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Abstract：
Sheep breeders requested that the U.S. Sheep Experiment Station (USSES) to participate in national genetic evaluation through the National Sheep Improvement Program (NSIP). The reasons included the need for (1) a comparison of the productivity of industry and United States Department of Agriculture (USDA) lines, (2) transparency of USDA flocks, (3) genetic ties for NSIP by sampling of industry flocks, and (4) development of premium genetic lines for public release. In response, USSES began to incorporate external sires from NSIP participating flocks into the USSES Targhee flock. Our objective, based on a pedigree analysis, was to test if introgression of external genetics into the flock was achieved. The pedigree included 13,189 animals with mean maximum generations, mean complete generations, and mean equivalent complete generations of 4.2, 1.8, and 2.6, respectively. The mean generation interval was 3.1 yr. The reference population was defined as lambs born from 2021 to 2023 (n = 792). Two additional populations were defined as the current mature ewe flock (n = 123) and the current mature rams (n = 14). The Genetic Conservation Index averaged 7.7 for the full population and 25.7 for the reference population. Overall inbreeding was 0.003 for the full population and 0.006 for the reference population. The rate of inbreeding was 0.0003 per generation. Average relatedness was 0.015 for the full population and 0.018 for the reference population. The effective number of founders, effective number of ancestors, and founder genome equivalents contributing to the reference population were 60, 39, and 19.1, respectively. The ratio of the effective number of founders to the effective number of ancestors was 1.5, indicating the presence of genetic bottlenecks. Measures of effective population size ranged from 102 to 547. Of the 704 offspring produced by external sires, 17 ram lambs and 132 ewe lambs were retained for breeding. The USSES sires produced 299 offspring with 2 ram lambs and 51 ewe lambs retained. Incorporating external sires resulted in a cumulative percentage of genetic variance of 48.8, 49.1, and 44.2 of external genetics for the reference population, current mature ewe flock, and current mature rams, respectively. Stakeholder needs were addressed by introgression of external sires and participation in NSIP, but future selection practices need to be modified to maintain a minimum of 50% USSES core genetics in the flock.
摘要：
绵羊饲养员要求美国绵羊实验站（USSES）通过国家绵羊改良计划（NSIP）参与国家遗传评估。原因包括需要（1）比较工业和美国农业部（USDA）的生产率，(2)美国农业部鸡群的透明度，(3)NSIP的遗传联系，通过对行业群体进行抽样，(4)开发供公开发布的优质遗传系。作为回应,USSES开始将来自NSIP参与羊群的外部父亲纳入USSESTarghee羊群。我们的目标,根据谱系分析，是为了测试外部遗传学是否渗入羊群。谱系包括13189只平均最大世代的动物，意味着完整的世代，和平均等效完整代分别为4.2、1.8和2.6。平均世代间隔为3.1年。参考种群定义为2021年至2023年出生的羔羊（n=792）。另外两个种群被定义为当前的成熟母羊群（n=123）和当前的成熟公羊群（n=14）。整个种群的遗传保护指数平均为7.7，参考种群为25.7。整个种群的总体近亲繁殖为0.003，参考种群为0.006。近交率为每代0.0003。整个人群的平均亲缘关系为0.015，参考人群的平均亲缘关系为0.018。创始人的有效数量，祖先的有效数量，对参考人群有贡献的创始人基因组当量分别为60,39和19.1.创始人的有效数量与祖先的有效数量之比为1.5，表明存在遗传瓶颈。有效人口规模的度量范围为102至547。在外来父亲产生的704个后代中，保留了17只公羊和132只母羊用于繁殖。USSES父亲产生了299个后代，其中保留了2只公羊羔羊和51只母羊羔羊。合并外部父系导致参考人群的外部遗传学的遗传方差的累积百分比为48.8、49.1和44.2，当前成熟的母羊群，和目前成熟的公羊，分别。利益相关者的需求通过外部父亲的渗入和参与NSIP来解决，但是未来的选择实践需要进行修改，以保持羊群中至少50%的USSES核心遗传学。
