Embryo Transfer in the Boer Goat
Dr. Stuart Southwell, B.V.Sc. - M.R.C.V.S.
Premier Genetics NZ. Ltd. - Drury, New Zealand
Commercial embryo transfer in goats in New Zealand began in 1973, with the introduction of Angoras into the country with the expectations of Mohair. Initial methods were based around recovering embryos by fallopian tube flushes on the third or fourth day after mating. Those efforts were often variable in their recoveries, and if not done correctly caused permanent damage to the reproductive tract. Stimulation of the ovaries was by P.M.S.G. (Pregnant Mare Serum Gonadatropin) or F.S.H. (Follicle Stimulation Hormone), or a combination of both. Oestrous was normally surpressed by daily injections of Progesterone. A typical programme then was similar to this:
Day 1 thru Day 15: - Daily Injections Of Progesterone (12.5 mg per day)Variability was the main complaint, which may have been the programme, or the recovery method.
Day 16 thru Day 19: - F.S.H. Injections, Twice Daily
Day 20 - Bucks And Donor Does Were Mated
Day 24 - Embryos Were Receovered And Transferred To Surrogates
Recovery rates were improved dramatically by retreiving embryos on the
6th or 7th day after mating. Flushing took place at the
fallopian/uterine junction, which also reduced surgical trauma seen
previously. F.S.H. stimulation proved more consistent than P.M.S.G., and
is now used exclusively. F.S.H. products available in the marketplace
include: F.S.H.-P, Folltropin, Ovagen, Pluset, Super-Ov, and Ova-Plus.
Generally, as pertain to goats, F.S.H. products that are low in L. H.
(Lutenizing Hormone) perform better than those with higher L.H. As the
L.H. content increases, so does the variability in results increase.
Dose rates of 20-25mg should be given to each donor over a three or four
day period, at 12 hour intervals.
Oestrous suppression is now conveniently achieved by use of an
intra-vaginal device called a CIDR. In the goat, these will suppress
oestrous quite adequately for an 18 day period (ie: from CIDR in, to
superovulation). Changing the CIDR prior to superovulation is not
necessary.
A Standard Programme Today Is:
Day 1 - CIDR INVariations to this programme are because of:
Day 17 - F.S.H. A.M. - F.S.H. P.M.
Day 18 - F.S.H. A.M. - F.S.H. P.M.
Day 19 - F.S.H. A.M. - F.S.H. P.M.
Day 20 - F.S.H. A.M. - CIDR OUT A.M. - F.S.H. P.M
Day 21 - MATINGS
Day 26 - EMBRYO RECOVERY & TRANSFER
1) Age of donorBoer Goat Management:
2) Time of year
3) Use of fresh or frozen semen
These animals are sensitive to change. In order to acclimatize the Boer
for embryo transfer procedures that are going to take place during the
programme, any changes in environment, feeding, or handling must be
presented to the animal well beforehand. (ie: grouping donors together,
etc.) A lot of thought must be given to the pre-programming care of this
animal. It will perform exceptionally well or not at all. This is
dependent upon the owner's management.
Expectations:
An adult Boer doe will, on average, produce 13 useable embryos, with a
possible range of between 0 and 53. A seven month old Boer doe kid will
produce, on average, 8 useable embryos, and can range from 0 to 28. Note
that yields in the zero range are usually the result of poor management.
Pre-mature Luteal Regression:
Pre-mature luteal regression, a syndrome that is not uncommon in Boer
goats, is caused by stress. Prostaglandin is released soon after
ovulation causing the developing corpus luteum to regress pre-maturely.
By Day 6, the corpus is regressed, and normally embryos are not
recovered.
Embryo Splitting:
Embryo Splitting has only recently become commercially viable in the
goat. Approximately 50% of embryos recovered are suitable for splitting.
The pregnancy rates from these demi-embryos are similar to fresh whole
embryos (ie: 70-80% scanned foetuses to embryos implanted), and it has
now become very economic to use embryo splitting as a procedure.
Plan Ahead & Closely Follow Proven Procedures:
The absolute key to a successful embryo transfer in Boer goats is to think well ahead, not 4 weeks, but 4 months. What we have learned from many years of practice, is that the most successful results are achieved by those who closely follow the proven protocol, as setforth in this paper.
|
Dr. Stuart Southwell, B.V.Sc - M.R.C.V.S.
No one individual has contributed more to the development of the
international Boer goat industry than Dr. Stuart Southwell of Premier
Genetics N. Z. Ltd in Drury, New Zealand. He is widely known and
respected for pioneering many of the embryo transfer techniques and
programme protocols that are being employed by veterinarians and goat
producers in many different countries of the world, and has willingly
shared his knowledge and experience with those who have sought his
advice and counsel. In addition to sharing his surgical techniques with
other of his fellow veterinarians, Dr. Southwell has, himself, performed
embryo recovery, splitting, and transfer on many thousands of Boer
goats.
See also: "Artificial Insemination in the Boer Goat".
To confer with Dr. Southwell regarding Boer goat embryo transfer or AI
technology, or to engage his services, he may be contacted as follows:
Dr. Stuart Southwell, B.V.Sc. - M.R.C.V.S.
Phone: 0-9 236 0616 |
|
