|MCKIBBEN, HEATHER - University Of Wyoming|
|NOTTER, DAVID - Virginia Polytechnic Institution & State University|
|STEWART, WHIT - University Of Wyoming|
|MEANS, WARRIE - University Of Wyoming|
|Taylor, Joshua - Bret|
Submitted to: Translational Animal Science
Publication Type: Proceedings
Publication Acceptance Date: 6/1/2018
Publication Date: 6/21/2018
Citation: Mckibben, H.N., Notter, D.R., Stewart, W.C., Means, W.J., Pierce, N.L., Taylor, J.B. 2018. Comparison of the USSES terminal-sire and Siremax composite breeds with the Suffolk breed as terminal sires in an extensive production system: Prefabrication carcass traits. Translational Animal Science. 2(suppl.1):S155-S158. https://doi.org/10.1093/tas/txy042.
Interpretive Summary: Not required.
Technical Abstract: The objective of this study was to evaluate the U.S. Sheep Experiment Station (USSES) terminal-sire (TSC) and Siremax composite breeds with the Suffolk breed, when used as terminal-sires mated to range-type ewes, on pre-fabrication carcass characteristics of lambs that were reared in the U.S. West. We hypothesized that when used as terminal sires in a range-ewe production system, the composite breeds would result in crossbreed lambs having in similar consistency and yield of pre-fabrication carcass characteristics as lambs from the Suffolk breed. To test this hypothesis, lambs were produced by single-sire matings of adult (2 to 7-yr–old ) USSES Targhee (n = 80), Polypay (n = 80), and Rambouillet (n = 80) ewes to Suffolk (n = 8), Siremax (n = 8), or TSC (n = 8) rams. The goal was to generate at least 12 lambs from each ram to be finished for the study. Crossbreed lamb were reared with their dams on sagebrush steppe and subalpine range through the spring and summer, and ewe and wether lambs were weaned at 101 to 127 d of age. Lambs were finished in groups of 10 to 12 lambs per pen. Within pen, lambs were assigned to 1 of 3 slaughter groups, with a mean target BW of 54.4, 61.2 or 68.0 kg. A total of 286 lambs were harvested. Sire breed did not affect 12th rib fat depth, body wall thickness, longissimus muscle (LM) area, % boneless closely trimmed retail cuts, and USDA and calculated yield grades (P > 0.13). Sire breed affected (P = 0.08) hot carcass weight (HCW). Suffolk-sired lambs had greater (P = 0.03) HCW, 1.06 kg (3.43%) larger than both Siremax and TSC. Furthermore, Suffolks were greater (P = 0.03) when comparing HCW with both composite breeds (Table 2). Sire breed also affected (P = 0.08) trimmed carcass weight (TRCWT). Suffolk-sired lambs had greater TRCWT, 0.43 kg (3.01%) larger than both Siremax and TSC composites. Suffolks were also greater (P = 0.03) when comparing TRCWT of Suffolk- sired lambs with lambs sired by composites, with Siremax and TSC not differing (P = 0.99). Preliminary results from 1 yr of harvest data indicated that Suffolk- sired lambs produced heavier HCW and TRCWT compared with the TSC and Siremax composite breeds. This data in conjunction with forthcoming pre-weaning and post-weaning production information will elucidate the overall utility of the breeds evaluated in extensively managed sheep productions systems.