Medeiros Bruno B, Barcelos Kate M C, Andrade Millena Oliveira, Cristina da Paz Carvalho Michele, Miranda Victoria Rocha, de Oliveira Maia Kalebe, Reinhardt Susana, Patterson Rosa Laura
Department of Agriculture and Industry Sul Ross State University, Alpine, TX, USA.
Escola de Veterinária e Zootecnia Universidade Federal de Goias, Campus Samambaia, Goiânia, Brazil.
Vet Med Int. 2024 Aug 23;2024:4714077. doi: 10.1155/2024/4714077. eCollection 2024.
The genetic diversity of Breton horses in Brazil is a critical concern, mainly due to the small population size and low number of births per year. Given that the inbreeding was overlooked by breeders for multiple generations, we estimated the genetic diversity of this population utilizing pedigree-based measures of population diversity. A total of 1394 six-generation pedigrees representing the full population of registered Breton horses in Brazil defined a total population (TP, = 2679), with horses born between 2000 and 2022, reproductively active and alive, as reported by the breed association, representing the reference population (RP, = 731). Using the R package , we estimated inbreeding coefficient ( ), maternal inbreeding coefficient ( ), paternal inbreeding coefficient ( ), individual reproductive values, number of equivalents to complete generations (), and unbiased ancestral inbreeding coefficient (). We established the equivalent complete generations (ECG), effective population size (), total number of founders (), effective number of founders (), total number of ancestors (), effective number of ancestors (), founder genomes (), and the inbreeding coefficient estimated with effective population size () and generation numbers () ( ), as well as / and / ratios for the RP. The RP inbreeding levels have stabilized, although they are still significantly rising by generation (), and the / ratio strongly suggests genetic drift. Pedigree-based analysis demonstrates that only five stallions have sired 52.83% of the RP individuals, which along with the value of 36.73 implies that the observed inbreeding can be arising from patrilines. Our results suggest that observed inbreeding is due to Popular Sire Effect, highlighting the importance of monitoring breeding schemes and genetic diversity to maintain health.
巴西布列塔尼马的遗传多样性是一个关键问题，主要是由于种群规模小且每年出生数量少。鉴于多代育种者都忽视了近亲繁殖问题，我们利用基于系谱的种群多样性指标来估计该种群的遗传多样性。巴西布列塔尼马登记在册的全部种群共有1394个六代系谱，定义了一个总人口数（TP，= 2679），这些马出生于2000年至2022年之间，据品种协会报告，具有繁殖活性且存活，代表参考种群（RP，= 731）。使用R软件包，我们估计了近亲繁殖系数（ ）、母系近亲繁殖系数（ ）、父系近亲繁殖系数（ ）、个体繁殖价值、完成世代的等效个体数（）以及无偏祖先近亲繁殖系数（）。我们确定了等效完整世代（ECG）、有效种群大小（）、奠基者总数（）、有效奠基者数（）、祖先总数（）、有效祖先数（）、奠基者基因组（），以及用有效种群大小（）和世代数（）估计的近亲繁殖系数（ ），还有RP的 / 和 / 比率。RP的近亲繁殖水平已趋于稳定，尽管仍随世代显著上升（），且 / 比率强烈表明存在遗传漂变。基于系谱的分析表明，只有5匹种马繁育了52.83%的RP个体，这与36.73的 值一起意味着观察到的近亲繁殖可能源于父系。我们的结果表明，观察到的近亲繁殖是由于公马效应，凸显了监测育种计划和遗传多样性以维持健康的重要性。
