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Proceedings of the 10th International Colloquium on Paratuberculosis

Proceedings of the 10th International Colloquium on Paratuberculosis

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#172 Whole genome associati<strong>on</strong> study for Holstein susceptibility to MAP infecti<strong>on</strong><br />

Brian W Kirkpatrick, Xianwei Shi, Xianwei Shi, Michael Collins, Michael Collins, George E. Shook,<br />

George E. Shook<br />

University <str<strong>on</strong>g>of</str<strong>on</strong>g> Wisc<strong>on</strong>sin-Madis<strong>on</strong>, USA<br />

The objective <str<strong>on</strong>g>of</str<strong>on</strong>g> this study was to identify genetic markers associated with host susceptibility to MAP infecti<strong>on</strong><br />

in Holstein cattle. Associated SNPs were identified by genotyping 521 Holstein cows, infected with MAP, and<br />

comparing allele frequency <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g>se positives with an estimate <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> general Holstein populati<strong>on</strong> allele frequency.<br />

The populati<strong>on</strong> allele frequency estimate was derived from genotypes <str<strong>on</strong>g>of</str<strong>on</strong>g> 6,283 Holstein sires used by<br />

artificial inseminati<strong>on</strong> (AI). The 521 infected cows were actually 233 and 288 animals from two resource populati<strong>on</strong>s<br />

<str<strong>on</strong>g>of</str<strong>on</strong>g> about 5,000 head each collected independently. Populati<strong>on</strong> 1 was comprised primarily <str<strong>on</strong>g>of</str<strong>on</strong>g> daughters<br />

<str<strong>on</strong>g>of</str<strong>on</strong>g> twelve Holstein sires, used heavily within <str<strong>on</strong>g>the</str<strong>on</strong>g> US dairy cattle populati<strong>on</strong> during <str<strong>on</strong>g>the</str<strong>on</strong>g> time preceding sample<br />

collecti<strong>on</strong> (1999-2003). Samples were obtained from 300 cooperating commercial dairy herds throughout <str<strong>on</strong>g>the</str<strong>on</strong>g><br />

US. Populati<strong>on</strong> 2 c<strong>on</strong>sisted <str<strong>on</strong>g>of</str<strong>on</strong>g> dairy cattle from six, large cooperating dairy herds in Wisc<strong>on</strong>sin, with all animals<br />

in <str<strong>on</strong>g>the</str<strong>on</strong>g> herds tested for Johne’s disease as part <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> research project. In both cases, <strong>on</strong>ly <str<strong>on</strong>g>the</str<strong>on</strong>g> animals with <str<strong>on</strong>g>the</str<strong>on</strong>g><br />

highest ELISA scores (categorized as positive or str<strong>on</strong>gly positive, versus low positive, suspect or negative)<br />

and/or positive fecal culture tests (Populati<strong>on</strong> 1) were genotyped. Genotyping was performed with <str<strong>on</strong>g>the</str<strong>on</strong>g> Illumina<br />

Bovine SNP50 Bead Chip, providing genotypes for 54,001 SNP markers. Data from <str<strong>on</strong>g>the</str<strong>on</strong>g> two resource populati<strong>on</strong>s<br />

was analyzed both in separate and combined analyses. The most significant markers from <str<strong>on</strong>g>the</str<strong>on</strong>g> individual<br />

and combined analyses (n=229) were used in a stepwise logistic regressi<strong>on</strong> analysis to identify a set <str<strong>on</strong>g>of</str<strong>on</strong>g> eleven<br />

markers that could be used as a predictor <str<strong>on</strong>g>of</str<strong>on</strong>g> genetics for Holstein cattle susceptibility to infecti<strong>on</strong> by MAP.<br />

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