PS4-16. Examining the Effects of Sire and Dam Breed on Offspring Production and Carcass Characteristics.

Abstract The Northern Agricultural Research Station (NARC), operated by Montana State University, introduced Simmental genetics into their primarily Angus production herd in 2015. For the 9-years, 1499 matings were evaluated, where Angus dams were artificially inseminated (AI) to either an Angus or a Simmental (Sim) bull and the half-Sim dams were AI'd to half-Sim bulls. Charolais bulls were then used as natural service cover bulls, as a terminal cross for a 45-day breeding season. Heifers not retained for breeding, all steers, and terminal crosses entered the onsite feedlot for an average of 211-days on feed. A dataset compiling cow production data and subsequent carcass data was created and analyzed using generalized linear mixed models to evaluate the effects of sire and dam breed as well as age of dam on calf production and carcass performance metrics. Sire breed had an effect on calf birth weight (P < 0.01), where Charolais bulls produced the heaviest birthweight calves; Simmental and half-Sim bulls produced heavier calves than Angus sires (P ≤ 0.02). Both sire and dam breeds had an effect on calf adjusted 205-day weaning weights (P < 0.01). Charolais and Simmental bulls sired calves with larger adjusted weaning weights compared to Angus sires (P ≤ 0.01). Calves from half-Sim dams had greater adjusted weaning weights compared to straight Angus dams (P < 0.01). Calves from Angus, half-Sim and full Simmental sires had greater average daily gains (ADG) on feedlot when compared to Charolais sired calves (P < 0.01), with those sired by half-Sim outgaining Simmental sired calves (P < 0.01). Additionally, calves from straight Angus dams had greater ADG on feedlot compared to half-Sim dams (P < 0.01). Angus- and half-Sim- sired cattle had higher yield grades than Charolais and Simmental sired cattle (P < 0.01). Angus dams produced calves with higher yield grade values than that of the half-Sim dams (P < 0.01). Cattle born to bulls with Simmental genetics had greater ribeye areas than Angus- and Charolais-sired cattle (P ≤ 0.02). Cattle born to half-Sim dams had greater ribeye areas than those born to Angus dams (P = 0.03). Age of dam had a quadratic effect on calf birth weights (P < 0.01), 205-day adjusted weaning weights (P < 0.01), and feedlot ADGs (P ≤ 0.04). Additionally, four- to seven-year-old dams produced cattle with greater yield grade values than those of two-year-old dams (P ≤ 0.03). Overall, crossbreeding with Simmental genetics into an Angus-based herd improved preweaning growth performance. These results highlight that strategic use of Simmental-Angus crossbreeding allows producers to balance feedlot efficiency, and carcass quality depending on their production goals.