The amount of a UDP-GlcNAc:betaGal beta-1,3-N-acetylglucosaminyltransferase 8 when measured in blood serum. The trait is level of UDP-GlcNAc:betaGal beta-1,3-N-acetylglucosaminyltransferase 8 in blood serum (Ontology of Biological Attributes identifier OBA_2040754). Also known as: blood serum UDP-GlcNAc:betaGal beta-1,3-N-acetylglucosaminyltransferase 8 amount.