Association of polymorphisms in exons 2 and 10 of the insulin-like growth factor 2 (IGF2) gene with milk production traits in Polish Holstein-Friesian cattle

Abstract

Insulin-like growth factor 2 (IGF2) is considered to be a regulator of post-natal growth and differentiation of the mammary gland. In the present work, associations of two single nucleotide polymorphisms in the bovineIGF2gene with milk production traits were studied in dairy Holstein-Friesian cows: the already described g.8656C>T transition in exon 2 (RFLP-BsrI) and the newly found g.24507G>T transversion in exon 10 (RFLP-HaeIII), found by sequencing 273-bp exon 10 of theIGF2gene in six individuals. Associations were analysed individually and in combination with the multi-trait repeatability test-day animal model. The CT/GT haplotype appeared to be associated with most of the milk traits studied (differences were significant atP⩽0·001). The most frequent CT/GG haplotype seemed inferior to others in fat and protein content and daily yield of fat and protein but superior (together with the TT/GG genotype) when the daily milk yield is considered.