Live and carcass production traits for progeny of an F1 USDA Prime-Yield Grade 1 carcass clone sire compared to progeny of popular beef terminal sires.

The cloning of beef carcasses that grade United States Department of Agriculture (USDA) Prime-yield grade (YG) 1 (P1) has produced a sire that ranked well against high-performing bulls from multiple breeds. An F1 (P1 × P1 - first generation offspring) sire would ideally outperform its high-performing parents. A terminal sire study was conducted comparing progeny of an F1 (P1 × P1) sire (AxG1) against progeny (heifers and steers) of four high-performing sires of varying breeds {P1 (ALPHA); Angus; Simmental; Angus × Simmental}. Production traits included morbidity and mortality frequencies, weaning weight, feedlot arrival weight, and days on feed; carcass traits included frequency of abscessed liver and lung health, quality grade and YG parameters, total carcass value (US$), and carcass value per hundredweight (CWT [45.4 kg]; US$). A completely randomized experimental design was used; data were analyzed using a mixed model with a fixed effect of sire and random effects of harvest date, sex, and pen. AxG1 sired heifers had the highest (P < 0.01) marbling score, the highest (P < 0.01) carcass value per CWT, and numerically had the lowest calculated YG and highest frequency of YG one carcass. Steers sired by AxG1 had the least (P = 0.05) backfat, lowest (P < 0.01) calculated YG, highest (P < 0.01) marbling score, highest (P < 0.01) frequency of USDA Prime carcasses, the greatest (P < 0.03) total carcass value, and greatest (P < 0.01) carcass value per CWT. Collectively, AxG1 steer and heifer carcasses exhibited the least 12th rib fat thickness and lowest USDA YG in addition to the largest longissimus muscle area, highest marbling score, and greatest frequency of USDA Prime. These data suggest that AxG1 performed comparably to other high-performing industry terminal sires in carcass quality and YG outcomes.

Live and carcass production traits for progeny of purebred sires in comparison with the clone of a USDA prime yield grade one carcass.

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 (P ≤ 0.02) concomitant with the most backfat (P < 0.01), and the greatest marbling scores (P < 0.01). Calves sired by the Charolais had the heaviest carcass weight (P = 0.04), greatest cutability as assessed by USDA calculated YG (P < 0.01) and were the heaviest muscled based on "longissimus" muscle area (P < 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 (P = 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.