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 3 4 5 5 6

Social organization Social strategies 1 2 HS 3 1 4 5 6 LS 7 to 31 NS 2 3 4 5 6 7 LS 7 to 31 NS 32 33 34 35 36 37

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

Consequences Stress hormone concentration Productivity Brain size *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) 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 interval between trials). Noyes and Zanella (in prep.)

Spatial memory in young pigs

Silveira de Souza and Zanella (in prep.) 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)