Artificial Insemination (AI)
by Haenlein, Cassese and Smith,
About the Authors
1) Is AI For You?
If you have a few backyard does that you enjoy as a hobby, with
little concern for genetic improvements of their offspring, then
artificial insemination (AI) is probably not for you, assuming a
suitable buck can be located for servicing the does. The expense of
purchasing the necessary equipment and learning to do AI are likely not
worthwhile. However, if there is an experienced inseminator in the area
who is willing to work with your goats, then this may prove to be a
viable alternative and certainly is much simpler than hauling your
does in heat to the buck's home.
2) AI has some key advantages over natural breeding.
- 1) It eliminates the necessity of keeping one or several bucks on
the farm (depending on herd size). Costs of feeding, housing, separate
fencing and labor are eliminated. However, heat detection may be more
difficult in the absence of a buck.
- 2) AI can increase the rate of genetic improvement in an herd, as
long as superior bucks are consistently selected. In natural service,
the prospective breeder has only the buck's pedigree to rely on,
whereas AI bucks should be progeny tested for their transmitting
ability of milk and fat percentage, weight gain, type conformation,
etc.
- 3) AI allows breeding of different portions of the herd to
different bucks. Young does may be bred to not yet proven but high
potential bucks, while the majority of the herd can be bred to proven
high quality bucks.
- 4) AI permits breeding of many does on one day when synchronization
is practiced. No long drives to top bucks are involved.
- 5) The danger of transmission of diseases or parasites is greatly
reduced. (The transmission of diseases through frozen semen needs
further study.)
- 6) The time of breeding can be more carefully regulated, and the
owner knows exactly when the doe was bred, as opposed to pasture
servicing by a buck that is allowed to run with the herd.
- 7) AI induces good recordkeeping of dates of heat, breeding,
pedigrees, etc. This will aid in herd improvements and enable the owner
to make better culling decisions.
3) Once the decision to use AI has been made, the next step is to
determine whether to do the inseminating yourself or pay someone else to
do it. If there are only a few does in your herd, and an experienced
inseminator of goats is available, then it may be more practical to pay
to have the service done. However, if the number of does in the herd is
rather large, or an experienced inseminator is nowhere to be found,
then its probably time to learn how to practice AI techniques yourself.
4) AI technicians of the cattle industry may not necessarily be of
much help when it comes to inseminating goats, for the modern method of
inseminating cattle (rectal palpation) differs from that of breeding
goats (speculum method) considerably. The speculum was used on cattle
early in AI history, and some cattle inseminators may be capable of
teaching goat insemination.
5) The cost of getting started in AI, not including semen purchases,
will generally run around $500, of which $400 to $450 is tied up in the
liquid nitrogen tank, which is necessary for storing semen any length
of time. Temperatures must be kept at -320F (-196C) for sperm survival
to be maximized at breeding time. It may be possible to share the cost
of the tank with neighboring goat owners or dairy farmers, thus
alleviating some initial costs of an AI program.
6) If AI is to be used with any hope of achieving a good level of
success must be known and well understood by the prospective inseminator.
1) basic knowledge of the doe's reproductive organs and their
functions;
2) understanding of storage and handling of semen;
3) ability to use, in a proper and sanitary manner, the equipment
required for inseminating goats;
4) ability to accurately detect heat at an early stage;
5) necessity of keeping accurate, up to date records of heat
cycles, breeding, kidding, reproductive problems, treatments, and
any other pertinent information that may reflect on the goat's
reproductive patterns.
7) Reproductive Organs and Functions
The two ovaries are the sites of egg formation. They produce
estrogens and progesterone, and as such are determining factors of heat
cycle, ovulation and pregnancy. Basically the estrus (heat) cycle in
goats operates as follows:
- 1) Proestrus is the time of follicle growth. As an egg (ovum)
begins to mature in an ovary, it becomes surrounded by a fluid filled
sac on the outside of the ovary, much like a blister forms on the
skin. This growth is accompanied by increasing levels of estrogen in the
blood.
- 2) Estrus - As estrogen levels peak, the doe will come into heat.
This can be observed by changes in behavior (increased bleating and
restlessness), willingness to be bred, and the swelling of the external
genital area. The period of ''standing heat'' (acceptance of the buck)
will generally last for 24 to 36 hours.
- 3) Ovulation, or the release of the egg, is accomplished by the
rupturing of the follicle, expelling the egg from the ovary, and
receiving it into the oviduct via the fimbria funnel. This occurs very
near, or soon after, the end of standing heat (6 hours before to 12
hours after). Egg life is 12 to 24 hours, while the sperm lasts 24 to
48 hours.
- 4) Metaestrus - in this stage, the ruptured follicle is undergoing
cellular differentation to form a functionally important tissue mass,
the corpus luteum (yellow body). This structure is responsible for the
secretion of progesterone, a hormone which prevents the development of
another follicle and prepares the uterus to receive a fertilized egg.
- 5) Diestrus - is the longest period of the estrous cycle in does.
During this period of corpus luteum influence, two events may happen:
- a) if fertilization of the egg occurred, the corpus luteum will
persist for the entire gestation period, preventing follicular
develop ment and keeping estrogen levels low.
- b) if no fertilization took place, the progesterone secretions of
the corpus luteum gradually lessen, allowing a new cycle of
follicular development to begin, with a corresponding increase in
estrogen levels. The length of time required for one estrous
cycle without fertilization, ranges from 17 to 24 days in goats,
with the majority taking 21 days. Shorter cycles are not
uncommon (5-10 days).
8 The egg, after being expelled from the ovary, passes into the
oviduct via the infundibulum, and toward the cornua (horns) of the
uterus. This movement is produced by wave-like motions of the ciliated
(hair-like projections) cells of the oviduct. Sperm and eggs meet in
the oviduct and fertilization occurs in the middle to upper one third of
the duct.
9 The egg continues into the horn of the uterus, where, if it has
been fertilized and undergone several cellular divisions, it will
become attached to the uterine wall. If no fertilization has occurred,
the egg will degenerate and the cycle goes on.
10 The cervix of the uterus plays a key role in artificial
insemination, as it is the external entrance to the uterus which must
be located and penetrated with the inseminating instrument. The cervix
is normally tightly closed, except during periods of heat or kidding.
Semen is deposited on the vaginal side of the cervix in natural
services, but AI requires the deposition of semen in the uterine side
of the cervix. This is because of the greatly reduced volume of semen
that is used in AI. If the 0.5 to 1 cc of semen in AI were deposited
on the vaginal side of the cervix, there is a good chance that none of
the sperm would reach the egg.
11) The vagina serves as the connecting tube between the uterus and the
outside opening, the vulva. It is part of the birth canal, and also
contains the urethral opening, from which urine will pass during
emptying of the bladder.
12) Purchase and Preparation of Semen
In most cases, the inseminator will acquire the semen needed by
direct purchase from a commercial operation, in which case it will be
shipped to the inseminator. It is of the greatest importance that the
semen be transferred to permanent storage (the liquid nitrogen tank)
without exposing it to anything approaching air temperature.
Generally, this means transferring the container element which houses
the semen directly to the liquid nitrogen tank. Here it can be safely
stored for long periods of time, since biological activity practically
stops at liquid nitrogen temperatures (-320F). Semen is generally to be
used within 6 months, but conceptions have resulted from semen stored
for several years, although sperm survival is decreased, resulting in
lower conception rates.
13) Semen Collection
Bucks are handled basically the same way as bulls for semen
collection. Three basic methods may be employed, but all three require
an artificial vagina, a double walled device with an opening at one
end and collection tube at the other. The inner lining holding warm
water should be coated with a light application of water soluble
lubricating jelly. The three methods are:
- 1) A buck may be allowed to mount a doe, with the semen collector
manually diverting the buck's penis into the artificial vagina (ram or
dog size). Don't touch the penis directly, instead direct the penis into
the artificial vagina by grasping the buck's sheath. After ejaculation
(usually 0.5 to 1.0 cc) has occurred, remove the artificial vagina and
tip it so that the semen will all run into the collection tube. This
method may require practice and adjustment by both the buck and the
collector before good samples are collected.
- 2) A buck is trained to mount a dummy instead of a live doe. The
same procedures are followed for sample collection. Mounting may be
facilitated by applying vaginal mucus scrapings of a doe that is in heat
to the dummy, at least during the training process.
- 3) Use of electro-ejaculation. The buck is not required to mount an
object, although an artificial vagina should still be used for semen
collection. An electrode unit, which has a number of contact rings, is
inserted into the buck's rectum. Slight electric stimulation brings on
ejaculation. This technique generally results in good samples in
quantity and quality. However, the sperm concentration of the sample
will be lower. This method does not require extensive training, and
will allow collections from bucks that may refuse or are unable to
mount and serve an artificial vagina.
14 Semen, once collected, may be used in one of three different ways:
- 1) As liquid semen, directly or on the same day one ejaculate can
serve 3 to 5 does. If kept at body temperature, the semen may be good
for three hours.
- 2) Semen may be stored 24 to 48 hours by placing the collection tube
in a container of water and putting this unit in a refrigerator. No
diluter is needed, although plain egg yolk can serve as simple extender
to double the number of does that can be served.
- 3) Semen that is to be stored for longer periods of time must be
mixed with a diluter and very carefully frozen. A commercially prepared
diluter extender, such as Ortho Semen Diluter is desirable, although
plain milk can be used successfully also. Following are steps in semen
extending:
- a) with a commercial preparation, use a diluter to semen ratio of
19:1, adding the semen to the diluter, and rolling the bottle gently
to achieve a thorough mixing. The semen and diluter should be at the
same temperature. This mixture can be stored in the refrigerator and
used for a week, or slowly cooled and stepwise frozen for storage in a
liquid nitrogen tank for later insemination.
- b) for a homemade milk diluter, it is best to use fresh 3.5
pasteurized, homogenized whole milk. It must be heated and held at
210F for 10 minutes in a glass boiler, keep the lid in place so that no
moisture is lost. Next, the milk is cooled in a water bath with the
lid on. When the milk is in equilibrium temperature with the water
bath, the water condensation on the inside of the lid is shaken back
into the milk. To every 400 cc of milk, add 100,000 units of potassium
G crystalline penicillin and 500 mg crystallin di-hydrostreptomycin
sulfate, mixing well. Warm this diluter to about body temperature
before adding the fresh semen at 19:1 ratio. Place the diluted semen
in a water bath at body temperature of 101F and allow to cool slowly.
Semen may be frozen, if the extender contains an antifreeze compound,
slowly, stepwise for storage on dry ice or in liquid nitrogen.
15) A microscope, capable of 900x magnification is an essential tool
when doing your own semen collection in order to determine semen
quantity and quality. First, place a semen sample on a clean slide and
cover with a coverslip or another slide. Set the magnification to 400x
and observe the appearance of dark patches or spots thru the scope;
four dark areas or more per microscope field represent high
concentrations of sperm, a really good sample. Three dark areas is
somewhat chancy for use at a diluted service, but is good enough for
natural service. Two dark areas should be used only for natural
services and one dark area means that the concentration of sperm is too
low for even natural service.
16) Switching to 900x, the sperm cells can be individually observed for
normal structures. Diluting in warm saline is helpful. Coiled tails,
broken tails, absence of tails and abnormal shapes all constitute
deficient sperm cells. Sixty to 70 2.256835e+199ood motility before freezin
should be observed in a good sample, with a minimum of 30motility
after freezing and thawing. Any insemination program, no matter how
carefully carried out, will yield poor results if the concentration and
quality of the collected sperm is not of high standards. Sophisticated
techniques of washing the sperm free of seminal plasma before extending
and freezing will improve post-thaw viability.
17) The concentration of a buck semen ejaculate can be determined
accurately by using a red blood cell diluting pipette and standard
hemocytometer techniques. Typical results during the breeding season
are 3 to 5 billion sperm per cc. Optical density can also be used to
estimate sperm concentration if the photometer has been calibrated for
buck semen. A simpler technique involves the determination of a
spermatocrit using microhematocrit pipettes. The aliquot of semen is
centrifuged for 10 minutes; for each percentage point of packed sperm,
approximately 200 million sperm cells per cc are present. Correction is
made for the percent motile sperm, after which the ejaculate can be
diluted appropriately to supply a minimum of 125 million motile sperm
in each breeding dose. It is often difficult to introduce more than 0.2
ml of semen into the cervix, so dilution to a final concentration of
600 million to 1.2 billion live sperm per cc has been recommended. When
no laboratory support is available, fresh semen for immediate use may
be diluted up to 5 times in extender if it is yellowish and 10 times if
the ejaculate is white. A straw holding 0.5 cc of this diluted semen
will provide adequate sperm if excessive reflux does not occur.
18) Storage and Removal of Semen from the Liquid Nitrogen Tank
A liquid nitrogen tank is basically a very large thermos-bottle in
which liquid nitrogen is placed to keep the inner temperature near
-320F (-196C). The spacing between the inner and outer walls is
insulated and under vacuum. The temperature in the tank is maintained
uniformly at -320F up to the bottom of the tank neck until the liquid
nitrogen level gets down to around 5''. To measure liquid nitrogen, use
a piece of black metal rod that is long enough to hold and touch the
bottom of the tank. Dip the rod to the tank bottom and remove after 30
seconds. By waving it in the air, a white frost line will appear on the
rod. This line indicates the liquid nitrogen depth of the tank. Levels
nearing 5'' require a refill. The only real differences between tanks is
their storage capacity (number of ampules or straws that they will
hold) and their length of holding time (liquid nitrogen evaporation
rate). The neck diameter varies somewhat also, with wider openings
being easier to work with, but an increased evaporation rate usually
results.
19) When working with semen in the liquid nitrogen tank, it is
important to keep the racks below the frost line in the neck of the
tank. Removal of semen from the tank for periods as brief as 10
seconds, such as for identification, before replacing it to the tank
will often result in lowered fertility levels. If the right rack can't
be located in 5 seconds, lower the canister back to the bottom of the
tank for at least 30 seconds before trying again. Also, when handling
semen, try to stay out of any direct sunlight, as ultraviolet light
has a spermicidial effect.
20) The semen comes in two basic types of packaging: ampules (1 ml) and
straws (0.5 or 0.25 ml). The ampule is the most common type of
packaging for buck sperm. Both ampules and straws are stored in racks
(canes), which are aluminum pieces that hold a vertical row of ampules,
usually six, or two g ++++MISSING DATA++++
21) A few key reminders concerning semen storage:
- 1) Always keep the liquid nitrogen level above 5''.
- 2) Never lift a canister above the frost line of the tank.
- 3) When the semen is removed with a forceps from the tank it should
be placed immediately in the thaw box.
- 4) Never expose semen to direct ultraviolet light.
- 5) Never refreeze semen that has been thawed as it will be
destroyed.
- 6) Check for proper identification on ampule or straw.
- 7) A defective ampule may blow up after it is removed from the
tank. This is due to a small leak that allows nitrogen to enter
the ampule. When removed from the tank, the gas expands too
rapidly to vent back out the hole and it explodes the glass. A
hissing sound is usually audible when it is removed. Keep your
hand between the ampule and your face when putting it into thaw
box.
- 8) Always wear gloves and goggles for your own protection when
working inside a liquid nitrogen tank.
22) Thawing Procedures
Methods for semen thawing vary among manufacturers, and it is best
to follow their recommendation. The thawing procedure for 1cc ampules,
the most common for goat semen, is generally the ice water bath:
- 1) Ice water (38-42F) is placed in a styrofoam box long enough
before-hand to allow temperature to equilibrate.
- 2) Remove the ampule from tank and place immediately into thaw box.
Ampule may be placed in a small plastic cup with holes in the
bottom. This prevents ice from coming into direct contact with
ampule.
- 3) Ampule should thaw in 3 to 5 minutes. Check for slushiness and
allow more time if needed.
- 4) Ampule may sit in ice water for as long as 30 minutes with no
damage. Once removed, the semen must be used right away.
- 5) The layer of ice on the ampule must be peeled off before opening
to avoid possible contamination.
23) The ice water thaw method is especially good during winter breeding
of does because of low risk of cold shock to thawed and exposed semen.
Thawing of semen can be done from -320F rapidly, but any subsequent
exposure to lower temperatures after thawing will kill many or all of
the sperm.
24) The warm water method of thawing is more exact than the ice water
method, but probably will not work in cold weather, although it may
give somewhat better results the rest of the year. The procedure is
basically the same as for the ice water thaw except that:
- 1) The water must be maintained at 92 to 98F. This requires a
source of warm water and an accurate thermometer.
- 2) Thawing will be complete in about 1 minute with no ice layer
formation of the ampule.
- 3) Ampules thawed with the warm water method should be used within
5 minutes.
25) Straws (0.5 or 0.25 ml) can be thawed by either of the previous two
methods. A given amount of semen in a straw will take about one half as
long to thaw as an equal amount in an ampule. Many inseminators simply
thaw straws by placing them into their shirt or pants pocket.
26) Inseminating Procedures
All the care in handling, storage and preparation of semen will be
useless if the inseminating process is not done carefully and cleanly.
Hygienic practices at this point cannot be over-emphasized. All
reusable items such as inseminating guns (for straws), scissors for
cutting straws, scribe for cutting ampules, etc. must be wiped clean
with 70 0sopropyl alcohol and allowed to dry before reuse. Disposable
items should be kept in their sealed packages until they are to be
used. The speculum should be sterilized after each use (this is one
reason why the cattle industry discontinued the speculum method; the
inseminator would have to carry a few dozen specula on his daily
rounds, sterilizing them each night). This is best accomplished by
boiling for 10 minutes, allowing to air dry. Then place inside a
sterile container or wrapping, such as a new plastic AI glove.
Disposable plastic type specula for goats can be obtained from mail
order companies, eliminating the need for constant resterilization.
27) Materials needed for artificial insemination:
- 1) Speculum, Pyrex 22 x 175 mm for doelings; 25 x 200 mm for adult
does; or stainless steel human vaginal speculum; or plastic
disposables; with a small clip-on flashlight.
- 2) Sterile lubricating jelly (K-Y)
- 3) Thaw box
- 4) a. Inseminating pipette with bulb or syringe (ampules only) or b. Inseminating gun (straws only)
- 5) Paper towels
- 6) Facility for securing doe (stanchion, fence, rope hoist)
- 7) Recording journal for breeding dates, buck's name, etc.
28) Preparing Ampules:
- 1) Partially remove an inseminating pipette from its plastic bag.
- 2) Place bulb or syringe on exposed end.
- 3) Thaw ampule according to the described methods.
- 4) Dry ampule after thawing, hold in paper towel and scribe (with
proper tool) one side of ampule collar. Some ampule types do not
need to be scribed, but can be snapped open.
- 5) Pull syringe back 1/2 cc on plunger or squeeze bulb closed
before placing pipette into ampule.
- 6) Tip ampule to slight angle and maintain constant suction on
pipette while it is slowly inserted into the ampule. Try to get
all the semen into the pipette, keeping the semen column down near
the end of the pipette.
- 7) When filled, the pipette should have a semen column with no air
spaces, with the bottom of the column being 1 to 2'' from the
pipette tip. Do not draw semen into the syringe or bulb.
- 8) Keep the ampule for information to complete breeding records.
- 9) Keep the pipette away from sunlight or cover with paper towels.
- 10) The semen is now ready to be placed into the doe in estrus.
29) Preparing Straws:
- 1) An inseminating gun, designed for your type of straw is needed,
obtainable thru farm supply houses or the local cattle AI
technician. Have cover sheath available, sealed until needed.
- 2) Place straw in thaw box.
- 3) Remove when thawed, wipe dry. Check buck information.
- 4) Pull plunger on gun back 4 to 6'' and insert straw into gun,
cotton plug end first (towards plunger).
- 5) Hold gun in upright position, allowing air bubble to rise to the
sealed end.
- 6) Cut sealed end of straw with scissors. Take care to cut straw
squarely for proper seating.
- 7) Install the sheath over the gun, fastening it down with the
provided O-ring. Install it so that the wider side of the ring
faces the straw, with the narrower side facing the syringe end.
30) Insemination:
Assuming that the doe has been observed in heat, has been suitably
restrained (i.e. in stanchion) and the steps for preparing the ampule
or straw have been followed. The next steps are:
- 1) Position doe on milk stand. The inseminator places his left foot
on the stand and drapes the hindquarters of the goat across his
horizontally positioned thigh. The goat is allowed to stand as
long as she does not struggle or collapse. The vulva is cleaned.
- 2) Hold pipette or inseminating gun, wrapped in a paper towl, in
your mouth; or let someone else hold it if extra hands are
available.
- 3) Turn head light on and insert lubricated speculum in a slow and
gentle manner. Begin entrance at a somewhat upward angle for the
first several inches. This is to prevent the speculum from
scraping across the vaginal floor, possibly doing damage to the
urethral opening.
- 4) Complete insertion of speculum and locate cervix. Center the end
of the speculum over the os uteri (entrance to cervical canal).
- 5) Cervix should be of a red-purple coloration with a viscous
whitish mucus present if doe is truly in heat.
- 6) Insert pipette or inseminating gun into speculum to the cervix.
Gently manipulate the instrument through the cervical canal
(cervix is 1 to 2'' long) to the 4th or 5th annular ring.
- 7) Deposit semen near the uterine end of the cervix or just inside
the uterus. Do not enter too far into the uterus as the semen will
then tend to be dumped into one horn or the other. If the semen
is pushed into the wrong horn (i.e. egg produced in left ovary,
semen dumped into right horn) then fertilization may not occur.
- 8) Deposit semen slowly, taking at least five seconds.
- 9) Slowly withdraw instrument without release of syringe or
depressed bulb, then carefully remove the speculum.
- 10) Record all pertinent breeding information.
- 11) Carefully discard all disposable materials. Arrange to sanitize
reuseable items and sterilize the speculum (if it is a
non-disposable type).
31) Frequently, the pipette cannot be passed all the way through the
cervix even though the doe is in heat. If it has penetrated deeply into
the cervix (3 to 4 cm, as determined by laying another pipette
alongside the first and observing the distance by which the outer ends
are offset), cervical insemination will provide a conception rate almost
equal to that of intrauterine semen deposition. The conception rate
expected from intra-vaginal insemination, however, is less than 30 If
semen is very valuable, it may be advisable to pass a trial pipette to
determine patency of the cervix before thawing the semen unit.
32 In France, a doe is usually restrained by a second person who
straddles the doe's neck and elevates the hindquarters to a vertical
position while holding the hind limbs tightly flexed. The inseminator
is free to stand in a comfortable position. He holds the speculum and
the goat's tail in one hand and the pipette or straw gun in the other
hand. If excess mucus is a problem, the assistant lowers the goat's
hindquarters almost to the ground; if the mucus does not run out of the
speculum, the latter is removed and shaken to clear it. The goat is
then lifted to its former position. If many goats are to be bred, the
assistant may tire using this technique. If the doe is not held in a
vertical position, it is often impossible to adequately visualize and
penetrate the cervix. Various slings have been devised to suspend the
goat in the appropriate position.
About the authors:
G.F.W. Haenlein, R. Caccese; U. of Delaware, M.C. Smith; Cornell Univ.
This material was contributed from collections at the National Agricultural
Library. However, users should direct all inquires about the contents to
authors or originating agencies.
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