Manipulation of reproduction in animals:
One of the natural laws of life is to be many from one which is possible through reproduction. In animals, sexual reproduction occurs through fertilization of female gametes (ova) by male gametes (sperms) followed by fusion of two nuclei coming from two gametes. Thus sexual reproduction maintains the genetic traits of organism. But offspring develop and born in natural way. To meet the demand of animal products due to gradual increasing propulsion there is need of increase in number of animals too which is possible bio technologically because natural process of increase in number is slow.
In nature female mammals produce only one egg in a month except pigs. Secondly, ruminant females can have only one offspring in a year. Therefore, biotechnology can help to meet increasing demand and need of quality products of animals. In this regard principles of artificial breeding system has been discussed that may be useful further in the area of animal biotechnology.
Artificial Insemination:
A male animal produces millions of sperms daily. Theoretically, it can inseminate females regularity and produce several offspring. This excess capacity of male has been utilized through developing new technologies for artificial insemination which can be said as the first animal biotechnology.
The most effective factor that has increased the productivity of cattle is the artificial insemination. However, the breeder must replace the nature through artificial insemination if he ensures about the ovulation of female in herd together at a time. In contrast, if a breeder awaits for female to ovulate and then inseminate separately, the importance and economic significance of artificial insemination get reduced. Therefore, through artificial insemination technology increased number of females can be inseminated by a male.
Semen and its storage:
In addition methods have been developed to produce semen from male by ejaculation. Semen ejaculate is collected and diluted (extended). Sperm motility and there number per millilitre are examined under the microscope. About 0.2 ml bull semen contains about 10 million motile sperms. The diluted sperms may be used fresh within a few days or cryopreserved at -196 Degree Celsius by using liquid nitrogen. The cryopreserved semen can be stored for a long time and easily transported across states or countries. Thus cryopreserved semen of a single male is capable of inseminating thousands of females of a country or other countries. For example, one ejaculate semen of a bull is sufficient to inseminate about 500 cows.