BACKGROUND Infrared spectral analysis of milk is cheap, fast, and accurate. Infrared light interacts with chemical bonds present inside the milk, which means that Fourier transform infrared milk spectra are a reflection of the chemical composition of milk. Heritability of Fourier transform infrared milk spectra has been analysed previously. Further genetic analysis of Fourier transform infrared milk spectra could give us a better insight in the genes underlying milk composition. Breed influences milk composition, yet not much is known about the effect of breed on Fourier transform infrared milk spectra. Improved understanding of the effect of breed on Fourier transform infrared milk spectra could enhance efficient application of Fourier transform infrared milk spectra. The aim of this study is to perform a genome wide association study on a selection of wavenumbers for Danish Holstein and Danish Jersey. This will improve our understanding of the genetics underlying milk composition in these two dairy cattle breeds. RESULTS For each breed separately, fifteen wavenumbers were analysed. Overall, more quantitative trait loci were observed for Danish Jersey compared to Danish Holstein. For both breeds, the majority of the wavenumbers was most strongly associated to a genomic region on BTA 14 harbouring DGAT1. Furthermore, for both breeds most quantitative trait loci were observed for wavenumbers that interact with the chemical bond C-O. For Danish Jersey, wavenumbers that interact with C-H were associated to genes that are involved in fatty acid synthesis, such as AGPAT3, AGPAT6, PPARGC1A, SREBF1, and FADS1. For wavenumbers which interact with -OH, associations were observed to genomic regions that have been linked to alpha-lactalbumin. CONCLUSIONS The current study identified many quantitative trait loci that underlie Fourier transform infrared milk spectra, and thus milk composition. Differences were observed between groups of wavenumbers that interact with different chemical bonds. Both overlapping and different QTL were observed for Danish Holstein and Danish Jersey.

中文翻译：

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全基因组关联研究两个丹麦奶牛品种的傅里叶变换红外牛奶光谱。

背景技术牛奶的红外光谱分析便宜，快速且准确。红外线与牛奶中存在的化学键相互作用，这意味着傅立叶变换红外牛奶光谱是牛奶化学成分的反映。先前已经分析了傅里叶变换红外牛奶光谱的遗传力。傅里叶变换红外牛奶光谱的进一步遗传分析可以使我们对牛奶成分的基础基因有更好的了解。品种影响牛奶成分，但关于品种对傅立叶变换红外牛奶光谱的影响知之甚少。更好地了解品种对傅里叶变换红外牛奶光谱的影响可以增强傅里叶变换红外牛奶光谱的有效应用。这项研究的目的是对丹麦霍尔斯坦和丹麦泽西岛的波数选择进行全基因组关联研究。这将增进我们对这两个奶牛品种中牛奶成分的遗传学认识。结果对于每个品种，分别分析了十五个波数。总体而言，与丹麦霍尔斯坦相比，丹麦泽西岛观察到更多的数量性状基因座。对于这两个品种，大多数波数与BTA 14上带有DGAT1的基因组区域密切相关。此外，对于这两个品种，都观察到了与化学键CO相互作用的波数的大多数定量性状基因座。对于丹麦泽西岛，与CH相互作用的波数与参与脂肪酸合成的基因有关，例如AGPAT3，AGPAT6，PPARGC1A， SREBF1和FADS1。对于与-OH相互作用的波数，观察到与已与α-乳白蛋白相关的基因组区域的关联。结论当前的研究确定了许多数量性状基因位点，这些位点是傅立叶变换红外牛奶光谱的基础，因此也是牛奶成分的基础。在与不同化学键相互作用的波数组之间观察到差异。丹麦霍尔斯坦和丹麦泽西岛均观察到重叠和不同的QTL。