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Philippe

Genetic parameters and environmental effects which characterise the
defence ability of the Belgian shepherd dog

Jean-François Courreau and Bertrand Langlois

Applied Animal Behaviour Science
Article in Press, Corrected Proof - doi:10.1016/j.applanim.2004.09.003

The aim of the present study was to evaluate the heritability of
defence capacity traits in the Belgian shepherd dog and to calculate
the genetic correlations between traits and the role of particular
environmental factors. The study used 15,772 competition results from
defence dogs involving 2427 Belgian shepherd dogs in France from 1986
to 1996. A competition included 6–19 different tests and according to
their difficulty five levels. The tests were grouped together in
order to class the dogs in eight general ability measures: Jumping,
Following at heel, Fetching an object, Attacking, Guarding,
Obedience, Biting and Global success. The analysis was performed on
the calculated scores after the dogs had been ranked within a
competition. The scores were corrected according to the average level
of the dogs participating in the competition. This method is used in
horses, the "performance rate". This was used to produce scores,
which had a normal distribution. The genetic parameters were
estimated using a mixed animal model using the Restricted Maximum
Likelihood method (REML). The fixed effects of the model were
estimated by the Best Linear Unbiased Estimation (BLUE) and their
significance by an F-test. The heritability estimates are low for
Following at heel (h2 = 0.07) and Global success (h2 = 0.07) but
moderate for the other criteria ( h2 = 0.13–0.18 ). The repeatability
of results was relatively high (r = 0.39–0.59). The phenotypic
correlations between abilities were low to moderate, however, the
genetic correlations were moderate to high, except for Jumping which
appears to be independent from the other abilities. The males
performed better than the females. The Malinois was the best variety
of dog. The effect of age was studied within each level of
competition difficulty. The best results were obtained as early as
1.5 years-of-age for level 1 and between 3 and 7 years-of-age for
levels 4 and 5.