While fresh semen may remain viable in the uterus for 3 to 5 days, frozen/thawed semen will only remain viable for up to 12 hours -and most for less than 6 hours-. Timing of insemination is therefore critical.
Our pregnancy rates using frozen/thawed semen are still improving. Per-cycle pregnancy rates and seasonal pregnancy rates with frozen/thawed semen have been similar to results achieved with cooled semen in recent years.
The pregnancy rate is however highly dependant on the ability to freeze and thaw semen of the individual stallions, without compromising its fertilising ability. Therefore careful selection of stallions and mares is imperative for high pregnancy rates.
Advantages of frozen/thawed semen:
- Semen can be stored indefinitely
- Semen can be transported internationally
- Stallions may continue to be used for breeding whilst performing or recovering from an injury
- Eliminates the cost and stress of transporting mare and foal
- The genetic pool is increased
- Reduction of disease transmission (CEM, Klebsiella spp, Pseudomonas spp, EHV1,4)
- Reduction of possible injury to stallion or mare
- Prevents overuse of a stallion
- Evaluation of semen
- Breeding of mares with a abnormal breeding history
- Use of small volumes
- Reduced danger of contamination of the uterus of the mare
Disadvantage of frozen/thawed semen:
- In many stallions the processing techniques (freezing, packaging, thawing, insemination) affects the pregnancy rates. Overall pregnancy rates from frozen semen are just above half that achieved with fresh semen for the same stallion. Selection of stallions with semen suitable for freezing now and in the future will dramatically improve the per cycle pregnancy rate. Semen of some stallions will not be suitable for freezing or even cooling for transport.
- Limited viability of frozen/thawed semen.
- Costs of freezing, transport and insemination.
- Skilled and experienced centres mandatory to optimise pregnancy result. High degree of veterinary input required.
- Processing of semen affects fertility and clients can become frustrated and upset if their mare fails to become pregnant in just one cycle.
Common Misconceptions
- Success rates are high (Get adequate information regarding the quality of the semen of the stallion you wish to use, e.g. per cycle pregnancy rate). However good success rates can be expected when choosing high quality semen for a reproductive healthy mare.
- Everybody can successfully inseminate a (your) mare.
- AI is a cheaper alternative to natural breeding.
COMMUNICATION between veterinarian, mare owner and semen supplier or stallion owner is extremely important. Management is the key to success.
Costs
A certain number of rectal and ultrasonographic examinations and or medical treatments will be required pre and post insemination to ensure the highest chance of conception. These treatments will vary depending on the individual needs of your horse.
Drugs regularly used include; Chorulon, Intra-Uterine Antibiotics, Prostaglandin, Oxytocin, Ovuplant and Progesterone.
The time your mare will be required to stay at the practice will vary due to a number of factors;
- age of the mare
- maiden, barren or foaling mare
- damage to her reproductive tract due to previous foaling, abortion or placentitis are all important towards her future fertility and breeding potential
- semen quality
Most of the potential difficulties can be overcome by medical or sometimes surgical treatment of your mare when indicated.
Mares are routinely scanned for a pregnancy at around 14 days. This can be done at the practice, the stud the mare is boarding, or at home. Our service includes follow-up scans of the pregnancy at around 21, 30 and 45 days.
Duration of boarding/livery depends on the number of attempts you are prepared to budget for to achieve a pregnancy in the case your mare does not go in foal after the first insemination. This does not entirely depend on your mare but on the quality of the semen as well.
Some stallion owners or semen suppliers will charge for the transport of the (chilled) semen, others offer an all-in package, which include the costs of semen collection and transport. Some stallion owners may choose to limit the number of doses of semen they will send.
Most stallion owners or semen suppliers quote a service fee payable before the actual use of the semen. Individual arrangements must be made between stallion and mare owner regarding payment of these costs.
Summarising, the success or failure of the use of frozen semen depends on:
- Stallion fertility and specifically the quality of its frozen/thawed semen
- Mare fertility
- Management
Success or failure will come at a cost.
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