the homozygous state MM produces excessive dilution resulting in nearly completely white individuals often accompanied by eye & ear defects probably as the result of pleitropic effects of the gene. Merele & merle crosses result in one-fourth of the offspring being homozyous mereles & they recmmend these individuals be euthanatized at birth. So to avoid that, breeding the merele female to a tri or bi colored male would be the thing to do.