Effects of breed of sire on carcass composition and sensory traits of lamb

This experiment was conducted to compare meat quality and carcass composition of a diverse sampling of sheep breeds. Finnsheep, Romanov, Dorper, White Dorper, Katahdin, Rambouillet, Suffolk, Texel, Dorset, and Composite (1/2 Columbia rams to 1/4 Hampshire x 1/4 Suffolk) rams were mated to mature Composite ewes. Lambs (n = 804) were reared intensively, grain finished, and serially harvested over a 63-d period. Average harvest age was 216 d and average HCW was 30.7 kg. At a common harvest age, progeny of Suffolk sires were heavier than progeny of all other breeds (P < 0.05) and their carcasses were heavier (P < 0.05) than progeny of all other breeds, except White Dorper and Dorper. Progeny of Finnsheep and Romanov sires had lighter (P < 0.05) carcasses than progeny of all other breeds. Progeny of Texel, Suffolk, White Dorper, and Dorper sires had larger (P < 0.05) LM area than all other breeds. Progeny of Finnsheep and Romanov sires had smaller (P < 0.05) LM area than all other breeds. Fat thickness at the 12th rib was greater (P < 0.05) for progeny of Dorper sires than those of all other breeds, except White Dorper and Katahdin. Fat thickness at the 4th sacral vertebrae was greater (P < 0.05) for progeny of White Dorper and Dorper sires than those of all other breeds. On a carcass weight-constant basis, progeny of Suffolk sires had a lesser (P < 0.05) percentage of ether-extractable carcass fat than progeny of all other breeds, except Texel. Regardless of harvest endpoint (age-constant or HCW-constant), LM of progeny of Finnsheep and Romanov sires contained a greater (P < 0.05) percentage of intramuscular fat and received greater (P < 0.05) marbling scores than Rambouillet, Suffolk, Texel, Dorset, or Composite. Regardless of harvest endpoint, progeny of Finnsheep, Romanov, and Katahdin sires had smaller LM slice shear force values and greater trained sensory panel tenderness ratings at 7 d postmortem than did progeny of Composite, Suffolk, and Dorset sires (P < 0.05). At an age-constant basis, small differences (P < 0.05) were observed among breeds for lamb flavor intensity scores; however, when means were adjusted to a carcass weight-constant basis, breed of sire did not affect flavor intensity or off-flavor scores. These results document that each breed has relative strengths and weaknesses across traits, and that no single breed excels for all growth, carcass, and sensory traits.