Association between IGF1R / i16 / TaqI and IGF1 / SnaBI polymorphisms and milk production traits in Polish Holstein-Friesian cows

The insulin-like growth factor (IGF) signalling pathway plays a crucial role in the regulation of growth and development of mammals. The strong mammary insulin-like growth factor receptor type 1 (IGF1R) mRNA expression during lactation suggests a role for peripheral insulin-like growth factor I (IGF-I) in maintenance of lactation. The aim of the study was to identify the frequencies of alleles and genotypes of IGF1/SnaBI polymorphism and two known polymorphisms within intron 16 of the bIGF1R gene (SNP ID rs41960582 and rs41960583) as well as to determine associations between these polymorphisms and milk production traits in Polish Holstein-Friesian cows. The frequency of IGF1/SnaBI allele A occurred similar to that of allele B (0.55 and 0.45, respectively). No effect was found of IGF1 genotype on milk production traits. In the case of IGF1R polymorphisms detected by TaqI digestion (frequency of allele A = 0.61 and 0.39 of allele B), no significant effects of the IGF1R/TaqI polymorphism on the fat and protein yield and milk fat content was identified as well as no association between BB genotype and milk yield (P≤0.05). The high frequencies of all genotypes for both polymorphisms enabled the analysis of association between genotype combinations and milk traits. Cows with the IGF1RBB/IGF1AB genotype combination (9% of the examined population) yielded more milk, fat and protein compared to other combinations (P≤0.05).

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