Sheep embryo transplantation is to take the early embryos of the bred ewes and transplant them into the same ewes whose physiological state is the same so that they can continue to develop into new individuals. Sheep embryo transfer can greatly improve the utilization rate of excellent ewes and reduce the introduction of foreign exchange expenditures. At the same time, the sheep can be mass-produced, facilitate feeding and management, increase the survival rate, and reduce production costs. Embryo transfer is a complex biological engineering system, and any one of the links directly affects the effect of embryo transfer. The physiological basis of sheep embryo transfer is that the development of reproductive organs after estrus is conducive to pregnancy, regardless of whether the breeding or not, are ready for pregnancy. At the same time, the early embryos are in a free state, and the recipients have no rejection to the embryos, so that the transplanted embryos can continue to develop. When embryo transfer is performed, strict technical principles must be followed and procedures should be followed. Embryo transplantation principle Consistency of donor recipient reproductive environment Embryo transplantation must ensure that the donor and recipient environment are the same or similar. It mainly includes three aspects: First, the donor and the recipient belong to the same species. In general, species that are distantly related in taxonomy are quite different due to differences in embryo structure, development conditions, and developmental processes. Such two species undergo embryo transfer, and most of the species cannot survive or survive. short time. However, you can use this short-term survival time to temporarily save the embryos. For example, early embryos of pigs, cattle, and sheep can be transplanted into the fallopian tubes of rabbits for temporary storage for several days. Second, the donor receptors are physiologically synchronous. Physiological synchronization mentioned here means that the estrus time of the donor recipient sheep must be the same, or that the difference between the two is not more than 24 hours, otherwise the transplantation will be difficult to succeed. Third, the sites of donor and recipient sheep embryos must be identical, that is, the principle of identity should be followed for transplantation. In other words, the monthly embryos collected from the donor's uterus must be transplanted into the recipient's uterus, and the embryos collected from the donor's fallopian tubes must be transplanted into the recipient's fallopian tubes. This is mainly because the developing embryos are very sensitive to the environment. The uterus is constantly changing with the action of ovarian steroid hormones. The suitability of embryo transfer time The choice of embryo transfer time is strictly regulated. It usually takes place early in the luteal phase and before embryo transfer. Therefore, the collection of embryos must be strictly controlled within 1 week after the estrus season, preferably after the estrus season. 3 days - 4 days for collection. Normality of the embryo itself When embryo transfer is performed, it must be carefully examined and transplants can only be performed if it is ensured that it has developed normally. In addition, in the embryo collection and preservation process, we must try to protect it from physical, chemical, biological and other aspects to ensure its integrity. Operation points Choose the right time Comprehensive consideration should be given to the condition of the estrus of the donor receptor and the development of the uterus and embryos, and embryo transfer time should be selected. Only when these two aspects are consistent can embryo transfer be performed. Because the donor sheep only provides superovulation, there is a large difference in the discharge time of individual eggs. It is necessary to comprehensively consider the above two factors. Experienced individuals can fully identify the development of the uterus based on the luteal characterization. Before transplanting, examine the recipient sheep, learn more about the development of the corpus luteum, and then determine whether embryo transfer can be performed. Recipient sheep preoperative treatment Prior to embryo transfer, detailed examination should be performed to determine whether the corpus luteum on the recipient's ovary is well developed. When conditions permit, laparoscopic examination of the recipient sheep can be performed to further determine the number, quality, and location of the corpus luteum to ensure that the ovaries do not need to be pulled out after the start of transplantation. In addition, in order to ensure the smooth operation, the recipient sheep should be hungry for about 20 hours before surgery, and shave their hair before surgery to prepare for the next operation. Embryo transfer operation At present, commonly used methods of embryo transfer include uterine transplantation and fallopian tube transplantation. In uterine transplantation, embryos should be transplanted to the first 1/3 of the uterine horn and the fallopian tube should be implanted by the umbrella. When sucking the embryo, in order to avoid losing the embryo when the straw is moved, it may be performed in the order of "aspiration of a portion of the culture fluid, inhalation of a small bubble, suction of an embryo, inhalation of a small bubble, and inhalation of a culture fluid using a pipette". The fallopian tube method prior to transplantation of the fallopian tube of the umbrella is in a relatively straight state, so that the oviter can see the pull-out part of the fallopian tube directly above the mesentery of the delivery tube and can see the side of the bellmouth. At this time, the ommmmer inserts the tip of the oviduct into the fallopian tube, and then gradually increases the pressure inside the oviduct, and inputs the preservation solution with the embryo into the fallopian tube. After the oviposition, keep finger pressure inside the fallopian tube and pull out the oviduct. If the finger pressure is relaxed in the fallopian tube, the negative pressure inside the oviduct will suck the embryo inside the fallopian tube again. After oviposition, we must also microscopically inspect the removal of the oviduct to see if there is an embryo. If not, it means that it has been transferred. Timely organs are reset and abdominal wall sutures are made. When the uterus moves eggs, you can use homemade tube removal. When the egg is transferred, the embryo to be moved is sucked into the oviduct and directly inserted into the uterine horn cavity of the ewes with a blunt catheter. When the occlusion tube enters the uterine cavity, there will be an empty hand. At this time, slightly pressurize the oviduct. If the occlusion tube has been inserted into the sub-chamber, the liquid in the occlusion tube will move. If it cannot be moved, adjust the direction or depth of the blunt catheter or the occlusion tube, and pressurize it until the liquid is successfully squeezed. Precautions In the early and late stages of embryo transfer, both the donor sheep and the recipient sheep must maintain a balanced level of nutrition and a good body condition. Protein feeds, energy feeds, mineral feeds, and vitamins should be properly matched, and should not be increased arbitrarily or Reduce to prevent feed spoilage of forage grass feed. Also pay attention to epidemics and deworming. After embryo transfer has entered the schedule, do not use drugs (such as antibiotics, antiparasitic drugs, vaccines, etc.) arbitrarily, and avoid the influence of some drugs on embryogenesis and development. Strengthening the rearing and management of the rear-receptor sheep is an important means to increase the conception rate, especially under the conditions of feeding, nutrition should be met at all stages, and exercise should be strengthened to prevent extrusion collisions. 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