Genome wide association study of passive immunity and disease traits in beef-suckler and dairy calves on Irish farms.

Calves with lower concentrations of immunoglobulin G (IgG) in their blood, have a greater risk of developing diseases. There is a lack of knowledge on genetic markers known to be associated with immunological variability or disease resistance. Therefore, the objective of this study was to identify SNP markers associated with passive immunity measures (serum IgG, serum protein, albumin, globulin and total protein concentrations, total solids Brix percentage, zinc sulphate turbidity units) and disease (pneumonia, diarrhoea, crude illness) traits in Irish commercial beef-suckler and dairy calves through genome wide association studies (GWAS). Genotyping was performed on DNA samples from beef-suckler (n = 698) and dairy (n = 1178) calves, using the IDBv3 chip. Heritability of passive immunity associated traits (range 0.02-0.22) and the disease traits (range 0.03-0.20) were low-to-moderate. Twenty-five and fifteen SNPs approached genome wide significance (P < 5 × 10 ^-5 ) for the passive immunity and the disease traits, respectively. One SNP "ARS-BFGL-BAC-27914" reached Bonferroni genome wide significance (P < 1.15 × 10 ^-6 ) for an association with serum IgG concentration in beef calves. Further work will evaluate these SNPs in larger cattle populations and assess their contribution to genomic selection breeding strategies, aimed towards producing more disease resistant livestock.