Sex selection with monoclonal H-Y antibody.

H-Y antigen defined by antibody from male-sensitized female mice has been reported in male embryos of mouse, rat, cattle, goat, pig, and sheep. We now describe the use of monoclonal H-Y antibodies in identification of male and female during embryo transfer in cattle. Monoclonal H-Y antibodies were applied with fluorescein-isothiocyanate-conjugated goat antimouse immunoglobulin (Ig), and the embryos were scored for fluorescence under ultraviolet light. In alternative trials with 149 embryos, the method could be applied with 73% to 82% efficiency. Pregnancy rates for treated embryos were at least as high as those expected for untreated embryos. The calves that developed from the treated embryos are normal and growing.