CONCEPT NOTES ON ARTIFICIAL INSEMINATION-AI IN GOAT

CONCEPT NOTES ON ARTIFICIAL INSEMINATION-AI IN GOAT

In goat production, this technique has been limited to mostly dairy goat herds. However, meat goat producers have shown interest in learning this technique to accelerate genetic gain in their herds.

 

 compiled and edited by-DR. RAJESH KR. SINGH

Advantages of AI

• AI is the best way to spread elite genetic material throughout a population. Semen can be collected from top bucks, frozen, and then transported throughout the world where it can be utilized by large populations to facilitate progeny testing. Progeny testing involves breeding offspring to determine their genetic merit.
• AI helps producers to utilize their prize bucks that may be physically injured and unable to mate.
• AI allows producers to increase their herds without purchasing and maintaining bucks or losing them to predators, injury, or illness.
• AI is effective in controlling diseases.
• AI is an important breed preservation process.

Disadvantages of AI

• The technician must be well trained in the anatomy, function, and regulation of the doe reproductive tract to manipulate the reproductive function and estrus synchronization.
• AI requires special equipment and facilities.
• It requires a great deal of time to check heat that is crucial for a successful process. On average, a doe’s heat phase lasts for 12 to 48 hours.
• AI increases capacity to disseminate undesirable genes in a population.

The Doe’s Estrous Cycle

The doe’s estrous cycle is the interval between two estrus or heat periods that lasts an average of 21 days. The estrus or heat can last from 12 to 48 hours. During estrus does are receptive to being mounted by bucks. For artificial insemination, it is important to identify when a doe is in heat. Producers are encouraged to utilize teasers, usually a vasectomized buck to identify a doe in heat. The signs of a doe in heat are:

• Swelling of the vagina
• Seeking the buck
• Standing for mating by the buck, teaser, or by other does
• Frequent urination
• Flagging tail
• Vocalization
• Presents vagina with mucus discharge that appears crystalline at the beginning, but may have a cheesy appearance near ovulation time.

Steps to Conduct Intrauterine AI in Does with Frozen Semen

• Identify the doe in heat and certify the correct time for AI.
• For a better access to the doe’s cervical os, place doe in the stand, with the back legs up, raising its back and leaving its front legs in support and its neck and head toward the ground.
• If needed, wash the doe’s vulva with clean water to remove any dirt, and dry the area with a clean paper towel.
• Introduce the vaginal speculum and be sure to check for the appropriately-sized speculum. If needed, apply a nonspermicidal lubricant or petroleum jelly to facilitate the introduction of the speculum in the vagina. To introduce the speculum, open the labia of the vulva with one hand and with the other hand, gently introduce the thinner extremity of the speculum. As soon as it is introduced in the vagina, use a little pressure to orient the speculum toward and down to the vaginal floor. Use light source to visualize the cervical os. Be sure to distinguish the cervical os from the pleats of the vagina.
• Examine mucus consistency and, if needed, remove excessive vaginal mucus with the speculum.
• If it is time for AI ­ Determine which buck the doe should be inseminated to before thawing the semen.
• Thaw the semen. Prior to thawing the semen, use a thermometer to check for water temperature (95 to 98° F) before withdrawing the straw from the tank. Never lift a canister above the frost line of the tank. When the straw is removed with a forcep or tweezer from the tank it should be placed immediately in the thaw bath.
• Do not expose semen to direct sun light.
• Do not refreeze semen that has been thawed.
• Remove straw from the tank for periods as brief as 5 seconds. If you cannot remove the straw at the first attempt, lower the caner back to the bottom of the tank for at least 30 seconds before trying again. Stay out of direct sunlight because ultraviolet light has a spermicidal effect that will kill the sperm cells.
• Rapidly deposit the straw in the thaw bath to protect it from the sunlight.
• Warm the barrel of the straw gun.
• Dry the straw with a clean paper towel.
• Cut the correct extremity of the straw or the opposite side of the cotton plug.
• Insert straw into gun; be sure to protect the straw from the sunlight and extreme temperatures.
• Place the plastic sheath over the gun barrel.
• Return to the doe, introduce a clean vaginal speculum, and remove excess mucus.
• Introduce the gun into the vagina to the direction of the cervical os, passing the gun through cervical rings until it reaches the uterine lumen, the interior of the uterus. If the operator encounters resistance in accessing the interior of the uterus, deposit the semen in the exterior of cervix, and make a note of this in your records.
• Remove the gun speculum and leave the doe for a few minutes in the standing position before releasing her.
• Observe if reflux of the semen to the gun occurred.
• If possible, use a microscope to check for semen left in the straw. Check for sperm motility.
• Release the doe from the AI stand gently. Record information from empty straw before discarding.

Keep records of the following:

• Day and time of heat detection
• Date and time of AI
• Technician
• Doe and buck’s ID by breed and name
• Straw identification by date when semen was frozen and processor

 

Why should we adopt AI in Goat

1. Only method to have the cross breed of local and Beetal or Sirohi or selective breeding of prolific local goat which brings optimum economic benefits in commercial goatary production.
2. Shortage of male of superior genetic make up in the country for natural service. AI can help multiply the number of service in manifold from a valuable buck.
3. The farmer’s flock is small hence they cannot afford to bear the cost of maintaining the breeding buck.
4. Symptoms of heat are pronounced and it is easy to detect a doe in estrous.
5. Contraception rate are fairly satisfactory with A.I. technology in goat.
6. Considerable potential exist in obtaining two kids from each doe in 13-14 months. The post partum contraception rates with A.I. are quite satisfactory.

 

Reproductive behaviour of Goat

 

Breeding Season: The breeding activities in the temperate breeds generally occur in the spring / autumn season of the year. Most of the Indian breeds exhibit estrous( Heat) throughout the year.

 

HEAT SYMPTOMS IN DOE (female goat): Restlessness, off fed, frequent and peculiar type of bleating, frequent urination, flagging of tail, swollen valva, moist and pink vulval mucosa are few prominent sign of estrous or heat in female goat.

 

BEST TIME OF A.I.:

 

At the beginning of heat, very little mucus is present. As the estrous progress the mucus is transparent and observed in the floor of vagina. Towards the end of estrous it becomes cloudy which is the best time for breeding (24-30 hrs after onset of estrous or 24-30 hrs after showing the heat symptoms.). At the end of heat period the mucus becomes cheesy. While in case of cattle when the clear thick mucus is hanging from the valva to the floor is the best time for A.I. (16-18 hrs). Double insemination is also practiced in case of doe. First insemination at 24 hrs of onset of heat and second insemination at 12 hrs after first insemination.

 

 

Female reproductive cycle

 

Young female goats or doelings reach puberty at about 6 to 8 months of age and may be bred at 7 to 10 months of age depending on how they have been fed and grown. Puberty is the stage of sexual development at which the doe is capable of getting pregnant, if it is mated. Various factors affect the onset of puberty, including, healthcare, nutrition, season of birth and breed. Poor nutrition delays puberty; smaller breeds of goats attain puberty earlier; whereas kids born during the season when feed is plenty and of good quality attain puberty earlier. Breeding of does for the first time should be based on body weight as proportion of mature weight, and not age at which puberty is attained. It is recommended that young females should be bred after they have attained 60 to 70% of their adult weight to ensure kidding ease and avoid dystocia. Puberty is more dependent on body weight than age, so breeding should not be done until the right weight is attained.

 

The oestrus cycle

 

Once puberty is attained, the doe comes on heat (oestrus) at regular intervals thereafter. Oestrus is associated with the desire to be bred. This behavior (oestrus) is repeated at regular intervals, unless interrupted by pregnancy or disease, and this repetition is referred to as the oestruscycle. Therefore, the oestruscycle is defined as the number of days between two consecutive periods of oestrus. A healthy doe will come into oestrus every 20 to 21 days, except when pregnant. In different individuals and breeds, however, the oestruscycle length can range between 17 to 25 days. To help determine the oestruscycle length of each breeding doe, the producer should maintain a breeding diary or records. Good records are important for informing a breeding program, as they can help the breeder predict when a doe is likely to come on heat, and thus enable more careful observation for heat signs at that time. Additionally, good records will help determine if a doe has a problem, if she comes on heat too early, delays, or fails to come on heat at the expected time and she has not been previously bred.

 

When does are on heat, they exhibit various physiological and behavioral changes, referred to as signs of oestrus. These signs of heat are:

• Bleating continuously
• The vulva may become swollen, reddened and may appear moist, dirty or muddy due to mucus discharge from the reproductive tract
• There is frequent twitching of the tail
• She may urinate small amounts of urine frequently
• A clear, stringy mucus discharge may be seen from the vulva (may mat hair in perineal area)
• The doe displays restlessness
• She may mount other goats and stand to be mounted

The doe may not exhibit all the above signs, and under adverse conditions, such as extreme heat and injuries, may not show any signs at all. Standing to be mounted is the most obvious or accurate sign that a doe is on heat. Standing to be mounted will be enhanced in the presence of a buck. Does not in oestrus will always resist mounting attempts by the buck or other does. Standing oestrus in does may last for 12 to 36 hours.

 

 

Hormonal control of the oestrus cycle

 

Upon reaching puberty, every three weeks the doe’s brain signals the follicle in the ovary to start developing the egg. The signal from the brain is from the hypothalamus which releases the hormone Gonadotropin Releasing hormone, or GnRH. This hormone stimulates the pituitary gland at the base of the brain to produce gonadotropin hormones, Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH). Follicle stimulating hormone, as the name implies, initiates the development of follicles on the ovary from small pinhead sized structures to fluid-filled structures that are about half an inch in diameter. As a follicle grows in size, fluid accumulates in its cavity and secretes estrogen hormone. Estrogen is the female sex hormone. It is secreted into the blood stream and circulates throughout the body. Estrogen production is greatest when the follicle reaches its maximum size. High levels of estrogen act on the does’ brain resulting in the changes in the doe that are manifested as heat signs. It affects the nervous system causing behavioral changes such as restlessness, increased vocalization, twitching of the tail, lack of appetite, desire to mate by standing to be mounted, and also affects the reproductive system by increasing blood flow to the reproductive tract causing swelling of the vulva, reddening of the vulva, and the mucus discharge seen from the vulva during oestrus. Once estrogen levels from the mature follicle reach a certain threshold, they stimulate a peak release of LH (LH surge). The LH surge causes the mature follicle to undergo changes that result into its rupture and release of the egg. This rupture of the mature follicle and release of the egg is referred to as ovulation. After ovulation, the cells inside the ruptured follicle begin to grow and undergo changes (luteinization) under the influence of the gonadotropin hormone LH to form a gland called the Corpus Luteum (CL), the yellow body. The CL produces progesterone, the hormone of pregnancy. Its function is to prepare the uterus for accepting the fertilized egg, and to maintain pregnancy by preventing recurrence of the oestruscycle during gestation. If fertilization does not occur, the CL is destroyed at about 16 days after heat and consequently stops producing progesterone. Destruction of the CL is caused by the hormone prostaglandin F2α (PGF2α) which is produced by the inner wall of the uterus. The drop in progesterone concentration is consequently followed by a rise in gonadotropin release (FSH and LH), development of another follicle(s) and egg(s), and recurrence of heat about 20 to 21 days after the previous heat period. This cycle will continue throughout the reproductive life of the doe and will only be interrupted by pregnancy, disease, malnutrition or senility

When the egg is fertilized and accepted, the presence of the developing foetus in the uterus sends a signal to the dam causing the CL to remain active and produce progesterone for maintenance of pregnancy. This process is referred to as maternal recognition of pregnancy.

 

Heat detection

 

Heat detection is one of the factors that greatly determines the success or failure of any AI program. Under natural mating conditions, the buck accurately picks the does that are on heat, and if he is normal, promptly mates them. However, with AI, the inseminator replaces the buck. Therefore, for optimal conception rates to be achieved with AI, the doe has to be inseminated at the appropriate time, and thus it is important to recognize when a doe is on heat and to breed her at the right time. For a successful genetic improvement program and efficient delivery of superior genetics through AI service, good heat detection is therefore critical. It is recommended that a person be designated to observe animals in the herd for heat signs at least twice a day. Sufficient time (at least 15 minutes depending on herd size) should be allocated for the exercise, and it should not coincide with periods of activities, such as feeding, that would distract the attention of the animals. Preferably it should be done during the cooler parts of the day (morning and evening) when the animals are resting. Accurate heat detection greatly enhances the success of an AI program.

 

 Oestrus detection techniques:

 

• Having a buck in close proximity to the does. Does in heat are more easily identifiable if a buck is housed nearby. The signs of heat will be more intense, and she will pace restlessly along the pen in an effort to try and get to the buck or she will stand close to the fence with the hope of enticing the buck.
• • Time to observe heat.
• Animals tend to be more sexually active during the cooler parts of the day (around dawn and dusk) and this is a good time to observe for heat. Thirty minutes before morning feeding/milking and 30 minutes after evening feeding/milking should be used for heat detection. Putting a number of does together in one area or pen will facilitate the interaction between animals and make it easier to notice the heat signs. • Using a teaser buck. This is a buck that has been prepared in various ways so that he can be able to pick out does that are on heat but cannot be able to make them pregnant. A teaser buck could be an entire buck with an apron or whole penis has been deviated, hence is able to detect and mount does on heat but whose penis will be unable to enter the female genitalia; it could also be a vasectomized buck, who will detect does on heat, mount and copulate with them but is incapable of depositing spermatozoa into the female reproductive system. • Using a teaser with a marking harness. Markers will leave identifications on the ramps of does that stood to be mounted (were on heat). This way labor is saved as someone does not have to be with the herd to check for the does standing to be mounted. The marked does would be noted in the morning or evening each day. • Anticipate heat with records. Using well-kept reproductive records, it is possible to predict when the doe would come on heat, thus enabling closer observation.

 

The success of any AI program is largely dependent on three primary factors:

 

. Use of viable semen. This is achieved by sourcing semen from reputable sources and proper handling and use of semen and the liquid nitrogen tank. 2. Appropriate timing of insemination relative to oestrus. If the doe is inseminated too early (before ovulation) or too late (after ovulation), the result will be low conception rates. It is important to try and establish at what stage of oestrus the doe is in prior to inseminating her. This can be done by establishing when the doe was first seen on heat by critically interviewing the farmer/herdsman, and also by examining the mucus in the anterior vagina using a speculum and light source. Clear, thin, mucus is indicative of a doe that is early in oestrus. Cloudy mucus indicates a doe towards the end of oestrus. White or pale yellow thick/cheesy mucus indicates a doe coming out of oestrus. 3. Proper deposition of semen in the doe’s reproductive tract. During natural mating, semen is deposited inside the vagina next to or around the opening of the cervix. However, during AI, semen is deposited within the cervix or uterine body. Processed semen is diluted and a smaller volume is used. One of the reasons for low conception rates in goat AI is deposition of semen in the anterior vagina of the doe. Therefore, for good conception rates, the AI gun should be passed through the cervical opening (os cervix) for the semen to be deposited in the cervix or uterine body. Not every doe presented for AI must be inseminated. Only does that are in good health (body condition score of 2.5 to 3 on a scale of 1 to 5), are on a rising plane of nutrition, free from diseases, and good mothers should be bred using AI. Does that do not have regular cycles or those which are difficult to determine when or if they are in oestrus should not be bred by AI, but rather by natural mating.

 

 

Artificial insemination equipment

 

 

The following equipment and facilities are required for proper AI execution: • Breeding stand or facilities to restrain the doe. • Carrying case. A compact metal or plastic case for the safe and clean storage of AI equipment. • Artificial insemination (AI) gun. A goat length (usually 12 inch) device for delivering semen via a 0.25 or 0.5 ml straw. It can be disposable, or metallic for multiple use. • AI gun sheaths. They are sterile disposable plastic tubes that are applied over the AI gun to anchor the semen straw. • A light source which should fit in the vaginal speculum. It should generate little or no heat. A penlight could also be used. • Vaginal speculum (Figure 8). It is used to open the reproductive tract and together with the light source enables clear visualization of the opening of the cervix. • Liquid nitrogen tank (Figure 9). A large metallic vacuum flask for holding liquid nitrogen in which semen straws are kept for long term storage. Figure 9. Liquid nitrogen tanks. • Liquid nitrogen tank measuring stick. For accurate monitoring of the level of liquid nitrogen in the tank. Measure the liquid nitrogen at least weekly. • Straw tweezers. For retrieval of semen straws from the liquid nitrogen tank, and also from the thawing bath. • Straw cutter. It enables a square cutting of the tip of the straw so that it seats properly in the AI gun sheath for appropriate semen deposition. A pair of scissors can also be used. • Lubricant. For lubrication of the vaginal speculum prior to its insertion into the vagina. It should be sterile and nonspermicidal.

• Semen thaw kit or thermos flask with water thermometer, and a timer. It is for the proper thawing of semen at the right temperature. Figure 10. Semen thawing kit: Should consist of a thermos flask with warm water, a thermometer and timer. • Paper towels. For cleaning the vulva and drying the straws. • Records. Can be in the form of a book, card, or electronic. Records are important for assessing the reproductive performance of the does.

 

Artificial insemination step by step and critical points:

 

1. Ensure the presented doe is actually on heat. This can be established by a thorough discussion with the farmer or animal handler on what has been observed to warrant the animal being said to be on heat. 2. Great care should be exercised to ensure that all the AI equipment is as clean as possible. 3. Restrain the doe. It can be placed in the breeding stand, on a milking stand, or a similar elevation. The hind quarters could also be held up by holding the rear legs up with flexed hocks  to allow ease of access to the reproductive tract. Wipe the perineum clean and dry it. 4. Apply lubricant on to the speculum and insert it into the reproductive tract of the doe to check the nature of mucus in the vagina. The lubricant should just be enough and not too much. Too much lubricant may interfere with sperm movement in the reproductive tract.  Lubricated speculum in reproductive tract of doe. Vaginal mucus changes during heat. At the beginning of heat, very little mucus is present. As heat progresses, the mucus is transparent and found on the floor of the vagina. Towards the end of heat the mucus is cloudy: this is the best time to inseminate. The AI should be just before or when the mucus turns cloudy – usually 12 to 15 h after start of heat. If the doe is still on heat 12 h later, it should be bred again. At the end of heat the mucus is cheesy and white.   Oestrus mucus in the doe. 5. Identify the right canister (usually in different colours or numbers, denoting different bucks) with the cane with the required semen straw . Immediately place the straw in the thawing bath. Make sure the temperature is right (35 to 40°C). Thaw the straw for 30 to 45 seconds. Rule of thumb: higher temperature shorter time and vice versa. 9. Remove straw from thaw bath, wipe it dry, and shake the air bubble to the end of the straw that will be cut. Load the semen straw into a warmed, dry, clean AI gun. Pull the plunger back on the AI gun and place the straw into the gun with the cotton plug toward the plunger. After the straw has been secured in the gun, the sealed end of the straw should be cut at a right angle with a straw cutter or sharp scissors. Apply the sheath over the AI gun and secure it with the O ring. 15 A training manual on artificial insemination in goats 11. Slowly and gently insert the lubricated speculum and light source into the reproductive tract by using a twisting motion and slight pressure to visualize the cervix. The speculum may have to be moved slightly back and forth or sideways to identify the cervix, which looks like a small rosette-shaped
2. Press the speculum against the opening of the cervix (os cervix). With the aid of the light source, insert the loaded AI gun into the speculum and thread it into the cervix. Use circular motion and slight pressure to advance the AI gun through the rings of the cervix and place it as far as possible into the cervix (1 to 1.5 inches). Semen is best deposited deep into the cervix or uterine body. Where it is difficult to get through the cervix, such animals should be bred naturally.  Slowly deposit the semen by gently pushing the plunger of AI gun . If the plunger is pushed too rapidly some semen will remain in the AI gun. Insertion of loaded AI gun through the speculum. Remove speculum and AI gun. Discard the AI sheath. Clean the speculum in warm soapy water, rinse in distilled water or alcohol and air dry in a dust free environment
3. Fill in the records. Record the breeding information, which should include, but not limited to: date, identity of the doe and the buck used. It is advisable to leave the used semen straw with the farmer, preferably attached to the AI record card. Note: AI can also be done using fresh or chilled semen.

 

• Oestrus synchronization

 

• Oestrus synchronization is the manipulation of the estrous cycle of does so that many can come on heat at the same predicted time, or a doe so that she comes on heat at a predictable time. Advantages of oestrus synchronization include: • It improves the accuracy of prediction of oestrus as heat is expected to occur within a specified time period. • It makes heat detection easier as observation for heat signs can be concentrated at the specific period within which it is expected to occur, and not every day. This will cut down on the time and labor costs of frequent heat observation. • It improves the efficiency and cost of AI as many synchronized does can be inseminated at the same time by the same inseminator. When an AI technician serves many does in the same area around the same time this will cut down on the cost of each insemination due to economics of scale. The AI will also be more efficient as determination of the stage of oestrus in inseminated does can be more easily established than in those that come on heat naturally. • It can enable fixed-time AI. Oestrus synchronization, especially under intensive goat production systems, can utilize protocols that enable AI to be done at a specific predetermined time following a synchronization treatment irrespective of whether the does are seen on heat or not. This saves on time and cost of heat observation. • It can allow for clustered kiddings thus enable more efficient herd management and market access: • Several young kids born around the same time can be more intensively taken care of for limited periods, as opposed to all year round when kiddings are not controlled. • Kidding can be synchronized to occur at specific times to coincide with market needs for example when there is feed availability for the dam and young for milk production and growth, or market demand for goats. Different methods are available to synchronize oestrus in does. These include: • Use of exogenous hormones • The male/buck effect

 

Hormones for estrous synchronization

 

 

Two hormones, progesterone and prostaglandin F2α (PGF2α) are the primary hormones used for oestrus synchronization. However, other hormones such GnRH have been incorporated in various protocols.

 

 

Progesterone

 

It mimics the function of the corpus luteum by preventing hormonal activity that controls the estrous cycle. Progesterone blocks the secretion of FSH and LH from the pituitary gland and therefore follicles do not develop and grow on the ovary, consequently blocking the estrous cycle. It is administered for a number of days and then discontinued. Once discontinued, the block it had on FSH and LH secretion is removed. The decreased progesterone concentration results in the release of FSH and LH, follicular development and maturation in the ovary, and oestrus can be expected in 24 to 36 hours of removal. It can be administered as: • Vaginal sponge. It is put in the anterior vagina of the doe. • A Controlled Intravaginal Drug Release (CIDR) device. A CIDR is a plastic device that contains progesterone. These devices are usually used in conjunction with GnRH and PGF2α. The CIDR is inserted in the doe’s vagina for 8 to 17 days following the injection of PGF2α. As long as the CIDR is in place it releases progesterone into the bloodstream of the doe. When the CIDR is removed, there is rapid fall in progesterone level, much as progesterone falls in the normal cycle, and the does come on heat within 72 hours. • Implant. It is put below the skin in the ear or tail.

 

Prostaglandin

 

F2α for oestrus synchronization It causes regression of the CL, resulting in removal of the negative block progesterone has on FSH and LH release. When this progesterone block is removed, follicles develop, mature and the does come on heat within 36 to 72 hours of administration. It is given as an injection. It is cheaper than using progesterone. However, it only works when there is a responsive CL on the ovary, and this limits its use as there are periods within the estrous cycle when it will not be effective. Two doses of PGF2α 11 days apart will synchronize a group of does. Prostaglandin has to be used with care as it can cause abortion in pregnant does. The male/buck effect for oestrus synchronization The buck can be used to stimulate oestrus activity in does that have been previously isolated from bucks. After a period of separation, the buck is suddenly introduced into a group of sexually mature does. Many does may come into heat within 3 days of buck introduction.

Reference – on request