Enables UDP-galactose:beta-N-acetylglucosamine beta-1,3-galactosyltransferase activity. Acts upstream of or within oligosaccharide biosynthetic process. Located in Golgi membrane. Is expressed in nervous system. Orthologous to human B3GALT1 (beta-1,3-galactosyltransferase 1). [provided by Alliance of Genome Resources, Apr 2022]