A commercial crossbreeding experiment at the Research Farm of Çukurova University in Adana with Ile-de-France, Rambouillet, Chios and Awassi sheep is reported. The Chios breed was chosen for prolificacy and high milk production potential, the Ile-de-France for early growth and carcass quality, and the Rambouillet for early growth; the Awassi is the local sheep which is to be improved. The objective was to increase meat production by exploiting the reproductive efficiency of crossbred sheep. Firstly, Awassi ewes were mated with Chios rams, producing the F1 generation. Secondly, the F1 ewes were mated with Ile-de-France sires to obtain F1 ram lambs (designated IlF1), and F1 ewes were also mated with Rambouillet sires to obtain F1 ram lambs (designated RF1). Rambouillet (Rmb) and Awassi (Aw) sheep served as the control lines. Lambing rate (lambs born per mated ewe) was 1.65, 1.16, 1.05 and 1.03 for Il × F1, R × F1, Aw × Aw and Rmb × Rmb matings respectively. Twelve ram lambs in the IlF1, RF1 and Aw groups, and eight Rmb ram lambs were used in a fattening trial. Ram lambs weighing 38-40 kg were slaughtered and the chilled carcass was divided into eight primal cuts. Average daily gains were 311.6, 253.2, 281.2 and 226.0 g for IlF1, Aw and Rmb lambs, respectively, and feed efficiency was 3.8, 4.2, 3.7 and 5.4. Dressing percentage was higher for IlF1 lambs than for other groups. For cold carcasses of IlF1, RF1 Rmb and Aw lambs, the total bone percentage was 18.8, 19.5, 19.5 and 19.7 respectively, total muscle percentage 54.9, 53.5, 54.3 and 54.1, total subcutaneous fat percentage 12.3, 14.1, 11.6 and 16.6, and total intermuscular fat percentage 10.5, 9.5, 10.1 and 6.6. Fat thickness and rib-eye areas at the 12th rib were generally largest for IlF1 ram lambs. © 1990.
