[Genetic analysis of markers of the performance test for herding dogs. 1. Performance traits].
The objective of the present study was to analyse data based on records of sheep dog trials in order to evaluate the importance of genetic and environmental sources of variation and to draw conclusions for breeding purposes. The data analysed consisted of 2745 test results recorded at 48 sheep dog trials carried out in Germany from 1994 to 1998, on which a total of 337 sheep dogs had attended. Tested dogs descended from 147 sires and 201 dams, with a mean inbreeding coefficient of about 2.8%. Variance components of working traits were estimated applying Restricted Maximum Likelihood methods. Additive genetic effects, permanent environmental effects of the animal and the effect of the handler were treated as random factors using multivariate linear models. Additionally, the model included the fixed effects of the age of the dogs at the sheep dog trial, sex, the level of difficulty of the exercises as well as the event itself, the starting number of the dog, the number of the dogs' tests at the particular event and the number of dogs presented on sheep dog trials by their handlers. The inbreeding coefficient was regarded as a linear covariate. Sex of the dog and starting number did not explain a significant proportion of variance for traits analysed, whereas the event of the sheep dog trial and the starting class usually were of significant importance. The analyses were performed using all sheep dog trial classes and for each of the three classes separately. Repeatabilities of herding traits within the same event of sheep dog trial estimated from animal effect mostly varied within a range from w = 0.1 to w = 0.5 whereas repeatabilities estimated over all events of sheep dog trials mostly gave estimates from w = 0.1 to w = 0.3. The estimated heritabilities for the herding performance traits ranged from h2 < or = 0.001 to h2 = 0.13 with standard errors in the range between 0.001 and 0.08. The selection possibilities appear to be rather limited given the heritability estimates and the low number of progeny of parents.
Hoffmann
Uta
U
Institut für Tierzucht und Vererbungsforschung, Tierärztliche Hochschule Hannover.
Hamann
Henning
H
Distl
Ottmar
O
D000822:Animal Husbandry / Q000379:methods; D000818:Animals; D001947:Breeding; D004285:Dogs / Q000235:genetics* / Q000502:physiology; D005260:Female; D014644:Genetic Variation; D005858:Germany; D016013:Likelihood Functions; D016014:Linear Models; D008297:Male; D008957:Models, Genetic; D012641:Selection, Genetic