2007 Annual Report 1a.Objectives (from AD-416) In a range sheep production environment, progeny test terminal-type sires for traits of survivability, rate and efficiency of growth, carcass composition, and meat quality in order to identify breeds and sires within breeds that warrant utilization in the development of a white-faced composite terminal sire line. Quantitative and molecular genetics and meat science will be used for enhancing rate and efficiency of growth, carcass composition, and muscle characteristics. 1b.Approach (from AD-416) Rate and efficiency of growth, carcass composition, and meat quality will be evaluated for four terminal-type breeds in a range sheep production environment. Approximate live animal target weights for the lambs are 54.4, 61.2 and 68.0 kg (120, 135, and 150 lb). Animals will be harvested under inspection in a commercial setting, and carcasses will be fabricated according to USDA Institutional Meat Purchase Specifications. During animal harvest and carcass fabrication, appropriate tissue samples and linear and weight measures will be collected as a means to characterize individual carcass composition and meat quality. Characterizations will include, but are not limited to, dressing percentage, carcass length, weights of untrimmed, trimmed, and boneless wholesale cuts, weight of kidney fat, subcutaneous loin fat thickness, longissimus muscle area, body wall thickness, longissimus pH, objective longissimus muscle color, and Warner-Bratzler shear force of the longissimus muscle. New genetic and meat science information will be used to develop a new white-faced composite terminal sire line that will produce progeny. Documents NFCA with Ohio State University. 3.Progress Report This report serves to document research conducted under a non-funded cooperative agreement between ARS and Ohio State University. Additional details of research can be found in the report for the parent project #5364-31000-007-00D, Integrated Systems for Increasing Production Efficiency of Sheep. The first crop of terminal sired lambs was harvested at the Ohio State University in three groups during the autumn of 2006. Carcass composition and meat quality data collections were completed for 172 wether lambs. Tissues were collected from all carcasses for future molecular characterization. Data collected from these harvested lambs were presented by OSU graduate students and scientists from USSES at the National Animal Science Meeting held in San Antonio, Texas and by a USSES scientist at the Western Animal Science Meeting in Moscow, Idaho. Lambs for the second year of the terminal sire project have been produced. Collaborative communication is maintained through email, conference calls and on site visits to OSU.