Artificial Insemination
Artificial insemination (AI) is the most widely utilized ART in farm animal species, having revolutionized the sector over the twentieth century.AI is the most common method of breeding intensively reared domestic livestock, such as dairy cattle, buffalo, and pigs.
AI is increasing in horses, beef cattle, sheep, goat, and dog. It has also been employed on rare or endangered animals such as monkeys, elephants, deer, and wild felids in conservation breeding.AI is a process by which sperm is collected from the male, processed, stored, and artificially introduced into the female reproductive tract for the purpose of conception by using means other than sexual intercourse or natural insemination.
24.1.1 Milestones
| 1780 | Lazzaro Spallanzani reported the first successful use of AI in dog |
| 1922 | E.I. Ivanoff successfully conducted AI in cattle and sheep |
| 1940 | The scientists of Denmark introduced the straw method for packing of liquid semen. |
| 1940 | Philips and Lardy developed egg yolk phosphate diluter for preserving the fertility and motility of refrigerated bull spermatozoa. |
| 1941 | Salisbury et al. developed egg yolk citrate diluter |
| 1949 | Polge, Smith, and Parkes discovered cryoprotective effect of glycerol in frozen semen technology |
| 1960 | Adler first froze the semen packed in straws by using liquid nitrogen vapor |
| 1964 | Cassou developed the straws by reducing their size and named it as “medium French straw” (135 mm long and 2.8 mm diameter with 0.5 mL semen capacity) |
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| 1968 | Cassou further developed the straws by reducing their diameter for better freezing and named it as “mini French straw” (135 mm long and 2.8 mm diameter with 0.5 mL semen capacity) |
| 1972 | Simmet introduced a new straw called “mini tube” or “German straws” or “Landshut system” in Germany |
24.1.2 Procedure
24.1.2.1 CollectionofSemen
Artificial vagina method is commonly used for collection of semen in most domestic animals bull, ram, and stallion.
Artificial vagina consists of a greased liner placed between two outer jackets, with warm water filling the area between them. To create an environment like natural vagina, air is forced via the nozzle into the water jacket to build pressure in it, and the rubber liner is subjected to the same pressure. Male animals are allowed to mount either an estrous female or a phantom. The ejaculate is deposited into an insulated collecting vessel attached to one end of the artificial vagina liner. Also, electrostimulation and manual stimulation of ampullae of the ductus deferens through rectal wall are performed in boar or dog or in case of injured bull of high quality.24.1.2.2 Semen Processing
Despite its importance in stimulating spermatozoa in the female reproductive tract, seminal plasma is harmful to long-term sperm survival outside the body. If the semen is used for preservation spermatozoa become exposed to seminal plasma for a long time. So, semen extenders are added to the semen to dilute noxious elements in seminal plasma, to provide nutrients for the spermatozoa during in vitro storage and to buffer their metabolic by-products. Also, the use of extender allows the semen to be split into numerous semen doses, each carrying a definite quantity of spermatozoa optimum for a successful fertilization process.
24.1.2.3 Preservation of Semen
Cryopreservation of semen is routinely used in livestock breeding sector especially in cases of cattle and buffalo bull semen. Sperm cryopreservation helps in the propagation of animals with better genetic features and species conservation. The spermatozoa are combined with a cryoprotectant such as glycerol and a protective solution including lipoproteins, carbohydrates, and a cryoprotectant. These components aid in the preservation of membrane integrity throughout the chilling and rewarming processes. However, sperm motility must be maintained so that frozen spermatozoa can reach and fertilize the oocytes following insemination.
In some species, such as stallion, boar, and goat, semen, the seminal plasma, is extracted by centrifugation before combining with the cryoextender. The extended semen is packed in straws and frozen in liquid nitrogen vapor before being stored in liquid nitrogen.24.1.2.4 Estrus Detection and Ovulation
Estrus detection is critical if the female is to be inseminated at the correct moment, as a successful outcome of AI depends on the deposition of spermatozoa at a suitable time relative to ovulation. Males of the same species are naturally good at recognizing estrus females, but because many livestock breeding units do not have male animals nearby, it is critical that husbandry staff learn to recognize estrous behavior. Although certain domestic animals, such as dairy cows, have well-developed estrous behavior, others do not. Restlessness or increased activity, vocalization, chin resting, vulva swelling, vaginal discharge, and mounting other cows are all indicators of estrus in cows. However, these behavior vary between individual animal and breed.
24.1.3 Insemination
24.1.3.1 Recto-Vaginal Method
The AI gun is inserted through the vulva to the vagina and cervix with one hand in the rectum to guide the gun in proper place. The semen is deposited by pressing the piston of the gun. The gun is removed after depositing the semen in the cervix.
24.1.3.2 Vaginal Speculum Method
Vaginal speculum is placed in the vagina of the cow. Then inseminating tube is passed through the speculum and semen is deposited at the cervix.
24.2