Artificial Insemination in SwineTamuli1, M.K. and Kayastha2, R.B.

National Research Centre on Pig, ICAR, Rani, Guwahati-781 131

Artificial insemination (AI) provides unique opportunity for the genetic improvement of pig industry. The rate of genetic progress is a direct function of selection intensity. Selection intensity is maximum through AI since the best sires available within individual breed are used for the purpose of genetic multiplication. Because of careful selection of boars, AI offers the most economically sound method of maintaining genetic variability in a positive direction. With all known advantages, AI requires optimum management for optimum results. To get optimum result through AI, the technician should be knowledgeable, observant and patience and should complete the AI procedure cleanly, accurately and completely and should possess patience and perseverance to perform hygienic AI for optimum conception. Training boars for semen collection:

Boars are to be selected from genetic point of view based on their pedigree records at the age of 5 to 8 months depending on the breeds. Although older boars that may have been used for natural service may also adapt to collection of semen over a dummy sow after proper training. The selected boars must be housed individually in individual pens. After 15 days of their separation, they are exposed to training with the dummy. With regard to training the boar for semen collection, the key word to be followed is patience. Allow sufficient time for introducing the new boar to the collection area and let him investigate. As soon as the boar identifies the dummy, some will readily mount over it. If the boar has mounted the dummy, the boar should then be approached quietly from the rear without being touched or frightened. Gently reach around to the boar’s prepuce and massage the prepuce in an attempt to stimulate pelvic thrusting. Once the boar protrudes his penis, digital pressure to the curled tip of the penis. If properly stimulated, the boar should fully extend his penis and become very quiet when adequate pressure is applied. Once the boar has extended his penis, thrusting ceases, and the boar starts to ejaculate. Consequently, if mounting or an interest in the dummy has not occurred, the boar is then removed from the collection pen and needs to try on next day.Semen collection and processing:The semen collection is done in the prewarmed thermos flask at 370C. The sago like gel mass which is a portion of semen is separated on the sterile Buchner funnel fitted with a miracloth. The semen is ejaculated in three phases and each phase consist of three fractions: pre-sperm, sperm rich and post sperm fraction. Pre sperm fraction is watery copious discharge and post sperm usually the gel mass while sperm rich, the middle fraction is rich in sperms. Each phase of ejaculation is differentiated with a pause of silience without any action and if digital pressure is intermittently maintained constantly, ejaculation promts vigorously. Better is the digital pressure maintained throughout collection, maximum is volume of semen is expected to achieve. Semen can be collected with or without a hand glove. However, to avoid contamination of glans penis, the crok screw portion, it is essential to dip the palm and fingers in 1:1000 Potassium permanganate solution every time before the penis is hold. Ejaculation time usually extended from 5 to 30 minutes depending upon the volume ejaculated and age of the boar with higher volume.

Figure 1: Semen collection over dummy

Processing of fresh semen:After collection of semen, it is necessary to evaluate the ejaculate to determine

how many doses can be made. Standard tests currently used to evaluate boar semen include sperm motility, sperm morphology and sperm concentration. Routine examination of AI boar semen quality is very important because their impact on herd reproductive efficiency is increased many folds when compared to natural mating.Minimum values of fresh, unextended boar semen for use in AI:

Appearnce: Milky to creamy consistencyColour: Gray-white to white in colourTotal sperm number: >15x109 sperm/ejaculateGross Motility (unextended): >80%Abnormal morphology: <15% (includes mainly cytoplasmic droplet)

a. Sperm motility: Motility involves subjective estimation of the viability of spermatozoa and the quality of the motility. Light microscopic analysis of sperm is most commonly used. Evaluation of sperm motility is conducted with raw and extended semen. Measuring motility in the raw form can be hampered by higher sperm concentrations making it difficult to discern individual motility patterns. To overcome this limitation, an aliquot of semen should be extended in a good quality extender.b. Sperm morphology: Every semen sample contains some abnormal sperm cells. Morphological abnormalities of sperm have the greatest relationship to fertility of livestock. In case of boar, the percent of sperm possessing an intact acrosomal membrane is regarded as an important parameter of semen quality.c. Sperm concentration: Accurate determination of the number of sperm and volume of the ejaculate determines how many females can be inseminated. Concentration is measured using a hemacytometer. A hemacytometer is a microscope slide with precisely scored chambers. The number of sperm per chamber are manually counted. This is very time consuming, however, it is very accurate. The concentration in the sperm rich fraction of the boar sperm approaches 6-10x108 sperm/ml with final concentration due to total volume being lower.

Semen extension, preservation and AI:Based on the motility and concentration of spermatozoa, semen is so extended in

suitable extender (GEPS/BTS). 80-100ml volume of extended semen contains at least 2.5 to 3.0 billions of sperm for insemination of sow or gilts. Extended semen is preferably preserved at 13-150C up to 96 hours.

All prospects to be bred should be observed for signs of standing heat twice daily. The symptoms of onset of heat are restless, loss of appetite, trying to ride other sows, reddening and swelling of the vulva and a clear discharge from the vulva. All symptoms may not appear on all animals. Usually, sows will express sign of standing heat after 24 hours after symptoms appear.

Figure 2 Redding of vulva in estrus sow

When to inseminate: Successful AI in swine is influenced by the variation that exist in the onset of heat after weaning, duration of estrus and the time between estrus and ovulation. Gilts and sows should be bred 12-24 hours after they are found in standing heat. A second breeding should follow 12 hours later.

Figure 3 AI in an estrus sow

Insemination technique:In every facet of the AI procedure, the technician must be clan or performance

may be hindered. Accuracy of entry and semen placement is areas in which the qualified technician can definitely excel the capabilities of the boar. The technician should invert the semen dose several times slowly to mix the semen. The sterilized catheter should be swabbed with Povidine Iodine to check the sterility. After that end of the catheter is lubricated before hand with non-spermicidal K-Y jelly (Johnson & Johnson). The vulva is wiped clean and the vulva lips are opened to allow the catheter to be inserted in an upwards/forwards motion. The technician will feel the end of the catheter lock into the cervix. Attached the semen dose to the catheter and allow semen to flow by gravity into the female. Make sure the sow is being stimulated during insemination by gently rubbing her underline and lower flank region may help her receptiveness. This will promote uterine contraction, helping to move the semen from the cervix to the oviducts for fertilization of the ovum. Carefully, when the semen pouch becomes empty, not to allow any air to enter the cervix. It is better to leave a little semen in the catheter than to risk air entering. If air enters, it will push semen out of the sow. After finishing insemination, catheter should remove slowly.

Figure 4 : AI born piglets

One necessary part needed for AI on the swine farm is a microscope so that semen can be evaluated and monitored before preparation of insemination. It is essential to keep good breeding records so that important breeding parameters can be maintained. The final and most important part needed to become successful in AI is experience.References: Hafez, E.S.E. and Hafez, B. ‘Reproduction in Farm Animals’. Seventh Edition; Blackwell Publication. Pg. 376-389.Johnson, L.A. and J.G. Aalbers, 1984. Artificial insemination of swine: Fertility using several liquid semen diluents. VIIIth International Pig Veterinary Society Congress. Page293.Timothy, G. Page. ‘Artificial Insemination’. Issued in furtherance of Cooperative Extension work. Pub. 2713(500)7/98.

Note: 1: Principal Scientist, NRC on Pig, ICAR, Rani, Guwahati-781 131(India)2: Senior Research Fellow, NAIP project NRC on Pig, ICAR, Rani, Guwahati-781 131(India)