Improving the Adaptability of Animals by Selection - Genetics and the Behavior of Domestic Animals - page 300

4 4

Activity Activity

(a) (b)

LT I

HSR C

2 2

HSR

LT I

C

0 0

Peeps
and
jumps

Peeps
and
jumps

LSR

LSR

-2 -2

STI

STI

_Period 1

-4 -4

_Period 2

-6 -6

-6 -4 -2 0 2 4 -6 -4 -2 0 2 4

4

(c) Activity

LSR

2

HSR

C

Peeps
and
jumps

0

LT I

-2

STI

_Period 3

-4

-6

-6 -4 -2 0 2 4

FIGURE 8.12 Discriminant analysis of the open-field behavior of lines of Japanse quail
selected for long or short duration of tonic immobility and for high or low levels of social
reinstatement behavior over 12 generations.

states of the lines were different. These differences in motivation can be
explained by the fact that the behavior of the long TI and short TI lines are
primarily motivated by differing levels of fear, but the differences between
the two lines wane after habituation to a novel environment. This illustrates
why it was important to conduct the open-field test with three different time
periods. Fear behavior, which is observed after a short period in the open-
field test, disappears after the birds habituate. Conducting the tests in three
time periods also provides information on the time requires for habituation
in the different lines.
The differences between chicks of the high SR and low SR lines is
primarily due to differences in social reinstatement tendencies which do not
attenuate or change during the 30-minute test period. As suggested by other
authors ( Faure et al., 1983; Gallup and Suarez, 1980 ), these results demon-
strate that open-field behavior is the expression of two different motivations:
fear which leads to inhibition of activity, and social reinstatement which
induces high levels of activity related to the search for social companions
(see also Mills et al., 1993 ). This also demonstrates that short open-field
tests may not allow differentiation between fear and social reinstatement
tendencies.