A technique for reproduction of goats is called as embryo transfer also known as super-ovulation embryo transfer (SOET). This technique includes embryo freezing.
Researchers have concluded that the stage of the embryos recovered varied from 4-16 cells to expand blastocyst stage. The embryo stages used for transfer were four-cell, morula and blastocysts. The recipient doe that received four embryos on the seventh day of the cycle post estrus gave birth to four kids of different breeds [2 Anglo-Nubian, 1 Boer, 1 Saanen) after 139 days post estrus. To ensure a higher pregnancy rate following transfer of fresh or frozen-thawed goat embryos, factors such as embryo stage-recipient synchrony, site of embryo deposition and recipient condition should be given consideration.
The birth of viable animals originating from cryopreserved embryos in nitrogen had been registered for the first time in 1976 in Australia and in Brazil in 1997.
The Embryo Transfer (ET) offers wide possibilities of incrementing genetic gain, mainly, for reducing the interval between generations, as well as attending to sanitary and commercial standards. The embryo survival is influenced by some factors: body condition and health of the donors and receivers; the superovulatory answer from the donors; the ovulation rate (OR) of the receivers; the number of unovulated embryos for each receiver and the synchrony between the physiological state of the receivers and the age of the embryos.
ET associated with cryopreservation makes it available to the producers, technicians and the society, the possibility of defeating the barriers of time and space, transforming it into a technique of great zootechnical and economic importance. With the use of cryopreservation of embryos, it is possible to: import and export germplasm exempting the animal transport and periods of quarantine, indicating a reduction in the cost of the process of acquiring animals; transfer embryos to females in natural oestrus, without the need of artificial synchronization of oestrus and of the receiver ovulation; preserve collected embryos exceeding the number of synchronized receivers; adequate the time of births, independently from the date of the collection of the embryos; accelerate the genetic improvement, especially, by the rapid multiplication of genetically superior females, even when they meet at a long distance; benefit the implementation of progeny in females; and commercialize, transport and spread genetic material among producers, regions and countries. ET is important as a practice of reproductive handling but, mainly, a tool for the genetic improvement of the caprine flock.