Improving the Adaptability of Animals by Selection - Genetics and the Behavior of Domestic Animals - page 304

interindividual distances between fixed or same line pairs. Given that genetic
line differences in treadmill behavior persist into adulthood, this last finding
may appear surprising. However, age-related variations in interindividual
distances occurred only in the high SR lines. Low SR line birds appeared
to space themselves at random. This implies that social factors influenced
spacing in high SR line birds but not in low SR line birds.
In the high and low social reinstatement lines an age-related variation in
behavior was found using the time budget test. In this test, quail of the high
SR and low SR lines were given a long-term choice between being in social
contact with conspecifics (flockmates) without access to food and water, and
having access to food and water in the absence of conspecifics. At 1 week
of age, chicks of both lines spent most of their time (about 80%) in proxim-
ity to conspecifics; the time spent close to flockmates decreased with age in
both lines ( Figure 8.17 ). However, this effect was more pronounced in the
low SR line than in the high SR line. At 4 and 6 weeks of age high SR line
chicks spent more time in close proximity to conspecifics than did low SR
line chicks.
Under the three experimental conditions employed, the results show that
the social motivation of the high SR animals varied with age and test condi-
tions. In the treadmill test, line differences were stable from hatching until
10 weeks of age. Line differences were also present in the young animals
but they disappeared by 6 weeks of age. However, in the time budget rest,
line differences were absent in the young birds but appeared at 4 and
6 weeks of age. The results of the time budget experiment can probably be
explained by the fact that the birds being tested were familiar with each
other and the test environment. This was not the case in the treadmill and
open-field tests.

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25

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W 1 W 2 W 4 W 6

FIGURE 8.17 Time spent in social contact by 1-, 2-, 4- or 6-week-old quail from lines selected

for high or low level of social reinstatement behavior over 18 generations. ( ' ) HSR, ( & ) LSR.