The effects of an activity ball and ropes on pigs’ behaviours

Institutionen för fysik, kemi och biologi Examensarbete 16 hp

The effects of an activity ball and ropes on

pigs’ behaviours

Emma Nilsson

Handledare: Per Jensen, Linköpings universitet Examinator: Anders Hargeby, Linköpings universitet

Institutionen för fysik, kemi och biologi Linköpings Universitet

Denna rapport är ett examensarbete på kandidatnivå (16 hp) som har genomförts av författaren i samarbete med en studentkollega, Johan Jönsson. Samarbetet har omfattat projektplanering samt insamling och bearbetning av data, medan studenterna individuellt var för sig har författat och strukturerat rapporten i alla dess delar.

This report is a degree thesis at the Bachelors level (16 ECTS credits) performed by the author in collaboration with a study colleague, Johan Jönsson. This cooperation included the planning of the study, the

collection of data and analyses. Thereafter each student has written and structured the report in all its parts individually.

Rapporttyp Report category Bachelor thesis Språk/Language Engelska/English Titel/Title:

The effects of an activity ball and ropes on pigs’ behaviours

Författare/Author:

Emma Nilsson

Sammanfattning/Abstract: Rooting and exploring are two behaviours pigs in the wild spend

considerable time doing. When kept in pens with limited access to bedding materials stress can originate and often lead to undesired behaviours. The purpose of this study was to investigate whether environmental enrichment in terms of ropes and an activity ball containing piglet food, can provide an outlet for their natural behaviours and thus reduce undesired behaviours. In total, 141 pigs were used and divided into three groups, control-, activity ball- and rope groups. The observation methods used were 1/0

recording and instantaneous recording with 15 second intervals. In the rope group a significant difference was seen in the interaction with enrichment, as it was higher on day 1. Between the three groups, a decrease in ear-, tail- and equipment biting was seen in the two enriched groups on day 1. On day 3 these difference could only be seen

between the control group and the other two groups in equipment biting. However, few data ware collected and so we cannot confirm our hypotheses, concerning whether the environmental enrichments decreased the undesirable behaviours or not. However, most of our findings are in compliance with earlier studies as we among other things found that the rope worked better than the activity ball and that the interest of the enrichments decreased with time.

ISBN

LITH-IFM-G-EX—12/2668—SE

__________________________________________________ ISRN

__________________________________________________ Serietitel och serienummer ISSN

Title of series, numbering

Handledare/Supervisor Per Jensen

Ort/Location: Linköping

Nyckelord/Keyword:

Environmental enrichment, rope, activity ball, pig, behaviour

Datum/Date

2012-05-31

URL för elektronisk version

Institutionen för fysik, kemi och biologi

Department of Physics, Chemistry and Biology

Avdelningen för biologi

Contents

1   Abstract ... 2  

2   Introduction ... 2  

3   Materials & methods ... 4  

3.1   Housing of the animals ... 4  

3.2   Behavioural observations ... 5   3.2.1   Control group ... 6   3.2.2   Rope-group ... 6   3.2.3   Activity ball-group ... 6   3.3   Statistical analysis ... 6   4   Results ... 7  

4.1   Differences between day 1 and day 3 ... 7  

4.2   Differences between the three groups ... 9  

5   Discussion ... 12  

5.1   Conclusion ... 14  

6   Acknowledgements ... 15  

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1 Abstract

Rooting and exploring are two behaviours pigs in the wild spend

considerable time doing. When kept in pens with limited access to bedding materials stress can originate and often lead to undesired behaviours. The purpose of this study was to investigate whether environmental enrichment in terms of ropes and an activity ball containing piglet food, can provide an outlet for their natural behaviours and thus reduce undesired behaviours. In total, 141 pigs were used and divided into three groups, control-, activity ball- and rope groups. The observation methods used were 1/0 recording and instantaneous recording with 15 second intervals. In the rope group a significant difference was seen in the interaction with enrichment, as it was higher on day 1. Between the three groups, a decrease in ear-, tail- and equipment biting was seen in the two enriched groups on day 1. On day 3 these difference could only be seen between the control group and the other two groups in equipment biting. However, few data ware collected and so we cannot confirm our hypotheses, concerning whether the environmental enrichments decreased the undesirable behaviours or not. However, most of our findings are in compliance with earlier studies as we among other things found that the rope worked better than the activity ball and that the interest of the enrichments decreased with time.

2 Introduction

A widespread problem in housing of both wild and domesticated animals is the occurrence and development of abnormal behaviours. It has been seen in for example elephants kept in zoos (Iossa et al, 2009), pet-parrots

(Garner et al, 2005) and slaughter pigs (Lawrence and Terlouw, 1993). The reason why stereotypic behaviours emerge is that they are kept in an

environment where the animals have little or no possibility to perform their innate behaviours (Lawrence and Terlouw, 1993). An example, and the focus of this study, is that slaughter pigs often are kept in a very bare environment and undesired behaviours may develop.

Pigs are under normal circumstances curious, exploring and gregarious animals and live in herds of four to six closely related sows and their

progenies. However, the boars leave the mother herd when sexually mature and thereafter live in solitary (Graves, 1984). Under natural conditions it is very uncommon for unrelated pigs to meet and form a herd together

(Jensen, 1996). The environment for slaughter pigs differs from their natural conditions in many ways. To mention some examples they are kept on a limited area with unrelated pigs in the same age. In addition to these

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unnatural conditions the pigs often have limited access to bedding material which decreases their possibility to root and explore their environment (Jensen, 1996 and 2006). Rooting and exploring are two behaviours pigs in the wild spend considerable time doing. Already at an early age the piglets starts to manipulate different object in trying to learn what is edible

(Petersen, 1994). Another difference between wild pigs and slaughter pigs is the time it takes to wean the piglets from the sow. The slaughter pigs are being abruptly weaned after just seven weeks which is much earlier than the weaning in the wild which is a slow process that occurs when the piglets are 13-17 weeks old according to Newberry & Wood-Gush (1985) quoted by Lindahl (2003).

The abrupt, early weaning, the mixture of pigs from different litters,

crowding and lack of stimulation in their environment may lead to stress in slaughter pigs (Lindahl, 2003). To identify behaviours related to stress, Dybkjaer (1992) did an experiment with early weaned pigs. The study showed that pigs that lived in stressful environments spent more time massaging other pigs with their snouts, belly-nosing, and also spent more time sniffing, biting and chewing on other pigs or equipment (Dybkjaer, 1992). Belly-nosing, however, is a behaviour thought to originate from the need to suckle for milk and their abrupt weaning (Weary et al, 1999). Lawrence and Terlouw (1993) also showed in their study that undesired behaviours, thought to be derived from the inability to perform foraging and exploratory behaviours, are ear biting, tail biting and biting on

equipment. These behavioural disorders can be harmful for the pigs and are often expensive for the producers. That is the reason why one as much as possible wants to reduce these undesired behaviours and a way to do that, is through environmental enrichment.

The use of straw has been shown to be effective in reducing stereotypes (Day et al, 2008; Van de Weerd and Day, 2008). In modern housing systems of slaughter pigs straw can be a problem for the farmers. Too much straw can jam the slatted floors preventing the feces from going down through the slots. To make it as convenient and usable as possible for the farmers and at the same time giving the pigs a more suitable

environment, it is important to try finding new ways to enrich their environment.

The purpose of this study is to investigate whether environmental

enrichment in the form of ropes and an activity ball containing piglet food, can provide an outlet for their natural behaviours and thus reduce undesired behaviours. The reason why these two objects where chosen is because

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they both can be used to increase the pigs’ exploratory and foraging

behaviours. The ropes are easy for the pigs to manipulate with their mouth and the activity ball give of a scent of piglet food.

One prediction for this study is that a decrease in the undesirable

behaviours ear biting, tail biting and equipment biting will be seen in the two enriched groups compared with the control group. However, a decrease in belly-nosing is not expected to see (Weary et al, 1999). On day 3, in comparison to day 1, at least a small decrease in interaction with the enrichment is expected.

3 Materials & methods 3.1 Housing of the animals

The study was performed at Vreta Naturbruksgymnasium in Linköping over a period of 17 days and included 141 pigs of the breed Piggham in the age of 16 weeks when the experiment started. They were kept in 18 pens with the measurements 3.2 m x 2.1 m of concrete floor and 1.6 m x 1.4 m of slatted floor (figure 1). The pens were made of wooden walls, steel piping, concrete and slatted floors. The remnant of the straw that was given to the pigs in connection with their early breakfast at 4:00 am was left in the pens but no new straw was distributed before the observations. The pigs were fed through apparatus at 4:00 am, 10:30 am and 5:30 pm.

Figure 1. A drawing of the pig pens and their dimensions. The striped part represents the slatted floor and the unstriped part represents the concrete floor.

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3.2 Behavioural observations

The 18 pens were divided into three groups with six pens in each group; one control group, one rope group and one activity ball group. The three different groups were scattered evenly through the pig stable in relation to windows, fans and doors. To disturb the pigs as little as possible by human presence, the observations were made immediately after they finished their meal served at 10:30 am and 5:30 pm. Each observation lasted for an hour. The objects, the ropes and the activity ball, were placed in the pens while the pigs were busy eating and the observer took place as well. The objects were left in the pens for three days and the pens were observed at day 1 and day 3. The observation methods used were 1/0 recording and instantaneous recording with 15 second intervals. The first mentioned recording was used to observe undesired behaviours (the five first behaviours in table 1) and the instantaneous recording was used to record the other behaviours where total focal sampling was used. At the end of every interval the number of pigs performing each behaviour was registered. The ethogram gives the descriptions of the behaviours of interest in this study (table 1).

Table 1. Ethogram with the behaviours and the description of them. Functional term Describing term

Tail biting Putting the tail of a fellow pig in the

mouth and manipulating it with the jaw muscles.

Ear biting Putting the ear of a fellow pig in the

mouth and manipulating it with the jaw muscles.

Equipment biting Putting pieces of equipment in the mouth

and manipulating it.

Belly-nosing Nibbling, sucking and chewing motions

directed towards a fellow pig´s belly. Aggressive

behaviour

Biting towards fellow pigs in an aggressive manner. Using the snout to push other pigs away (aggressively). Otherwise dominating behaviours directed towards fellow pigs. Interaction with

enrichment

Rooting, chewing, eating, sniffing, licking, and otherwise manipulative behaviours directed towards the enrichment.

Lying down Lying passively on the floor (sleeping),

stomach touching the ground or lying on the side. No manipulation of any

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3.2.1 Control group

The pens with the control groups were kept as described above and were not given any enrichment. Six pens with a total of 48 pigs were kept and observed under these circumstances.

3.2.2 Rope-group

Six pens with a total of 48 pigs were given access to two ropes weaved of a ´´förtöjnings- och ankarlina´´ (18 mm x 10 m; article 25-0776). The rope was twisted of three minor ropes that were separated from each other. The minor ropes were then cut into a length of 1.8 m and then paired and tied together until they only consisted of ties. The ropes were placed at the end of the pen that did not border to another pen and were tied to a steel pipe.

3.2.3 Activity ball-group

For this enrichment six pens with a total of 45 pigs were used. The activity ball was of the model Snak-a-ball, size large from the manufacture Likit. It was filled with one litre of shredded paper, three litres of sawdust and three litres of piglet food. The hole where the piglet food fell out had a diameter of 5 cm and to keep the piglet food from falling out all at once the ball was filled with the sawdust and the shredded paper.

3.3 Statistical analysis

The behavioural observations of lying down and interaction with the enrichment were collected in a way to give a mean of how many pigs in every box, were spending time doing what in each 15-second interval. The observations of the undesirable behaviours were collected to yield a mean of how often the behaviours were carried out during each interval in every box. To perform the analyses the software IBM spss statistics 20 was used and the statistical unit was the mean of each behaviour in each box and also the mean for the respective days. A two-tailed paired-sample t-test and a one-way ANOVA with P-levels at P< 0.05 were used.

The two-tailed paired-sample t-test was used to analyse if there was a

significant difference in how often the behaviours were carried out between day 1 and day 3. Every behaviour described in the ethogram (table 1) was analysed.

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To analyse how the rope-, activity ball- and the control group relate to each other a one-way ANOVA was used. This because there was only one factor affecting the pigs, the presence or no presence of an enrichment.

4 Results

4.1 Differences between day 1 and day 3

No significant difference of the total number of times the behaviours

occurred was found between day 1 and day 3 in the control group (P>0.05). In the activity ball group a significant difference (P = 0.034) was found in the behaviour lying down. On day 3 the pigs laid down 1.63 times more of the time compared to day 1 (figure 2).

Figure 2a. The behaviours occurrence during day 1 and day 3 in the group of pigs exposed to an activity ball. The error bars shows the standard deviation. (*) A significant difference between day 1 and day 3 was found. 0,0   1,0   2,0   3,0   4,0   5,0   6,0   7,0   Interaction with

enrichment Lying down Aggressive behaviour Belly nosing Equipment biting Ear biting Tail biting

T h e m ea n o f al l p en s in b eh av io u r occurence Behaviours Day1   Day3   *  

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Figure 2b. An enlargement of figure 2a showing the undesirable behaviours.

A significant difference in the rope group was found in the behaviours interactions with the rope (P = 0.001), lying down (P = 0.001) and

aggressive behaviour (P = 0.008). On day 1 the pigs spent 5.34 times more time on interactions with the ropes compared to day 3 and lying down increased 2.26 times on day 3. Aggressive behaviours occurred 2.30 times more on day 1 than day 3 (figure 3).

Figure 3a. The behaviours occurrence during day 1 and day 3 in the group of pigs exposed to the ropes. The error bars shows the standard deviation. (*) A significant difference between the days was found.

0,00   0,02   0,04   0,06   0,08   0,10   0,12  

Aggressive behaviour Belly nosing Equipment biting Ear biting Tail biting

T h e m ea n o f al l p en s in b eh av io u r occurence Behaviours Day1   Day3   0,0   1,0   2,0   3,0   4,0   5,0   6,0   7,0   8,0   Interaction with

enrichment Lying down Aggressive behaviour Belly nosing Equipment biting Ear biting Tail biting

T h e m ea n o f al l p en s in b eh av io u r occurence Behaviours Day  1   Day  3     * *   *  

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Figure 3b. An enlargement of figure 3a showing the undesirable behaviours.

4.2 Differences between the three groups

When analysing the occurrence of interaction with the enrichment a significant difference was found between all three treatments on day 1. This means that even between the rope and the activity ball a bigger interest was shown towards the rope. A significant difference was also found between the control group and the two treatments in the behaviours lying down, equipment biting, ear biting and tail biting. However, no difference was found between the activity ball- and rope group. No significant difference was found in the behaviours belly-nosing and aggressiveness towards other pigs (figure 4).

0,00   0,02   0,04   0,06   0,08   0,10   0,12  

Aggressive behaviour Belly nosing Equipment biting Ear biting Tail biting

T h e m ea n o f al l p en s in b eh av io u r occurence Behaviours Day  1   Day  3   *  

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Figure 4a. The distribution of the behaviours in the three groups on day 1.The error bars shows the standard deviation. (*) A significant difference was found between all three groups. (**) A significant difference was found between the control group and the two others.

Figure 4b. An enlargement of figure 5 showing the undesirable

behaviours. (**) A significant difference was found between the control group and the two others.

0,0   1,0   2,0   3,0   4,0   5,0   6,0   7,0   Interaction with

enrichment Lying down Aggressive behaviour Belly nosing Equipment biting Ear biting Tail biting

T h e m ea n o f al l p en s in b eh av io u r occurence Behaviours Control  group   Ac;city  ball  group   Rope  group   * **   **   **   **     0,00   0,05   0,10   0,15   0,20   0,25  

Aggressive behaviour Belly nosing Equipment biting Ear biting Tail biting

T h e m ea n o f al l p en s in b eh av io u r occurence Behaviours Control  group   Ac;vity  ball  group   Rope  group   **  

**   **  

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On day 3 a significant difference was found between the control group and the other two groups when it comes to equipment biting. In the other

behaviours no difference was found between the different treatments (figure 5).

Figure 5a. The distribution of the behaviours in the three groups on day 3.The error bars shows the standard deviation. (*) A significant difference was found between the control group and the two others.

Figure 5b. An enlargement of figure 5a showing the undesirable behaviours. (*) A significant difference was found between the control group and the two others.

0,0   1,0   2,0   3,0   4,0   5,0   6,0   7,0   8,0   Interaction with

enrichment Lying down Aggressive behaviour Belly nosing Equipment biting Ear biting Tail biting

T h e m ea n o f al l p en s in b eh av io u r occurence Behaviours Control  group   Ac;city  ball  group   Rope  group   * 0,0   0,1   0,1   0,2   0,2   0,3  

Aggressive behaviour Belly nosing Equipment biting Ear biting Tail biting

T h e m ea n o f al l p en si n b eh av io u r occurence Behaviours Control  group   Ac;vity  ball  group   Rope  group   *  

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5 Discussion

The aim of this experiment was to investigate whether manipulative enrichment would decrease the occurrence of undesirable behaviours (described in section 2). In this study we found that the rope as an environmental enrichment worked better than the activity ball. We also found that the interest for the enrichments decreased on day 3. On day 1, a decrease in ear biting, tail biting and equipment biting was seen in the two enriched groups compared with the control group. However, on day 3, a significant difference could only be seen in equipment biting in the enriched groups.

The comparison between day 1 and day 3 was made to see whether the interest in the enrichment would decrease with time. Gifford et al. (2007) did a study showing that pigs in greater extent give more interest to novel objects than to familiar ones. The same study also showed that when exposed to an object for two days, it took longer time for the pigs to treat the object as a novel one when re-exposed. For this reason the prediction was that the interest would be high on day 1 and then at least have

decreased a bit on day 3. In the rope group the interaction with the enrichment was higher, a significant difference, on day 1 than on day 3. This was an expected result, however it was not expected to not see a significant difference between day 1 and day 3 in the activity ball group. On day 3 the interest for the objects was so low that there was no

difference between the treatment groups and the control group. The big interest on day 1 and the lack of it on day 3 indicates that the enrichment is more interesting when it comes into a pen as a novel object. This confirms our prediction.

When comparing the behaviour occurrences on day 1 with day 3 it showed a difference in lying down in both the activity ball group and the rope group. On day 3 both groups laid down more of the time which is an indication of a decrease in interest of the enrichments. The lying down increased so much on day 3 that there was no longer a significant

difference to be found between the treatment groups and the control group (figure 5a), which could be seen on day 1 (figure 4a). When it comes to the undesirable behaviours a significant difference between day 1 and day 3 could only be seen in aggressive behaviours in the rope group (figure 3b). On day 1 when the rope was a novel object the aggressiveness towards each other was higher. In an earlier study Ishiwata et al. (2004) claims that the presence of a novel object can increase aggressive behaviour as the pigs is trying to take dominance over the object. This could be the case in our

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study and as the interest of the rope decreased over time, so did the dominance and aggressive behaviour. However, due to few data it would be incorrect to make a clear statement, based on this study, on how the aggressiveness is affected by the enrichments over time. It would neither be correct to make a statement concerning whether the enrichments decreased the other undesirable behaviours or not since no significant difference was found and even here, few data was collected.

The enrichments were not expected to decrease the occurrence of belly-nosing. This prediction in view of the fact that belly nosing is not thought to derive from stress (Gardner et al, 2001), like biting behaviour (Schrøder-Petersen and Simonsen, 2001). In this study, the occurrence of belly-nosing was very different from pen to pen. The variation gave high standard

deviations, which may have led to that no significant difference was found between either the three groups or between day 1 and day 3. Nevertheless, not enough data for this behaviour was collected and since the variations were big between the pens, a statement would not be correct to give. When comparing the three groups of pigs, the control-, the activity ball- and the rope group, it was predicted that the enrichments would decrease the biting behaviour towards other pigs and equipment. This prediction was made because both enrichments are easy for pigs to manipulate with their mouths in one way or another. Stolba and Wood-Gush (1989, cited by Studnitz 2007) found that foraging and exploratory behaviour is something pigs, in more natural environments than a bare pen, spend most of their time doing. It was found on day 1 that the enrichments reduced three of the five undesirable behaviours. A significant difference was found between the control group and the two enriched groups in equipment-, ear- and tail biting. However, it would not be correct to make a statement on the results from ear- and tail biting since these behaviours did not occur often enough to give reasonable data. Nevertheless, a statement on equipment biting can be made. On day 1 the enrichments decreased the behaviour with 78% in the activity ball group and with 95% in the rope group in comparison to the control group (figure 4b). On day 3 only one significant difference was found and that was in the behaviour equipment biting. So, even on day 3 the enrichments seem to decrease this undesired behaviour since the control group still had the highest number of equipment biting. Worth mentioning is that no difference between the treatments was found in the interaction with enrichment on day 3. So even though the interactions with the

enrichments had decreased so much that there was no difference between the treatments and the control group, the study still shows that the

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When comparing the effects of the ropes and the activity ball, the study shows that the interest for the ropes was bigger than the interest for the activity ball. The reason for this may be that the ropes are easy to

manipulate with their mouth. The activity ball had a diameter big enough to not let the pigs get their jaws around it and chew on it. A study made by Feddes and Fraser (1994, cited by Van de Weerd et al., 2003) showed that pigs use the enrichment more if they can alter it by chewing. Ropes can remind a bit of straw and other studies have showed that when given straw, big interests from the pigs are given and unwanted behaviours are reduced. However, Day et al. (2008)showed that pigs given chopped straw still engage in tail biting. From these results the researchers drew the conclusion that this undesirable behaviour still occurred because the pigs were not able to manipulate the chopped straw in the same way as non-copped or half chopped straw.

Using the activity ball, the goal was to see if the pigs when using their sense of smell would start exploring the activity ball and try getting the piglet food out of the ball instead of executing undesirable behaviours. In a recent study, Oostindjer et al. (2011) showed that perinatal flavour learning could help reduce stress in later life. When re-exposed to the same flavour an effect in their behaviour was seen which suggests that in a stressful environment the perinatal flavour learning may decrease the stress level in the pigs. The piglet food used in our study was the same as what they were given when they were little and still shared pen with their mother and siblings. To be re-exposed to the same smell they sensed at a secure place near their mother could, as Oostindjer et al (2009) suggested, lower the stress level. A problem with our test, which could have affected the interest of the activity ball, is the fact that the pigs almost immediately pushed the activity ball down on the slatted floor. This resulted in a ball covered with feces that probably concealed the scent of the piglet food. So, to see if exploring with their sense of smell could affect their behaviour, a stronger scent or some kind of blockage between the concrete floor and the slatted floor could give more reliable results.

5.1 Conclusion

This study showed that ropes are a more interesting enrichment than an activity ball. This result is in compliance with previous research (Feddes and Fraser 1994). Over time the interest of the enrichments decreased and on day 3 no significant difference could be seen between the enrichment groups and the control group. Due to few collected data on the undesirable behaviours we cannot confirm whether the enrichments decreased these

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behaviours or not. However, at least the ropes seems promising as an

environmental enrichment and should be investigated further. It would also be interesting to continue investigating the effects of perinatal flavour learning (Oostindjer et al. 2011) and see whether an activity ball can be used in a better way.

6 Acknowledgements

Great thanks to my supervisor Per Jensen, professor in Ethology, for his help and guidance through this project. I would also like to thank my fellow student Johan Jönsson, who I conducted all the practical parts with. Also a special thank to Christer Nilsson, pig farmer on Vreta

Naturbruksgymnasium, for all his help through the practical parts.

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