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>> Kristine Adams: So, up next we have a little change
in the way we've been doing things.
Dr. Candace Croney is here with us,
but she's going to be speaking to us over the phone.
There were some mechanical difficulties with
the plane yesterday.
But I would like to give her a brief introduction to let you
know a little bit about her.
And I met Dr. Croney when she was a post-doc working
in the same lab that I worked in as a graduate student
at the University of Maryland, and I was lucky enough to get
involved with some of the cognition work that she
was doing with some pigs at that time.
So I learned a lot from her.
And I'm sorry, Candace, I'm pulling up the bio.
So, she currently is an associate professor of animal
behavior and wellbeing in the Animal Sciences Department
at Purdue University.
Her research teaching and extension efforts focus
on the interactions between animal behavior, cognition,
and wellbeing, the effects of rearing environments
and enrichment on animal behavior and welfare,
the ethical implications of animal care and use decisions,
and public perceptions of animal agriculture,
and her research on farm animal cognition has been featured
in national and international broadcast programs by National
Geographic, the BBC, and their affiliates.
And she currently serves as scientific advisors on various
animal welfare groups, such as the American Humane Association,
the National Pork Board, and the National Pork Producers Council.
And with that, I'm going to let Candace start,
and I'll be running the slides, so it's sort of a circus,
but thank you Candace.
>> Candace Croney: Yup.
Kristina, can you hear me?
>> Kristina Adams: I can.
>> Candace Croney: Perfect.
I'll just let you know when to advance the slides.
I'll just tell you to go to the next point or the next slide,
okay?
>> Kristina Adams: Okay.
>> Candace Croney: Okay.
Hi, everyone.
I'm really sorry I could not be there.
Our pilot is apparently a weenie and thought that brakes were
important to land the plane or something like that.
So I'm really sorry I couldn't be with you in person,
but I'm delighted I can at least join you by phone.
I'm really happy to talk to you about social housing in pigs,
particularly in research settings.
It is a very important consideration,
and so Kristina, we'll go to the next slide.
>> Kristina Adams: Okay.
>> Candace Croney: What I plan to cover for you is just touch
a little bit on the importance of pigs as a biomedical model,
talk about the ethical and, really,
the scientific need for socially housing these animals in order
to promote their wellbeing, and also to really enhance
the validity of the research that we're conducting using
them as subjects.
I'll spend most of my time on, really what constitutes social
housing, especially in this species,
and then move on to the specific considerations that
are important when we think about social housing of pigs.
Okay?
Next slide, Kristina.
>> Kristina Adams: Okay.
>> Candace Croney: So, the pig is clearly a popular animal
model, particularly in biomedical research.
Obviously the reason for this is the number of physiological
and anatomical similarities they have to humans, but,
as you're well aware, there's quite a bit of societal pressure
to move away from using animal models in general,
and certainly pressured to move away from using certain species,
such as non-human primates and even dogs.
So the pig has actually been used more and more frequently,
and it's very interesting that when I did my dissertation
research in 1999, I had this exact next line in my thesis
presentation, which says that there is minimal literature
on the welfare needs of pigs in biomedical research.
That is as true today as it was in 1999.
Unfortunately, there's even less published on the social housing
needs of pigs.
So when Kristina asked me to do this talk, I was delighted,
and then wondered what I had done to really irritate
her because clearly there's no literature that I could
easily go to.
So I really had to do a lot of pulling,
and so what you'll hear today is really a compilation of a number
of different studies, and also based a lot on the work I
and several of my colleagues are doing with these animals.
Fortunately, we've actually had quite a lot of experience
working not just on farms using these animals as our models,
but also in laboratory research, as well.
It is really important to incorporate normal social
behavior in any research model that involves maintenance
of the animals over time.
This is just as important in the pig, and, in fact,
doing this allows us to better meet our ethical obligations
to their wellbeing as a function of deciding that
it's appropriate to use them.
The other issue is, and we'll get into some of the details
of this a little bit later, is the accuracy and potentially
the validity of the data that we're conducting is much more
rigorous and trustworthy if we're really comprehensively
ensuring that the welfare needs of the animals are met in all
domains, in the physiological aspects as well
as the behavioral and the psychological
components of wellbeing.
Next slide, Kristina.
>> Kristina Adams: Okay.
>> Candace Croney: So, a little bit on the isolation and stress
and how this applies to pigs.
Oftentimes for biomedical research purposes,
as well for other types of research,
pigs are often isolated.
Okay.
This is well documented to cause behavioral as well
as physiological signs of distress, and so providing some
form of social support potentially provides a way
to buffer these sorts of responses.
Click again, Kristina.
One of the things we know is, when we provide this kind
of intervention, we tend to see decreased activation of the HPA
axis following exposure to any sort of stressor.
Next point.
A number of different metrics of this have been well
documented over time.
We've seen reduced CRH release.
Next point.
Reduced ACTH release.
Next point.
Reduced glucocorticoid levels.
All of these, of course, mitigated through the --
mediated through the HPA axis.
Next slide, Kristina.
So the question becomes, yes, we've got some data that
suggests that, in general, social support is important,
but does social housing really matter to the pig?
And, obviously, if we're going to answer this question one
of the things we really need to look at is the ethology
of the pig and what it tells us in regards to this question,
and then also how to implement things.
Next slide.
If you look at the ethology of the pig,
one of the bases for making any of the decisions of the animals
that we're working with, it's oftentimes look at what feral
pigs do, what wild species of pigs do when left
to their own devices.
So in regards to normal social organization in the pig,
what is typical is to have stable female grouping.
What we'll often observe are several sows and piglets living
together in groups, usually fairly harmoniously.
We'll also see herds of young what's referred to as bachelor
boars who will live together, and then you will oftentimes
also see solitary older boars who may live in the vicinity,
establish a territory, and then both the young group living
boars and the solitary older boars will tend to join
the female group during the breeding season.
We also know that there are key behaviors that are observed
in virtually all pigs, including those that are bred
for research, which suggests that they are important aspects
of the pig's ethogram, and these include rooting behaviors,
exploring, and -- most important to what we're going to talk
about today -- establishing social groups and hierarchies.
Next slide.
It is pretty clear and very well known that it's really
undesirable to mix unfamiliar pigs.
If that's done, and it needs to be minimized,
we know what happens: those pigs will absolutely get into fights.
Depending on the age, the experience, the breed,
and a number of different factors,
the severe -- the severity of the fighting is going to vary,
but we know that that will typically occur over a 24- to
48-hour period until the dominance
hierarchy is established.
However, once that hierarchy is set,
aggression is pretty infrequent.
What is more common to see are affiliative behaviors where what
you'll oftentimes see are pigs making a lot of tactile contact
with each other.
They will group together, lie together, nuzzle each other,
and you see lots of social facilitation,
including learning from each other, new behaviors,
foraging behaviors, exploratory behaviors, and so on.
Next slide.
We also know that pigs are highly motivated for social
contact with each other.
Next point.
They have been demonstrated in numerous studies.
I've just added one view here where they will work for access
to a companion by using different operant means.
Next slide.
Next point, sorry.
When singly housed, they will oftentimes seek out some type
of conspecific contact.
So if they are allowed to have some kind of fence line contact,
you will oftentimes, when they're resting,
find them lying against each other or against that enclosure
so they're getting at least some level of tactile interaction.
Next point.
Some studies have shown that they will actually choose feed
and social contact over bedding.
When I'm done with this talk, I'll show you some more data
that supports this finding.
Next point.
And we know that isolated pigs will show chronic stress
response compared to group-housed pigs.
Next point.
So, collectively, just a small amount of data would suggest
that social housing is indeed important to the pig,
and clearly then, once we know that,
ought to be important to our considerations of how we house
these animals for research purposes.
Next slide.
We do know that something about the cognitive abilities of these
animals is going to interact with their social behavior
and cumulatively add up to tell us something about what's
important in regards to their wellbeing.
Next point.
Several studies have demonstrated that pigs
are fairly cognitively complex, they are behaviorally flexible
and adaptable, and among the things that we know that
are going to become relevant to how we interact with, manage,
and house them are the idea that they absolutely have memory.
They have memory for a number of different items, objects,
events, and so on.
They can absolutely do discrimination learning.
So they can distinguish between companions,
they can distinguish between odors, visual stimuli,
and also location cues.
And they are absolutely able to form concepts.
And a lot of the work that has been done with this stuff has
occurred in Europe, but we were fortunate in my group to do some
of the earliest work in pig cognition.
So the picture you see of the pig working on a computer task
is actually work that I did in my dissertation research.
Next point, Kristina.
Collectively, the information that we have on pigs' cognitive
abilities suggest that they have the capacity to both learn and
more importantly remember negative as well as positive
experiences in the settings they find themselves -- so this
of course would apply to laboratory settings --
and thus the potential exists for them to either suffer
and behave accordingly or to cope well and behave accordingly
in the settings in which they find themselves.
Next point.
As such, it's likely that they need and potentially benefit
from support for their behavioral and psychological
wellbeing, and that includes interventions that promote
their social support.
Next slide.
We do have some evidence that stress suffering does occur
in pigs, but that's really important that you consider
the familiarity of the companion animal that is provided
to do this kind of buffering.
We know that there are negative physiological and behavioral
effects that are induced by social aggression,
and we also know that these actually can be mitigated
if the animal that has had that experience is subsequently
housed with a familiar pen-mate.
A number of other studies also show that when you provide
familiar pen-mates as conspecifics or companions
in conjunction with enrichment -- so, for instance,
several of the studies I've cited here looked at -- in young
piglets, providing a simulated utter.
What we see is decreased distress behavior in early
piglets that are weaned at a certain stage of time
for experimental reasons.
Next slide.
So, again, I think we've given a lot of evidence that social
housing of pigs may be a very important consideration,
so the question becomes when we're making decisions relative
to their housing or trying to implement social housing,
what factors do we really need to consider?
Next slide.
And one of the first questions that we should be asking is what
constitutes social housing in pigs?
Right.
Is it conspecific housing?
Is it actually having the ability to interact with animals
of the same species?
A point that's not on here is, is just being housed in the
presence of other animals sufficient to support the social
needs of these animals?
And then we also have to look at other alternatives.
Are social interactions with animals of a different species,
such as human animal interactions,
are -- would they suffice?
Are interactions with other species -- for instance,
other prey species, other farm animal species -- sufficient?
And so one of the things we need to consider,
and this relates nicely back to the talk we previously heard,
do pigs actually look at humans as potential conspecifics or can
human interactions at least fill in as a substitute if we can't
provide social interactions with members of their own species?
And then the last bit, and I will spend just a little bit
of time on this, is are there other sort of inanimate forms
of social support that are useful, viable,
and salient for the pigs in the types of settings they may find
themselves in for research purposes?
Next slide, Kristina.
Clearly, if we're going to talk about conspecific housing
considerations, we have to think about what the risks are.
Next bullet point.
And there are several when it comes to pigs.
The first one, based on what I've already told you,
should be thinking about how you introduce pigs so as to minimize
aggressive interactions, which we know will occur within
the first couple days, and how do you manage that when
and if it does occur, because it actually will occur.
We have to consider this not just because there are risks
to the equipment that we might be using -- so, for instance,
if you have catheterized animals,
you certainly don't want them ripping catheters out.
But there's severe risks potentially to the animals
themselves, which is actually the more important consideration
in regard to their wellbeing.
Now, of course this interacts because pigs that are being
treated for different purposes, if they're getting into fights
with each other and have equipment attached to them
or have, for instance -- depending on the type
of research being done -- any sort of wounded area
or vulnerable area, you absolutely want to consider
that to make sure the animals are protected.
Next bullet point.
Another factor to think about is the stability of the group.
So, clearly, again, making sure that not only are introductions
done well, but that once a group is set,
even if that group is as small as a dyad,
it stays stable unless there's really good reason
to disrupt it.
Absolutely has to be a factor.
Next bullet point.
The other question -- and I know there was actually a question
already posed in advance about the size of pen-mates.
So there's a number of different points of research that will
point to the idea that, actually, if, for instance,
you have let's say -- the smallest group you could
get is a dyad.
If, for instance, you have disparate pair sizes,
what you'll oftentimes see is reduced
or less severe aggression.
Pigs typically will tend to suss each other up, get into fights,
and oftentimes avoid fights or avoid longer fights
or prolonged, repeated fights as a function simply of the size
of the animal they're engaged with.
And so, although it is really uncommon to see this in both
farm animal research settings and particularly less
so in biomedical research settings because we oftentimes
want to have consistency in the size of animals that we're
getting in -- if it is at all possible, if you pair animals
that are clearly different in terms of their weights,
you will oftentimes have an easier time establishing
the social hierarchy, maintaining it,
and avoiding future aggressive encounters.
One of the things we know is that pigs of uneven size
and weights will also establish a social rank much more
quickly than if they're evenly matched.
Next slide.
Other factors that we need to consider are -- what else
is in the pen with the animals?
So it's not just that they're in there with each other,
but what else is in there?
Unless you socially house these animals,
any form of resource becomes potentially a point around which
aggressive encounters can occur.
First bullet point.
So, in group housing, we absolutely have to take care
to avoid that, and any of the resources can become important:
food, water, as well as enrichment.
And I will tell you, from a study that we're -- a cognitive
study that we're doing right now -- we have our animals pair
housed, and while people are typically careful about
not having inappropriate competition around food,
and even thinking about enrichment,
water can become a very clear resource that can run us into
problems, as well.
So we have observed just very recently that when it's quite
warm in some of the rooms that we're in,
some of our pigs are using their operant waterers to create
a little wallowing area.
These become a point of contention, as well,
not something that we really anticipated
and probably should have.
Next bullet point.
If resources are provided, as they have to be,
we have to make sure that there is enough of them.
Next bullet point.
But it's not enough to just make sure that they've got enough
of the resources, it's important to think about how these
are dispersed throughout the space that they have.
So with the pigs, we know it's important that they have
adequate feeder space.
In a laboratory setting, it's important that you think about
how many feeding stations are provided for the pigs,
and also how closely they are set out next to each other
if you've got multiple feeding stations.
In some animals, or in some pairs, or some groups,
individual feeding may absolutely be necessary because
oftentimes you will have an animal that is going to protect
the most important resource, and consistently do it,
and ensure that other animals don't have access to it.
So we oftentimes will see -- this is very common in sows,
for instance, that are limit-fed,
but you absolutely can see this in pigs in other stages of life.
If there is limit feeding, one of the problems that you
can have happen is one animal literally blocks access
or disrupts other animals consistently as they're trying
to access that resource.
If this happens, one of the things to think about
if it's pair housing is potentially splitting up that
pair and then allowing them to have fence line or pen line
access to each other, again to provide social support,
because unless you really want to go into re-homing with
another animal, which is going to result in aggression until
that hierarchy is established again,
there are a number of different ways and different reasons
to not necessarily do that.
But individual feeding may absolutely be necessary.
So temporary removal for feeding may have to be done.
In other instances, what may have to happen is that
the animals are fed in the same area,
depending on the size of the enclosure,
and just monitored while they are eating so that
the one animal does not commandeer feed away
from the other.
If it's a group housing scenario,
the problem animal really is the one that ought to be removed
from the group.
Next bullet point.
In regards to interaction with enrichment in the -- in a group
housing scenario, one of the things to think about is what
type of enrichment you're giving.
In the picture that I've given you here,
where we've got -- Panepinto micro pigs
are interacting with balls.
We definitely want to think about not giving the sort
of enrichment that can be commandeered.
And so this where having multiple forms of enrichment --
so not just a single toy, but multiple toys -- as well
as other features of the environment that they can
interact with becomes important to really provide
good social support.
Whenever possible, providing for pigs enrichment that allows
cooperative use should really be encouraged.
So, for instance, in our -- both farm settings and laboratory
research settings, we will oftentimes hang toys so that
they actually don't get dirty, and if I'm giving them a chew
toy that is suspended by a hook, I will absolutely give them two
so that if they're tugging on it they can tug against each other,
and we will alternate out which -- or rotate out which types
of toys they're given.
That way if there is competition,
it's a useful dispersal of resources in regards
to the energy they're expending against each other.
It also becomes a nice way for the animal to redirect
frustrated oral behaviors, which we oftentimes will see in pigs,
especially if they're limit-fed and are anticipating feeding
around normal feeding time.
Next slide, Kristina.
In regards to managing aggressive behavior in these
animals, I'm just going to give you an older slide.
This is actually a slide done by my PhD advisor,
and one of the things they looked at is the effect
of providing a simple hide area for pigs to tuck their heads
into when they're engaging in aggressive interactions.
If you look at the picture, what you will see is a nice little
spotted pig off to the side is doing what's referred
to as a flank attack towards the pig that he's engaged in.
One of the things we know is when these interactions go on,
simply allowing pigs to stick their heads and parts of their
shoulders into a protected area so that they can turn off that
direct eye contact and protect the parts of the body that their
conspecifics will tend to go after will reduce aggression.
It will certainly reduce the duration of attack in those
animals that can occur, especially
after they're regrouped.
Now, this may not be practical to do in a small cage setting,
but I illustrate it just to show you that there are oftentimes
very simple forms of intervention that can actually
help to manage these sorts of behaviors.
Next slide, Kristina.
Other considerations, if you're looking at conspecific housing:
what's the group size, is there an optimal group size,
and how do you figure that as a function of this allocated
space, the design of the pen, and the purpose of the research?
So these things must be considered.
Another factor that we know is important is the social
compatibility of the animals that are housed together.
We know that pigs form preferential social associations
with each other, and thus, once you keep that in mind,
housing them in social groups in which they're incompatible can
actually do more harm than if they're housed individually,
but, for instance, in a room where they can actually see
and hear each other.
Therefore it's important, if possible,
to purchase pigs in groups so that they're maintaining that
familiarity, because we already talked about familiarity being
a potential factor in the effectiveness of their ability
to buffer stress in each other, and also maintaining groups that
are socially compatible.
Next slide.
Experience of the pigs and their temperament is absolutely going
to be a key factor, as well.
So we know that the efficacy of social support is impacted
by the experience that the companion animal who, let's say,
is not necessarily the subject of the research,
but is providing that social support.
That animal's previous experience and also their
temperament can influence the youthfulness as a form of social
support for the subject animal.
Next bullet point.
The emotional state of that companion absolutely has been
demonstrated to be able to either provide or undermine
the quality of social support provided.
Next bullet point.
And in several studies we've had,
and I'll give you a couple more of these after this point,
what we've seen is that if you have a structure that
is present, the companion animal that is non-fearful,
in part because it has not experienced that stressor,
is actually able to provide an effect that shows reduced fear
responses in the test subject more so than if that companion
is fearful, especially because it's experienced
that same stressor.
Next slide.
Okay, first bullet point.
In a study that was done in 2004,
animals that were conspecifics or companions that were not
shocked -- this was a stressor that was being tested -- were
more effective buffers than companion animals that also
received shock at reducing stress-induced hyperthermia
and behavioral indicators of fear, and also brain changes
-- Fos expression in the PVN -- in response to actually
experiencing electric shock.
Next bullet point.
We also know that stressed familiar partners in pigs can
buffer each other's responses, but if the animal that
is providing that social support is unfamiliar,
they do a poorer job of providing adequate support,
and in some instances may actually exacerbate the stress
experienced by the subject animal.
Next bullet point.
And then an important point to keep in mind is that
we absolutely do have strains of pigs that
are stress-susceptible, and we certainly have breeds,
including some lines of minipigs,
that have a higher tendency to be very quickly and highly
aroused or reactive and have a lower threshold for aggressive
behavior to occur.
So one of the things to think about is the experience
of the companion, the temperament of the individuals,
and the breed of the animals should be
considerations for compatibility.
Next slide.
When we are looking at specific animals in terms of social
housing, boars are sometimes used for research purposes.
Their management has to be considered separately
and different from animals at other stages.
Because we know that in the wild boars tend to be solitary,
it is theoretically possible that they may tolerate
individual housing or solitary housing better than other pigs.
Competition for resources in boars,
especially as a function of their age,
is likely to result in serious fights and more serious, though,
as the animals progress through age if they're group housed.
And one of the things that we know -- and I can attest to this
personally, having worked with micro pigs and minipigs,
as well as farm pigs -- is that this can occur even when those
animals have been housed harmoniously
when they're younger.
So this is a factor both of age, practice at fighting behavior,
and hormonal support for the behavior
as these animals mature.
So, absolutely, again, the breed of the pig and the genetic line
have to be considered, in boar management in particular.
Next bullet point.
Because some lines of minipigs really do tend to show low
threshold for aggression and some of them are tusked,
if their tusks are not being clipped or trimmed,
if the tusks are present, the risk that these animals get into
fights is absolutely compounded, and so one of the things we must
think about is how to protect them.
So there are instances where the physical risk to the animals,
particularly in this regard, may lead one to housing them
individually, and one of the things we'll talk about is how
to support those animals in those circumstances.
Next slide.
Some of the other risks, in addition to aggression,
that we have to think about, and again this ties very nicely back
to the dog talk that preceded mine,
is that particularly in some breeds of pigs, in the minipigs,
sexually mature boars will mount each other.
And they don't do this just as a function of *** behavior;
hierarchical rank does come into play here.
But what we know is that monitoring of these animals
is really important because it's the low-ranking pigs that tend
to be repeatedly mounted.
This can, of course, lead into a chronic stress scenario,
and depending on what else is happening,
the animals can get injured as a result of this behavior,
and so the intervention that's appropriate here is actually
to remove the lowest ranking animals
if the behavior is persistent.
Now, if singly housed, boars -- but this applies to all pigs --
really should be kept in visual, olfactory,
and potentially protected tactile contact with companions.
Next slide.
When isolation's necessary, caretaker interactions
absolutely become much more important.
The quality and the quantity of the interactions the animals
are having with people matter.
One of the things that we know is that pigs are able
to recognize, distinguish between, and respond to familiar
caretakers accordingly, and so what we don't want to have
happen is have some caretakers handling the animals
roughly or inconsistently.
Positive social contact and behavior,
such as talking to the animals, stroking them, petting them,
and so on, and providing low-stress handling when
handling is necessary is critical here.
What's just as important, if not more so,
is avoiding aversive handling, and what's even worse than that
is inconsistent handling.
When the animals have no ability to predict how they're going
to be handled, we know that a chronic stress response tends
to get activated because the animals simply cannot adapt
to what is happening to them, and they can't predict it.
Next slide.
Now, adding caretaker interaction -- and what
we do in our labs oftentimes involves training pigs
to facilitate our procedures -- can definitely add to management
time, but a lot of benefits come out of this
sort of intervention.
Depending on what you do -- as in, for instance,
we do in our lab -- the pigs actually help
us to collect their data.
In previous studies that we've done,
we've actually been able to train pigs to present for blood
draws, or at least to hold still for blood draws so that we don't
have to snare them to do that.
Depending on what you're measuring,
we absolutely do not want handling stress to compound
anything else that we're looking at,
and so that becomes a very helpful tool.
The rigor, therefore, and the quality of the data,
it can be supported through positive
human-animal interactions.
One of the other factors that oftentimes isn't taken into
consideration is this can impact caretaker affect and attitude
about interacting with those animals.
That actually feeds back to the animals themselves.
So we get this nice feedback loop where caretakers who
are having positive interactions with the animals enjoy what
they're doing more, interact with the animals more
appropriately, and, as a result, the animals give us more
desirable behaviors than undesirable behaviors
as a result.
So, overall, doing this kind of thing can prove to be practical
as well as cost-effective.
Next slide.
Okay, so last thing I'll talk to you about
is conspecific housing alternatives.
Are there viable options to conspecific housing?
We certainly could think about housing with other species that
are appropriate companions.
Certainly wouldn't want to put a predator species in with a farm
animal or a food animal species like a pig.
This is really uncommon, though, although it has been seen
in some of the medical research facilities I've worked in,
where pigs are being used as research subjects
and they are isolated.
Oftentimes across the hallways there may be other farm animal
species -- sheep are pretty common -- who are also being
singly housed for the research purposes.
The benefit of that sort of interspecific social support
is really not well studied.
So I'm not going to spend any time on that.
Passive or inanimate forms of enrichment obviously
can be options.
Many people have looked at these -- TVs, video recordings,
and the use of mirrors.
I've got a picture here showing a pig interacting with
a mirrored surface.
We'll look at whether or not this is useful.
Next slide.
Mirrors clearly are oftentimes used for enrichment purposes.
We know that they'll allow primates, for instance,
to view their reflections or better see activities that
are taking place outside their pens.
There's some evidence that they can now attenuate stress
responses in isolated sheep, but may only be partially effective
as a substitute for another animal,
because in isolation there are a number of factors that are going
to contribute to this stress.
So the thought process is they may primarily provide visual
support for the animals, or visual stimuli.
Next slide.
The question is do mirrors provide social -- or useful
social support for pigs?
Next bullet point.
The data here doesn't give us clear answers,
because there are actually very few studies on this topic.
Next point.
Clearly the mirror has no ability to provide auditory --
maybe minimally tactile support.
So it may be useful as a form of enrichment in other ways.
Next bullet point.
Pigs have been shown to use mirrors to obtain information
about the environment or to locate, for instance,
hidden food, as in Don Broom's study of 2009.
Studies done by Ray Stricklin, for instance -- so in the early
2000s -- showed similar patterns or similar trends.
Next bullet point.
Now, one thing to -- that we have to think about is how
cognitive ability comes into play here.
If pigs are able to recognize themselves,
the mirror as a form of social support now diminishes in terms
of its usefulness.
Next bullet point.
However, there is limited evidence that pigs do recognize
themselves when they look at mirrors,
so it may be that they are actually somewhat useful
in that regard.
Next bullet point.
Or, sorry, next slide.
In a study that was done here at Purdue that was published last
year, one of our very talented graduate students,
who I'm fortunate to work with, looked at enrichment preferences
for several different substrates.
Her enrichments were a companion animal,
which you see in the darkest bars,
having access to a rubber mat, having access to a pen with
a mirrored surface, and a control area which was simply
another open pen.
And she used 14 animals that had continuous access
to these resources.
Next slide.
And what she found is that if you looked at the social
enrichments -- so here we're really focusing on the provision
of a companion or that mirrored surface as a potential form
of social enrichments.
If you looked at the probability of choosing social enrichment
when there was a human in the room,
what we see is the likelihood goes up that they're going
to choose one of these enrichments when a human
is present, period.
Next slide.
What we also see is that when you look at the probability
of choosing a mirror over a conspecific,
the probability goes up that they'll choose the mirror at all
when a human -- or they're more likely to do this when a human
is present in the room than when a human is absent in the room.
And, Kristina, I'm going to ask you to go backwards just
a little bit, two slides over to the first
enrichment preference slide.
>> Kristina Adams: Okay.
>> Candace Croney: And if you look at all of the four
enrichments, you'll see that, overall, the pigs,
when given a choice, prefer the companion -- or access
to a companion over any of the other form of enrichments.
Mirror choice here is very low relative to having access
to a companion or having access to a pen where there's a rubber
mat that they can lie on for comfort.
Okay.
Kristina, we'll go back -- we'll go forward, sorry,
to the slide that we ended on, which is the difference between
the mirror and a conspecific when a human is present.
>> Kristina Adams: Okay.
>> Candace Croney: And so you'll clearly see that use
of the mirror, even though it's much less than choice
of a conspecific, goes up in regards to the presence
of a human.
One of the things that that tells us is that when they
perceive some sort of threat, pigs actually are going
to the mirror potentially as a form of social support,
but really we're not entirely sure what's happening here.
Next slide.
I would like to acknowledge my colleague and graduate student,
Shelly DeBoer, for providing her research and her original data
for the presence of this talk, and very quickly, to wrap up,
I'm going to just point out what some
of the take-home messages are.
Social housing is clearly an important component of pig
welfare in laboratory settings.
It is absolutely supported by the ethology of the pig,
the cognitive studies that exist,
and the physiological data we have when these animals
are socially isolated.
For optimal results, we want to consider the compatibility
of animals, their -- and as compatibility factors go,
we want to take into consideration the previous
experience of companion animals, the familiarity of those
animals, the temperament, age, and breed of the individuals
that we're working with.
Proper management in social housing has to consider
appropriate space, appropriate pen design,
and resource allegation -- allocation.
And finally, further study of the usefulness of inanimate
forms of social support, such as mirrors, absolutely is needed.
So, with that, I will take questions.
>> Kristina Adams: All right.
Thank you, Candace.
[applause]