Artificial reproduction-hybridization combined breeding method for meat goats

Abstract

The invention discloses an artificial propagation-hybridization combined breeding method for meat goats, and relates to the technical field of animal breeding, and the method comprises the following specific steps: selecting a goat variety with good meat performance as a female parent, and selecting a goat variety with large physique as a male parent; the method comprises the following steps: performing in-vitro culture on female parent oocytes to obtain mature oocytes containing first polar bodies, screening high-activity sperms by adopting a temperature gradient screening device, performing in-vitro fertilization on the mature oocytes and the high-activity sperms, culturing the mature oocytes and the high-activity sperms to a hybrid blastocyst form, transplanting the mature oocytes and the high-activity sperms into a female body, and developing the mature oocytes and the high-activity sperms until the mature oocytes and the high-activity sperms are naturally delivered to obtain a hybrid F1 generation; backcrossing the F1 generation with the female parent, backcrossing the backcrossed offspring with the female parent for multiple times until a breeding target is met, and carrying out cross-crossing fixation to obtain a new variety / line with excellent characters; the sperm screening efficiency is improved by utilizing the screening device, and the quality of the screened sperms is ensured, so that the fertilization efficiency and the embryo survival rate are remarkably improved.

Description

Technical Field

[0001] The invention relates to the field of animal breeding, and in particular to an artificial breeding-hybridization combined breeding method for meat goats. Background Art

[0002] In the breeding practice of meat goats, traditional hybrid breeding methods occupy a dominant position. However, this method has obvious limitations. First, due to the limitation of the number of embryos in the natural reproduction process of animals, the number of offspring produced each time by traditional hybrid breeding is limited, resulting in a long breeding cycle and difficulty in responding to market demand quickly. Secondly, after the sperm that has not been strictly screened combines with the oocyte, the quality of the fertilized eggs formed is uneven, and the embryo survival rate is low, which further affects the breeding efficiency. In addition, the application of existing artificial assisted reproductive technology in meat goat breeding is still immature, especially in terms of sperm quality control, fertilization efficiency and embryo survival rate. There are still many challenges.

[0003] For example, the Chinese patent with application number CN202010432054.0, a method for artificial breeding and hybridization of meat goats, belongs to the field of animal breeding, and specifically relates to a method for artificial breeding and hybridization of meat goats, wherein goat breeds with good meat performance are selected as the mother, and goat breeds with large physique are selected as the father; the maternal oocytes are cultured in vitro to mature oocytes containing the first polar body, and the paternal semen is treated with sperm motility enhancement liquid to prepare a sperm suspension; the mature oocytes and sperm suspension are fertilized in vitro, cultured to the hybrid blastocyst morphology, and transplanted into the mother's body so that the hybrid blastocyst develops in the mother's body to natural delivery, and a hybrid F1 generation is obtained; the F1 generation is backcrossed with the mother, and the backcross offspring is backcrossed with the mother for multiple times until the breeding goal is met, and then the cross is fixed to obtain a new variety / line with excellent traits. This invention combines artificial assisted reproductive technology with traditional hybridization technology, which can increase the number of animal embryos and improve the survival rate of animal embryos, and has good application prospects in the field of animal breeding.

[0004] In the above method, sperm motility enhancing liquid is used to treat sperm, but the treated sperm is not screened and has uneven quality, which affects the subsequent fertilization efficiency and embryo survival rate. Summary of the invention

[0005] The embodiment of the present application solves the problem in the prior art that sperm quality is uneven, affecting subsequent fertilization efficiency and embryo survival rate, by providing an artificial breeding-hybridization combined breeding method for meat goats. The sperm screening efficiency is improved through a temperature gradient screening device, and the quality of the screened sperm is ensured, thereby significantly improving the fertilization efficiency and embryo survival rate.

[0006] The present application embodiment provides a method for artificial propagation-hybridization combined breeding of meat goats, which specifically comprises the following steps:

[0007] S1. Select goat breeds with good meat performance as the female parent and goat breeds with large physique as the male parent;

[0008] S2, culturing the isolated maternal oocyte in vitro until it becomes a mature oocyte containing the first polar body for later use;

[0009] S3, fertilizing the mature oocytes with the selected high-motility sperm in vitro, culturing the fertilized eggs in vitro to the hybrid blastocyst morphology, and finally transplanting the hybrid blastocyst into the mother's body, allowing the hybrid blastocyst to develop in the mother's body until natural delivery, and obtaining the hybrid F1 generation;

[0010] The screening of high-motility sperm is specifically as follows: a sperm suspension is placed in a screening device, and the sperm swims to the end of the pipe driven by the temperature gradient, and is observed in the counting area at the end of the screening device. When 30% of the sperm are counted to arrive, the screening is stopped and the high-motility sperm are collected;

[0011] S4, selecting an individual with excellent comprehensive traits from the hybrid F1 generation as the male parent, and backcrossing it with the female parent. The backcrossing steps refer to S2-S3 to obtain the first backcross generation;

[0012] S5. Repeat the steps of S4, i.e. backcross the backcross offspring with the mother parent for multiple times until the breeding goal is met, and then cross-cross to fix it to obtain a new variety / line with excellent traits.

[0013] Furthermore, the screening device is set as a 10 cm long pipe, the temperature at the starting end of the pipe is set to 36.5°C, the temperature at the end end is set to 37.5°C, and five temperature zones of 36.5°C, 36.75°C, 37.0°C, 37.25°C and 37.5°C are set in the middle, and the temperature increases successively to form a temperature gradient.

[0014] Furthermore, the screening device is heated at 36.5°C, 37°C, and 37.5°C to maintain a temperature gradient, and both ends of the pipe are counting areas for observing and counting sperm.

[0015] Furthermore, the screening device is also provided with an injection pipeline.

[0016] Furthermore, the screening of highly motile sperm is specifically as follows: placing the sperm suspension into the screening device, observing in the counting area at the terminal end of the screening device, when sperm appears in the counting area at the terminal end, rapidly injecting polyethylene glycol through the injection pipe of the screening device, and continuing to observe the counting area at the terminal end until 30% of the sperm are counted, then stopping the screening and collecting the highly motile sperm.

[0017] Furthermore, the injection pipeline is arranged in the middle position of the upper part of the screening device, the concentration of polyethylene glycol is 35%-40%, and the injection amount is 4%-6% of the sperm suspension.

[0018] Furthermore, the screening device is arranged in the screening box, and the screening device can rotate around its central axis.

[0019] Furthermore, an injector is arranged at the middle position of the upper part of the screening device, and the inside of the injector is filled with polyethylene glycol.

[0020] Furthermore, the injector is a capsule made of flexible material, which can expand and contract. A magnet is arranged on the upper part of the injector, and a corresponding magnet is arranged at the corresponding position of the screening box, and the magnetic poles of the two magnets repel each other.

[0021] Furthermore, the screening of highly motile sperm is specifically as follows: placing the sperm suspension into the screening device, observing in the counting area at the terminal end of the screening device, when sperm appears in the counting area at the terminal end, the screening device rotates, and the injector is in an expanded state in the initial state. When the magnet of the injector rotates to correspond to the upper magnet of the screening box, the magnetic poles repel each other, the injector contracts, and polyethylene glycol is injected into the screening device. The counting area at the terminal end is continuously observed until 30% of the sperm are counted, then the screening is stopped and the highly motile sperm are collected.

[0022] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

[0023] First, through the difference in sperm's swimming ability under a specific temperature gradient, high-motility sperm can be screened. Sperm is most active when it is close to the normal body temperature of 37°C. Therefore, by setting a temperature gradient and utilizing sperm's sensitivity to temperature, sperm can be guided to swim to areas with higher temperatures. By observing and counting the proportion of sperm reaching the end of the pipe, sperm with higher motility can be screened out. Through temperature gradient screening, the sperm that can be used for fertilization is the most active part, thereby significantly improving the overall quality of sperm. Using high-motility sperm for in vitro fertilization can increase the success rate of sperm-egg combination, thereby improving the fertilization rate. At the same time, Due to the high quality of sperm, fertilized eggs are more likely to develop into healthy hybrid blastocysts during in vitro culture, thereby improving embryo survival rate; since high-motility sperm improves fertilization rate and embryo survival rate, and reduces early embryo death caused by low sperm quality, it can shorten the breeding cycle, improve breeding efficiency, and obtain new varieties / lines that meet breeding goals more quickly; using screened high-motility sperm for hybrid culture can more stably pass on the excellent genetic characteristics of the father and mother to the offspring, enhance the meat performance, physique and other important traits of the new variety / line, and at the same time, enhance the genetic stability and consistency of the new variety / line;

[0024] Secondly, by setting a heat dissipation area above the screening device, a temperature gradient is also formed in the longitudinal direction inside the device, providing a more complex and delicate temperature environment for sperm; the introduction of the longitudinal temperature gradient makes the swimming path of sperm more diverse during the screening process, and sperm with different motility will show the best state in their respective suitable temperature ranges, making it easier to be accurately screened; under the stimulation of temperature at different heights, the swimming ability and directionality of sperm will change, and this change provides more information for screening, so as to more accurately identify high-motility sperm; the longitudinal temperature gradient makes the difference in the swimming ability of sperm in different temperature zones more obvious, thereby speeding up the screening process, and the screening device can more quickly identify sperm that can quickly adapt and swim to the higher temperature zone on the right, that is, high-motility sperm; the single gradient screening speed is slow and there is a problem of missing high-motility sperm, while the introduction of the longitudinal temperature gradient provides a more delicate screening environment for sperm, which can capture more potential high-quality sperm and avoid the problem of missing high-quality sperm due to improper screening conditions;

[0025] Third, by introducing the combined effect of polyethylene glycol and temperature gradient, the accuracy and efficiency of screening are further improved, thereby improving the breeding efficiency; by setting an injection pipe in the middle position of the upper part of the screening device, and quickly injecting polyethylene glycol when sperm appears in the terminal end counting area, Example 3 can accurately screen out sperm with high motility; by changing the viscosity and fluidity of the liquid environment, and forming a concentration gradient and micro-liquid flow, the efficiency of screening and the fertilization rate are effectively improved. During the screening process, sperm with low motility are blocked on the left, while sperm with high motility can follow the liquid flow and move to the high temperature zone at a higher rate. This screening method not only avoids the interference of low-motility sperm, but also ensures the effective collection of high-motility sperm, thereby improving the fertilization rate and breeding efficiency, and promoting new varieties / lines to have more stable genetic characteristics;

[0026] Fourthly, by introducing a rotatable screening device and a magnetically controlled injector, precise injection of polyethylene glycol is achieved, which not only ensures the stability of the injection, but also changes the chemical potential energy in the sperm suspension, provides a rotational flow, and accelerates the movement of highly motile sperm; utilizing the principle of magnetic pole repulsion, when the magnet of the injector rotates to correspond to the upper magnet of the screening box, a repulsive force is generated, causing the injector to contract, thereby precisely injecting polyethylene glycol into the screening device, ensuring precise control of the injection time and amount. The rotation of the screening device not only provides a dynamic screening environment for sperm, but also accelerates the movement of sperm, especially the movement of highly motile sperm, through the centrifugal force and centripetal force generated by the rotation, further intensifies the separation of sperm with different motility, thereby improving the accuracy and efficiency of screening. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1This is a schematic diagram of a screening device according to Embodiment 1 of the present invention;

[0028] Figure 2 This is a schematic diagram of a screening device according to a second embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of a screening device according to Embodiment 3 of the present invention;

[0030] Figure 4 This is a schematic diagram of a screening device according to Embodiment 4 of the present invention. DETAILED DESCRIPTION

[0031] To facilitate the understanding of the present invention, the present application will be described more comprehensively below with reference to the relevant drawings; the drawings show preferred embodiments of the present invention, but the present invention can be implemented in many different forms and is not limited to the embodiments described herein; on the contrary, the purpose of providing these embodiments is to enable a more thorough and comprehensive understanding of the disclosed content of the present invention.

[0032] It should be noted that the terms “vertical”, “horizontal”, “up”, “down”, “left”, “right” and similar expressions used in this document are only for illustrative purposes and do not represent the only implementation method.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which the present invention belongs; the terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention; the term "and / or" used herein includes any and all combinations of one or more related listed items.

[0034] Embodiment 1: A method for artificial propagation and hybridization of meat goats, comprising the following steps:

[0035] S1. Select goat breeds with good meat performance as the female parent and goat breeds with large physique as the male parent;

[0036] S2, culturing the isolated maternal oocyte in vitro until it becomes a mature oocyte containing the first polar body for later use;

[0037] The male parent's in vitro semen is soaked in sperm motility enhancement solution for 30-40 minutes, and then centrifuged at 2000 rpm for 10-15 minutes. After the sperm precipitate is washed with sperm motility enhancement solution, the sperm precipitate is centrifuged again at 2000 rpm for 10-15 minutes. Finally, the precipitate is suspended with sperm supernatant to prepare a sperm suspension.

[0038] The formula of sperm motility enhancement solution is as follows: 97ml embryo culture water, MgSO 4 7H 2O 0.02-0.03 g, KCl 0.05-0.06 g, streptomycin 0.005 g, penicillin 0.006 g, NaHCO 3 0.04~0.05g, sodium pyruvate 0.004g, CaCl 2 ·2H 2 O 0.02 g, FBS 3 ml;

[0039] The selection of high-motility sperm is as follows: Figure 1 As shown, a sperm suspension is placed in a screening device, and the sperm swims toward the end of the pipe driven by the temperature gradient. The sperm is observed in the counting area at the end of the screening device. When 30% of the sperm are counted, the screening is stopped and the sperm with high motility are collected.

[0040] The screening device is set as a 10 cm long pipe, the temperature at the starting end of the pipe is set to 36.5°C, the temperature at the end end is set to 37.5°C, and five temperature zones are set in the middle, namely 36.5°C, 36.75°C, 37.0°C, 37.25°C and 37.5°C, and the temperature increases in sequence to form a temperature gradient; heating is performed at 36.5°C, 37°C and 37.5°C to maintain the temperature gradient, and both ends of the pipe are counting zones for observing and counting sperm;

[0041] S3, fertilizing the mature oocytes with the selected high-motility sperm in vitro, culturing the fertilized eggs in vitro to the hybrid blastocyst morphology, and finally transplanting the hybrid blastocyst into the mother's body, allowing the hybrid blastocyst to develop in the mother's body until natural delivery, and obtaining the hybrid F1 generation;

[0042] S4, selecting an individual with excellent comprehensive traits from the hybrid F1 generation as the male parent, and backcrossing it with the female parent. The backcrossing steps refer to S2-S3 to obtain the first backcross generation;

[0043] S5. Repeat the steps of S4, i.e. backcross the backcross offspring with the mother parent for multiple times until the breeding goal is met, and then cross-cross to fix it to obtain a new variety / line with excellent traits.

[0044] The following experiments were performed for this embodiment:

[0045] S1. Select Lüliang black goat with good meat performance as the female parent, and select Jintang black sheep with large physique as the male parent;

[0046] S2. (1) Performing ovulation induction treatment on the maternal parent in a conventional manner, culturing the maternal oocytes in vitro until they become mature oocytes containing the first polar body, and collecting a total of 13 mature oocytes for standby use; (2) Collecting the paternal semen in a conventional manner, soaking it in a sperm motility enhancement solution, and preparing a sperm suspension, placing the sperm suspension in a screening device, and allowing the sperm to swim to the end of the pipe under the drive of the temperature gradient, and observing it in the counting area at the end of the screening device. When 30% of the sperm are counted to arrive, stopping the screening and collecting the sperm with high motility;

[0047] Sperm motility enhancement solution formula: embryo culture water 97ml, MgSO 4 7H 2 O 0.02g, KCl 0.05g, streptomycin 0.005g, penicillin 0.006g, NaHCO 3 0.04g, sodium pyruvate 0.004g, CaCl 2 ·2H 2 O 0.02g, FBS 3ml, Hepes 0.5g;

[0048] S3, fertilizing the mature oocytes and sperm suspension in vitro by intracytoplasmic sperm injection (ICSI), culturing the fertilized eggs in vitro to hybrid blastocyst morphology, and finally transplanting the hybrid blastocyst into the mother's body, allowing the hybrid blastocyst to develop in the mother's body until natural delivery, and obtaining a hybrid F1 generation; it should be noted that step S3 adopts conventional ICSI methods, conventional hybrid blastocyst culture and transplantation methods;

[0049] S4, selecting an individual with excellent comprehensive traits from the hybrid F1 generation as the male parent, and backcrossing it with the female parent. The backcrossing steps refer to S2-S3 to obtain the first backcross generation;

[0050] S5. Repeat the steps of S4, i.e. backcross the backcross offspring with the mother parent for multiple times until the breeding goal is met, and then cross-cross to fix it to obtain a new variety (line) with excellent traits.

[0051] The comparative example adopts the method of application number CN202010432054.0 for combined breeding. The difference from the experiment in this embodiment is that no screening device is used to screen high-motility sperm.

[0052] The technical solutions in the above embodiments of the present application have at least the following technical effects or advantages:

[0053] Highly motile sperm can be screened by the difference in sperm's swimming ability under a specific temperature gradient. Sperm is most active when it is close to the normal body temperature of 37°C. Therefore, by setting a temperature gradient and taking advantage of sperm's sensitivity to temperature, sperm can be guided to swim to areas with higher temperatures. By observing and counting the proportion of sperm that reach the end of the pipe, sperm with higher motility can be screened.

[0054] Through temperature gradient screening, the sperm that can be used for fertilization is the most active part, thereby significantly improving the overall quality of sperm; using high-motility sperm for in vitro fertilization can increase the success rate of sperm-egg combination, thereby improving the fertilization rate. At the same time, due to the high sperm quality, the fertilized egg is more likely to develop into a healthy hybrid blastocyst during in vitro culture, thereby improving the embryo survival rate; since high-motility sperm improves the fertilization rate and embryo survival rate, and reduces early embryo death caused by low sperm quality, it can shorten the breeding cycle, improve breeding efficiency, and obtain satisfaction faster. New varieties / lines as breeding targets; using screened high-motility sperm for hybridization culture can more stably pass on the excellent genetic characteristics of the father and mother to the offspring, enhance the meat performance, physique and other important traits of the new varieties / lines, and at the same time, enhance the genetic stability and consistency of the new varieties / lines; this method combines artificial assisted reproductive technology and traditional hybridization technology, and further optimizes the sperm quality by introducing the step of temperature gradient screening of high-motility sperm, which not only improves the sperm quality and fertilization rate, but also optimizes the breeding efficiency and enhances the genetic advantages of the new varieties / lines.

[0055] Embodiment 2: Embodiment 1 above not only improves the quality and fertilization rate of sperm, but also optimizes breeding efficiency and enhances the genetic advantages of new varieties / lines by introducing a screening device to screen highly motile sperm. In order to further improve the quality and fertilization rate of sperm, further improvements are made on the basis of Embodiment 1.

[0056] like Figure 2 As shown, a heat dissipation area is arranged above the screening device so that the upper temperature of each temperature area is 0.25°C lower than the temperature of the lower temperature area, forming a temperature gradient in the longitudinal direction.

[0057] The experiment of this embodiment is conducted on the basis of the experiment of the first embodiment. The difference between the experiment of this embodiment and the experiment of the first embodiment is that the temperature gradient is set in the longitudinal direction of the screening device.

[0058] The technical solutions in the above embodiments of the present application have at least the following technical effects or advantages:

[0059] By setting a heat dissipation area above the screening device, a temperature gradient is formed in the longitudinal direction inside the device, providing a more complex and delicate temperature environment for sperm;

[0060] The introduction of the longitudinal temperature gradient makes the swimming paths of sperm more diverse during the screening process. Sperms of different motility will show their best state in their respective suitable temperature ranges, making them easier to be accurately screened. Under temperature stimulation at different heights, the swimming ability and directionality of sperm will change. This change provides more information for screening, thereby more accurately identifying high-motility sperm. The longitudinal temperature gradient makes the difference in the swimming ability of sperm in different temperature zones more obvious, thereby speeding up the screening process. The screening device can more quickly identify sperm that can quickly adapt and swim to the higher temperature zone on the right, that is, high-motility sperm. The single gradient screening speed is slow and there is a problem of missing high-motility sperm. The introduction of the longitudinal temperature gradient provides a more sophisticated screening environment for sperm, which can capture more potential high-quality sperm and avoid the problem of missing high-quality sperm due to improper screening conditions.

[0061] By more accurately screening out highly motile sperm, the fertilization rate and breeding efficiency are improved. The success rate of the combination of highly motile sperm and oocytes is higher, and the fertilized eggs are more likely to develop into healthy hybrid blastocysts during in vitro culture. Since the screening process is more efficient and accurate, the breeding cycle is shortened and the cultivation speed of new varieties / lines is accelerated. Using precisely screened highly motile sperm for hybrid culture can more stably pass on the excellent genetic characteristics of the father and mother to the offspring, thereby enhancing the meat performance, physique and other important traits of the new variety / line, and improving its genetic stability and consistency.

[0062] Example 3: The above-mentioned Example 2 introduces a longitudinal temperature gradient to screen high-motility sperm, thereby improving the screening accuracy and efficiency, avoiding the problem of omissions, and thus improving the fertilization rate and breeding efficiency. In order to further improve the sperm quality and fertilization rate, further improvements are made on the basis of Example 2.

[0063] The screening device is also provided with an injection pipeline;

[0064] The selection of high-motility sperm is as follows: Figure 3 As shown, a sperm suspension is placed in a screening device and observed in the counting area at the terminal end of the screening device. When sperm appears in the counting area at the terminal end, polyethylene glycol is quickly injected through the injection pipe of the screening device. The terminal end counting area is continuously observed until 30% of the sperm are counted to arrive, then the screening is stopped and the sperm with high motility is collected.

[0065] The injection pipeline is arranged in the middle of the upper part of the screening device, the concentration of polyethylene glycol is 35%-40%, and the injection amount is 4%-6% of the sperm suspension.

[0066] This embodiment is experimented on the basis of the experiment of the second embodiment. The difference between this embodiment and the experiment of the second embodiment is that when sperm appears in the counting area at the terminal end, polyethylene glycol is rapidly injected through the injection pipe of the screening device. The concentration of polyethylene glycol is 38%, and the injection amount is 5% of the sperm suspension.

[0067] The technical solutions in the above embodiments of the present application have at least the following technical effects or advantages:

[0068] When sperm first appears in the counting area at the terminal end, polyethylene glycol is injected into the pipe through the injection pipe set in the middle position of the upper part of the screening device; the injection of polyethylene glycol increases the concentration of the liquid in the pipe, making it more viscous, which further affects the swimming ability and direction of the sperm. The change in viscosity will affect the flow characteristics of the liquid and form a micro-liquid flow. In the micro-liquid flow, the diffusion and movement of sperm will be affected by the driving force of the fluid; sperm is sensitive to temperature and will show different swimming abilities under a specific temperature gradient. The injection of polyethylene glycol further affects the swimming behavior of sperm under this temperature gradient, and affects the swimming speed and direction of sperm by changing the viscosity and fluidity of the liquid environment; in a viscous liquid environment, sperm, as tiny biological molecules, will be affected by molecular potential energy. Sperm with medium and low motility are more easily blocked by the viscous liquid environment due to their low molecular potential energy, while sperm with high motility can overcome this resistance and continue to move to the high temperature area;

[0069] The injection of polyethylene glycol forms a concentration gradient in the pipe. The high-concentration liquid area exerts a high-concentration liquid pressure on the sperm. Under this pressure, it is more difficult for low-motility sperm to pass through the high-concentration area and is blocked on the left. Due to the combined effect of concentration difference and temperature gradient, micro-liquid flow is formed in the pipe. This micro-liquid flow promotes the sperm to diffuse to the high-temperature area and increases the driving force for sperm to swim. Under the action of micro-liquid flow, sperm are affected by molecular potential energy and rheology. Sperm with medium and low motility are more likely to be blocked or deviate from the mainstream direction due to their low potential energy. Sperm with high motility can follow the liquid flow and move to the high-temperature area at a higher rate, further improving the accuracy and efficiency of screening.

[0070] By introducing the combined effect of polyethylene glycol and temperature gradient, the accuracy and efficiency of screening are further improved, thereby improving the breeding efficiency; by setting an injection pipe in the middle position of the upper part of the screening device and quickly injecting polyethylene glycol when sperm appears in the terminal counting area, Example 3 can accurately screen out sperm with high motility; by changing the viscosity and fluidity of the liquid environment, and forming a concentration gradient and micro-liquid flow, the screening efficiency and fertilization rate are effectively improved. During the screening process, low-motility sperm are blocked on the left, while high-motility sperm can follow the liquid flow and move to the high-temperature zone at a higher rate. This screening method not only avoids the interference of low-motility sperm, but also ensures the effective collection of high-motility sperm, thereby improving the fertilization rate and breeding efficiency, and promoting new varieties / lines to have more stable genetic characteristics.

[0071] Embodiment 4: Embodiment 3 above improves the accuracy and efficiency of screening, and improves the fertilization rate and breeding efficiency by introducing an injection pipe and injecting polyethylene glycol at the right time. In order to further improve the sperm quality and fertilization rate, further improvements are made on the basis of Embodiment 3.

[0072] like Figure 4 As shown, the screening device is arranged in the screening box, and the screening device can rotate around its central axis; an injector is arranged at the middle position of the upper part of the screening device, and the inside of the injector is filled with polyethylene glycol. The injector is a capsule made of a flexible material and can expand and contract. A magnet is arranged on the upper part of the injector, and a corresponding magnet is arranged at the corresponding position of the screening box, and the magnetic poles of the two magnets repel each other;

[0073] The screening of highly motile sperm is specifically as follows: the sperm suspension is placed in the screening device, and the counting area at the terminal end of the screening device is observed. When sperm appears in the counting area at the terminal end, the screening device rotates, and the injector is in an expanded state in the initial state. When the magnet of the injector rotates to correspond to the upper magnet of the screening box, the magnetic poles repel each other, the injector contracts, and polyethylene glycol is injected into the screening device. The counting area at the terminal end is continuously observed until 30% of the sperm are counted, then the screening is stopped and the highly motile sperm are collected.

[0074] For this embodiment, an experiment was conducted on the basis of the experiment in embodiment three. The difference between the experiment in this embodiment and the experiment in embodiment three is that when sperm appears in the counting area at the terminal end, the screening device rotates, and the injector is in an expanded state in the initial state. When the magnet of the injector rotates to correspond to the upper magnet of the screening box, the magnetic poles repel each other, the injector contracts, and polyethylene glycol is injected into the screening device.

[0075] The technical solutions in the above embodiments of the present application have at least the following technical effects or advantages:

[0076] By introducing a rotatable screening device and a magnetically controlled injector, the precise injection of polyethylene glycol is achieved, which not only ensures the stability of the injection, but also changes the chemical potential energy in the sperm suspension, provides a rotating flow, and accelerates the movement of highly active sperm; by utilizing the principle of magnetic pole repulsion, when the magnet of the injector rotates to correspond to the upper magnet of the screening box, a repulsive force is generated, causing the injector to contract, thereby accurately injecting polyethylene glycol into the screening device, ensuring precise control of the injection time and amount. The rotation of the screening device not only provides a dynamic screening environment for sperm, but also accelerates the movement of sperm, especially the movement of highly active sperm, through the centrifugal force and centripetal force generated by the rotation, further intensifies the separation of sperm with different vigours, thereby improving the accuracy and efficiency of screening;

[0077] The magnetically controlled injector can ensure that polyethylene glycol is injected at a precise time and position, avoiding the errors and instability that may be caused by manual injection, thereby improving the accuracy and repeatability of screening; the rotation of the screening device provides a dynamic screening environment for sperm, which can more realistically simulate the swimming state of sperm in the body, thereby more accurately screening out highly active sperm; the rotating flow not only increases the contact area between sperm and the screening device, but also accelerates the movement of sperm, especially the movement of highly active sperm, through the action of centrifugal and centripetal forces, thereby shortening the screening time and improving the screening efficiency;

[0078] Since the selected sperm is of higher quality and more active, the success rate of combining with oocytes will be higher, and the fertilized eggs will be more likely to develop into healthy hybrid blastocysts during in vitro culture. This can not only improve the fertilization rate, but also shorten the breeding cycle and improve breeding efficiency; using precisely selected high-motility sperm for hybrid culture can more stably pass on the excellent genetic characteristics of the father and mother to the offspring, thereby enhancing the meat performance, physique and other important traits of the new breed / line, and improving its genetic stability and consistency.

[0079] Performance test: The sperm quality of the comparative example and Examples 1 to 4 was tested, and the results are shown in the following table:

[0080]

[0081]

[0082] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for artificial breeding and hybridization of meat goats, characterized in that: The specific steps include: S1. Select goat breeds with good meat performance as the female parent and goat breeds with large physique as the male parent; S2, culturing the isolated maternal oocyte in vitro until it becomes a mature oocyte containing the first polar body for later use; S3, fertilizing the mature oocytes with the selected high-motility sperm in vitro, culturing the fertilized eggs in vitro to the hybrid blastocyst morphology, and finally transplanting the hybrid blastocyst into the mother's body, allowing the hybrid blastocyst to develop in the mother's body until natural delivery, and obtaining the hybrid F1 generation; The screening of high-motility sperm is specifically as follows: a sperm suspension is placed in a screening device, and the sperm swims to the end of the pipe driven by the temperature gradient, and is observed in the counting area at the end of the screening device. When 30% of the sperm are counted to arrive, the screening is stopped and the high-motility sperm are collected; S4, selecting an individual with excellent comprehensive traits from the hybrid F1 generation as the male parent, and backcrossing it with the female parent. The backcrossing steps refer to S2-S3 to obtain the first backcross generation; S5. Repeat the steps of S4, i.e. backcross the backcross offspring with the mother parent for multiple times until the breeding goal is met, and then cross-cross to fix it to obtain a new variety / line with excellent traits.

2. The artificial propagation-hybridization combined breeding method for meat goats according to claim 1, characterized in that: The screening device is set as a 10 cm long pipe. The temperature at the starting end of the pipe is set to 36.5°C, the temperature at the end end is set to 37.5°C, and five temperature zones are set in the middle at 36.5°C, 36.75°C, 37.0°C, 37.25°C and 37.5°C. The temperatures increase successively to form a temperature gradient.

3. The artificial propagation-hybridization combined breeding method for meat goats according to claim 2, characterized in that: The screening device is heated at 36.5°C, 37°C, and 37.5°C to maintain a temperature gradient, and both ends of the pipe are counting areas for observing and counting sperm.

4. The artificial propagation-hybridization combined breeding method for meat goats according to claim 3, characterized in that: The screening device is also provided with an injection pipeline.

5. The artificial propagation-hybridization combined breeding method for meat goats according to claim 4, characterized in that: The screening of highly motile sperm is specifically as follows: placing the sperm suspension into the screening device, observing in the counting area at the terminal end of the screening device, when sperm appears in the counting area at the terminal end, rapidly injecting polyethylene glycol through the injection pipe of the screening device, and continuing to observe the counting area at the terminal end until 30% of the sperm are counted to arrive, then stopping the screening and collecting the highly motile sperm.

6. The artificial propagation-hybridization combined breeding method for meat goats according to claim 5, characterized in that: The injection pipeline is arranged at the middle position of the upper part of the screening device, the concentration of polyethylene glycol is 35%-40%, and the injection amount is 4%-6% of the sperm suspension.

7. The artificial propagation-hybridization combined breeding method for meat goats according to claim 4, characterized in that: The screening device is arranged in the screening box, and the screening device can rotate around its central axis.

8. The artificial propagation-hybridization combined breeding method for meat goats according to claim 7, characterized in that: An injector is arranged at the middle position of the upper part of the screening device, and the inside of the injector is filled with polyethylene glycol.

9. The artificial propagation-hybridization combined breeding method for meat goats according to claim 8, characterized in that: The injector is a capsule made of flexible material, which can expand and contract. A magnet is arranged on the upper part of the injector, and a corresponding magnet is arranged at the corresponding position of the screening box, and the magnetic poles of the two magnets repel each other.

10. The artificial propagation-hybridization combined breeding method for meat goats according to claim 9, characterized in that: The screening of highly motile sperm is specifically as follows: the sperm suspension is placed in the screening device, and the counting area at the terminal end of the screening device is observed. When sperm appears in the counting area at the terminal end, the screening device rotates, and the injector is in an expanded state in the initial state. When the magnet of the injector rotates to correspond to the upper magnet of the screening box, the magnetic poles repel each other, the injector contracts, and polyethylene glycol is injected into the screening device. The counting area at the terminal end is continuously observed until 30% of the sperm are counted, then the screening is stopped and the highly motile sperm are collected.

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