Ovulation control:
In many animals it is difficult to find out oestrous (sexual heat) in animals because it persists only for a few hours and occurs mostly at night. After ovulation (which is indicated by oestrous) females are inseminated. But in herd it would be economical, easy and simplified management if females are inseminated at a times. However, it is possible only when all the female ovulate at a time; in practice it is not possible to get synchronisation of oestrous. Moreover, it is possible to bring about ovulation in about 80 per cent of females by using hormones, for example progesterone and/or prostaglandin. These hormones regulate ovulation cycle of female and result in total synchrony of oestrous.
Sperm sexing:
Sperms are produced in the testes of males and ova in female’s ovaries. Sperms and ova contain half of chromosomes as compared to somatic cells. An ovum possesses autosomes and one X chromosome. Similarly, a sperm contains autosomes and one Y chromosome. In animals, sex is determined genetically i.e. by sex chromosomes. X chromosome determines femaleness and Y maleness. All the ova contain X chromosome, whereas a sperm consists of either X or Y chromosomes. One sperm ejaculate contains half X and half Y chromosomes.
In dairy industry demand of females is more than the males. Secondly, females have more desirable characteristics. The livestock industry prefers animals of one sex. Therefore, through artificial insemination technology X and Y chromosomes can be detected and sex of progenies determined accordingly.
There is fluorescence dye (Hoechst 33342) that stains X and Y chromosomes with different intensities. Thus, these two chromosomes possibly can be separated by using an instrument, fluorescent activated cell sorter (FACS). Sperms are present in the form of suspension. The FACS converts a suspension of sperms into micro droplets. Each droplet consists of a single sperm cell. Individual micro droplet passes through a laser beam. Micro droplets of different intensities are deflected into separate collection tubes as the fluorescence of dye is measured electronically. The sperms separated by using FACS have recently been used and pre-sexed calves have been produced through in vitro fertilization technique. Moreover, FACS is very expensive and slow. It takes about 24 hrs to process one semen ejaculate, whereas the sperm cannot remain viable for a long time. Therefore, more refinement in technique is required for its use on a large scale (Read and Smith, 1996)