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Molecular characterization of two common Chadian cattle breeds

  • C. Flury (a1), B.N.R. Ngandolo (a2), B. Müller (a3), J. Zinsstag (a3) and H.N. Kadarmideen (a4)...

Summary

In previous studies, significant differences in Mycobacterium bovis infection prevalence was reported between two Chadian cattle breeds. Those findings and the established differentiation due to phenotypic characteristics suggest that the two breeds (Arab and Mbororo) are genetically different. To evaluate the genetic structure and the differences between these breeds, the genetic diversity within and between breeds was evaluated based on a total of 205 multilocus genotypes (21 microsatellite loci).

All of the loci under investigation were polymorphic and the number of alleles ranged from 4 to14 within the two populations. The analysis of population fixation resulted in a FST value of 0.006. Further the population assignment of the individual genotypes and the exact test of population differentiation did not support the hypothesis that the samples drawn from the two populations are genetically different. Population admixture and sample collection are discussed as possible reasons for the rejection of the hypothesis. Finally, recommendations for sample collection in extensive systems are given.

Dans des études précédentes on avait observé des différences significatives dans les infections par Mycobacterium bovis chez les races bovines de Chadian. Ces observations et la différence due aux caractéristiques phénotipiques suggèrent que les deux races (Arabe et Mbororo) sont génétiquement différentes. Pour évaluer la structure génétique et les différences entre ces races on a évalué la diversité génétique dans et entre races sur un total de 205 génotypes multiloci (21 loci microsatélites). Tous les loci étudiés étaient polymorphiques et le nombre d'allèles allaient de 4 á 14 dans les populations. L'analyse de la fixation de la population a donné un Fst de valeur 0,006. Après l'asségnation des génotypes individuels á la population et le test exact de différence de la population, l'hypothèse des échantillons sortis de deux populations génétiquement différentes n'était pas correcte. Le mélange des populations et la saisie des échantillons sont étudiés comme possible cause du rejet de l'hypothèse. Pour finir, on présente une série de recomandations pour la saisie des échantillons dans des systèmes extensifs.

En estudios anteriores se observaron diferencias significativas en infecciones prevalentemente por Mycobacterium bovis en dos razas bovinas de Chadian. Estos hallazgos y la diferenciación establecida debida a las características fenotípicas sugieren que las dos razas (Arabe y Mbororo) son genéticamente distintas. Para evaluar la estructura genética y las diferencias entre estas razas, se evaluaron la diversidad genética dentro y entre razas en un total de 205 genotipos multiloci (21 loci microsatélites). Todos los loci estudiados eran polimórficos y el número de alelos iba de 4 a 14 dentro de las dos poblaciones. El análisis de fijación de la población resultó en F con valor 0,006. Tras la asignación de genotipos individuales a la población y el test exacto de diferenciación de la población quedó eliminada la hipótesis de que las muestras sacadas de las dos poblaciones eran genéticamente diferentes. La mezcla de poblaciones y la recogida de muestras se discuten como posibles motivos que hicieron rechazar la hipótesis. Por fin, se presentan una serie de recomendaciones para la recogida de muestras en sistemas extensivos.

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References

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Keywords

Molecular characterization of two common Chadian cattle breeds

  • C. Flury (a1), B.N.R. Ngandolo (a2), B. Müller (a3), J. Zinsstag (a3) and H.N. Kadarmideen (a4)...

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