Aspects of the present invention also provide methods based on novel UCN3 nucleotide polymorphisms selected from the group consisting of AAFC03043460.1:g.8272-8281AATAATAAAT(SEQ ID NO: 9)>GGAGC, g.8208C>T, g.8265C>T, g.8287T>C, g.8412A>G, g.8426T>A, c.8786C>T, g.9074T>C, c.12609C>T, c.12621T>C, c.12667T>G and c.12669C>A , which may provide novel markers for marbling and/or subcutaneous fat. Additional aspects provide for novel methods which may comprise marker-assisted selection or marker-assisted management to improve marbling and/or subcutaneous fat depth in cattle.