Artificial insemination has grown to be one of the greatest biotechnologies applied in the agriculture industry throughout the world. The method of reproducing offspring without the natural actions of mating has become one of the most significant programs for livestock improvement. This process has become very successful and widely used over the years in all parts of agriculture and has helped agriculture grow into a productive and reliable industry.
The first successful documented experiment of artificial insemination in animals was performed by Lazzaro Spallanzani, who was an Italian physiologist, in 1780. While Spallanzani was investigating reproduction, he refined a technique for artificial insemination. Spallanzani performed this experiment on a dog, which successfully birthed three pups sixty-two days after the procedure. There were efforts of making artificial insemination a practical procedure in Russia by Ivanow in 1899. By the year of 1907, Ivanow greatly studied artificial insemination in domestic farm animals, dogs, foxes, rabbits, and poultry. He was able to develop semen extenders and trained technicians to carefully select superior males to multiply their offspring using artificial insemination. By 1938 an abundant amount of artificial insemination work in Russia was taken over by Milovanov. In his workshop, Milovanov designed and developed practical artificial vaginas, by which semen is obtained directly from the bull preventing contamination of the semen.
In 1938, a group of dairymen in New Jersey organized and developed the first cooperative in the United States for the artificial insemination of their cows. After the invention of the artificial vagina came the development of the rectovaginal insemination technique, which permits the placement of semen into the cow’s cervix or uterus and improves the conception rate. The development of the yolk-phosphate diluent made it possible for semen to be stored for as long as two days without seriously effecting the sperm’s fertilization ability. One of the newest developments is the freezing of semen, this technique makes it possible to store diluted semen for an indefinite period. The improvement of semen diluents, methods of handling, and insemination techniques have enabled most studs to maintain breeding efficiency equal to or even slightly higher than natural service.
Before this improvement, the shortcoming of artificial insemination was that a sire could only be made available to dairymen for only two days out of each week. The collection of semen from the bulls was done in weekly intervals, and satisfactory fertilizing capacity could not be maintained for more than two days. The method of freezing bull semen without destroying its fertilizing capacity is done by adding glycerol as a protecting agent, then freezing, and storing the diluted semen at very low temperatures. The method of freezing semen makes it possible for agriculturalists to have semen from the desired bull wherever and whenever they need it. By 1961, an estimate of 40 percent of all artificial inseminations in the United States was carried out using frozen semen. The advantages of frozen semen are usually only seen by agriculturalists that breed large amounts of cows.
Early work began in the United States by Mckenzie starting in 1931. He designed an artificial vagina for boar semen collection this provided a means for applying pressure to the glans penis or a gloved hand can be used directly. The artificial vagina consists of a soft rubber tube that is 16 inches long. One end is fitted over the mouth of the test tube and the other end is fitted over a 1 5/8-inch key ring. The test tube should be large enough to hold at least 55 ccs. of semen. Mckenzie trained many early reproductive physiologists and attended animal science meetings even after retiring. Hudjahov devised another type of model of the artificial vagina, which closely resembled the one used for cattle, in 1936. It consists of an ebonite cylinder provided with valves that regulated the pressure and an inner rubber chamber. In addition, there is a rubber tube that is 180 mm. long and 88 mm. wide that connects with a semen receptacle of 500-800 cc. capacity. According to Hudjahov, this newly developed model overcomes two deficiencies that the old model had. It is larger and has facilities for keeping the boar’s penis warm during collection and consists of a pressure control feature. There was another type of artificial vagina that was improvised by Mckenzie and Lasley in 1940. It consists of an inner tube that is 1 5/16 inches in inner diameter and 1 3/8 inches in outer diameter, it also has an outer rubber casing that ranges from 12-15 inches. The semen is collected into any convenient class receptacle preferably a test tube that is 50 cc.
For a successful insemination of a sow, the second day of heat is considered the best time for the insemination procedure. Reported by Anderson in 1937 ovulation in sows begins about 24 hours after the onset of heat and is completed in 30 hours or at most 38 hours after the onset of heat (Herrick, 1950). The insemination technique of sows according to Mckenzie and Lambert in 1940 is that before the sow is brought to be inseminated all apparatus should be placed in a convenient place. Herrick (1950) states that according to Mckenzie and Lambert The sow should be placed in a crate or breeding chute or tied to a wall by means of a’ rope about her upper jaw and should, of course, be at the proper stage of oestrus. When the sow is ready for the insemination process and the equipment is prepared the tube is to be pushed forward into the cervix and the semen is slowly expelled. In 1936 Hudjakov described a special contraption for creating injections which It consists of a 600 cc. glass cyclinder which is firmly fixed in a wooden stand. The lower end opens into a rubber tube which is attached to a glass tube in the vagina of the sow. (Herrick, 1950) The semen will then go into the vagina because of the pressure that is created from the different levels of the fluid and the absorbing capacity of the uterus.