INRA, UMR 1313 Unité de Génétique Animale et Biologie Intégrative, F-78350 Jouy en Josas, France.
J Anim Sci. 2010 Feb;88(2):446-54. doi: 10.2527/jas.2009-2385. Epub 2009 Dec 4.
The availability of genetic tests to detect different mutations in the myostatin gene allows the identification of heterozygous animals and would warrant the superiority of these animals for slaughter performance if this superiority is confirmed. Thus, 2 mutations of this gene, Q204X and nt821, were studied in 3 French beef breeds in the program Qualvigène. This work was done with 1,114 Charolais, 1,254 Limousin, and 981 Blonde d'Aquitaine young bulls from, respectively, 48, 36, and 30 sires and slaughtered from 2004 to 2006. In addition to the usual carcass traits recorded at slaughter (e.g., carcass yield, muscle score), carcass composition was estimated by weighing internal fat and dissecting the 6th rib. The muscle characteristic traits analyzed were lipid and collagen contents, muscle fiber section area, and pH. Regarding meat quality, sensory qualities of meat samples were evaluated by a taste panel, and Warner-Bratzler shear force was measured. Deoxyribonucleic acid was extracted from the blood samples of all calves, the blood samples of 78% of the dams, and the blood or semen samples of all the sires. Genotypes were determined for 2 disruptive mutations, Q204X and nt821. Analyses were conducted by breed. The superiority of carcass traits of calves carrying one copy of the mutated allele (Q204X or nt821) over noncarrier animals was approximately +1 SD in the Charolais and Limousin breeds but was not significant in the Blonde d'Aquitaine. In the Charolais breed, for which the frequency was the greatest (7%), young bulls carrying the Q204X mutation presented a carcass with less fat, less intramuscular fat and collagen contents, and a clearer and more tender meat than those of homozygous-normal cattle. The meat of these animals also had slightly less flavor. Also in the Charolais breed, 13 of 48 sires were heterozygous. For each sire, the substitution effect of the wild allele by the mutant allele was approximately +1 SD for carcass conformation and yield, showing that the estimate of the substitution effect was independent of family structure, as it ought to be for a causal mutation. These results illustrate the challenge of using genetic tests to detect animals with the genetic potential for greater grades of carcasses and meat quality.
该基因的 2 种突变，Q204X 和 nt821，在 3 个法国肉牛品种中进行了研究，该研究是 Qualvigène 计划的一部分。这项工作是用分别来自 48 个、36 个和 30 个公牛的 1114 头夏洛来牛、1254 头利木赞牛和 981 头 Blonde d'Aquitaine 青年公牛进行的，这些公牛在 2004 年至 2006 年期间屠宰。除了屠宰时记录的通常的胴体特征（例如胴体产肉率、肌肉评分）外，还通过称重内部脂肪和解剖第 6 肋骨来估计胴体成分。分析的肌肉特征性状包括脂质和胶原蛋白含量、肌纤维截面积和 pH 值。关于肉质，通过品尝小组评估肉样的感官品质，并测量 Warner-Bratzler 剪切力。从所有小牛的血液样本、78%的母牛的血液样本以及所有公牛的血液或精液样本中提取脱氧核糖核酸。对 2 种破坏性突变，Q204X 和 nt821 进行了基因型测定。按品种进行分析。在夏洛莱牛和利木赞牛品种中，携带一个突变等位基因（Q204X 或 nt821）的小牛的胴体性状优于非携带者动物，大约为+1 SD，但在 Blonde d'Aquitaine 中不显著。在夏洛莱牛品种中，携带 Q204X 突变的青年公牛的胴体脂肪更少，肌肉内脂肪和胶原蛋白含量更少，肉质更清晰、更嫩，与纯合正常牛相比。这些动物的肉也有稍微少一点的味道。同样在夏洛莱牛品种中，48 个公牛中有 13 个是杂合子。对于每个公牛，野生等位基因被突变等位基因取代的替代效应大约为+1 SD，用于胴体形态和产肉率，表明替代效应的估计独立于家族结构，就像因果突变应该的那样。这些结果说明了使用基因测试来检测具有更高等级胴体和肉质遗传潜力的动物所面临的挑战。
