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Maria Rosario Marques
National Institute for Agricultural and Veterinary Research, Portugal
Keynote: J Pharmacol Med Cheml
Growth Hormone (GH) has long been known to indirectly support the synthesis and secretion of milk and milk components in lactating animals by increasing blood flow and nutrient availability to the mammary gland1 or through stimulation of IGF¬I secretion by the liver and by stromal cells within the mammary gland2. These physiological stimuli increase epithelial cell proliferation or secretory activity in the lactating mammary gland, indicating the involvement of signalling pathways regulating cell turnover and renewal 3,4, RNA transcription at postranscriptional level of miRNAs5, and protein synthesis6. Molecular markers in the genes from the principal pathways triggered by GH has been reported to control milk production and milk protein genes expression in sheep7,8. Animal selection based on such markers offers an enormous potential to improve sheep milk productivity. Thus, the objective of this study is to uncover polymorphism in ovine somatotrophic axis associated with high yielding Assaf dairy ewes. Eighteen SNPs in GH, GHR, PRL, PRLR, IGF1, IGF1R and STAT5B genes have been genotyped by SNapShot analysis in 450 Assaf dairy ewes from Fertiland flock divided into two groups: high (H – total milk yield higher than 500 L/lactation) or medium yielding ewes (M – average total milk yield of 300±100 L/lactation. Data collected for ten years regarding milk yield adjusted to 150 lactation days, total milk yield and lactation duration was analysed for individual SNPs with MAF>0.05 using the PROC MIXED procedure, considering the effect of the genotypes, lactation number, type of lambing, and production group. The analysed SNPs showed to be highly polymorphic, and associations has been stabilised with milk yield traits. The results from this study provided new insights into allelic frequencies of the analysed SNPs, and their effects on milk production traits in Assaf dairy ewes. Its future use in selection programs could contribute to increase economic sustainability of sheep’s milk farms.
Marques has a PhD degree in Biology, specialty of Population Biology. She has her expertise in animal production and molecular biology techniques applied to genetic polymorphism detection in animals. Her current research interest is the detection of genetic polymorphism in the somatotrophic axis and milk protein genes in sheep, and to disclose its’ possible correlations with milk traits in dairy sheep breeds.
E-mail: rosario.marques@iniav.pt
