Genomic analyses underpin the feasibility of concomitant genetic improvement of milk yield and mastitis resistance in dairy sheep
Genomic analyses underpin the feasibility of concomitant genetic improvement of milk yield and mastitis resistance in dairy sheep
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基因组分析支持奶羊产奶量和乳腺炎抵抗力同步遗传改良的可行性
DOI：
10.1101/577015
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Banos G
中科院分区：
文献类型：
--
作者：
Banos G
产奶量是奶牛最重要的性状，是通过选择育种进行遗传改良的关键目标。乳腺炎是最普遍的疾病之一，显著影响动物福利、牛奶产量和质量，同时产生大量成本。我们的目标是确定可行性的同时遗传改良计划，提高牛奶产量和乳腺炎的抵抗力。产奶量和四个乳房炎相关性状（牛奶体细胞计数，加州乳房炎测试评分，总活菌数在牛奶和临床乳房炎的存在）的个人记录，每月收集整个哺乳期的609只母羊的希奥斯品种。所有母羊的基因型与乳腺炎特异性定制的960单核苷酸多态性（SNP）阵列。我们进行了有针对性的基因组关联研究，（协）方差分量估计和途径富集分析，并表征了基因表达水平和等位基因表达不平衡的程度。证实了产奶量存在遗传变异。产奶量与乳房炎性状之间不存在显著的遗传相关。环境因素似乎有利于产奶量和乳房健康。希奥斯羊与乳腺炎抗性和产奶量相关的SNPs没有重叠。此外，4个不同的数量性状位点（QTL）影响产奶量检测到染色体2，12，16和19，在其他的位置比以前确定的影响乳房炎抗性。位于QTL区域内的5个基因（DNAJA1、GHR、LYPLA1、NUP35和OXCT1）在乳腺和乳汁转录组中均高表达，表明它们参与了乳汁的合成和生产。此外，这些基因中的两个（NUP35和OXCT1）的表达在免疫组织中富集，这意味着乳房感染期间的潜在多效性效应或可能在产奶中起作用，这需要在未来的研究中进一步阐明。总之，产奶量和乳腺炎抗性之间不存在遗传拮抗作用，表明这两个性状的同时遗传改良是可以实现的。
Milk yield is the most important dairy sheep trait and constitutes the key genetic improvement goal via selective breeding. Mastitis is one of the most prevalent diseases, significantly impacting on animal welfare, milk yield and quality, while incurring substantial costs. Our objectives were to determine the feasibility of a concomitant genetic improvement programme for enhanced milk production and resistance to mastitis. Individual records for milk yield, and four mastitis-related traits (milk somatic cell count, California Mastitis Test score, total viable bacterial count in milk and clinical mastitis presence) were collected monthly throughout lactation for 609 ewes of the Chios breed. All ewes were genotyped with a mastitis specific custom-made 960 single nucleotide polymorphism (SNP) array. We performed targeted genomic association studies, (co)variance component estimation and pathway enrichment analysis, and characterised gene expression levels and the extent of allelic expression imbalance. Presence of heritable variation for milk yield was confirmed. There was no significant genetic correlation between milk yield and mastitis traits. Environmental factors appeared to favour both milk production and udder health. There were no overlapping of SNPs associated with mastitis resistance and milk yield in Chios sheep. Furthermore, four distinct Quantitative Trait Loci (QTLs) affecting milk yield were detected on chromosomes 2, 12, 16 and 19, in locations other than those previously identified to affect mastitis resistance. Five genes (DNAJA1,GHR,LYPLA1,NUP35andOXCT1) located within the QTL regions were highly expressed in both the mammary gland and milk transcriptome, suggesting involvement in milk synthesis and production. Furthermore, the expression of two of these genes (NUP35andOXCT1) was enriched in immune tissues implying a potentially pleiotropic effect or likely role in milk production during udder infection, which needs to be further elucidated in future studies. In conclusion, the absence of genetic antagonism between milk yield and mastitis resistance suggests that simultaneous genetic improvement of both traits be achievable.