In this study we carried out genome-wide association studies (GWAS) for milk nitrogen fractions in a cohort of 1,011 Brown Swiss cows. We uncovered 170 significant single nucleotide polymorphism (SNPs), mostly located on BTA6 and BTA11. The network-based Associated Weight Matrix (AWM) approach was used to exploit the results from GWAS and, in combination with network inference algorithms, to generate gene networks with regulatory and functional significance. Genes associated with milk nitrogen fractions were variously involved in several biological functions, in particular ion and cation transmembrane transporter activity and neuronal and hormone signalling, in line with the structure and function of casein micelles. Deeper analysis of the transcription factors and their predicted target genes within the network revealed that GFI1B, ZNF407 and NR5A1 might act as master regulators of milk protein synthesis and secretion. The results provide insight into the regulatory mechanisms that control milk protein synthesis and secretion in the bovine mammary gland and may be useful in breeding programmes aimed at improving milk nutritional and technological properties. Keywords: milk nitrogen fractions, dairy cattle, association weight matrix

Sara Pegolo, Núria Mach, Yuliaxis Ramayo-Caldas, Attilio Rossoni, Enrico Santus, Giovanni Bittante, Alessio Cecchinato

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume Methods and Tools - GWAS, , 549, 2018
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