Genetic selection for carcass traits is paramount to maximize the profitability and long-term sustainability of any meat-producing livestock species. The main objectives of this research were to evaluate the efficiency of indicator traits for the genetic improvement of lamb carcass traits and to determine the value of including carcass traits into terminal sire selection indexes for the Canadian sheep industry. The carcass traits included hot carcass weight (HCW), fat depth at the GR site (FATGR) and average carcass conformation score (AVGCONF), and were measured on heavy lambs (slaughter age less than 365 days and HCW greater than 16.3 kg) in commercial abattoirs. Growth traits were found to be moderately efficient indicator traits for the genetic improvement of HCW but selection on ultrasound traits was necessary to substantially improve the carcass quality traits (FATGR and AVGCONF). Economic selection indexes were designed by adding various combinations of carcass traits into the Canadian Sheep Genetic Evaluation System terminal indexes. Records measured on individuals and progeny were assumed to be the sources of information for live animal and carcass traits, respectively. The changes in index accuracy, efficiency and expected correlated response were used to assess the value of their inclusion. HCW was found to have a large economic value, and its inclusion into terminal selection indexes was expected to substantially increase their accuracy (0.08-0.12 points) and efficiency (20%-30%). However, further including FATGR (measured 110 mm from the carcass midline over the 12th rib) and AVGCONF had little impact on the accuracy (≤0.03) and efficiency (1%-7%) of the proposed indexes. Thus, the inclusion of carcass traits into the existing terminal selection indexes could be beneficial for the genetic improvement of HCW, but further research is needed to determine optimal methods of increasing carcass fatness and muscularity.

中文翻译：

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将胴体性状表型纳入终产良种选择指标对提高重羔羊胴体重量和品质的价值

胴体特性的遗传选择对于最大限度地提高任何肉类生产牲畜物种的盈利能力和长期可持续性至关重要。本研究的主要目的是评估指标性状对羔羊胴体性状遗传改良的效率，并确定将胴体性状纳入加拿大绵羊业终端公种选择指数的价值。胴体性状包括热胴体重 (HCW)、GR 部位的脂肪深度 (FATGR) 和平均胴体构象评分 (AVGCONF)，并在重羔（屠宰日龄小于 365 天且 HCW 大于 16.3 kg）上进行测量。商业屠宰场。发现生长性状是 HCW 遗传改良的中等有效指标性状，但对超声性状的选择对于大幅改善胴体质量性状（FATGR 和 AVGCONF）是必要的。经济选择指标是通过在加拿大绵羊遗传评估系统终端指标中加入胴体性状的各种组合来设计的。假定对个体和后代进行测量的记录分别是活体动物和尸体特征的信息来源。指标准确性、效率和预期相关响应的变化用于评估其包含的价值。HCW被发现具有很大的经济价值，将其纳入终端选择指标有望大幅提高其准确性（0.08-0.12分）和效率（20%-30%）。然而，进一步包括FATGR（在第12肋骨上距离屠体中线110 mm处测量）和AVGCONF对建议指标的准确性（≤0.03）和效率（1％-7％）几乎没有影响。因此，将胴体性状纳入现有的终端选择指标可能有利于 HCW 的遗传改良，但需要进一步研究以确定增加胴体脂肪和肌肉的最佳方法。