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Open Access Highly Accessed Research article

Polymorphisms in bovine immune genes and their associations with somatic cell count and milk production in dairy cattle

Christine Beecher12, Mairead Daly1, Stuart Childs1, Donagh P Berry3, David A Magee4, Tommie V McCarthy2 and Linda Giblin1*

Author Affiliations

1 Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland

2 Biochemistry Department, University College Cork, Cork, Ireland

3 Teagasc, Animal and Bioscience Research Department, Animal and Grassland Research and Innovation Centre, Moorepark, Fermoy, Co. Cork, Ireland

4 Animal Genomics Laboratory, UCD School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland

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BMC Genetics 2010, 11:99  doi:10.1186/1471-2156-11-99

Published: 5 November 2010

Abstract

Background

Mastitis, an inflammation of the mammary gland, is a major source of economic loss on dairy farms. The aim of this study was to quantify the associations between two previously identified polymorphisms in the bovine toll-like receptor 2 (TLR2) and chemokine receptor 1 (CXCR1) genes and mammary health indictor traits in (a) 246 lactating dairy cow contemporaries representing five breeds from one research farm and (b) 848 Holstein-Friesian bulls that represent a large proportion of the Irish dairy germplasm. To expand the study, a further 14 polymorphisms in immune genes were included for association studies in the bull population.

Results

TLR4-2021 associated (P < 0.05) with both milk protein and fat percentage in late lactation (P < 0.01) within the cow cohort. No association was observed between this polymorphism and either yield or composition of milk within the bull population. CXCR1-777 significantly associated (P < 0.05) with fat yield in the bull population and tended to associate (P < 0.1) with somatic cell score (SCS) in the cows genotyped. CD14-1908 A allele was found to associate with increased (P < 0.05) milk fat and protein yield and also tended to associate with increased (P < 0.1) milk yield. A SERPINA1 haplotype with superior genetic merit for milk protein yield and milk fat percentage (P < 0.05) was also identified.

Conclusion

Of the sixteen polymorphisms in seven immune genes genotyped, just CXCR1-777 tended to associate with SCS, albeit only in the on-farm study. The lack of an association between the polymorphisms with SCS in the Holstein-Friesian data set would question the potential importance of these variants in selection for improved mastitis resistance in the Holstein-Friesian cow.