Social behavior/2
ANS 305
My lecture
 Will discuss two experiments looking at the
consequences of social environment on
indicators of animal welfare
Individual recognition
 Social stability
 Parent and offspring interactions
 Avoid inbreeding
 Mate choice
 Major histocompatibility complex (MHC)
– Maximizing diversity in immunological
responsiveness
Challenges
 The majority of pregnant sows are kept in
gestating crates
– High levels of unresolved aggressive
interactions (Broom, Mendl & Zanella, 1996)
 The concentration of environmental
contaminants (e.g. ammonia) may interfere
with olfactory memory (Mendl personal
communication)
Challenges..
 Maternal deprivation stress, at an early age,
may alter social memory in pigs (Yuan et al.
1999)
Social organization
 Stallions related to a group of mares in a
very stable way (harem). Non-breeding
males may form bachelor groups.
• Testosterone levels are, oftentimes, below the level
of detection in stallions living in a “bachelor” group.
Acceptance into a group of mares is related to an
instantaneous rise in testosterone and changes in
behavior (McDonnell, 1997).
 Stallions are not territorial.
Challenges
 In some commercial farms horses are
housed in individual stalls, with restrict
social contact
Social Organization
 Female grouping is observed in sheep, goats &
cattle. During non-breeding season males may
form “bachelor” groups. Social grooming is an
important feature of cattle social behavior
 Hens and cocks have separate “peck orders”. They
are territorial. Social unit: dominant cock, 4 to 6
hens, pullets and several subordinate males
Social organization
 Social strategies
1
1
2
2
3
4
5
4
3
5
6
Social organization
 Social strategies
1
1
2
HS
3
4
5
2 3
4 5
6
7
6
7 to 31
NS
32 33 34 35 36 37
LS
Social organization
 Sows were divided
into three groups:
– HS= High success in
agonistic interactions
– LS= Low success in
agonistic interactions
– NS= Now success in
agonistic interactions
1
2
HS
3
4
5
6
7 to 31
NS
32 33 34 35 36 37
LS
Consequences
 Stress hormone concentration
– *Higher in the LS sows than HS and NS
 Productivity
– *Lowest litter weight in LS sows
 Brain size
– **Smallest is NS sows
*Mendl, Zanella & Broom, 1992
**Zanella et al., 1996
Hippocampal
function /
memory
consolidation
Glucocorticoid level
Agonistic interactions
3 days post-mixing (Yuan et al., 1999)
SEW and CW (n=452)
34%
SEW and SEW (n=186)
46%
CW and CW (n=176)
32%
66%
54%
68%
Clear outcomes
Unclear outcomes
24 weaned between 9-12 days of age= SEW
23 weaned between 20-23 days of age= CW
Spatial memory in young pigs
 Piglets (14-20 days of age)
were trained to swim in a
heated (37oC) pool.
 We measured mean
latency (seconds) taken by
individual pigs to reach a
submersed platform.
 Piglets were tested for 12
sessions (6 days)
consisting of 5 trials per
session (10 minutes of
•Noyes and Zanella (in prep.)
interval between trials).
Spatial memory in young pigs
Mean latency (seconds) to reach the
submersed platform
Morris- watermaze
60
Piglet 1
50
Piglet 2
40
Piglet 3
30
Piglet 4
20
Piglet 5
10
0
Trial 1
Trial 2
Trial 3
Trial 4
Latency
5
Social recognition
 Piglets were subjected to
four sessions (60 seconds)
repeated at 10 min of
interval.
 We measured the % of the
time that the resident
female pig (n=12) spent
investigating or interacting
with the intruder.
•Silveira de Souza and Zanella (in prep.)
Social recognition
 Ten minutes following the
fourth exposure a naïve
unfamiliar pig was
exposed to the resident
animal.
 We measured the % of the
time that the resident
female pig (n=12) spent
investigating or interacting
with the unfamiliar
intruder.
Social recognition
•(P<0.01; axb)