.2.4. Separation test in home pen After the tests in the TA, the sow returned to her empty HP, i.e. without her piglets. The observation started immediately when the sow had reached the empty HP (Pitts et al., 2002). The behaviour of the sow, posture and vocalisation were recorded every ten seconds for five minutes (31 observations per sow and test) (Table 1). The aim of this test was to investigate whether the sow had searched for her piglets. Restlessness such as standing postures, searching the ground for piglets and calling for the piglets was evaluated as searching and stressed behaviour. 2.2.5. Reunion test in home pen The piglets were then transported from the TA to their HP and were placed with the sow. The observation started when the first piglet was placed in the pen (Pitts et al., 2002). The behaviour of the sow, posture and vocalisation was recorded every ten seconds for five minutes (31 observations per sow and test) (Table 1). Similar to the reunion test in the TA, the reaction of the sow was observed when her piglets suddenly entered the HP. Caring behaviour as nursing, nose-to-nose contacts and vocalisation of the sow was evaluated as good maternal behaviour. 2.3. Statistical analysis The count data of the behavioural tests was analysed with a factor analysis by using the statistical software SAS ® 9.4 (SAS Institute Inc., 2008). The PROC FACTOR procedure was carried out, whereby a promax rotation was applied to facilitate the interpretation of results. Each behavioural parameter achieved a certain loading on each factor, which is a number between -1 and 1. Factor loadings were defined as significant if they were greater than or equal to 0.4 (highly positive) and if they were less than or equal to -0.4 (highly negative). This procedure and the interpretation was based on O'Rourke et al. (2013). For location 2, 3, 4 (away from the piglet nest) in the TA only a few observations were performed and were therefore combined for analysis purposes as one location 234.
3. RESULTS Table 2 demonstrates the median, minimum and maximum of the frequencies and the percentage of the behavioural parameters in each maternal test. In the separation test 68.8 % of the sows vocalised, 69.9 % were near the piglet nest in location 1, 26.2 % explored the piglet nest and 22.6 % explored the TA. In the reunion test in the TA 37.1 % of the sows vocalised, 34.8 % were near the piglet nest in location 1, 33.6 % were active, 38.2 % had contact with their piglets and 42.6 % explored the TA. In the third test, the piglet scream test in the TA, 57.5 % of the sows vocalised, 61.2 % were near their screaming piglet in location 1, 30.9 % were active, 15.4 % had contact with their other piglets in the TA and 23.1 % explored the TA. In the separation test in the HP 41.0 % of the sows vocalised, 70.1 % were active and 27.8 % explored the floor. In the last test, the reunion test in the HP, 48.2 % of the
5
sows vocalised, 36.5 % were active, 21.1 % had contact with their piglets, 20.8 % nursed their piglets and 1.3 % explored the floor.
The different factor loadings of the behavioural parameters (greater than or equal to 0.4 and less than or equal to -0.4) of the five maternal tests are shown in Table 3. Five factors are retained by the Kaiser-Guttman criterion (Guttman, 1954; Kaiser, 1960). These five factors explain 89.2 % of the total variance of which Factor 1 explains 33.5 %, Factor 2 18.4 %, Factor 3 14.5 %, Factor 4 12.6 % and Factor 5 10.2 %. The parameter ‘vocalisation’ loads positively on Factor 1 in the separation and the piglet scream test in the TA and in the separation test in the HP (Table 1 and Table 3). Furthermore, the sow’s presence ‘near the piglet nest’ loads on Factor 1 positively, while ‘exploring TA’ loads negatively in the separation and piglet scream test in the TA. On Factor 2 the behavioural parameters ‘vocalisation’, ‘active’ and ‘exploring floor’ in the separation test in the HP are positively related to the parameters ‘active’ and ‘contact with piglets’ of the sows in the reunion test in the HP. In the reunion test in the TA ‘vocalisation’, ‘active’ and ‘contact with piglets’ loads positively on Factor 3, while ‘exploring TA’ loads negatively. On Factor 4 ‘vocalisation’ and ‘nursing’ are positively related. In the piglet scream test in the TA ‘active’ and ‘contact with piglets’ of the sows load positively together on Factor 5, while the sow’s presence ‘near the piglet nest’ in the separation test and ‘near the screaming piglet’ in the piglet scream test in the TA loads negatively.
4. DISCUSSION The five extracted factors of the behavioural parameters in the five maternal behavioural tests present different forms of maternal motivation and make the complexity and diversity of maternal behaviour visible. Factor 1 explains for the largest part of variance and indicates the most important maternal factor, the reaction of the sows when their piglets are in danger. Špinka et al. (2000) evaluated the protective reactions of the sow to piglets in threating situations also as important maternal factor by using a factor analysis. In the present study, ‘vocalisation’ loads in three maternal tests together on the first factor and this indicates that communication is an important instrument for sows with piglets in threatening situations. Hutson et al. (1991) stated that the scream of a piglet is the most important stimulus for a sow to react to. The responsiveness of the sows to it plays a central role in piglet survival with regard to piglet crushing. For instance, Weary et al. (1996) demonstrates that piglet survival increased immensely when the sow reacted to a trapped piglet within one minute. Grimberg-Henrici et al. (2016) found that group-housed sows reacted more strongly in a piglet scream test compared to conventional single-housed sows and showed fewer piglet losses in the course of their study. Another maternal factor belonging to Factor 1 is the local attachment of the sows to their piglets, which is demonstrated by the positive loading of ‘near the piglet nest’. The study conducted by Špinka et al. (2000) found comparable results, where more than half of the experimental sows did not leave the nest and thus their piglets for food. The negative loadings on ‘exploring TA’ for Factor 1 showed the behaviour of the sows that was not directed towards their piglets. In this study, the sow explored the TA during
6
threating test situations for their piglets and expressed no behaviour that demonstrated interest in the piglets and thus indicated disinterest towards their piglets. Factor 2 illustrates the reaction of the sows while searching for their piglets and recognising their piglets. Vocalisation of the sows is also used here to obtain information from their piglets. However, another situational type of vocalisation is detected here compared to Factor 1. If vocalisation of Factor 1 and Factor 2 would be the same type they would load only on one collective factor. Marchant et al. (2001) identified in their study three categories of calls: single grunts, single squeals and rapidly repeated grunts. For the single grunts two types were found which differed in their duration. Additionally, the practical experiences in the stables and during testing approve different forms of vocalisation. Furthermore, the tactile contact between sow and piglets is an important maternal factor. Andersen et al. (2005) discovered that higher sow contact with piglets is related to lower mortality in piglets. The same behavioural parameters as on Factor 2, i.e. ‘vocalisation’, ‘active’, ‘contact with piglets’ load positively on Factor 3. However, these are the behavioural parameters measured in another test. Thus the tests do not load together on one factor. The experimental environment in which the test is placed influences the significance of the test and thus the maternal response of the sows. Furthermore, the negative loading of ‘exploring TA’ demonstrates the disinterest of the sows with regard to their piglets as explained for Factor 1. ‘Vocalisation’ and ‘nursing’ load together on Factor 4 and this indicates a care factor of maternal behaviour. Here, vocalisation is used to call the piglets for nursing and thus to synchronise nursing with other sows. This synchronisation of nursing bouts with other sows has an evolutional background and is observed in domestic free-range pigs (Newberry and Wood-Gush, 1985) as well as in grouphoused sows (Wechsler and Brodmann, 1996). Wechsler and Brodmann (1996) concluded that the synchronisation of the nursing bouts of sows coordinates their daily rhythm and minimises the crosssuckling of piglets between sows. Factor 5 indicates two different maternal factors of sows. On the one hand, Factor 5 demonstrates the local attachment of the sows to their screaming piglet. On the other hand, Factor 5 shows the motivation of the sows to get into contact with their remaining piglets in the TA. The piglet scream test combines two different but equivalent maternal factors in one test. The sows which decide to be attached to the screaming piglet in danger and the other sows which decide to get into contact with their remaining piglets to ensure that they are unharmed. Summarising the different factor loadings, four underlying maternal factors can be extracted: communication, care, contact and local attachment (Table 4). The present results illustrate that more than one maternal test is needed to prove maternal factors. Furthermore, the results validate that different maternal tests can include one or more maternal factors in one test. Hence, maternal tests can provide more than one statement about maternal characteristics and need to be interpreted very carefully. For example, sows that do not focus on a screaming piglet in a piglet scream test but try to get in contact with their remaining piglets show a contact factor of maternal behaviour instead of a communication or local attachment factor. Pitts et al. (2002) tested sows in five comparable maternal tests which were used in the present study and found large differences between the sows concerning
7
their performance in the maternal tests. However, on an individual level the sows were highly consistent in their maternal performance. This indicates how important it is to test sows in a number of maternal tests to cover the different factors of maternal behaviour. The present study reveals that a single test cannot be sufficient to fully detect maternal behaviour. Furthermore, the results prove that different maternal tests explain different proportions of the total variance. This information could be useful in choosing the most suitable test. Hence, it is an important contribution to future research to rely on different maternal tests. Moreover, further research is needed to gain knowledge on whether there are additional maternal factors which should also be taken into consideration.
5. CONCLUSION Five factors were extracted by the factor analysis. The interpretation of these factors revealed four underlying maternal factors: communication, care, contact and local attachment. The results indicate that the reaction of the sow to their piglets in threating situations has a high significance with regard to the maternal motivation of a sow. Furthermore, it was proven that one test can cover more than one maternal factor. Moreover, a comprehensive and careful interpretation of the results is required. It was shown that the experimental environment has an influence on the significance of the tests. This is an important contribution to knowledge when testing and describing maternal behaviour in sows as the retained factors make the complexity and diversity of maternal behaviour visible. Maternal behaviour is multidimensional, thus we recommend the evaluation of sows in a number of tests concerning their maternal performances.
Conflict of interest None declared
Acknowleggments We gratefully acknowledge funding by Rentenbank.
8
REFERENCES Andersen, I.L., Berg, S., Bøe, K.E., 2005. Crushing of piglets by the mother sow (Sus scrofa) - purely accidental or a poor mother? Applied Animal Behaviour Science 93, 229-243. Burri, M., Wechsler, B., Gygax, L., Weber, R., 2009. Influence of straw length, sow behaviour and room temperature on the incidence of dangerous situations for piglets in a loose farrowing system. Applied Animal Behaviour Science 117, 181-189. Grandinson, K., Rydhmer, L., Strandberg, E., Thodberg, K., 2003. Genetic analysis of on-farm tests of maternal behaviour in sows. Livestock Production Science 83, 141-151. Grimberg-Henrici, C.G.E., Büttner, K., Meyer, C., Krieter, J., 2016. Does housing influence maternal behaviour in sows? Applied Animal Behaviour Science 180, 26-34. Guttman, L., 1954. Some necessary conditions for common-factor analysis. Psychometrika 19, 149161. Held, S., Mason, G., Mendl, M., 2006. Maternal responsiveness of outdoor sows from first to fourth parities. Applied Animal Behaviour Science 98, 216-233. Hellbrügge, B., Tölle, K.H., Bennewitz, J., Henze, C., Presuhn, U., Krieter, J., 2008. Genetic aspects regarding piglet losses and the maternal behaviour of sows. Part 1. Genetic analysis of piglet mortality and fertility traits in pigs. 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. Applied Animal Behaviour Science 32, 129-137. Kaiser, H.F., 1960. The application of electronic computers to factor analysis. Educational and psychological measurement. Løvendahl, P., Damgaard, L.H., Nielsen, B.L.m., Thodberg, K., Su, G., Rydhmer, L., 2005. Aggressive behaviour of sows at mixing and maternal behaviour are heritable and genetically correlated traits. Livestock Production Science 93, 73-85. Marchant, J.N., Whittaker, X., Broom, D.M., 2001. Vocalisations of the adult female domestic pig during a standard human approach test and their relationships with behavioural and heart rate measures. Applied Animal Behaviour Science 72, 23-39. Melišová, M., Illmann, G., Chaloupková, H., Bozděchová, B., 2014. Sow postural changes, responsiveness to piglet screams, and their impact on piglet mortality in pens and crates. Journal of animal science 92, 3064-3072. Miekley, B., Traulsen, I., Krieter, J., 2013. Principal component analysis for the early detection of mastitis and lameness in dairy cows. Journal of Dairy Research 80, 335-343. Newberry, R.C., Wood-Gush, D.G.M., 1985. The suckling behaviour of domestic pigs in a semi-natural environment. Behaviour 95, 11-25. O'Rourke, N., Psych, R., Hatcher, L., 2013. A step-by-step approach to using SAS for factor analysis and structural equation modeling. Sas Institute. Pitts, A.D., Weary, D.M., Fraser, D., Pajor, E.A., Kramer, D.L., 2002. Alternative housing for sows and litters.: Part 5. Individual differences in the maternal behaviour of sows. Applied Animal Behaviour Science 76, 291-306. SAS Institute Inc., 2008. User's Guide (release 9.4). Cary, North Carolina, USA. Špinka, M., Illmann, G., de Jonge, F., Andersson, M., Schuurman, T., Jensen, P., 2000. Dimensions of maternal behaviour characteristics in domestic and wildxdomestic crossbred sows. Applied Animal Behaviour Science 70, 99-114. Temple, D., Manteca, X., Velarde, A., Dalmau, A., 2011. Assessment of animal welfare through behavioural parameters in Iberian pigs in intensive and extensive conditions. Applied Animal Behaviour Science 131, 29-39. Weary, D.M., Pajor, E.A., Fraser, D., Honkanen, A.-M., 1996. Sow body movements that crush piglets: a comparison between two types of farrowing accommodation. Applied Animal Behaviour Science 49, 149-158. Wechsler, B., Brodmann, N., 1996. The synchronization of nursing bouts in group-housed sows. Applied Animal Behaviour Science 47, 191-199. 9
Wemelsfelder, F., Hunter, A.E., Paul, E.S., Lawrence, A.B., 2012. Assessing pig body language: Agreement and consistency between pig farmers, veterinarians, and animal activists. Journal of animal science 90, 3652-3665.
10
Fig. 1. Schematic view of the test arena.
11
Table 1. Ethogram for behavioural observation in the maternal tests in the home pen (HP) and in the test arena (TA) (modified according to Pitts et al. (2002) and Andersen et al. (2005)).
Variable
Behaviour
Location
Description
Posture
Active
HP
Sow stands or kneels down.
Inactive
HP
Sow sits or lies.
Active
TA
Sow walks or kneels down.
Inactive
TA
Sow stands, sits or lies.
Exploring floor
HP
Sow sniffs or roots with the nose within 0.2 m of the floor.
Exploring nest
TA
Sow explores with her nose or scratches with her front
Behaviour
legs the front wall of the piglet nest in the TA. Exploring TA
TA
Sow sniffs or roots with the nose within 0.2 m of the floor and explores with her nose or scratches with her front legs the side walls of the TA.
Contact
HP / TA
Sow has contact with her nose with a piglet or searches for contact by running after a piglet.
Nursing
HP / TA
Sow lies laterally. Suckling starts with udder massage of 70% of the piglets and is followed by the milk flow. The suckling ends if less than 30% of the piglets are present at the udder or if the sow stopped lying on her side.
Vocalisation
Vocalisation
HP / TA
Any vocalisation by the sow.
12
Table 2. Median, minimum (min) and maximum (max) of the frequencies and the percentage (%) of the behavioural parameters of the sows (n = 47) tested in week 2 and 4 of lactation in the separation test, reunion test and piglet scream test in the test arena (TA) and in the separation and reunion test in the home pen (HP). Test
Parameter
median
min
max
%
Separation test in TA
Vocalisation
24.0
0.0
31.0
68.8
5min observation
Near piglet nest (location 1)
21.5
6.0
31.0
69.9
(31 observations per sow)
Exploring nest
9.0
0.0
26.0
26.2
Exploring TA
5.0
0.0
27.0
22.6
Reunion test in TA
Vocalisation
8.0
0.0
31.0
37.1
5min observation
Near piglet nest (location 1)
11.0
2.0
25.0
34.8
(31 observations per sow)
Active
10.0
1.0
22.0
33.6
Contact with piglets
11.0
2.0
28.0
38.2
Exploring TA
13.0
1.0
28.0
42.6
Piglet scream test in TA
Vocalisation
3.0
0.0
4.0
57.5
30s observation
Near screaming piglet (location 1)
3.0
0.0
4.0
61.2
(4 observations per sow)
Active
1.0
0.0
3.0
30.9
Contact with piglets
0.0
0.0
3.0
15.4
Exploring TA
0.0
0.0
4.0
23.1
Separations test in HP
Vocalisation
11.0
0.0
31.0
41.0
5min observation
Active
23.5
4.0
31.0
70.1
(31 observations per sow)
Exploring floor
8.0
0.0
24.0
27.8
Reunion test in HP
Vocalisation
13.0
0.0
31.0
48.2
5min observation
Active
10.0
0.0
31.0
36.5
(31 observations per sow)
Contact with piglets
7.0
0.0
21.0
21.1
Nursing
0.0
0.0
29.0
20.8
Exploring floor
0.0
0.0
7.0
1.3
13
Table 3. Factor loadings on behavioural parameters on the five maternal tests in the test arena (TA) and in the home pen (HP) are shown. For clarity of the table all factor loadings are illustrated greater than or equal to 0.4 and less than or equal to -0.4.
Test
Parameter
F1
Separation test in TA
Vocalisation
-0.76
Near piglet nest (location 1)
-0.74
Exploring TA
-0.67
Reunion test in TA
F2
Vocalisation
F3
F4
-0.48
Near piglet nest (location 1)
Piglet scream test in TA
Separations test in HP
Reunion test in HP
F5
-0.48
Active
-0.64
Contact with piglets
-0.77
Exploring TA
-0.68
Vocalisation
-0.60
Near screaming piglet (location 1)
-0.56
Active
-0.72
Contact with piglets
-0.65
Exploring TA
-0.57
Vocalisation
-0.50
-0.43
Active
-0.69
Exploring floor
-0.67
Vocalisation
-0.87
Active
-0.72
Contact with piglets
-0.64
Nursing
-0.82
14
Table 4. Schematic view of the maternal factors in the different behavioural tests in the test arena (TA) and in the home pen (HP). Test Separation test in TA
Communication
Contact
Care
Factor 1
Reunion test in TA
Factor 1 Factor 3
Factor 5 Factor 5
Piglet scream test TA
Factor 1
Factor 5
Separation test in HP
Factor 1
Factor 2 Factor 2
Reunion test in HP
15
Local attachment
Factor 4
S0168-1591(17)30030-8 http://dx.doi.org/doi:10.1016/j.applanim.2017.01.010 APPLAN 4397
To appear in:
APPLAN
Received date: Revised date: Accepted date:
10-10-2016 17-1-2017 22-1-2017
Please cite this article as: Grimberg-Henrici, C.G.E., Czycholl, I., Burfeind, O., Krieter, J., What do maternal tests actually test?.Applied Animal Behaviour Science http://dx.doi.org/10.1016/j.applanim.2017.01.010 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
What do maternal tests actually test? C.G.E. Grimberg-Henricia, I. Czycholla, O. Burfeindb, J. Krietera a
Institute of Animal Breeding and Husbandry, Christian-Albrechts-University,
Olshausenstr. 40, D-24098 Kiel, Germany b
Chamber of Agriculture of Schleswig-Holstein, Gutshof 1, D-24327 Blekendorf, Germany
Corresponding author: Charlotte G. E. Grimberg-Henrici Email: [email protected] Address: Institute of Animal Breeding and Husbandry, Christian-Albrechts-University, Olshausenstr. 40, D-24098 Kiel, Germany Phone: +49 (0)431 8804363 Fax: +49 (0)431 8802588
Highlights
We investigated the maternal behaviour of 47 sows in week 2 and 4 of lactation in five successive tests in the home pen and in a test arena.
Factor analysis extracted five factors by the Kaiser-Guttman criterion, explaining together 89.2 % of the total variance.
The results revealed different underlying maternal factors: communication, contact, care and local attachment.
Factor 1 explains for the largest part of variance and indicates the most important maternal factor, the reaction of sows to their piglets in threatening situations.
ABSTRACT Several studies have used behavioural tests to characterise sows regarding their maternal performance. These studies have always chosen a selection of behavioural tests and the combination of tests varied between the studies. In the present study, 47 sows were tested in week 2 and 4 of lactation in five successive maternal tests, which were conducted in their home pens and in a test arena. The sows’ reaction to piglet stress signals, separation from and reunion with their piglets were tested. The behavioural parameters observed in these maternal tests were examined by means of a factor analysis to identify redundancies in behavioural parameters. Five factors were extracted,
1
explaining together 89.2 % of the total variance, of which Factor 1 explains 33.5 %, Factor 2 18.4 %, Factor 3 14.5 %, Factor 4 12.6 % and Factor 5 10.2 %. The interpretation of the factor loadings revealed four underlying maternal factors: communication, care, contact and local attachment. Communication, thus vocalisation, was extracted by the factor analysis as the most important maternal factor and is used in sows to call their piglets in threatening situations as in the separation test and the piglet scream test. Furthermore, communication plays a role for the maternal contact and care factors. Sows used vocalisation to contact their piglets using nose-to-nose contacts, which were observed in the reunion test and also in the piglet scream test. With regard to the care factor, sows use vocalisation to call their piglets for nursing and to synchronise nursing with other sows. The willingness to stay with their piglets, thus local attachment to their piglets, was shown by sows in the separation and reunion test in the test arena and the piglet scream test. Furthermore, the factor analysis proves that single maternal tests can also combine more than one maternal factor and that the experimental environment in which the tests are placed influences the significance of the tests. The present results demonstrate the complexity and diversity of maternal behaviour.
Keywords Factor analysis; Maternal behaviour; Behavioural testing; Sow
1. INTRODUCTION Piglet performance such as survival and growth is greatly dependent on the quality of maternal behaviour. For instance, sows with lower piglet mortality rates are known to show more maternal behaviour such as more nest building (Andersen et al., 2005), expressing more nose-to-nose contacts with their piglets during posture changes (Andersen et al., 2005) and being more careful when lying down (Burri et al., 2009). Maternal behaviour which leads to decreased piglet mortality and to increased piglet growth is an important breeding goal. Different tests have been used to investigate maternal behaviour. The piglet scream test is a commonly used maternal test in which the reaction of the sow towards a screaming piglet (Grandinson et al., 2003; Løvendahl et al., 2005; Melišová et al., 2014) or a sound (Grandinson et al., 2003) is tested. The piglet handling test is a maternal test related to the piglet scream test, in which the reaction of the sow to the handled piglet is observed (Grandinson et al., 2003; Held et al., 2006). Furthermore, sows are tested in piglet-separation tests to investigate whether they search for their piglets, for example by being more restless and by vocalising more frequently (Andersen et al., 2005; Hellbrügge et al., 2008). A separation test is often followed by a reunion test in which the reactions of the sows are tested when their piglets are returned to them (Pitts et al., 2002; Andersen et al., 2005). Most of the studies which have investigated maternal behaviour have used a selection of these tests. To our knowledge, it has still not been proven which types of maternal behaviour these tests evaluate
2
and what these tests exactly test for. Furthermore, it is not known which combinations of maternal tests and what types of tests are advisable. The aim of this present study was therefore to give new insights into the structure of the maternal behaviour of sows and to obtain more information on the significance of these tests. To do this, sows were tested in week 2 and 4 of lactation in their home pens and in a test arena in a piglet scream test, a separation test and a reunion test. As there are redundancies between the tests, factor analysis was used as a helpful tool to investigate the actual underlying structure of behaviour. This method has been used in animal welfare science, for instance as a tool for lameness detection (Miekley et al., 2013) as well as for the evaluation of emotional states in animals (Temple et al., 2011; Wemelsfelder et al., 2012).
2. MATERIAL AND METHODS 2.1. Animals and housing The study was conducted on Futterkamp, the research farm of the Chamber of Agriculture of Schleswig-Holstein
from
May
2014
until
September
2014.
A
total
of
47
cross-bred
(Large White x Landrace) multiparous sows were tested during lactation in a group-housing system (GH) and in a conventional, single-housing system (SH) with regard to their maternal behaviour (Grimberg-Henrici et al., 2016). The treatment groups were used in a previous study (Grimberg-Henrici et al., 2016). In the present study, the different treatment groups (SH, GH) were not considered for data analysis and thus were summarized as research population. Data were collected in four batches with 12 sows per batch. It was considered that the sows did not differ to a large extent concerning their number of parities within and between the batches. All litters were standardised to 13 piglets for each sow until two days postpartum. In the GH system, six sows were housed together. Each sow had a single pen (1.8 m × 2.6 m) provided with a farrowing crate and electronically controlled gates. In addition, all sows shared a running area (2.4 m × 5.4 m). The sows were only fixed in the farrowing crates from three days antepartum to one day postpartum. A flat barrier prevented the piglets from leaving the single pen, whereas the sow could leave the pen. The barrier was removed five days postpartum and all litters of the six sows had the possibility to mix in the running area. Sows in the SH system were fixed in farrowing crates (2.0 m × 2.6 m). Boars were not castrated and the piglets were weaned on average 27.8 ± 0.15 days postpartum. The farrowing stables had water-heated piglet resting areas (0.6 m2) and manipulable material (e.g. plastic balls) was available for the sows and the piglets. The temperature in the stables varied between 19 and 21 °C. Lights (80 lx) were switched on at 6 am and off at 8 pm. Sows were fed a commercial lactating meal, the amount of which was increased constantly during lactation to a maximum of 7.5 kg per day. The piglets received a commercial creep diet. Sows and piglets shared a drinking bowl and had free access to water. 2.2. Behavioural testing All sows were tested in five different successive tests to investigate their maternal behaviour. For the sequence of testing, which is described below, was chosen for reasons of animal welfare, feasibility and practical relevance. The sows were observed in behavioural tests in week 2 (12.8 ± 0.15 days
3
postpartum) and in week 4 (25.8 ± 0.15 days postpartum) of lactation. The tests were performed in the home pens (HP) of the sows and in a test arena (TA) (Fig. 1). The TA was built to create a test situation for the sows, which was uncoupled from their housing system and, thus, a new environment for all sows. The tests started at 8 am and all sows were tested in a random order. The TA was in a separate room and was 3.9 m x 3.7 m large and the opaque side walls were 1.1 m high. The entrance for the sow was 1.2 m wide and there was a piglet nest in one corner. The nest was 1.5 m x 1.5 m x 2.12 m large and the opaque side walls were 1.1 m high. The front wall of the nest had a door (0.8 m wide and 0.4 m high) and was connected with the inside of the TA. The TA was divided into four parts with four possible locations of the sows. 2.2.1. Separation test in test arena The sow was brought to the TA and had ten minutes to habituate to the new environment. After habituation, the piglets were transported to the TA and were put in the piglet nest. Before transportation, one piglet was separated for the piglet scream test in the TA, which was performed later in the experimental set-up. During the separation test the sow was able to hear and smell her piglets. The separation test started when the first piglet was put in the piglet nest. The sow was observed every ten seconds for a whole observation period of five minutes (31 observations per sow and test) concerning location in the TA (Fig. 1), posture, behaviour and vocalisation (Table 1). The test design was modified according to previous experiments by Pitts et al. (2002) and Andersen et al. (2005). The test was supposed to showed how focused the sow was towards her piglets during separation and investigated the responsiveness of the sow to her piglets. We concentrated on behaviour directed towards the piglets such as vocalisation, occupation with the piglet nest, staying near the piglet nest and stress signals. 2.2.3. Reunion test in test arena After the separation test, the reunion test was performed: the door of the piglet nest was opened to reunite the sow with her piglets. The test started when the door was opened. The piglets were carefully pushed with a broom to leave the nest. When all piglets had left the nest, the door was closed. The reaction of the sow was recorded again every ten seconds for an observation period of five minutes (31 observations per sow and test) with regard to location (Fig. 1), posture, behaviour and vocalisation (Table 1). This test was a modified version of the test by Pitts et al. (2002) and Andersen et al. (2005). In this test the reaction of the sow to her piglets was observed when the piglets were suddenly reunited. Behaviour which focused on the piglets such as nose-to-nose contact with the piglets, running after the piglets, nursing and vocalisation were evaluated as good maternal behaviour. 2.2.3. Piglet scream test in test arena For the piglet scream test, the previously separated piglet was now taken to the TA where the sow with the rest of her piglets was walking around. One experimenter stood outside the TA with the piglet next to the piglet nest (location 1) and motivated the piglet to scream by placing it on its back. The reaction of the sow was observed again every ten seconds for 30 seconds (four observations per sow and test) with regard to location (Fig. 1), posture, behaviour and vocalisation (Table 1). This test was similarly constructed compared to the experiments of Grandinson et al. (2003). It investigated the
4
willingness of the sow to protect her piglets and the reactivity and responsiveness of the sow to a piglet distress call. The behaviour was scored as good maternal behaviour when the sow turned towards her piglet using vocalisation, by staying near the screaming piglet and by coming into contact with her other piglets. 2.2.4. Separation test in home pen After the tests in the TA, the sow returned to her empty HP, i.e. without her piglets. The observation started immediately when the sow had reached the empty HP (Pitts et al., 2002). The behaviour of the sow, posture and vocalisation were recorded every ten seconds for five minutes (31 observations per sow and test) (Table 1). The aim of this test was to investigate whether the sow had searched for her piglets. Restlessness such as standing postures, searching the ground for piglets and calling for the piglets was evaluated as searching and stressed behaviour. 2.2.5. Reunion test in home pen The piglets were then transported from the TA to their HP and were placed with the sow. The observation started when the first piglet was placed in the pen (Pitts et al., 2002). The behaviour of the sow, posture and vocalisation was recorded every ten seconds for five minutes (31 observations per sow and test) (Table 1). Similar to the reunion test in the TA, the reaction of the sow was observed when her piglets suddenly entered the HP. Caring behaviour as nursing, nose-to-nose contacts and vocalisation of the sow was evaluated as good maternal behaviour. 2.3. Statistical analysis The count data of the behavioural tests was analysed with a factor analysis by using the statistical software SAS ® 9.4 (SAS Institute Inc., 2008). The PROC FACTOR procedure was carried out, whereby a promax rotation was applied to facilitate the interpretation of results. Each behavioural parameter achieved a certain loading on each factor, which is a number between -1 and 1. Factor loadings were defined as significant if they were greater than or equal to 0.4 (highly positive) and if they were less than or equal to -0.4 (highly negative). This procedure and the interpretation was based on O'Rourke et al. (2013). For location 2, 3, 4 (away from the piglet nest) in the TA only a few observations were performed and were therefore combined for analysis purposes as one location 234.
3. RESULTS Table 2 demonstrates the median, minimum and maximum of the frequencies and the percentage of the behavioural parameters in each maternal test. In the separation test 68.8 % of the sows vocalised, 69.9 % were near the piglet nest in location 1, 26.2 % explored the piglet nest and 22.6 % explored the TA. In the reunion test in the TA 37.1 % of the sows vocalised, 34.8 % were near the piglet nest in location 1, 33.6 % were active, 38.2 % had contact with their piglets and 42.6 % explored the TA. In the third test, the piglet scream test in the TA, 57.5 % of the sows vocalised, 61.2 % were near their screaming piglet in location 1, 30.9 % were active, 15.4 % had contact with their other piglets in the TA and 23.1 % explored the TA. In the separation test in the HP 41.0 % of the sows vocalised, 70.1 % were active and 27.8 % explored the floor. In the last test, the reunion test in the HP, 48.2 % of the
5
sows vocalised, 36.5 % were active, 21.1 % had contact with their piglets, 20.8 % nursed their piglets and 1.3 % explored the floor.
The different factor loadings of the behavioural parameters (greater than or equal to 0.4 and less than or equal to -0.4) of the five maternal tests are shown in Table 3. Five factors are retained by the Kaiser-Guttman criterion (Guttman, 1954; Kaiser, 1960). These five factors explain 89.2 % of the total variance of which Factor 1 explains 33.5 %, Factor 2 18.4 %, Factor 3 14.5 %, Factor 4 12.6 % and Factor 5 10.2 %. The parameter ‘vocalisation’ loads positively on Factor 1 in the separation and the piglet scream test in the TA and in the separation test in the HP (Table 1 and Table 3). Furthermore, the sow’s presence ‘near the piglet nest’ loads on Factor 1 positively, while ‘exploring TA’ loads negatively in the separation and piglet scream test in the TA. On Factor 2 the behavioural parameters ‘vocalisation’, ‘active’ and ‘exploring floor’ in the separation test in the HP are positively related to the parameters ‘active’ and ‘contact with piglets’ of the sows in the reunion test in the HP. In the reunion test in the TA ‘vocalisation’, ‘active’ and ‘contact with piglets’ loads positively on Factor 3, while ‘exploring TA’ loads negatively. On Factor 4 ‘vocalisation’ and ‘nursing’ are positively related. In the piglet scream test in the TA ‘active’ and ‘contact with piglets’ of the sows load positively together on Factor 5, while the sow’s presence ‘near the piglet nest’ in the separation test and ‘near the screaming piglet’ in the piglet scream test in the TA loads negatively.
4. DISCUSSION The five extracted factors of the behavioural parameters in the five maternal behavioural tests present different forms of maternal motivation and make the complexity and diversity of maternal behaviour visible. Factor 1 explains for the largest part of variance and indicates the most important maternal factor, the reaction of the sows when their piglets are in danger. Špinka et al. (2000) evaluated the protective reactions of the sow to piglets in threating situations also as important maternal factor by using a factor analysis. In the present study, ‘vocalisation’ loads in three maternal tests together on the first factor and this indicates that communication is an important instrument for sows with piglets in threatening situations. Hutson et al. (1991) stated that the scream of a piglet is the most important stimulus for a sow to react to. The responsiveness of the sows to it plays a central role in piglet survival with regard to piglet crushing. For instance, Weary et al. (1996) demonstrates that piglet survival increased immensely when the sow reacted to a trapped piglet within one minute. Grimberg-Henrici et al. (2016) found that group-housed sows reacted more strongly in a piglet scream test compared to conventional single-housed sows and showed fewer piglet losses in the course of their study. Another maternal factor belonging to Factor 1 is the local attachment of the sows to their piglets, which is demonstrated by the positive loading of ‘near the piglet nest’. The study conducted by Špinka et al. (2000) found comparable results, where more than half of the experimental sows did not leave the nest and thus their piglets for food. The negative loadings on ‘exploring TA’ for Factor 1 showed the behaviour of the sows that was not directed towards their piglets. In this study, the sow explored the TA during
6
threating test situations for their piglets and expressed no behaviour that demonstrated interest in the piglets and thus indicated disinterest towards their piglets. Factor 2 illustrates the reaction of the sows while searching for their piglets and recognising their piglets. Vocalisation of the sows is also used here to obtain information from their piglets. However, another situational type of vocalisation is detected here compared to Factor 1. If vocalisation of Factor 1 and Factor 2 would be the same type they would load only on one collective factor. Marchant et al. (2001) identified in their study three categories of calls: single grunts, single squeals and rapidly repeated grunts. For the single grunts two types were found which differed in their duration. Additionally, the practical experiences in the stables and during testing approve different forms of vocalisation. Furthermore, the tactile contact between sow and piglets is an important maternal factor. Andersen et al. (2005) discovered that higher sow contact with piglets is related to lower mortality in piglets. The same behavioural parameters as on Factor 2, i.e. ‘vocalisation’, ‘active’, ‘contact with piglets’ load positively on Factor 3. However, these are the behavioural parameters measured in another test. Thus the tests do not load together on one factor. The experimental environment in which the test is placed influences the significance of the test and thus the maternal response of the sows. Furthermore, the negative loading of ‘exploring TA’ demonstrates the disinterest of the sows with regard to their piglets as explained for Factor 1. ‘Vocalisation’ and ‘nursing’ load together on Factor 4 and this indicates a care factor of maternal behaviour. Here, vocalisation is used to call the piglets for nursing and thus to synchronise nursing with other sows. This synchronisation of nursing bouts with other sows has an evolutional background and is observed in domestic free-range pigs (Newberry and Wood-Gush, 1985) as well as in grouphoused sows (Wechsler and Brodmann, 1996). Wechsler and Brodmann (1996) concluded that the synchronisation of the nursing bouts of sows coordinates their daily rhythm and minimises the crosssuckling of piglets between sows. Factor 5 indicates two different maternal factors of sows. On the one hand, Factor 5 demonstrates the local attachment of the sows to their screaming piglet. On the other hand, Factor 5 shows the motivation of the sows to get into contact with their remaining piglets in the TA. The piglet scream test combines two different but equivalent maternal factors in one test. The sows which decide to be attached to the screaming piglet in danger and the other sows which decide to get into contact with their remaining piglets to ensure that they are unharmed. Summarising the different factor loadings, four underlying maternal factors can be extracted: communication, care, contact and local attachment (Table 4). The present results illustrate that more than one maternal test is needed to prove maternal factors. Furthermore, the results validate that different maternal tests can include one or more maternal factors in one test. Hence, maternal tests can provide more than one statement about maternal characteristics and need to be interpreted very carefully. For example, sows that do not focus on a screaming piglet in a piglet scream test but try to get in contact with their remaining piglets show a contact factor of maternal behaviour instead of a communication or local attachment factor. Pitts et al. (2002) tested sows in five comparable maternal tests which were used in the present study and found large differences between the sows concerning
7
their performance in the maternal tests. However, on an individual level the sows were highly consistent in their maternal performance. This indicates how important it is to test sows in a number of maternal tests to cover the different factors of maternal behaviour. The present study reveals that a single test cannot be sufficient to fully detect maternal behaviour. Furthermore, the results prove that different maternal tests explain different proportions of the total variance. This information could be useful in choosing the most suitable test. Hence, it is an important contribution to future research to rely on different maternal tests. Moreover, further research is needed to gain knowledge on whether there are additional maternal factors which should also be taken into consideration.
5. CONCLUSION Five factors were extracted by the factor analysis. The interpretation of these factors revealed four underlying maternal factors: communication, care, contact and local attachment. The results indicate that the reaction of the sow to their piglets in threating situations has a high significance with regard to the maternal motivation of a sow. Furthermore, it was proven that one test can cover more than one maternal factor. Moreover, a comprehensive and careful interpretation of the results is required. It was shown that the experimental environment has an influence on the significance of the tests. This is an important contribution to knowledge when testing and describing maternal behaviour in sows as the retained factors make the complexity and diversity of maternal behaviour visible. Maternal behaviour is multidimensional, thus we recommend the evaluation of sows in a number of tests concerning their maternal performances.
Conflict of interest None declared
Acknowleggments We gratefully acknowledge funding by Rentenbank.
8
REFERENCES Andersen, I.L., Berg, S., Bøe, K.E., 2005. Crushing of piglets by the mother sow (Sus scrofa) - purely accidental or a poor mother? Applied Animal Behaviour Science 93, 229-243. Burri, M., Wechsler, B., Gygax, L., Weber, R., 2009. Influence of straw length, sow behaviour and room temperature on the incidence of dangerous situations for piglets in a loose farrowing system. Applied Animal Behaviour Science 117, 181-189. Grandinson, K., Rydhmer, L., Strandberg, E., Thodberg, K., 2003. Genetic analysis of on-farm tests of maternal behaviour in sows. Livestock Production Science 83, 141-151. Grimberg-Henrici, C.G.E., Büttner, K., Meyer, C., Krieter, J., 2016. Does housing influence maternal behaviour in sows? Applied Animal Behaviour Science 180, 26-34. Guttman, L., 1954. Some necessary conditions for common-factor analysis. Psychometrika 19, 149161. Held, S., Mason, G., Mendl, M., 2006. Maternal responsiveness of outdoor sows from first to fourth parities. Applied Animal Behaviour Science 98, 216-233. Hellbrügge, B., Tölle, K.H., Bennewitz, J., Henze, C., Presuhn, U., Krieter, J., 2008. Genetic aspects regarding piglet losses and the maternal behaviour of sows. Part 1. Genetic analysis of piglet mortality and fertility traits in pigs. 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. Applied Animal Behaviour Science 32, 129-137. Kaiser, H.F., 1960. The application of electronic computers to factor analysis. Educational and psychological measurement. Løvendahl, P., Damgaard, L.H., Nielsen, B.L.m., Thodberg, K., Su, G., Rydhmer, L., 2005. Aggressive behaviour of sows at mixing and maternal behaviour are heritable and genetically correlated traits. Livestock Production Science 93, 73-85. Marchant, J.N., Whittaker, X., Broom, D.M., 2001. Vocalisations of the adult female domestic pig during a standard human approach test and their relationships with behavioural and heart rate measures. Applied Animal Behaviour Science 72, 23-39. Melišová, M., Illmann, G., Chaloupková, H., Bozděchová, B., 2014. Sow postural changes, responsiveness to piglet screams, and their impact on piglet mortality in pens and crates. Journal of animal science 92, 3064-3072. Miekley, B., Traulsen, I., Krieter, J., 2013. Principal component analysis for the early detection of mastitis and lameness in dairy cows. Journal of Dairy Research 80, 335-343. Newberry, R.C., Wood-Gush, D.G.M., 1985. The suckling behaviour of domestic pigs in a semi-natural environment. Behaviour 95, 11-25. O'Rourke, N., Psych, R., Hatcher, L., 2013. A step-by-step approach to using SAS for factor analysis and structural equation modeling. Sas Institute. Pitts, A.D., Weary, D.M., Fraser, D., Pajor, E.A., Kramer, D.L., 2002. Alternative housing for sows and litters.: Part 5. Individual differences in the maternal behaviour of sows. Applied Animal Behaviour Science 76, 291-306. SAS Institute Inc., 2008. User's Guide (release 9.4). Cary, North Carolina, USA. Špinka, M., Illmann, G., de Jonge, F., Andersson, M., Schuurman, T., Jensen, P., 2000. Dimensions of maternal behaviour characteristics in domestic and wildxdomestic crossbred sows. Applied Animal Behaviour Science 70, 99-114. Temple, D., Manteca, X., Velarde, A., Dalmau, A., 2011. Assessment of animal welfare through behavioural parameters in Iberian pigs in intensive and extensive conditions. Applied Animal Behaviour Science 131, 29-39. Weary, D.M., Pajor, E.A., Fraser, D., Honkanen, A.-M., 1996. Sow body movements that crush piglets: a comparison between two types of farrowing accommodation. Applied Animal Behaviour Science 49, 149-158. Wechsler, B., Brodmann, N., 1996. The synchronization of nursing bouts in group-housed sows. Applied Animal Behaviour Science 47, 191-199. 9
Wemelsfelder, F., Hunter, A.E., Paul, E.S., Lawrence, A.B., 2012. Assessing pig body language: Agreement and consistency between pig farmers, veterinarians, and animal activists. Journal of animal science 90, 3652-3665.
10
Fig. 1. Schematic view of the test arena.
11
Table 1. Ethogram for behavioural observation in the maternal tests in the home pen (HP) and in the test arena (TA) (modified according to Pitts et al. (2002) and Andersen et al. (2005)).
Variable
Behaviour
Location
Description
Posture
Active
HP
Sow stands or kneels down.
Inactive
HP
Sow sits or lies.
Active
TA
Sow walks or kneels down.
Inactive
TA
Sow stands, sits or lies.
Exploring floor
HP
Sow sniffs or roots with the nose within 0.2 m of the floor.
Exploring nest
TA
Sow explores with her nose or scratches with her front
Behaviour
legs the front wall of the piglet nest in the TA. Exploring TA
TA
Sow sniffs or roots with the nose within 0.2 m of the floor and explores with her nose or scratches with her front legs the side walls of the TA.
Contact
HP / TA
Sow has contact with her nose with a piglet or searches for contact by running after a piglet.
Nursing
HP / TA
Sow lies laterally. Suckling starts with udder massage of 70% of the piglets and is followed by the milk flow. The suckling ends if less than 30% of the piglets are present at the udder or if the sow stopped lying on her side.
Vocalisation
Vocalisation
HP / TA
Any vocalisation by the sow.
12
Table 2. Median, minimum (min) and maximum (max) of the frequencies and the percentage (%) of the behavioural parameters of the sows (n = 47) tested in week 2 and 4 of lactation in the separation test, reunion test and piglet scream test in the test arena (TA) and in the separation and reunion test in the home pen (HP). Test
Parameter
median
min
max
%
Separation test in TA
Vocalisation
24.0
0.0
31.0
68.8
5min observation
Near piglet nest (location 1)
21.5
6.0
31.0
69.9
(31 observations per sow)
Exploring nest
9.0
0.0
26.0
26.2
Exploring TA
5.0
0.0
27.0
22.6
Reunion test in TA
Vocalisation
8.0
0.0
31.0
37.1
5min observation
Near piglet nest (location 1)
11.0
2.0
25.0
34.8
(31 observations per sow)
Active
10.0
1.0
22.0
33.6
Contact with piglets
11.0
2.0
28.0
38.2
Exploring TA
13.0
1.0
28.0
42.6
Piglet scream test in TA
Vocalisation
3.0
0.0
4.0
57.5
30s observation
Near screaming piglet (location 1)
3.0
0.0
4.0
61.2
(4 observations per sow)
Active
1.0
0.0
3.0
30.9
Contact with piglets
0.0
0.0
3.0
15.4
Exploring TA
0.0
0.0
4.0
23.1
Separations test in HP
Vocalisation
11.0
0.0
31.0
41.0
5min observation
Active
23.5
4.0
31.0
70.1
(31 observations per sow)
Exploring floor
8.0
0.0
24.0
27.8
Reunion test in HP
Vocalisation
13.0
0.0
31.0
48.2
5min observation
Active
10.0
0.0
31.0
36.5
(31 observations per sow)
Contact with piglets
7.0
0.0
21.0
21.1
Nursing
0.0
0.0
29.0
20.8
Exploring floor
0.0
0.0
7.0
1.3
13
Table 3. Factor loadings on behavioural parameters on the five maternal tests in the test arena (TA) and in the home pen (HP) are shown. For clarity of the table all factor loadings are illustrated greater than or equal to 0.4 and less than or equal to -0.4.
Test
Parameter
F1
Separation test in TA
Vocalisation
-0.76
Near piglet nest (location 1)
-0.74
Exploring TA
-0.67
Reunion test in TA
F2
Vocalisation
F3
F4
-0.48
Near piglet nest (location 1)
Piglet scream test in TA
Separations test in HP
Reunion test in HP
F5
-0.48
Active
-0.64
Contact with piglets
-0.77
Exploring TA
-0.68
Vocalisation
-0.60
Near screaming piglet (location 1)
-0.56
Active
-0.72
Contact with piglets
-0.65
Exploring TA
-0.57
Vocalisation
-0.50
-0.43
Active
-0.69
Exploring floor
-0.67
Vocalisation
-0.87
Active
-0.72
Contact with piglets
-0.64
Nursing
-0.82
14
Table 4. Schematic view of the maternal factors in the different behavioural tests in the test arena (TA) and in the home pen (HP). Test Separation test in TA
Communication
Contact
Care
Factor 1
Reunion test in TA
Factor 1 Factor 3
Factor 5 Factor 5
Piglet scream test TA
Factor 1
Factor 5
Separation test in HP
Factor 1
Factor 2 Factor 2
Reunion test in HP
15
Local attachment
Factor 4