Improving the Adaptability of Animals by Selection - Genetics and the Behavior of Domestic Animals - page 291

40 cm 50 cm 100 cm 50 cm

Goal box containing
stimulus group

Running zone Neutral zone Far zone

Direction of carpet movement

FIGURE 8.1 Schematic plan of the treadmill apparatus used to measure social reinstatement
behavior in Japanese quail chicks.

5 minutes). Social reinstatement behavior was measured using the treadmill
test ( Mills and Faure, 1990 ). The apparatus has two compartments, one con-
taining flockmates and the other a treadmill on which the test animal is
placed ( Figure 8.1 ). If the test animal moves toward the other birds, the
treadmill moves in the opposite direction. Movement of the treadmill serves
as a measurement of the effort made by the test animal to reinstate social
contact. If the test animal moves away from the other birds, the time spent in
the “far end” of the apparatus is also measured. Tests were performed when
chicks were between 6 and 8 days of age and lasted 5 minutes.
High and low levels of fear were determined using the tonic immobility
reaction ( Jones, 1987 ). In this test, the chick is placed on its back in a U-shaped
cradle covered with several layers of white cloth and is restrained by the experi-
menter for 10 seconds. If the chick remains immobile for 10 seconds after the
removal of restraint, tonic immobility is considered to have been induced.
Animals that remain immobile for “long periods” are considered to be fearful
( Jones and Mills, 1982 ; Mills and Faure, 1986 ). If the chick rights itself within
10 seconds, it is considered that TI (tonic immobility) has not been induced
and a further attempt at induction is made. If five attempts at induction are
unsuccessful, the duration of TI is considered to be 0 and the number of
attempts at induction is recorded as five. The TI test is performed when the
chicks are 9 10 days of age. For the purpose of selection, the maximum

duration of TI was set at 5 minutes.
Selection over 20 generations resulted in lines showing either high or low
levels of social reinstatement (SR) behavior and long or short duration of TI.
Appropriate control lines (CSR and CTI) were also maintained ( Mills and
Faure, 1991 ). At each generation, 20 males and 40 females were kept in
cages containing one male and two females. These animals were the breed-
ing population of each line. Approximately 200 quail chicks were hatched at