Abstract

Summary Dairy cows classified as high immune responders, have inherently enhanced concentrations of total immunoglobulin G (IgG), and antibodies (antigen-specific immunoglobulin) in their colostrum and milk compared to average and low immune responders. FcRn (Fc receptor neonatal), a specialized receptor in the mammary tissue aids in the transport of circulating IgG from the blood of the dam into colostrum and the subsequent uptake of IgG from the digestive tract of calves into the systemic circulation. The present study was conducted to identify autosomal genomic regions associated with total IgG in colostrum and milk using a 50K SNP panel with imputation to the high-density panel (777K) and 556,279 markers were included in a genome wide association study (GWAS). SNP markers on chromosomes 12 (at 60-65 Mb) and 15 (at 44-46 Mb), were found to be significantly associated with total IgG concentration in milk at a 5% false discovery rate (FDR) level. No significant associations in colostrum or milk were found between total IgG and SNPs in the gene region encoding FcRn. However, raw p-value (without FDR adjustment), for 2 SNPs located within the FCGRT gene region on chromosome 18 were shown to be significant at the 5% level for colostrum. One limitation of this study was the small number of animals tested (n=57), which will affect the power of the GWAS. Further evaluation of these SNPs with a larger sample size, and of their associated candidate genes and their biological pathways, is required to understand the genetics of development of high IgG concentrations in colostrum and milk.

Lauraine C Wagter-Lesperance, Mehdi Sargolzaei, Mehdi Emam, Douglas C Hodgins, Kelly Fleming, Shannon Cartwright, Bonnie Mallard

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume Electronic Poster Session - Molecular Genetics 2, , 779, 2018
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