Genetics and Behavior During Handling, Restraint, and Herding - Genetics and the Behavior of Domestic Animals - page 123

In a similar study using crossbred sheep which were not selected for high or
low activity, Wolf et al. (2008) report the existence of considerable genetic
variation in behavior. In addition, behavioral measures of locomotion/vocali-
zation and proximity to the human are genetically and environmentally
uncorrelated and represent independent measures of emotional state. The
authors hypothesize that locomotion/vocalization in an open field is probably
due to separation distress (PANIC).
Approach a Novel Objective or Novel Person Test
The tendency to approach or avoid a novel object or a person may be moti-
vated by the emotion systems FEAR, SEEK, or PANIC. Previous experience
and genetics strongly influence an animal's response to this type of test. In a
typical novel object test, an object the animal has never encountered is
placed in an arena and the time it takes to approach and/or touch the object
is measured. Kilgour et al. (2006) conclude that in order to assess individual
differences in beef cattle to conditions of social isolation, human proximity,
novelty, and restraint, the tests that best do this are the restraint test, the
open-field test, the following test, flight time, the fear of humans test and
flight distance.
Pen Testing
Pen testing measures FEAR, PANIC (separation distress) and Aggression. In
this test, cattle are placed in a small pen such as an auction arena and
actively approached by a person. In France, this test is used by Limousin
breeders to cull animals with a bad temperament. Cattle that charge people
are not kept for breeding. Variations of the test are also used to determine
size of the animal's flight zone.
Other Behavioral Indicators Which May Indicate Genetic
Differences in Fear
Eye White
The percentage of eye white showing in cattle is highly correlated with exit
speed score ( Core et al., 2009 ). Eye white percentage likely measures fear
because anxiety-reducing drugs, such as diapazen, decrease the percentage of
eye white that shows ( Sandem et al., 2006 ).
Physiological Measures
Animals highly agitated during restraint or with high exit speeds often have
higher levels of the stress hormone cortisol in blood, and/or increased heart
rate ( Curley et al., 2004; King et al., 2006 ). Genetic factors influence physio-
logical measures of handling stress. Zavy et al. (1992) found breed differ-
ences in cortisol (stress hormone) levels between Bos taurus and Bos indicus