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Analyse de données de ségrégations italiennes pour la livrée des bovins
Published online by Cambridge University Press: 01 August 2011
Résumé
Des ségrégations de la livrée ont été analysées sur des données de F1 et de back-cross sur les pères de races à viande phæomélaniques (Charolaise et Limousine) et phæomélaniques à extrémités eumélaniques dites PEE (Piémontaise, Chianine, Marchienne et Romagnole) accouplés à des femelles eumélaniques noir (Holstein Frisonne Italienne).
Les ségrégations sont interprétées en termes d'allèles au locus Extension E avec les quatre allèles ED,Er ,E et El, au locus Dilution Charolais DC avec les allèles DCD et DC+, au locus Albinos C avec les allèles C+ et Cch et au locus Spotting S avec les allèles S+ et Ss
Parfois il faut faire appel à des pénétrance incomplètes.
Summary
Phenotypic segregation of coat colour of cattle has been analyzed in F1 and paternal back-crosses between French and Italian Limousin, Charolais, Piemontese, Chianina, Marchigiana and Romagnola meat breeds on one hand and Italian Holstein Frisian milk breed on the other hand. The biallelism at the Extension locus, EDEr can explain the results of pheomelanic x eumelanic black crossing being Charolais and Limousin males ErEr and the Italian Holstein Friesian females EDED. Both parental phenotypes and one intermediate have been observed in F1 and back-crosses; the incomplete penetrance explains the segregation. The triallelism at the Extension locus, ED, E and E1 can explain the pheomelanic with eumelanic extremities x eumelanic black crossbreeding. Both parental phenotypes and several intermediates already described (inverted mule stripe, badger face and black and tan) or not described on cattle have been observed on F1 and back-cross.
The incomplete penetrance can explain the phenotypic variability of segregation. The biallelism at the Dilution Charolais locus, DC: DCD and DC+ explains the results of Charolais (white) x Italian Holstein Friesian (normal) cross for Charolais dilution. Incomplete penetrance and intermediate expressivity can explain the segregation, among the F1, of both normal and diluted no white phenotypes. The allelism at the Albino locus, C: C+ and Cch explains the results of Piemontese, Chianina, Marchigiana and Romagnola (chinchilla alteration) x Italian Holstein Friesian (normal) cross for the chinchilla alteration, readable on pheomelanoc basis. Incomplete penetrance can explain the segregation, among the F1 and the back-cross, of both normal and chinchilla phenotypes.
The allelism at the Spotting locus, S: S+ and Ss explains the results of the meat breeds (normal) x Italian Holstein Friesian (irregular spotting) cross for the irregular spotting. Incomplete penetrance can explain the segregation, among the F1 and the back-cross, of both normal and spotted phenotypes.
- Type
- Research Articles
- Information
- Animal Genetic Resources/Resources génétiques animales/Recursos genéticos animales , Volume 35 , April 2004 , pp. 9 - 19
- Copyright
- Copyright © Food and Agriculture Organization of the United Nations 2004