Good management is the cornerstone of any embryo transfer program,
and there are no shortcuts. You can't get good management out of a bottle or
through a needle, and for that reason, the following information is intended to
help you understand what is involved in setting up a basic ET program, what we
do, and why.
PLAN AHEAD: If I only had two words of advice that I
could give you about your embryo transfer program, they would be "plan
ahead". I almost feel safe in saying that I don't think you can start
AVOID STRESS: The biggest enemy you will have in any
part of your goat operation is stress, which unfortunately is not entirely
preventable. Some examples of how stress is induced are:
- Mixing groups or individual animals together that have not previously been
- Altering the goats regular routine.
- Handling the goats unnecessarily.
- Confining goats in close or unfamiliar surroundings.
- Causing goats to become frightened, such as exposure to predators
The ease with which your goats can be handled and the avoidance of
stress from a period of time before you began an ET period until at least the
second month of pregnancy will reflect drastically on your conception rates and
ultimately the number of kids born.
PLAN FOR THE USE OF TEASER BUCKS: Teaser bucks are one
of the most important components of the progam. Proper use of these animals can
influence your success in a very positive way. Recipients and Donors must be
exposed to teasers to initiate heat activity for a minimum of 30 days, and
preferably 60 days, prior to beginning a program. I prefer to use vassectomized
bucks rather than those which have been deviated, because the vassectomized
animals can still penetrate the females which allows for better
Donors should be in small groups, and one teaser buck is
sufficient. If as a breeder you don't like the aesthetics of an "off breed"
animal in the same pen with your donor females, then in most cases nose to nose
contact with bucks through a fence is sufficient to induce heat.
regards to your recipients, I feel that it is important to have teasers with
them in a ratio of 1-25, both before you begin a program and during heat
detection at mating time. Harnesses with different colored chalk can be strapped
to teaser bucks and is helpful in heat detection.
NUTRITION: Proper nutrition, as manifested by positive
weight gains throughout an ET program, can have a very beneficial result on
conception and kidding rates. Depending upon the initial condition of your
donors and recipients, at the onset of your preparations for a ET program, a
feeding regime needs to be initiated. Ideally, we would like to see your animals
in a start condition that would allow for approximately 0.5 lb. of gain per day
beginning 30 days prior to start of the program, through 45 days after breeding.
Remember, it is very difficult to put weight on a goat that is already fat, and
the boers seem to be very easy keepers. Some type of scale or weighing device
can be very helpful for monitoring the gain of your pureblood animals and
EXAMPLE OF AN ET PROGRAM SCHEDULE: The following is an
example of a programing schedule that we use in a flushing program:
- DAY 0 - Put CIDRS In Recipients
- DAY 1 - Put CIDRS In Donors - Official Start of ET Countdown
- DAY 16 - Donor FSH Injections in AM & PM
- DAY 17 - Donor FSH Injections in AM & PM
- DAY 18 - Donor FSH Injections AM & PM And Recip CIDRS Out in PM
- DAY 19 - FSH Inject. in AM & PM, Donor CIDRS Out in PM &
Record Recip Heats
- DAY 20 - Mate Donors in the AM & PM And Record Recipient Heats
- DAY 21 - Mate Donors in the AM And Record Recipient Heats
- DAY 23 - Put New CIDRS Back In Donors
- DAY 25 - Take Both Donors And Recipients Off Feed & Water
- DAY 26 - ET Day: Flush & Lutalyse Donors, And Transfer
Embryos To Recips
- DAY 36 - Remove Donor Stitches
As you can see, it is fairly
simple process, and one that is relatively easy to follow. The first item is the
implanting of your recipients with CIDRS, followed the next day by repeating
that procedure for your donors. CIDRS are a synchronization device used mainly
in sheep and goats, although they are also used in cattle. They are made of a
hard plastic and impregnated with a hormone called progesterone. While the CIDR
is in place, progesterone is released into the system of the goat. When the CIDR
is removed, there will be a rapid fall in the progesterone level, much in the
same way as the progesterone falls during the normal cycle. The other two
related hormones, FSH (Follicle Stimulating Hormone) and LH (Luteinizing
Hormone) effect growth, maturation, and ovulation of the
Looking back at the programming schedule, you will notice the
FSH injections that the donors receive for superovulation on days 16 to 19. This
process consists of eight injections given twice daily for four days., and the
dose is dependent upon the age of donor that is being superovulated. Timing of
estrus or heat in both the donors and recipients is controlled by CIDR removal.
You will notice that the recipient CIDRS are removed 24 hrs. earlier than the
donors. The reason for this is that it takes the recipients longer to respond to
CIDR removal because of lower estrogen levels when compared to the superovulated
Donors are mated using natural service over an extended period of
time because of ovulation occurring over 24-36 hours. Does are mated at 12 hr.
intervals beginning at onset of heat and continuing until she will no longer
accept the buck. Observe your animals, one ejaculation per breeding is
sufficient. Don't overwork your bucks. Do not put a buck with a group of donor
does and leave him. He will very likely service only one donor. If you have not
been using your bucks regularly prior to beginning a program, you may want to
artificially create heat in some extra does to test mate your bucks to be
assured that they will work, and/or you may wish to have your veterinarian
perform a fertility exam.
The next item on our list is the
re-implantation of your donors with another CIDR. We do this to help prevent
premature luteal regression. This is a condition where progesterone levels fall
and the donor begins to return to estrus even before she can be collected. By
increasing progesterone levels with the CIDR this problem can sometimes be
EMBRYO COLLECTION: We are now ready for the "big day" -
collecting the embryos. Our method of collection is surgical using general
anesthesia. To help prevent complications that can occur when animals
regurgitate, we take them off feed and water the day before surgery to
facilitate an empty rumen.
The goats uterus consists of two horns which
is referred to as a BIPARTITE. On the day of collection, the embryos are located
in the section of the horn of the uterus the most distal from the cervix. The
collection is done by literally washing the inside of the uterus with a fluid
media in which the embryos become suspended and then searching this fluid aided
with the use of a low powered microscope.
After evaluating the
superovulatory response of the donor by observing the ovaries through a
laparoscope, the horns of the uterus are exposed, one at a time, through a small
incision just in front of the udder. Each horn is collected separately, using
approximately 40 ml of media for each side.
IMPLANTING EMBRYOS: Results from superovulation are
varied. Our averages this past season were approximately 8 useable embryos from
doe kids and 10-12 useable embryos from adults with the older does working best.
With these numbers in mind we try to program 6-8 recipients on kid flushes and
8-10 recipients on adult flushes.
Two embryos are routinely transferred
to each recipient with the exception being when there is an odd number of
embryos from a given donor. The recipients undergo the same type of general
anesthesia as the donors. The ovaries and uterus are examined through the use of
a laparoscope. After a recipient has been determined acceptable, a small portion
of the uterus is exposed through a small incision in the abdominal wall, and two
embryos are injected via a needle puncture into the uterine horn on the same
side that ovulation occurred.
The freezing of embryos is a tool that can
be used when recipient numbers are short and embryo splitting can be utilized
when abundant recipients are available.
Post transfer recipient care is
also critically important. The avoidance of stress during this period can
influence conception and kidding rates in a positive direction. I would
recommend waiting at least 40 days post transfer before scanning for pregnancy
or moving goats.
SUMMARY: The actual collection and transferring of
embryos is only a small part of the entire program, the success of which, as you
can see, is dependent upon many small but critical steps. Please pay close
attention to all details, and remember that there are no easy
I hope that this information proves to be helpful in your
embryo transfer work and in the overall success of your goat operation.
About The Author
Dr. Sam Castleberry is a 1975 graduate of Texas A&M College of Veterinary
Medicine, and the majority of his career has been devoted to providing embryo
transfer services. He formed his own practice, Veterinarian Reproductive
Services, Inc. in 1983, and from that date until 1993, his work primarily
involved beef cattle. In the fall of 1993 and spring of 1994, Dr. Castleberry
worked with Dr. Stuart Southwell of Premier Genetics N.Z. LTD in New Zealand,
implanting frozen embryos and flushing Boer goats in order to familiarize
himself with that procedure.
Dr. Castleberry is an AETA certified member
and operates an AETA approved facility. He has performed embryo transfer
services for an international clientele, which has taken him to Mexico, Canada,
Japan, England, and New Zealand.
Veterinarian Reproductive Services, Inc.
8225 FM 471
Castroville, Texas 78009 USA
Phone: (830) 538-3421
Editor's note: This article was first published on Rodney Robinson's boergoats.com in 1996 and is reprinted here by permission of the author