Nonneman Dan J, Schneider James F, Lents Clay A, Wiedmann Ralph T, Vallet Jeffrey L, Rohrer Gary A
United States Department of Agriculture, Agricultural Research Service, U.S. Meat Animal Research Center, Clay Center, NE, 68933, USA.
BMC Genet. 2016 Feb 29;17:50. doi: 10.1186/s12863-016-0352-y.
Reproductive efficiency has a great impact on the economic success of pork production. Gilts comprise a significant portion of breeding females and gilts that reach puberty earlier tend to stay in the herd longer and be more productive. About 10 to 30% of gilts never farrow a litter and the most common reasons for removal are anestrus and failure to conceive. Puberty in pigs is usually defined as the female's first estrus in the presence of boar stimulation. Genetic markers associated with age at puberty will allow for selection on age at puberty and traits correlated with sow lifetime productivity.
Gilts (n = 759) with estrus detection measurements ranging from 140-240 days were genotyped using the Illumina PorcineSNP60 BeadChip and SNP were tested for significant effects with a Bayesian approach using GENSEL software. Of the available 8111 five-marker windows, 27 were found to be statistically significant with a comparison-wise error of P < 0.01. Ten QTL were highly significant at P < 0.005 level. Two QTL, one on SSC12 at 15 Mb and the other on SSC7 at 75 Mb, explained 16.87% of the total genetic variance. The most compelling candidate genes in these two regions included the growth hormone gene (GH1) on SSC12 and PRKD1 on SSC7. Several loci confirmed associations previously identified for age at puberty in the pig and loci for age at menarche in humans.
Several of the loci identified in this study have a physiological role for the onset of puberty and a genetic basis for sexual maturation in humans. Understanding the genes involved in regulation of the onset of puberty would allow for the improvement of reproductive efficiency in swine. Because age at puberty is a predictive factor for sow longevity and lifetime productivity, but not routinely measured or selected for in commercial herds, it would be beneficial to be able to use genomic or marker-assisted selection to improve these traits.
繁殖效率对猪肉生产的经济成功有着重大影响。后备母猪占繁殖母猪的很大一部分，较早达到青春期的后备母猪往往在猪群中停留的时间更长且生产性能更高。约10%至30%的后备母猪从未产过一窝仔猪，淘汰的最常见原因是发情期缺失和未能受孕。猪的青春期通常定义为母猪在公猪刺激下的首次发情。与青春期年龄相关的遗传标记将有助于对青春期年龄以及与母猪终生生产力相关的性状进行选择。
使用Illumina PorcineSNP60 BeadChip对发情检测时间在140 - 240天之间的759头后备母猪进行基因分型，并使用GENSEL软件采用贝叶斯方法测试单核苷酸多态性（SNP）的显著效应。在可用的8111个五标记窗口中，发现27个具有统计学意义，比较误差P < 0.01。10个数量性状基因座（QTL）在P < 0.005水平上高度显著。两个QTL，一个位于15兆碱基处的12号猪染色体（SSC12）上，另一个位于75兆碱基处的7号猪染色体（SSC7）上，解释了总遗传方差中的16.87%。这两个区域中最引人注目的候选基因包括12号猪染色体上的生长激素基因（GH1）和7号猪染色体上的PRKD1。几个基因座证实了先前在猪中确定的与青春期年龄相关的关联以及在人类中与初潮年龄相关的基因座。
本研究中确定的几个基因座对青春期的开始具有生理作用，并且在人类性成熟方面具有遗传基础。了解参与青春期开始调节的基因将有助于提高猪的繁殖效率。由于青春期年龄是母猪寿命和终生生产力的预测因素，但在商业猪群中并非常规测量或选择的指标，因此能够使用基因组或标记辅助选择来改善这些性状将是有益的。
