Abstract Limousine and Charolais cattle breeds are assuming increasing importance in the Italian beef cattle sector. Indeed, both breeds are involved in a national rural development project. The success of a breeding programme depends heavily not only on the defined breeding objective but also on the selected criteria used to attain it. Data from the Charolais and Limousine Italian Association (born between 1960 and 2017) were used to estimate both genetic parameters and trends for calving interval (CI) and age at first calving (AFC) and genetic diversity. Population structures were investigated through probabilities of gene origin approach whereas variance components estimation was used to obtain breeding values of reproductive parameters. Heritabilities for AFC and CI were 0.24 and 0.03 for Limousine and 0.32 and 0.02 for Charolais, respectively. An increasing genetic trend was observed for AFC. For CI, no significant gains of genetic origin have been verified. In both breeds, pedigree completeness was moderate, and the observed inbreeding coefficient was low. No herd is classified as a nucleus or isolated and they all use external bulls. Heritability for AFC in both breeds suggests possible improvements when selected. Limited improvements are expected for CI by means of a traditional genetic breeding scheme. A reduction in the generation interval might represent a cost-effective solution to increase annual genetic gain. Pedigree analysis suggests population bottleneck in both breeds. HIGHLIGHTS Limousine and Charolais breeds are involved in the national project for the genetic improvement of cattle populations raised in Italy. Genetic indexes will be developed following a genomic approach. This study is preparatory for the implementation of a selective programme of this type. The breeds presented a reduced number of animals in the genetic formation. High ‘bottleneck effect’. Moderate heritability for age at first calving.

中文翻译：

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来自意大利饲养的 Limousine 和 Charolais 牛的繁殖性状的谱系信息和遗传参数估计的遗传多样性

摘要 Limousine 和 Charolais 牛品种在意大利肉牛部门中的重要性日益增加。事实上，这两个品种都参与了国家农村发展项目。育种计划的成功在很大程度上不仅取决于确定的育种目标，还取决于用于实现该目标的选定标准。来自 Charolais 和 Limousine 意大利协会（出生于 1960 年至 2017 年）的数据用于估计产犊间隔 (CI) 和首次产犊年龄 (AFC) 和遗传多样性的遗传参数和趋势。通过基因起源概率方法研究种群结构，而方差分量估计用于获得繁殖参数的育种值。AFC 和 CI 的遗传力对于 Limousine 分别为 0.24 和 0.03，对于 Charolais 分别为 0.32 和 0.02。观察到 AFC 的遗传趋势增加。对于 CI，没有验证遗传来源的显着增益。在这两个品种中，谱系完整性中等，观察到的近交系数较低。没有牛群被归类为核心或孤立的，它们都使用外部公牛。两个品种中 AFC 的遗传性表明在选择时可能会有所改进。通过传统的遗传育种计划，预计 CI 的改进有限。世代间隔的减少可能代表增加年度遗传增益的具有成本效益的解决方案。谱系分析表明这两个品种都存在种群瓶颈。亮点 Limousine 和 Charolais 品种参与了意大利饲养的牛群遗传改良的国家项目。将按照基因组方法开发遗传索引。本研究是为实施此类选择性项目做准备。这些品种在遗传形成中的动物数量减少。高“瓶颈效应”。第一次产犊时年龄的中等遗传力。