Sperber Jessica L, Lust David G, Veneklasen Gregg O, Hawkins Dean E, McEvers Trent J, Lawrence Ty E
Department of Agricultural Sciences, West Texas A&M University, Canyon, TX 79016, USA.
Timber Creek Veterinary Hospital, Canyon, TX 79015, USA.
Transl Anim Sci. 2023 Apr 24;7(1):txad041. doi: 10.1093/tas/txad041. eCollection 2023 Jan.
Cloning is a technology by which an animal's tissue can be salvaged and replicated. Carcasses that grade USDA prime-yield grade 1 (P1) represent a rare and antagonistic outcome and are a goal for terminal sire selection in the United States. A terminal sire progeny test generated offspring for a crossbred bull (14% Zebu, 86% Angus; ALPHA), born in 2012 via somatic cell nuclear transfer (SCNT) from a carcass that graded P1. ALPHA progeny (steers and heifers) were compared against progeny of three purebred (Angus; Charolais; Simmental) reference sires. Live production traits included weaning weight, morbidity, mortality, and days on feed; carcass traits included abscessed liver frequency and lung lesion frequency, individual quality and yield grade (YG) parameters, and carcass value. Observed carcass traits for progeny from the Angus, Charolais, and Simmental sires were reflective of the carcass outcomes expected for each sire's respective breed. Calves sired by the Angus were the earliest maturing indicated by the youngest chronological age at harvest ( ≤ 0.02) concomitant with the most backfat ( 0.01), and the greatest marbling scores ( < 0.01). Calves sired by the Charolais had the heaviest carcass weight ( = 0.04), greatest cutability as assessed by USDA calculated YG (< 0.01) and were the heaviest muscled based on "longissimus" muscle area (< 0.01). ALPHA-sired calves were the most similar in carcass outcomes to calves sired by the Simmental, combining advantageous quality and yield parameters to produce an intermediate for carcass quality and yield. The economic value of moderate carcass outcomes is reflected in the carcass value per century weight, in which ALPHA-sired steers tended ( = 0.07) to be of the greatest value compared to other sire groups. ALPHA progeny performed comparably to high-performing reference sires for terminal sire production traits and the P1 genetics in which ALPHA was cloned have economical and biological value in modern U.S. beef production.
克隆是一种能够挽救并复制动物组织的技术。美国农业部优质产量等级为1（P1）的胴体代表了一种罕见且理想的结果，是美国终端父本选择的目标。一项终端父本后代测试为一头2012年通过体细胞核移植（SCNT）技术由一头等级为P1的胴体克隆而来的杂交公牛（14%瘤牛，86%安格斯牛；ALPHA）培育了后代。将ALPHA的后代（公牛和小母牛）与三头纯种（安格斯牛；夏洛莱牛；西门塔尔牛）参考父本的后代进行比较。活体生产性状包括断奶体重、发病率、死亡率和育肥天数；胴体性状包括肝脏脓肿频率和肺部病变频率、个体质量和产量等级（YG）参数以及胴体价值。安格斯牛、夏洛莱牛和西门塔尔牛父本的后代所观察到的胴体性状反映了每个父本相应品种预期的胴体结果。安格斯牛所生的犊牛成熟最早，表现为收获时的实际年龄最小（≤0.02），同时背膘最厚（0.01），大理石花纹评分最高（<0.01）。夏洛莱牛所生的犊牛胴体重最重（=0.04），根据美国农业部计算的YG评估，其可切割性最高（<0.01），并且基于“背最长肌”面积，其肌肉最发达（<0.01）。ALPHA所生的犊牛在胴体结果上与西门塔尔牛所生的犊牛最为相似，结合了有利的质量和产量参数，从而产生了胴体质量和产量的中间值。中等胴体结果的经济价值体现在每百磅胴体价值上，其中ALPHA所生的公牛相比其他父本组往往（=0.07）具有最高价值。在终端父本生产性状方面，ALPHA的后代表现与高性能参考父本相当，并且用于克隆ALPHA的P1基因在现代美国牛肉生产中具有经济和生物学价值。
