Artificial Insemination
Placing semen from the male into the female is called artificial insemination, or AI. Usually, for the females to bred by AI, the estrous cycle is synchronized so they will all show heat at a similar time. This reduces the time and labor for heat checking. Some estrus synchronization programs are designed so the females can all be inseminated (bred) at a fixed time without having to check heat. For more information on hormone programs that have been used for AI, see: http://www.extension.org/pages/63472/estrus-synchronization-for-timed-artificial-insemination-in-goats or http://www.extension.org/pages/19331/goat-reproduction-estrous-synchronization
A trained technician or producer can use AI, but practice is needed and the costs compared to the benefits and outcomes (such as profitability) for each farm should be carefully considered.
The benefits of artificial insemination, or AI, include:
- The producer can make genetic improvement in his/her livestock faster
- This procedure reduces the possibility of spreading sexually transmitted diseases between the male and the female
- The producer will not have the cost of maintaining a male (except maybe a sterile “teaser” male for heat checking)
- The producer can very accurately predict when kids or lambs will be born
Some disadvantages include:
- The cost of hiring a technician
- The cost of equipment (such as a liquid nitrogen tank)
- The buck is better in detecting heat than a person
The success of AI is dependent on:
- The appropriate timing of insemination in relation to estrus (heat) and ovulation (release of eggs0
- The ability to efficiently collect and cryopreserve (freeze) sperm from quality bucks
- The seasonality of goat reproduction
There are two AI methods currently used in the goat industry. The first is cervical insemination that involves deposition of sperm in the cervix through the vagina. The second method is laparoscopic (“surgical”) insemination and involves the use of a laparoscope and manipulating probe to aid in depositing fresh or frozen-thawed sperm directly into the oviduct. Laparoscopic AI is becoming less commonly used because it is more invasive, very expensive (a licensed/certified veterinarian is often needed), it can result in scars that may cause future sterility, and cervical insemination techniques are getting good enough that conception rates are quite similar. Some research is being considered to possibly develop vaginal AI in goats using fresh/chilled semen to make it even easier for producers to use this technology.
The advantages to cervical AI include:
- Less invasive procedure for AI
- More cost-effective and practical for the producer (the producer can learn to do this procedure)
- Reduces the likelihood of infection and pain to the doe
Conception rates achieved when using cervical AI range from 50 to 70% with timed AI, and 70-80% with breeding by heat check, though rates with any AI are typically lower during spring and summer months. Photoperiod treatment of bucks during the spring and summer months might assist in alleviating the impacts of season.
For classes in your area on cervical AI, contact your local County Extension Office or visit the website of AI trainers such as BIO-Genics, LTD at http://www.biogenicsltd.com (mention of providers names are not endorsement). You can contact your local county extension office for others that might be available in your area.
For a video of AI in goats see: http://www.youtube.com/watch?v=vF89Ar83M7g
More information about AI (dairy goats): http://aces.nmsu.edu/pubs/_d/d-704.pdf
Embryo Transfer
Another reproductive technique that can be used following the onset of heat is embryo transfer, or ET. Embryo transfer has been used extensively in beef and dairy cattle for years. In this technique, the doe and ewe are first synchronized and later administered a superovulatory hormone which causes the doe or ewe to ovulate more eggs at one time than usual. This process is called “superovulation.” The eggs are fertilized by means of AI or natural service, and at the appropriate time they are flushed out of the reproductive tract of the donor female and then transferred to recipient females (or frozen for future use). The recipient females (ones to be given the embryo) are also synchronized on the same day as the donor doe or ewe.
The advantages of this technology are:
- It increases the genetic improvement in a herd or flock significantly since all the genetics can be “new”
- It provides an additional source of income (“niche” market) to a producer who has superior breeding stock
- Frozen embryos from superior stock can be shipped to other farms to aid in improving the genetics of the goat herds or sheep flocks around the United States
- It reduces the spread of sexually transmitted diseases from the male to the females
The disadvantages of ET are:
- It is very expensive
- The response to the hormone treatments may be erratic
- It is hard to find a skilled technician who can perform this procedure in small ruminants
For more information on the hormonal control of reproduction please visit: http://www.extension.org/pages/19731/reproductive-biology-goat-reproductive-physiology
Resource: Advanced Reproduction