How Studying Interactions Between Animal Emotions, Cognition, and Personality Can Contribute to Improve Farm - Genetics and the Behavior of Domestic Animals - page 84

and reduce productivity and product quality in cattle, sheep, pigs, and poultry
( Bouissou et al., 2001; Faure and Jones, 2004; Fisher and Matthews, 2001;
Hemsworth and Coleman, 1998 ).
Diversity of Fear-Eliciting Events
According to Gray (1987) , the fear-eliciting properties of an event reflect
its general characteristics, for example novelty, movement, intensity, dura-
tion, suddenness, or proximity. Fear may also be elicited by specific stimuli,
such as height and darkness or bright light, in relation to the evolutionary
history of the species (ancestral fears). Additionally, a stimulus can elicit
fear through association with previous experience of another fear-eliciting
event (conditioned fear).
In modern farming systems, animals may be exposed to a large variety of
potentially stressful events from hatching or weaning through to puberty and
adulthood. These include social mixing, transport, transfer from a rearing or
nursing environment to a growing one, dietary change, new social partners,
exposure to different stockpersons, harvesting, etc. Gregariousness is com-
mon to most domestic animals ( Keeling and Gonyou, 2001 ) and the variety
of social stimuli that accompany social cohesion and structure may elicit or
modulate fear reactions. Social signals may represent particular cases of the
types of fear-eliciting stimulation mentioned above. Some social signals
are characterized by their unfamiliarity, for example the novelty of the
neonate that affects maternal behavior in primiparous females ( Poindron et al.,
1984 ), alarm calls can spontaneously elicit fear ( Boissy et al.,1998 ) and cer-
tain social odors can reduce fear and distress in the recipients ( Madec, 2008 ).
Some fear-eliciting social signals, for example threatening behaviors, may also
be acquired ( Bouissou et al.,2001 ). Under farming conditions, animals are fre-
quently exposed to changes in their social environment. For instance, sanitary
processes often require isolation, and sorting animals into new groups gener-
ally entails breaking relationships with familiar conspecifics as well as encoun-
tering unfamiliar ones. Encountering unfamiliar animals or simple isolation are
causes of marked stress reactions in the majority of domestic species that are
known to be gregarious ( Boissy et al.,2001 ). Additionally, social isolation is
one of the most stressful components of many fear tests when members of a
social species are tested individually. Most domestic species are strongly moti-
vated to rejoin conspecifics when isolated, and may consequently suffer more
from separation anxiety than from the presumed fear-eliciting event itself.
Diversity in Fear-Related Responses
Fear-related behaviors vary greatly depending on the nature of the threat.
They can sometimes seem contradictory, as both active and passive strategies
may be observed in a challenging situation: these strategies include active
defense (attack, threat), active avoidance (flight, hiding, escape) or passive