Abstract：
This is the first UK genome wide association study investigating potential links between Video Image Analysis (VIA) carcass traits and molecular polymorphisms in crossbred sheep. Phenotypic and genotypic data were collected from two crossbred lamb populations: Texel x Scotch Mule (TxSM, n = 2330) and Texel x Lleyn (TxL, n = 3816). Traits measured included live weights at birth, eight weeks and weaning (∼15 weeks). VIA-predicted traits included total weights and weights of fat, muscle and bone in the whole carcass and primal (hind leg, saddle, shoulder) regions. Within-breed heritabilities estimated for the VIA traits ranged from 0.01 to 0.70, indicating potential for inclusion of some traits in breeding programmes. The two crossbred populations differed in SNPs associated with different traits. Two SNPs on chromosomes two (s74618.1) and eight (s68536.1), respectively, reached genome-wise significance for TxSM, explaining <1% of trait variance, for whole carcass fat and muscle weights, hind leg and saddle fat weights and shoulder bone weights. For TxL, four SNPs reached genome-wise significance, on chromosome two for hind leg muscle weight (OAR2_117,959,202 and OAR2_11804335), on chromosome 10 for whole carcass bone weight (OAR19_8,995,957.1), and on chromosome 19 for weaning weight (s40847.1), each explaining <1% of trait genetic variation. Differences in apparent genetic control of carcass traits may be influenced by the lambs\' cross-breed, but also by management decisions affecting environmental variance and trait definitions, which should be understood in order to define protocols for incorporation of carcass traits into (cross)breeding programmes. IMPLICATIONS: Combining VIA-measured carcass traits with conventional production traits in a breeding programme could potentially improve the production and product quality of meat sheep. Phenotypes for VIA traits could be collected relatively easily if VIA machines were present at all abattoir sites. The current study and future Genome Wide Association Studies may help to identify potentially informative molecular markers, that explain large proportions of the genetic variance observed in VIA-measured carcass traits. Including this information in the estimation of breeding values could increase the accuracy of prediction, increasing the potential rate of genetic improvement for product quality. This study confirms the polygenic architecture of the investigated carcass traits, with a small number of molecular markers that each explain a small amount of genetic variation. Further studies across breed types are recommended to further test and validate molecular markers for traits related to lamb carcass quality, as measured by video image analysis.
摘要：
这是英国首个全基因组关联研究，调查了视频图像分析（VIA）car体性状与杂交绵羊分子多态性之间的潜在联系。从两个杂交羔羊种群中收集了表型和基因型数据：TexelxScotchMule（TxSM，n=2330)和TexelxLleyn(TxL，n=3816）。测量的性状包括出生时的活重，八周和断奶(~15周)。通过预测的性状包括总重量和脂肪重量，整个尸体和原始(后腿，马鞍,肩部)区域。VIA性状的品种内遗传力估计为0.01至0.70，表明在育种计划中可能包含某些性状。两个杂交群体在与不同性状相关的SNP上存在差异。染色体2（s74618.1）和8（s68536.1）上的两个SNP，分别,对TxSM达到基因组意义，解释<1%的性状变异，对于整个car体脂肪和肌肉重量，后腿和鞍座的脂肪重量和肩骨重量。对于TxL，四个SNP达到了基因组意义，在染色体2上的后腿肌肉重量（OAR2_117,959,202和OAR2_11804335），10号染色体上的整体骨重(OAR19_8,995,957.1)，和19号染色体上的断奶体重（s40847.1），每个解释<1%的性状遗传变异。car体性状的表观遗传控制差异可能受羔羊杂种的影响，而且还通过管理决策影响环境差异和特征定义，应理解，以定义将car体性状纳入（杂交）育种计划的协议。含义：在育种计划中将通过测量的car体性状与常规生产性状相结合，可以潜在地改善肉羊的生产和产品质量。如果VIA机器存在于所有屠宰场，则可以相对容易地收集VIA性状的表型。当前的研究和未来的全基因组关联研究可能有助于识别潜在的信息分子标记，这解释了在VIA测量的car体性状中观察到的大部分遗传变异。将这些信息包括在育种值的估计中可以提高预测的准确性，提高产品质量的遗传改良潜力。这项研究证实了所研究的car体性状的多基因结构，用少量的分子标记解释少量的遗传变异。建议进一步研究品种类型，以进一步测试和验证与羔羊car体质量相关的性状的分子标记，通过视频图像分析测量。
