Artificial Insemination in Goats
The training took place at Egerton University on the 13th – 15th of November, 2013.
The training started on a very high notch with the conduction of artificial insemination in dairy goats at the Dairy Goats Improvement Centre under the supervision of Dr. Terry Gipson of Langston University, a specialist with considerable experience in goat breeding.
Slaughtering of a doe
A doe (female goat) was slaughtered to demonstrate the basic female reproductive anatomy and physiology. The average length of the estrous cycle of goats is 21 days, with a normal range of 19 to 23 days. Estrus is basically the period in which the doe is sexually receptive to the buck (male goat). Does are approximately I estrus for 24hours and ovulate at the end of estrus.
The reproductive tract of the doe consists of several structures. The ovaries are the primary sex organs of the female. Its function is to produce ova and secrete the female reproductive hormone called estrogen. The fallopian tubes are site for fertilization.
They transport ova, sperm and zygote to the uterus. For both the ovaries and the fallopian tubes, there are two uterine horns but they connect to a single uterine body. The uterus is a site for embryonic implantation and fetal development.
The cervix is a muscular body consisting of several cervical rings made of cartilage. The opening of the cervix is called the OS cervix. The cervix is a gateway to the uterus. During estrus, the cervix secretes thin, clear mucus that changes consistency, elasticity and colour as estrus progresses. The vagina is the organ for copulation. Its function is to receive semen during natural mating.
Hormones involved in the estrus cycle
The estrus cycle is controlled by hormones secreted by the hypothalamus, the pituitary and the ovaries. Gonadotropin Releasing Hormone (GnRH) is produced in the hypothalamus of the brain and controls the release of two Gonadotropin hormones from the pituitary glands.
Follicle Stimulating Hormone (FSH) is produced by the pituitary gland and stimulates follicle development and estrogen production. Luteinizing Hormone (LH) is produced by the pituitary gland and triggers ovulation and is necessary for development and maintenance of the corpus luteum.
Estrogen is produced by the ovarian follicles. It causes sexual excitability, increases fluid production and muscular contractions of the reproductive tract, and triggers increased release of LH.
Progesterone is produced by the corpus luteum. It prevents further estrus during pregnancy and maintains pregnancy. Prostaglandin is produced by the uterine wall and causes regression of the corpus luteum when pregnancy does not occur.
The estrus cycle
Day 1 of the estrus cycle is called the estrus.
This is the period when the female is most sexually receptive, due to high levels of estrogen. An Increased estrogen levels bring about a surge of LH, which triggers ovulation towards end of estrus.
Days 2-5 of the cycle is called the metestrus and is the period when the corpus luteum forms and begins to produce progesterone.
Days 5-18 of the cycle is called diestrus and is the period when the corpus luteum is highly active in its production of the progesterone. If pregnancy occurs, the corpus luteum is maintained and further estrus is inhibited. If pregnancy does not occur, prostaglandin from the uterine wall causes regression of the corpus luteum.
Days 28-21 of the cycle is proestrus and is the period between the regression of the corpus luteum and estrus, when follicles development is occurring and estrogen production is increasing.
For artificial insemination, possibly the most important sign of estrus is the change in consistency, elasticity and colour of the vaginal mucus.
This is assessed by examining the mucus located in the anterior portion of the vagina. Mucus that is thin, watery and clear is an indication that the doe is too early in estrus for a properly timed insemination.
Mucus that is thick, pasty and white or pale yellow is an indication that the doe is past her proper time. Other signs of estrus include; increased vocalization,, increased vaginal mucus discharge, decreased milk yield, increased urination, tail wagging, swollen vulva e.t.c.
How to determine scrotal circumference
On the same line, the participants were taught how to determine the scrotal circumference of a buck. Scrotal circumference has been viewed to be the most controversial component of the BSE; this is because, scrotal circumference is highly correlated to testicular weight which in turn is highly correlated to sperm producing capacity. Generally, each gram of testicle produces 15 million sperm per day making it a total of at least 6billion sperms produced from both testicles a day.
Collection of semen
At this stage is when the participants were taught how to collect semen from the buck using the artificial vagina (AV). Due to the fact that a male is supposed to service a number of females, determining the potential fertility of the male is much more important than determining the fertility of any individual female.
First and foremost the participants were taught on how to conduct a Breeding Soundness Examination (BSE). This examination mainly gives the processor the opportunity to screen bucks.
They were taught on how to conduct physical examination on the bucks. This included evaluation of testicular consistency and scrotal shape, examination of the sheath, prepuce and the penis. Testis ought to be firm with a slight spongy feeling.
Mushy testis or enlarged epididymis could be a sign of infection or other abnormalities. Some scrotal shapes can affect sperm production.
The collection of the semen is done by the use of an AV. The AV uses thermal and mechanical stimulation to stimulate ejaculation. It is about 2cm in length and has an inner diameter of about 6cm. it has an inner rubber liner.
A latex rubber collection cone is placed in the AV and a graduated collection tube is placed at the end of the cone. The buck is then brought for semen collection by allowing him to mount the doe in estrus.
The doe is restrained so that the buck can become aroused and can mount her; this is because the doe emits a smell when in estrus that excites the buck and cause it to give a better ejaculate.
The doe is tied or held and the buck is allowed to go through his courting behaviour. The buck is then allowed a few false mounts, which in turn gives an increased ejaculate volume.
It takes two people in close proximity to the buck to perform a collection; one to semi- restrain the doe and the other to direct the penis into the AV. The collection tube containing the ejaculate should be protected from direct sunlight and cold temperatures.
Extension of semen
After collection of the semen, the team went further to extend the semen. The main reason as to why the semen was extended was; to provide nutrients as a source of energy; provide protection against the harmful effects of cooling, provide a buffer to prevent shifts in pH as lactic acid is formed.
To maintain the proper osmotic pressure and electrolyte balance; to inhibit bacterial growth; to increase the volume of semen so that multiple inseminations could be performed and to provide an environment in which metabolic activities of the sperm could continue.
In our scenario, a solution of skimmed milk, water and penicillin was used as an extender.
The water must boil to 95o C. After thorough mixing water and the skimmed milk, the antibiotic was added, mixed thoroughly. Thereafter, the solution was added to the collected semen. With this done, the semen was ready for artificial insemination. The extended semen is to be used within 24hours; this is because the extender slows down the rate of metabolism. If the semen is not extended, it can be used between 3- 4 hours because the semen is still very active.
Artificial Insemination
Artificial insemination is a simple technique that, when performed with skill properly founded on knowledge, offers ease of use and a good level of success. However, results can be discouragingly poor for an inseminator lacking knowledge and the necessary attention to details needed for a successful outcome.
Proper restraint of the doe is necessary to ensure the safety of the doe and the inseminator during the insemination process. The doe should be comfortable and should experience a minimum amount of stress. Excessive stress can have adverse effects upon the success of the inseminating event.
Restraining the doe in a vertical plane is a desirable option. An assistant is essential for restraining the doe. He or she stands with the doe’s neck between his or her legs, which act as a head gate. The inseminator lifts the hind legs of the doe and the assistant grabs the cannon bones just below the hock on both hind legs.
In twisting his or her hands slightly inwardly, the assistant will allow the stifle of the doe to rest on his or her forearms. The majority of the weight of the goat is then on the forearms of the assistant.
Determining the proper time to inseminate is not only critical with regard to the condition of the spermatozoa and ovum when they come in contact with one another, but is critical to facilitate proper placement of semen in the reproductive tract. It is necessary that proper timing be achieved to allow the artificial insemination gun to penetrate and traverse the cervix prior to semen deposition. A properly timed procedure should allow for relative ease in manipulating through the cervical rings.
Semen should be deposited within an approximation of like timing to the occurrence of ovulation. Ovulation occurs just before or shortly following the end of the doe’s standing heat. Once the men is properly deposited
Artificial insemination in goats is not as easy as one may think, it requires patience. Going by the words of the course- co-coordinator, Dr. Terry Gipson, the participants had every reason to be a happy lot. They were humbled by the coordinators comments of them being the best group that he has ever trained since time immemorial. The participants were an articulate lot with excellent skills of milking the semen in the AV. T o say the least , they were being taught by an expert with a wide experience in goat breeding, and yes the participants too did were too sharp, gaining all the skills and expertise on the first day of the workshop.
They were very patient, bearing in mind that the task of A.I in goats is not an easy one as one may perceive. You might be prompted to think that A.I in goats is an easy task, but wait till you do it, then you will get to know how the participants were very patient making the achieved results to be of an excellent nature.
