A purified antibody, or an antigen-binding fragment thereof, is provided that binds selectively to a protein specific to an X-chromosome of a mammalian sperm cell. The sperm cell protein comprises an amino acid sequence set forth in SEQ ID NOs: 4 and 9-16. The antibody or antigen-binding fragment thereof may be derived by immunization of a host by an antigenic peptide composition comprising one or more natural or synthetic antigenic peptide sequences set forth as SEQ ID NO: 1, SEQ ID NO: 2, SEQ ID NO: 3, and SEQ ID NOs: 4 and 9-16. The antibody finds utility in identifying an X-chromosome bearing sperm cell population, and in methods for skewing a sex ratio in mammals.
