Journal of Dairy Research

Research Article

Single nucleotide polymorphisms at the imprinted bovine insulin-like growth factor 2 (IGF2) locus are associated with dairy performance in Irish Holstein-Friesian cattle

Erik W Berkowicza1, David A Mageea1 c1, Klaudia M Sikoraa2 p1, Donagh P Berrya3, Dawn J Howarda4, Michael P Mullena4, Ross D Evansa5, Charles Spillanea2 p1 and David E MacHugha1a6

a1 Animal Genomics Laboratory, UCD School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland

a2 Genetics and Biotechnology Laboratory, Department of Biochemistry, University College Cork, Cork, Ireland

a3 Moorepark Dairy Production Research Centre, Teagasc, Fermoy, Co. Cork, Ireland

a4 Animal Production Research Centre, Teagasc, Mellows Campus, Athenry, Co. Galway, Ireland

a5 Irish Cattle Breeding Federation, Highfield House, Bandon, Co. Cork, Ireland

a6 UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin 4, Ireland

Abstract

The imprinted insulin-like growth factor 2 gene (IGF2) encodes a fetal mitogenic hormone protein (IGF-II) and has previously been shown to be associated with performance in dairy cattle. In this study we assessed genotype-phenotype associations between four single nucleotide polymorphisms (SNPs) located within the bovine IGF2 locus on chromosome 29 and a range of performance traits related to milk production, animal growth and body size, fertility and progeny survival in 848 progeny-tested Irish Holstein-Friesian sires. Two of the four SNPs (rs42196909 and IGF2.g-3815A>G), which were in strong linkage disequilibrium (r2=0·995), were associated with milk yield (P≤0·01) and milk protein yield (P≤0·05); the rs42196901 SNP was also associated (P≤0·05) with milk fat yield. Associations (P≤0·05) with milk fat percentage and milk protein percentage were observed at the rs42196901 and IGF2.g-3815A>G SNPs, respectively. The rs42196909 and IGF2.g-3815A>G SNPs were also associated with progeny carcass conformation (P≤0·05), while an association (P≤0·01) with progeny carcass weight was observed at the rs42194733 SNP locus. None of the four SNPs were associated with body size, fertility and progeny survival. These findings support previous work which suggests that the IGF2 locus is an important biological regulator of milk production in dairy cattle and add to an accumulating body of research showing that imprinted genes influence many complex performance traits in cattle.

(Received April 29 2010)

(Accepted July 09 2010)

(Online publication September 08 2010)

Correspondence:

c1 For correspondence; e-mail: david.magee@ucd.ie

p1 Current address: Genetics and Biotechnology Laboratory, Centre for Chromosome Biology, National University of Ireland Galway, Ireland