Growth performance and carcass traits of forage-fed hair sheep wethers

The objective of the present study was to compare live animal performance and carcass characteristics of 3/4 or 7/8 Dorper (DO; n= 30), purebred Katahdin (KA; n= 20), purebred St. Croix (SC; n= 17) and purebred Suffolk (SU; n= 10) lambs born in the spring and fall of 2001. After weaning, lambs were supplemented with up to 680 g of a corn-soybean meal supplement while grazing bermudagrass pastures overseeded with ryegrass. Lambs were slaughtered at approximately 210 d of age. From birth to weaning, DO lambs gained faster (P< 0.001) than KA or SC lambs, whereas KA lambs had higher (P< 0.001) ADG than SC lambs. Additionally, DO and SU wethers had greater (P< 0.02) ADG from weaning to slaughter than SC or KA wethers. Suffolk lambs were heavier (P< 0.001) at slaughter and produced heavier (P< 0.001) carcasses than lambs from hair-sheep breeds. Carcasses of KA lambs were fatter (actual fat thickness; P< 0.02) resulting in higher yield grades (P< 0.03) than carcasses of DO, SC, or SU lambs. Carcasses of DO and SU had larger (P< 0.001) longissimus muscle (LM) areas than those of KA or SC carcasses, whereas kidney fat weight and percentage were greater (P< 0.001) in carcasses from KA and SC than DO and SU lambs. Lean maturity was similar (P= 0.32) among breed-types. However, skeletal maturity was greater (P< 0.001) in SU than hair-sheep carcasses. Flank-streaking scores were similar (P= 0.19) among the breed-types, but conformation scores were higher (P< 0.001) for DO and SU carcasses and resulted in higher (P< 0.001) quality grades than SC carcasses. The LM of SU lambs was lighter (higher L* values; P< 0.05) * than that of KA and SC lambs, whereas the LM from DO lambs was redder (higher a values; P< 0.001) than SC and SU and more (P< 0.001) yellow than that of the other breed-types. Chops from SU lambs were tougher (higher shear force values; P< 0.007) than chops from the hair-sheep breeds. Results of this study indicate that ADG, carcass muscularity and meat quality were similar between DO and SU lambs, and, although fatter, carcass muscularity of KA was similar to that of DO lambs. © 2005 Elsevier B.V. All rights reserved.