Submitted to: American Meat Science Association Conference Reciprocal Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 6/20/2003
Publication Date: 6/20/2003
Citation: Shackelford, S.D., Leymaster, K.A., Wheeler, T.L., Koohmaraie, M. 2003. Effects of breed of sire on carcass composition and sensory traits of lamb [abstract]. American Meat Science Association Conference Reciprocal Proceedings. 56:112. Interpretive Summary: The sheep industry competes against beef, pork, poultry, and fish for food dollars of consumers who have many choices of high-quality meats. In this competitive environment, the sheep industry must monitor and react to changing preferences of consumers. A consumer-responsive goal of the sheep industry is consistent production of uniform, safe, nutritious, lean lamb that results in an enjoyable and pleasant eating experience. It is possible that important differences exist between breeds of sheep for traits that affect consumer perceptions of lamb quality. Such breed effects have a genetic basis and can be exploited by sheep producers. Therefore, a potentially efficient method to improve lamb quality is to evaluate breed effects and then to systematically use the most appropriate breeds in crossbreeding programs that produce market lambs. Yet, little was known about effects of breed on lamb meat quality. Thus, this experiment was conducted to compare the meat quality and carcass composition of a diverse sampling of sheep breeds. Breeds were chosen to represent wide ranges of performance and use in production of market lambs. Substantial differences were observed between breeds for loin eye muscle tenderness. Despite large differences between breeds in the level of marbling in the loin eye muscle, breed of sire did not affect flavor and differences among breeds for juiciness were small.
Technical Abstract: The present report includes results of the first year of a three-year-long experiment to evaluate effects of breed of sire on carcass composition and sensory traits of lamb. Dorset, Texel, Rambouillet, Finnsheep, Romanov, Suffolk, Composite, Katahdin, and Dorper rams (5 per breed) were mated to a common breed of ewes and 270 offspring (ewes and wethers) were slaughtered serially and evaluated. Data were adjusted to a common slaughter age of 217 d. Carcasses of progeny of Suffolk sires were heavier (P < 0.05) than those of the progeny of all other breeds except Dorper and Texel. Carcasses of progeny of Romanov sires were lighter (P < 0.05) than those of the progeny of all other breeds except Finnsheep. Progeny of Finnsheep and Romanov sires had a higher (P < 0.05) kidney-pelvic fat percentage than progeny of all other breeds. Leg score was greater (P < 0.05) for progeny of Texel sires than for those of all other breeds. Leg scores were lower (P < 0.05) for progeny of Romanov sires than progeny of all other breeds except Katahdin and Finnsheep. Longissimus area was larger (P < 0.05) for progeny of Texel and Suffolk sires than for those sired by all other breeds except Dorper. Longissimus area was smaller (P < 0.05) for progeny of Romanov sires than for progeny of all other breeds except Dorset and Finnsheep. Despite the diversity of breeds sampled, 12th rib fat thickness was only marginally (P < 0.10) affected by breed of sire. Fat thickness at the 4th sacral vertebrae was greater (P < 0.05) for progeny of Dorper sires than for progeny of all other breeds. Among the 270 carcasses sampled, whole-carcass ether-extractable fat percentage ranged from 18% to 40%. Breed of sire affected (P < 0.05) carcass ether-extractable fat percentage with breed means ranging from 27.2% for Rambouillet to 31.3% for Dorper. The longissimus of progeny of Finnsheep and Romanov sires contained a higher (P < 0.05) percentage of intramuscular fat and received higher (P < 0.05) marbling scores than that of the progeny of Rambouillet and Composite sires. Longissimus chops from progeny of Finnsheep sires had the lowest slice shear force values (17.3 kg) and, accordingly, the highest (P < 0.05) trained sensory panel tenderness ratings (6.1). Longissimus chops from progeny of Composite sires had the highest slice shear force values (27.6 kg) and the numerically lowest trained sensory panel tenderness ratings (5.2). Thus, it appears that there are breed differences in lamb tenderness that could affect consumer satisfaction. However, no differences among breeds were detected for lamb flavor intensity or off-flavor ratings. Although the level of difference between breeds was quite small, longissimus chops from progeny of Finnsheep sires were more juicy than those of progeny of Dorper, Rambouillet, and Texel sires. Finnsheep and Romanov, breeds known for having large litter size, share many common carcass composition and meat quality traits. Progeny of those breeds were slow growing and had a high percentage of kidney-pelvic fat, a high level of intramuscular fat, had small longissimus areas (primarily due to low weight), and produced the most tender loin eye muscle chops.