Enables beta-galactoside (CMP) alpha-2,3-sialyltransferase activity. Involved in ganglioside biosynthetic process via lactosylceramide. Acts upstream of or within protein glycosylation. Predicted to be located in Golgi membrane. Is expressed in several structures, including alimentary system; genitourinary system; hemolymphoid system gland; liver; and mammary gland. Orthologous to human ST3GAL2 (ST3 beta-galactoside alpha-2,3-sialyltransferase 2). [provided by Alliance of Genome Resources, Apr 2022]