Breeding system for optimizing donkey reproductive performance based on embryo transplantation technology

Abstract

The invention relates to the technical field of livestock breeding, in particular to a breeding system for optimizing the reproductive performance of donkeys based on an embryo transfer technology, and the breeding system comprises the following steps: selecting 4-8-year-old female donkeys with good body shape and appearance and reproductive performance as donor donkeys, and increasing the illumination time to 16 hours per day 2 months before the breeding season, carrying out comprehensive physical examination on the donor donkey, meanwhile, carrying out parasite expelling treatment, carrying out subcutaneous injection of ivermectin, and waiting for the female donkey to enter the estrus period. According to the breeding system for optimizing the donkey reproductive performance based on the embryo transplantation technology, superovulation treatment is carried out through drugs, a donor donkey can discharge multiple ova at a time, artificial insemination is combined, more embryos are obtained, the embryo quality is evaluated, the embryo transplantation success probability is confirmed, and the breeding system is used for screening high-quality donkey embryos for reproduction; the future breeding ability of the donkey group and the quality of the donkey are optimized, so that a more excellent gene breeding system is established, and the breeding quantity and quality of the donkey are improved.

Description

Technical Field

[0001] The invention relates to the technical field of animal husbandry and breeding, in particular to a breeding system for optimizing the reproductive performance of donkeys based on embryo transplantation technology. Background Art

[0002] Embryo transfer technology, also known as fertilized egg transfer, refers to the technology of transplanting early embryos in female animals, or embryos obtained through in vitro fertilization or other methods, into other female animals of the same species and physiological conditions, so that they continue to develop into new individuals. Donkeys are seasonal animals that have multiple estruses. They usually enter the estrus period from March to June each year, and the estrus weakens during the hot July and August. Donkeys usually give birth to two babies in three years. After the female donkey reaches sexual maturity, it needs to reach a certain age and weight before it can be bred. Usually, female donkeys reach sexual maturity at around 1.5 years old, but the first mating age is generally around 3 years old, and male donkeys start to mate at around 4 years old.

[0003] Nowadays, donkey breeding is mostly natural conception, and embryo transplantation technology, as an important technical means of modern livestock breeding, has been widely used in cattle, sheep and other livestock. However, the reproductive physiological characteristics of donkeys are different from those of other common livestock. Donkeys have relatively irregular estrus cycles and their estrus lasts for a short time, usually 3-7 days, and the ovulation time is difficult to grasp accurately. At the same time, the early development of donkey embryo transplantation embryos is slow, but after embryo transplantation, the implantation time and implantation rate are also low. Therefore, there is a problem of low success rate of donkey embryo transplantation breeding. Summary of the invention

[0004] The object of the present invention is to provide a breeding system for optimizing the reproductive performance of donkeys based on embryo transplantation technology, so as to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a breeding system for optimizing the reproductive performance of donkeys based on embryo transplantation technology, the breeding system comprising the following steps: 1) Select female donkeys aged 4-8 years old with good body shape, appearance and reproductive performance as donor donkeys. Two months before the breeding season, increase the light hours to 16 hours a day, conduct a comprehensive physical examination on the donor donkeys, including blood routine, biochemical index testing, brucellosis and tuberculosis screening, deworming, and use ivermectin subcutaneous injection at a dose of 0.2 mg per kilogram of body weight, and wait for the female donkey to enter estrus; 2) The donor donkeys were treated for estrus synchronization by intramuscular injection of cloprostenol, with a dose of 0.4 mg per donkey, followed by a second injection 11 days later, and 100 μg of follicle-stimulating hormone-releasing hormone compound was injected 30 hours after the second injection to induce estrus in the donor donkeys; 3) On the 9th day of the donor donkey's estrus cycle, superovulation treatment was performed. A total dose of 300 mg of follicle-stimulating hormone was diluted with normal saline and injected in 6 decreasing doses, each with an interval of 8 hours. The specific doses were 60 mg, 50 mg, 40 mg, 30 mg, 20 mg, and 10 mg. When the 4th injection of follicle-stimulating hormone was injected, 100 IU of luteinizing hormone was injected intramuscularly at the same time; 4) During the follicle formation process of the donor donkey, the follicle development is detected by rectal examination and ultrasound. When the follicle diameter reaches 30-40mm, frozen semen of a male donkey with good vitality and sperm density of not less than 150 million / ml is selected for artificial insemination. The amount of semen delivered each time is 10ml, and the semen is delivered deep into the uterine horn. The number of inseminations is 2 times, with an interval of 10 hours between the two times. 5) On the 7th day after artificial insemination, a three-way embryo collection tube was inserted into the uterine horn through the cervix, and the uterine horn was repeatedly flushed with 200 ml of PBS buffer containing 5% bovine serum albumin to collect the flushing fluid containing embryos. After the embryos were collected by the egg collection cup, they were immediately placed in the embryo culture medium in the incubator for embryo culture. After the embryo culture was stable, the collected embryos were morphologically evaluated under a microscope to screen the embryos; 6) Select healthy female donkeys aged 3-6 years old with normal reproductive performance as recipient donkeys. On the 7th day after the recipient donkey came into estrus, use non-surgical methods to transplant the embryos into the recipient donkey's uterus. Before the embryo transplantation, the recipient donkey was observed and monitored, and the optimal embryo transplantation time was calculated. A success rate prediction model was established to predict the transplantation success rate of conceived embryos. 7) On the 20th day after the embryo transfer, the recipient donkey is checked for pregnancy. Then, after the mother donkey gives birth, the performance of the foal born through the embryo transfer is measured, including the measurement of growth and development indicators such as birth weight, weight at 1 month, height, length, chest circumference, etc., and its appearance characteristics and health status are recorded in detail. When the foal is 6 months old, its meat performance-related indicators are measured and analyzed, and combined with the results of genetic marker detection, the foal with excellent genetic traits and high production performance potential is selected as the reserve breeding donkey.

[0006] In a further embodiment, the morphological assessment of the embryo specifically comprises the following estimation method: The morphological assessment of the embryo specifically includes the following estimation methods: First, construct a judgment matrix ,in Indicates the relative importance of a factor, using a 1-9 scale. Indication factors Factors Equally important, Indication factors Factors Slightly more important, among which, when Indication factors Factors When they are equally important, the fuzzy data of the 1-9 scale method is ,in, They are the lower bound, the most likely value, and the upper bound, respectively, so that the description of the importance of morphological evaluation is more consistent with the ambiguity in actual situations; Calculate the judgment matrix The maximum eigenvalue of and the corresponding eigenvector , the eigenvector The amount Indicates the weight of each factor; For the specific indicators at the bottom layer, after quantification, they are weighted and summed according to the weights to obtain the comprehensive evaluation score of embryo quality. The specific evaluation score formula is as follows:

[0007] in, is the quantitative value of the underlying indicator, is the embryo's assessment score, As the influencing factors, For the time factor.

[0008] In a further embodiment, the optimal time for embryo transfer of the recipient donkey is specifically monitored by the following methods: Obtaining the hormone level data sequence of the recipient donkey every day After that, the data is smoothed to reduce the interference caused by data fluctuations. The new hormone level sequence is , it can be seen that the formula for calculating the optimal embryo transfer time is:

[0009] in, Represents the number of The new hormone level value at each position can be calculated by this method to make the hormone level data smoother and effectively reduce the interference of random fluctuations on data trend judgment. is the number of days of the moving average, which serves to average the summation results. This is the summation symbol, indicating that The data starts from the first raw hormone level data and continues to accumulate until the data.

[0010] In a further embodiment, before the embryo transplantation of the recipient donkey, the embryo quality score of the embryo to be transplanted, the age of the recipient donkey, the endometrial thickness, the number of births and the hormone level are collected; Then, an embryo transfer success rate model was established, and the above data were set as independent variables. The independent variables were: , the specific calculation formula is as follows:

[0011] in, The success rate of embryo transfer ( Represents success, Represents failure) is the independent variable The corresponding coefficient.

[0012] In a further embodiment, the evaluation score is based on a 5-point system, and the evaluation score divides the embryos into three grades: A, B, and C, wherein scores 1 to 2 are grade C, scores 3 to 4 are grade B, and scores 5 are grade A.

[0013] In a further embodiment, the embryo culture temperature of the incubator is 37.5°C, and the incubator is filled with 5% carbon dioxide and 8% oxygen, and the osmotic pressure of the culture medium in the incubator is set to 260mmol / L-320mmol / L.

[0014] In a further embodiment, the recipient donkey is subjected to the same health check and deworming treatment as the donor donkey before embryo transfer and conception.

[0015] In a further embodiment, the embryo transplantation site is the upper third of the uterine horn of the recipient donkey, and the number of embryos transplanted into each recipient donkey is 2-3.

[0016] In a further embodiment, the pregnancy check of the recipient donkey is performed using ultrasound detection, and the detection interval is once every half a month.

[0017] In a further embodiment, the donor donkey and the recipient donkey are fed with concentrated feed, the crude protein content in the concentrated feed is 18%, the added amounts of vitamins A, D, and E are 8000 IU, 1500 IU, and 50 mg per kilogram of diet, respectively, and the calcium-phosphorus ratio of the concentrated feed is 3:1.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention uses drugs to perform superovulation treatment, so that the donor donkey releases multiple eggs at a time, and combines artificial insemination to obtain more embryos, and evaluates the quality of the embryos to confirm the success probability of embryo transplantation, which is used to screen high-quality donkey embryos for breeding, thereby optimizing the future breeding capacity and quality of the donkey herd, and then establishing a more excellent genetic breeding system to improve the breeding quantity and quality of donkeys; 2. The present invention utilizes embryo transplantation technology to break through the limitation of the natural reproduction cycle of the donor donkey, so that all the donor donkeys and recipient donkeys are subjected to long-term hormone level and status monitoring, ensuring that the donkey herd is cyclically uninterrupted in supply and reception breeding, and can perform multiple embryo transplantation operations in a shorter time, further improving the breeding efficiency, shortening the cultivation cycle of excellent donkey breeds, establishing a more efficient breeding system for donkey breeding, and thus meeting the market demand for high-quality donkey products more quickly; 3. The present invention monitors the estrus period of the recipient donkey, continuously detects the hormone level during the estrus period, and continuously accumulates data to calculate the optimal time for embryo transplantation, thereby improving the success rate of embryo implantation and predicting the success rate of embryo transplantation. The quality and other physical data of the recipient donkey and the embryo are collected, and then the previous success rate is statistically analyzed according to a logistic regression model. Then, statistical calculations are performed based on the data collected for this embryo transplantation, and the transplantation success probability of the corresponding recipient donkey and the corresponding embryo is predicted, and then the embryo is matched to a recipient donkey with a higher transplantation success rate, thereby improving the embryo transplantation success rate and establishing a more stable breeding system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the process of the donkey breeding system of the present invention; Figure 2 It is a schematic diagram of process 2 of the donkey breeding system of the present invention. DETAILED DESCRIPTION

[0020] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Example 1

[0022] See also Figure 1-2 This embodiment provides a breeding system for optimizing the reproductive performance of donkeys based on embryo transplantation technology, and the breeding system includes the following steps: 1) Select female donkeys aged 4-8 years old with good body shape, appearance and reproductive performance as donor donkeys. In the first two months of the breeding season, increase the light hours to 16 hours a day to improve the calcium absorption effect of the donor donkeys and ensure the physical fitness of the donor donkeys. Perform a comprehensive physical examination on the donor donkeys, including blood routine, biochemical index testing, brucellosis and tuberculosis screening, and deworming. Use ivermectin subcutaneous injection at a dose of 0.2 mg per kilogram of body weight, and wait for the female donkeys to enter estrus; 2) The donor donkeys were treated for estrus synchronization by intramuscular injection of cloprostenol, with a dose of 0.4 mg per donkey, followed by a second injection 11 days later, and 100 μg of follicle-stimulating hormone-releasing hormone compound was injected 30 hours after the second injection to induce estrus in the donor donkeys; 3) On the 9th day of the donor donkey's estrus cycle, superovulation treatment was performed. A total dose of 300 mg of follicle-stimulating hormone was diluted with normal saline and injected in 6 decreasing doses, each with an interval of 8 hours. The specific doses were 60 mg, 50 mg, 40 mg, 30 mg, 20 mg, and 10 mg. When the 4th injection of follicle-stimulating hormone was injected, 100 IU of luteinizing hormone was injected intramuscularly at the same time; 4) During the follicle formation process of the donor donkey, the follicle development is detected by rectal examination and ultrasound. When the follicle diameter reaches 30-40mm, frozen semen of a male donkey with good vitality and sperm density of not less than 150 million / ml is selected for artificial insemination. The amount of semen delivered each time is 10ml, and the semen is delivered deep into the uterine horn. The number of inseminations is 2 times, with an interval of 10 hours between the two times. 5) On the 7th day after artificial insemination, a three-way embryo collection tube was inserted into the uterine horn through the cervix, and the uterine horn was repeatedly flushed with 200 ml of PBS buffer containing 5% bovine serum albumin to collect the flushing fluid containing embryos. After the embryos were collected by the egg collection cup, they were immediately placed in the embryo culture medium in the incubator for embryo culture. After the embryo culture was stable, the collected embryos were morphologically evaluated under a microscope to screen the embryos; 6) Select healthy female donkeys aged 3-6 years old with normal reproductive performance as recipient donkeys. On the 4th and 5th day after the recipient donkeys come into estrus, use non-surgical methods to transplant the embryos into the recipient donkeys' uterus. Before the embryo transplantation, the recipient donkeys are monitored and observed, the optimal embryo transplantation time is calculated, and a success rate prediction model is established to predict the transplantation success rate of conceived embryos. 7) On the 20th day after the embryo transfer, the recipient donkey is checked for pregnancy. Then, after the mother donkey gives birth, the performance of the foal born through the embryo transfer is measured, including the measurement of growth and development indicators such as birth weight, weight at 1 month, height, length, chest circumference, etc., and its appearance characteristics and health status are recorded in detail. When the foal is 6 months old, its meat performance-related indicators are measured and analyzed, and combined with the results of genetic marker detection, the foal with excellent genetic traits and high production performance potential is selected as the reserve breeding donkey.

[0023] The specific embryo transplantation breeding method is: select 10 Texas donkeys aged 4-8 years old with good body shape, appearance and reproductive performance as donor donkeys. In the first two months of the breeding season, increase the light time to 16 hours a day to regulate the estrus of the donor donkeys. At the same time, strengthen feeding management and provide complete formula feed to ensure the nutritional needs of the donor donkeys. On the 9th day of the estrus cycle, superovulation treatment was performed on the donor donkeys, and artificial insemination was performed with high-quality male donkey semen 12 hours and 22 hours after estrus. On the 7th day after mating, embryos were collected by non-surgical method, and a total of 60 embryos were collected, including 35 morulae and 25 blastocysts. Through microscopic observation and identification of embryo development stages, 40 embryos with normal morphology and good development (20 morulae and 20 blastocysts) were selected for transplantation. 40 local female donkeys aged 3-5 years, healthy and disease-free, with regular estrus cycles were selected as recipient donkeys. While the donor donkeys were being superovulated, the recipient donkeys were injected with cloprostenol intramuscularly for estrus synchronization, so that the recipient donkeys would be in estrus within 2 days after the donor donkey embryos were collected. The 80 selected embryos were transplanted into the uterus of 40 recipient donkeys by non-surgical methods, with 2 embryos (40 morulae and 40 blastocysts) transplanted into each recipient donkey. After the embryo transplantation, the recipient donkeys were carefully cared for and raised. On the 20th day after the transplantation, the pregnancy status of the recipient donkeys was checked by ultrasound diagnosis. The results showed that 28 recipient donkeys were pregnant, with a pregnancy rate of 70% (the pregnancy rate of recipient donkeys transplanted with blastocysts was 80%, and the pregnancy rate of recipient donkeys transplanted with morulas was 60%). The pregnant recipient donkeys were given enhanced pregnancy preservation measures and feeding management, and 28 offspring donkeys were successfully born.

[0024] Example 2

[0025] Reference Figure 1-2 , further improvements were made on the basis of Example 1: The morphological assessment of the embryo specifically includes the following estimation methods: First, construct a judgment matrix ,in Indicates the relative importance of a factor, using a 1-9 scale. Indication factors Factors Equally important, Indication factors Factors Slightly more important, among which, when Indication factors Factors When they are equally important, the fuzzy data of the 1-9 scale method is ,in, They are the lower bound, the most likely value, and the upper bound, respectively, so that the description of the importance of morphological evaluation is more consistent with the ambiguity in actual situations; Calculate the judgment matrix The maximum eigenvalue of and the corresponding eigenvector , the eigenvector The amount Indicates the weight of each factor; For the specific indicators at the bottom layer, after quantification, they are weighted and summed according to the weights to obtain the comprehensive evaluation score of embryo quality. The specific evaluation score formula is as follows:

[0026] in, is the quantitative value of the underlying indicator, is the embryo's assessment score, As the influencing factors, For the time factor.

[0027] The optimal time for embryo transfer in the recipient donkey is determined by the following monitoring methods: Obtaining the hormone level data sequence of the recipient donkey every day After that, the data is smoothed to reduce the interference caused by data fluctuations. The new hormone level sequence is , it can be seen that the formula for calculating the optimal embryo transfer time is:

[0028] in, Represents the number of The new hormone level value at each position can be calculated by this method to make the hormone level data smoother and effectively reduce the interference of random fluctuations on data trend judgment. is the number of days of the moving average, which serves to average the summation results. This is the summation symbol, indicating that The data starts from the first raw hormone level data and continues to accumulate until the data.

[0029] Before embryo transfer in recipient donkeys, the embryo quality score of the embryo to be transferred, the recipient donkey age, endometrial thickness, number of births, and hormone levels were collected; Then, an embryo transfer success rate model was established, and the above data were set as independent variables. The independent variables were: , the specific calculation formula is as follows:

[0030] in, The success rate of embryo transfer ( Represents success, Represents failure) is the independent variable The corresponding coefficient.

[0031] The assessment score is based on a 5-point system, and the embryos are divided into three grades: A, B, and C. Scores 1 to 2 are C, scores 3 to 4 are B, and scores 5 are A. The collected embryos are morphologically observed under a microscope, and the embryos are preliminarily identified based on characteristics such as embryo morphology, size, cell number, and uniformity. Normal embryos should be spherical or elliptical, with clear cell boundaries and uniform size, and no obvious signs of fragmentation or degeneration. Assessment scores are made based on morphological observations, and then they are graded. Embryos are then given priority for use based on their grades, and embryos with low scores or abnormal morphology, small cell numbers, or obvious damage are eliminated.

[0032] Performance tests for breeding donkey foals include the following: Measurement of weight, physical fitness, pulling force, walking speed and walking endurance, and future breeding performance of female donkey foals; Specifically, the following measurement methods are included: Body weight measurement Measurement method: Measure the weight of the donkey foal regularly (such as weekly or monthly) to track its growth rate. This can be done using a digital scale or a floor scale.

[0033] Calculation formula: The absolute growth rate is (AG):

[0034] in, and The donkey is in time and Weight at time (unit: kg) The unit is kg / day or kg / week etc., depending on the time interval.

[0035] The relative growth rate is (RG):

[0036] The above formula reflects the proportion of the foal's weight growth relative to its initial weight.

[0037] Physical examination Measurement method: Measure the height, length, chest circumference and other body measurements of the donkey foal to assess its physical development. Use measuring sticks, tape measures and other tools for measurement.

[0038] Calculation formula: Taking body height as an example, suppose that at time The measured height is , at time The measured height is .

[0039] The absolute growth rate of height is:

[0040] The units are related to the time interval, such as cm / month.

[0041] The relative growth rate of body height is:

[0042] Pull force measurement Measurement method: Use a dynamometer to measure the maximum force a donkey foal can exert when pulling a heavy object. The test is usually carried out after the foal reaches a certain age and physical strength. During the test, the load is gradually increased until the foal can no longer pull.

[0043] Calculation formula: Maximum pulling force (MW): Directly read the maximum value of the pulling force meter (unit: kilogram force or Newton).

[0044] Pull coefficient (WC):

[0045] in, is the weight of the colt, The pull reading is used to compare the relative pull of foals of different weights; Measurement method: Let the donkey colt carry a certain weight (such as a weight that is a certain proportion of its body weight) and walk on a flat road, and record the walking speed and duration.

[0046] Calculation formula: Walking speed (VS):

[0047] in, is the distance walked (in meters) is the walking time (in seconds or minutes) and the unit can be meters per second or kilometers per hour.

[0048] Endurance Index (EI): can be measured by the longest time (in hours) or longest distance (in kilometers) walked under a specified load; Determination of future reproductive performance of female donkey foals Calculation method: Although the donkey foal itself has not yet reached breeding age, its future breeding performance can be estimated based on factors such as its family breeding history and physical development status.

[0049] Estimation formula: Expected age of first puberty (EA): can refer to the average age of first puberty of the same breed of donkeys , and make adjustments based on the growth and development of the foal. For example, if the foal grows faster than the average, the expected age of puberty may be advanced. Suppose the growth rate coefficient is (Indicates fast growth, express Average level, Indicates slow growth) The formula for calculating the expected age of puberty is as follows:

[0050] Expected fecundity (EF): Consider the fertility index of the family (such as the average number of foals born by female donkeys). ) and the foal's own health status (health coefficient , value range 0-1)

[0051] By tracking the physical performance of donkey foals bred by embryo transplantation and measuring their performance, the breeding direction of excellent donkey foals can be determined, and excellent donkey foals can be used as donors and recipients for future breeding. This can form a virtuous cycle in the breeding system of donkey embryo breeding, thereby improving the optimization of the future breeding system and the overall quality of the donkey herd.

[0052] Example 3

[0053] Reference Figure 1-2 , further improvements were made on the basis of Example 1: The embryo culture temperature of the incubator is 37.5℃, and the incubator is filled with 5% carbon dioxide and 8% oxygen. By simulating the real donkey's uterine environment in the incubator, the development of the embryo can be better guaranteed. It can ensure that the embryo can safely and stably develop to a transplantable state before transplantation, thereby improving the success rate and stability of the transplantation.

[0054] Before embryo transfer and conception, the recipient donkeys undergo the same health checks and deworming treatment as the donor donkeys.

[0055] The embryo transplant site is the upper third of the recipient donkey's uterine horn. Each recipient donkey is transplanted with 2-3 embryos, and the transplant is divided into two times. The specific operation is to insert the transplant tube containing the embryo into the uterine horn through the recipient donkey's vagina, and slowly inject the embryo into the uterus. The injection site should be selected in the upper third of the uterine horn, where the endometrial environment is conducive to the implantation and development of the embryo.

[0056] The pregnancy of the recipient donkey is checked by ultrasound, with the detection interval being once every half a month.

[0057] The donor donkeys and recipient donkeys were fed with concentrated feed, which contained 18% crude protein, 8000 IU, 1500 IU and 50 mg of vitamin A, D and E per kilogram of diet respectively, and the calcium-phosphorus ratio of the concentrated feed was 3:1.

[0058] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A breeding system for optimizing the reproductive performance of donkeys based on embryo transfer technology, characterized in that: The breeding system comprises the following steps: 1) Select female donkeys aged 4-8 years old with good body shape, appearance and reproductive performance as donor donkeys. Two months before the breeding season, increase the light hours to 16 hours a day, conduct a comprehensive physical examination on the donor donkeys, including blood routine, biochemical index testing, brucellosis and tuberculosis screening, deworming, and use ivermectin subcutaneous injection at a dose of 0.2 mg per kilogram of body weight, and wait for the female donkey to enter estrus; 2) The donor donkeys were treated for estrus synchronization by intramuscular injection of cloprostenol, with a dose of 0.4 mg per donkey, followed by a second injection 11 days later, and 100 μg of follicle-stimulating hormone-releasing hormone compound was injected 30 hours after the second injection to induce estrus in the donor donkeys; 3) On the 9th day of the donor donkey's estrus cycle, superovulation treatment was performed. A total dose of 300 mg of follicle-stimulating hormone was diluted with normal saline and injected in 6 decreasing doses, each with an interval of 8 hours. The specific doses were 60 mg, 50 mg, 40 mg, 30 mg, 20 mg, and 10 mg. When the 4th injection of follicle-stimulating hormone was injected, 100 IU of luteinizing hormone was injected intramuscularly at the same time; 4) During the follicle formation process of the donor donkey, the follicle development is detected by rectal examination and ultrasound. When the follicle diameter reaches 30-40mm, frozen semen of a male donkey with good vitality and sperm density of not less than 150 million / ml is selected for artificial insemination. The amount of semen delivered each time is 10ml, and the semen is delivered deep into the uterine horn. The number of inseminations is 2 times, with an interval of 10 hours between the two times. 5) On the 7th day after artificial insemination, a three-way embryo collection tube was inserted into the uterine horn through the cervix, and the uterine horn was repeatedly flushed with 200 ml of PBS buffer containing 5% bovine serum albumin to collect the flushing fluid containing embryos. After the embryos were collected by the egg collection cup, they were immediately placed in the embryo culture medium in the incubator for embryo culture. After the embryo culture was stable, the collected embryos were morphologically evaluated under a microscope to screen the embryos; 6) Select healthy female donkeys aged 3-6 years old with normal reproductive performance as recipient donkeys. On the 4th and 5th day after the recipient donkeys come into estrus, use non-surgical methods to transplant the embryos into the recipient donkeys' uterus. Before the embryo transplantation, the recipient donkeys are monitored and observed, the optimal embryo transplantation time is calculated, and a success rate prediction model is established to predict the transplantation success rate of conceived embryos. 7) On the 20th day after the embryo transfer, the recipient donkey is checked for pregnancy. Then, after the mother donkey gives birth, the performance of the foal born through the embryo transfer is measured, including the measurement of growth and development indicators such as birth weight, weight at 1 month, height, length, chest circumference, etc., and its appearance characteristics and health status are recorded in detail. When the foal is 6 months old, its meat performance-related indicators are measured and analyzed, and combined with the results of genetic marker detection, the foal with excellent genetic traits and high production performance potential is selected as the reserve breeding donkey.

2. A breeding system for optimizing donkey reproductive performance based on embryo transfer technology according to claim 1, characterized in that: The morphological assessment of the embryo specifically includes the following estimation methods: First, construct a judgment matrix ,in Indicates the relative importance of a factor, using a 1-9 scale. Indication factors Factors Equally important, Indication factors Factors Slightly more important, among which, when Indication factors Factors When they are equally important, the fuzzy data of the 1-9 scale method is ,in, They are the lower bound, the most likely value, and the upper bound, respectively, so that the description of the importance of morphological evaluation is more consistent with the ambiguity in actual situations; Calculate the judgment matrix The maximum eigenvalue of and the corresponding eigenvector , the eigenvector The amount Indicates the weight of each factor; For the specific indicators at the bottom layer, after quantification, they are weighted and summed according to the weights to obtain the comprehensive evaluation score of embryo quality. The specific evaluation score formula is as follows: ； in, is the quantitative value of the underlying indicator, is the embryo's assessment score, As the influencing factors, For the time factor.

3. A breeding system for optimizing donkey reproductive performance based on embryo transfer technology according to claim 1, characterized in that: The optimal time for embryo transplantation of the recipient donkey is specifically monitored by the following methods: Obtaining the hormone level data sequence of the recipient donkey every day After that, the data is smoothed to reduce the interference caused by data fluctuations. The new hormone level sequence is , it can be seen that the formula for calculating the best embryo transfer time is: ； in, Represents the number of The new hormone level value at each position can be calculated by this method to make the hormone level data smoother and effectively reduce the interference of random fluctuations on data trend judgment. is the number of days of the moving average, which serves to average the summation results. This is the summation symbol, indicating that The data starts from the first raw hormone level data and continues to accumulate until the data.

4. A breeding system for optimizing donkey reproductive performance based on embryo transfer technology according to claim 1, characterized in that: Before the embryo transplantation of the recipient donkey, the embryo quality score of the embryo to be transplanted, the age of the recipient donkey, the endometrial thickness, the number of births and the hormone level are collected; Then, an embryo transfer success rate model was established, with the above embryo quality score, recipient donkey age, endometrial thickness, number of births and hormone level data set as independent variables. The independent variables are: , the specific calculation formula is as follows: ； in, The probability of successful embryo transfer ( Represents success, Represents failure) is the independent variable The corresponding coefficient.

5. A breeding system for optimizing donkey reproductive performance based on embryo transfer technology according to claim 2, characterized in that: The evaluation score is based on a 5-point system, and the evaluation score divides the embryos into three grades: A, B, and C, where scores of 1 to 2 are grade C, scores of 3 to 4 are grade B, and scores of 5 are grade A.

6. A breeding system for optimizing donkey reproductive performance based on embryo transfer technology according to claim 1, characterized in that: The embryo culture temperature of the incubator is 37.5° C., and the incubator is filled with 5% carbon dioxide and 8% oxygen.

7. A breeding system for optimizing donkey reproductive performance based on embryo transfer technology according to claim 1, characterized in that: Before embryo transplantation and conception, the recipient donkey is subjected to the same health examination and deworming treatment as the donor donkey.

8. A breeding system for optimizing donkey reproductive performance based on embryo transfer technology according to claim 1, characterized in that: The embryo transplantation site is the upper third of the uterine horn of the recipient donkey. The number of embryos transplanted to each recipient donkey is 2-3, and the transplantation is divided into two times.

9. A breeding system for optimizing donkey reproductive performance based on embryo transfer technology according to claim 1, characterized in that: The pregnancy test of the recipient donkey is carried out by ultrasonic testing, and the testing interval is once every half a month.

10. A breeding system for optimizing donkey reproductive performance based on embryo transfer technology according to claim 1, characterized in that: The donor donkey and the recipient donkey are fed with concentrated feed, the crude protein content of the concentrated feed is 18%, the added amounts of vitamins A, D and E are 8000 IU, 1500 IU and 50 mg per kilogram of diet respectively, and the calcium-phosphorus ratio of the concentrated feed is 3:1.

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