Abstract

GARCIA-RUIZ, Adriana et al. Genome association with Cooperia punctata resistance in crossbreed cattle in the sub-humid tropics of Mexico. Rev. mex. de cienc. pecuarias [online]. 2019, vol.10, n.2, pp.482-489. ISSN 2448-6698.  https://doi.org/10.22319/rmcp.v10i2.4759.

This study is an evaluation of resistance to natural infection by Cooperia spp. in Zebu x Holstein crossbreed calves in the tropics. Fourteen four-month-old calves were dewormed and moved to pastures naturally infested with gastrointestinal nematodes under sub-humid tropical conditions. Fecal samples were collected from each animal every seven days for three months to quantify the number of eggs per gram of feces (EPG), and nematode species identified with end-point PCR. Hair samples were collected for genotyping using the GeneSeek Genomic Profiler HD-V3 panel, which contains 139,376 SNP markers. Variation in EPG per individual ranged from a minimum of 7+7 to a maximum of 4,657+1,886 EPG. The PCR identified breed differences between the Zebu x Holstein crossbreeds. Genome-wide association studies detected five statistically significant haplotypes (P<0.001). The haplotype in chromosome 2 includes four markers, that in chromosome 10 includes three, that in chromosome 15 includes two, that in chromosome 23 includes four and chromosome X includes three. Of these regions only chromosome 23 was found to be associated with parasite resistance, measured as EPG phenotypes. The remaining chromosomes exhibited no association in the studied animals. These regions could be sequenced and tested for gene expression against Cooperia and other gastrointestinal nematodes.

Keywords : SNP markers; Genomic association studies; Nematode resistance; Crossbreed calves.

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