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A polymorphism in the insulin-like growth factor 1 gene is associated with postpartum resumption of ovarian cyclicity in Holstein-Friesian cows under grazing conditions

Nicolini, Paula, Carriquiry, Mariana, Meikle, Ana
Acta veterinaria scandinavica 2013 v.55 no.1 pp. 11
Holstein, alleles, body condition, calving, conception, conjugated linoleic acid, dairy cows, early lactation, energy balance, genetic improvement, genetic markers, genotype, grazing, herds, insulin-like growth factor I, milk production, periodicity, single nucleotide polymorphism
BACKGROUND: Insulin-like growth factor 1 (IGF-1) gene is considered as a promising candidate for the identification of polymorphisms affecting cattle performance. The objectives of the current study were to determine the association of the single nucleotide polymorphism (SNP) IGF-1/Sna BI with fertility, milk production and body condition traits in Holstein-Friesian dairy cows under grazing conditions. METHODS: Seventy multiparous cows from a commercial herd were genotyped for the SNP IGF-1/Sna BI. Fertility measures evaluated were: interval to commencement of luteal activity (CLA), calving to first service (CFS) and calving to conception (CC) intervals. Milk production and body condition score were also evaluated. The study period extended from 3 wk before calving to the fourth month of lactation. RESULTS AND DISCUSSION: Frequencies of the SNP IGF-1/Sna BI alleles A and B were 0.59 and 0.41, respectively. Genotype frequencies were 0.31, 0.54 and 0.14 for AA, AB and BB, respectively. Cows with the AA genotype presented an early CLA and were more likely to resume ovarian cyclicity in the early postpartum than AB and BB ones. No effect of the SNP IGF-1/Sna BI genotype was evidenced on body condition change over the experimental period, suggesting that energy balance is not responsible for the outcome of postpartum ovarian resumption in this study. Traditional fertility measures were not affected by the SNP IGF-1/Sna BI. CONCLUSION: To our knowledge this is the first report describing an association of the SNP IGF-1/Sna BI with an endocrine fertility measure like CLA in cattle. Results herein remark the important role of the IGF-1 gene in the fertility of dairy cows on early lactation and make the SNP IGF-1/Sna BI an interesting candidate marker for genetic improvement of fertility in dairy cattle.