Sperm Sexing in Animals

Nature has gone to extreme lengths to make X- and Y- chromosome bearing spermatozoa phenotypically identical so that mammalian sex is determined randomly, with equal chances of male or female offspring. However, from an owner’s point of view the sex of the calf or any other young-one to be born does matter. At present, flow cytometric sorting of sperm based on difference in DNA content of X and Y sperm is the only confirmed commercial method with 90% accuracy but it has certain limitations such as damage of sperm, cost of straw, sorting rate etc. Development of techniques to nullify these limitations is an active area of research. In past, various techniques have been used to separate the X and Y sperm which were based on principle of difference in mass, size swimming pattern, immunological structure and surface charges etc. Some of them showed the encouraging results but lacking scientific validation and some remained yet to be established. It seems inevitable that some techniques will prove to be efficacious. This review is meant to update the knowledge of researchers regarding recent development of sperm sexing in bovine.