[Philippe]

Bonsoir à tous,

L'article suivant, publié sur un autre forum, devrait intéressé Perrotdog et d'autres... Seul inconvénient, il est en anglais!

Direct genetic, maternal and litter effects on behaviour in German
shepherd dogs in Sweden

Erling Strandberga, Jenny Jacobssona and Peter Saetre

Livestock Production Science
Article in Press, Corrected Proof doi:10.1016/j.livprodsci.2004.11.004

The aim of this study was to study genetic (co)variation of broader
behavioural traits in German shepherd dogs and to test whether there
is maternal and litter influence on these traits. Data were extracted
from the Swedish Dog Mentality Assessment (DMA) from 1989 to 2001 on
5959 German shepherd dogs. Based on previous results, personality
traits were created from the 15 behavioural variables extracted from
the test. These personality traits were (1) Playfulness, (2) Chase-
proneness, (3) Curiosity/Fearlessness, and (4) Aggressiveness. A
trait Boldness was constructed from all behaviour variables except
those included in Aggressiveness. Mixed linear models with fixed
effects of sex, test type, test year, test month, age, and judge were
used. Models with all combinations of random effects of animal
(direct genetic), genetic and non-genetic maternal, and litter were
tested. The best model included effects of animal and litter. Direct
heritability estimates were between 0.09 and 0.23, highest for
Playfulness and Curiosity/Fearlessness. Maternal heritabilities were
all low ( 0.01–0.08 ), lowest and not significant if litter or non-
genetic maternal effects were included in the model. Additive genetic
correlations among Playfulness, Chase-proneness, and
Curiosity/Fearlessness were higher (0.54–0.74) than genetic
correlations with Aggressiveness (0.29–0.40). Litter variance ratios
(c2) were larger than the maternal heritabilities (0.03–0.10).
Boldness had a direct heritability estimate of 0.27 and a direct
genetic correlation with Aggressiveness of 0.37. We conclude that
there is substantial additive genetic variation, that the mother has
rather little influence (both genetically and environmentally) and
that the litter seems to have a larger influence than the mother for
these personality traits. Genetic improvement in these behaviour
traits is thus possible.