Enables sialyltransferase activity. Involved in ganglioside biosynthetic process; glycoprotein metabolic process; and oligosaccharide metabolic process. Acts upstream of or within several processes, including blastocyst hatching; glycolipid biosynthetic process; and protein O-linked glycosylation. Predicted to be integral component of membrane. Is expressed in several structures, including early conceptus; genitourinary system; hindgut diverticulum; notochord; and olfactory epithelium. Orthologous to human ST8SIA6 (ST8 alpha-N-acetyl-neuraminide alpha-2,8-sialyltransferase 6). [provided by Alliance of Genome Resources, Apr 2022]