Method for breeding new strain of high-quality mutton sheep
By combining excellent domestic and foreign meat sheep breeds for three generations of hybridization and locked breeding, a new high-quality meat sheep series has been formed, which has solved the problem of insufficient breeding technology in my country, and has achieved the improvement of meat sheep traits and enhanced market competitiveness.
Patent Information
- Application Number
- CN202510494823.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-21
- Publication Date
- 2025-05-30
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
my country's meat sheep breeding technology integration and innovation efforts are insufficient. The existing meat sheep breeds are small in size, slow in growth speed, and low meat production performance, resulting in a lack of high-quality meat sheep breeds and poor market competitiveness.
By combining excellent domestic and foreign meat sheep breeds for three generations, a basic group is formed, and the basic group is blocked and reproduced for 4 to 5 generations, forming a new high-quality meat sheep product. The method includes selecting ewes and rams of different ancestry for hybridization, selecting offspring with appropriate retention rates, forming a basal group, and avoiding mating of whole siblings during the atresia reproduction process, promoting genetic recombination and homozygation.
The traits of meat sheep are outstanding and neat, with high average population level, simple and easy to cultivate, and are suitable for improving traits with high heritability and medium, and the quality of the strain is easier to ensure, and the average level of the main traits exceeds that of the basic group.
Smart Images
Figure CN120052309A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of livestock breeding, and particularly relates to a method for cultivating a new strain of high-quality meat sheep. Background Art
[0002] Since the late 1980s of the 20th century, China has become the country with the largest number of sheep and goats in terms of feeding quantity, slaughter quantity, and meat sheep production in the world. With the change of national consumption concept and the understanding of the nutritional value of mutton, the market demand for mutton is increasing day by day. However, the production of meat sheep in China lags behind the world advanced level, the integrated innovation of meat sheep breeding technology is insufficient, the technical level and efficiency in Chongqing are low, resulting in a shortage of high-quality meat sheep breeds, a low contribution rate of existing improved breeds, and poor market competitiveness.
[0003] The quality of meat sheep breeds determines the growth rate, feed conversion rate, meat yield, and meat quality. Compared with excellent meat sheep, the existing local sheep breeds generally have a small body size, slow growth rate, and low meat production performance. In order to rapidly improve the meat production performance of existing breeds through genetic improvement, improve meat quality, and cultivate new breeds (strains), it is a beneficial choice to cultivate suitable new meat sheep breeds (strains) by introducing excellent foreign breeds. In recent years, livestock enterprises have introduced meat sheep breeds such as Merino sheep, Charolais sheep, and Suffolk sheep many times. Due to the lack of conservation awareness in most enterprises, the population scale of the introduced breeds is small and there is a lack of corresponding breeding technology. Except for a few of the introduced breeding sheep that are locally bred, purified, and selected for improvement, most of them directly enter the market. This situation of "only introducing but not breeding, only breeding but not improving" in the breeding sheep industry has led to an over-reliance on foreign breeding enterprises in the breeding sheep industry and ultimately fallen into a vicious cycle of "introducing breeds, maintaining, degenerating, and introducing breeds again". In order to get rid of this vicious cycle and reduce the dependence on foreign germplasm, meat sheep breeding must have an effective breeding and conservation strategy and method for the introduced foreign meat sheep breeds. Summary of the Invention
[0004] The present invention provides a method for cultivating a new strain of high-quality meat sheep, which combines excellent domestic and foreign meat sheep breeds to form a basic population through three generations of crossbreeding, and performs closed breeding on the basic population for 4 to 5 generations to form a new strain of high-quality meat sheep. The cultivation method is simple and easy to implement and is an effective breeding and conservation strategy.
[0005] The present invention provides a method for cultivating a new strain of high-quality meat sheep, including:
[0006] S1. Select 25 to 45 female sheep of excellent domestic breeds with no less than 8 different bloodlines to form 4 to 7 mating sub-groups;
[0007] S2. Introduce 12 to 18 male sheep of excellent foreign breeds with 4 to 7 different bloodlines, and cross them with the female sheep in the mating sub-groups respectively to produce the first-generation crossbred meat sheep;
[0008] S3. Select the first-generation crossbred ewes from the first-generation crossbred meat sheep at a retention rate of less than 20%.
[0009] S4. Introduce 5 - 10 rams of excellent foreign breeds belonging to different bloodlines, and breed them with the first-generation crossbred ewes to produce the second-generation crossbred meat sheep.
[0010] S5. Select the second-generation crossbred ewes from the second-generation crossbred meat sheep at a retention rate of not less than 20%.
[0011] S6. Introduce 12 - 22 rams of excellent foreign breeds with 6 - 11 different bloodlines, and breed them with the first-generation crossbred ewes and the second-generation crossbred ewes respectively to produce the third-generation crossbred meat sheep.
[0012] S7. Select rams from the first-generation crossbred meat sheep, the second-generation crossbred meat sheep and the third-generation crossbred meat sheep at a retention rate of less than 8%, and select ewes at a retention rate of less than 20% to form the basic population.
[0013] S8. Conduct closed breeding for 4 - 5 generations on the said basic population without introducing external blood during the process to form a new high-quality meat sheep strain with beneficial traits.
[0014] Further, in step S4, the 5 - 10 rams of excellent foreign breeds have no consanguinity with the 12 - 18 rams of excellent foreign breeds with 4 - 7 different bloodlines introduced.
[0015] Further, during the process of selecting the basic population, the domestic excellent breed ewes and the foreign excellent breed rams selected are from breeding farms without germplasm exchange with each other.
[0016] Further, in step S8, in the early stage of closed breeding and selection, avoid random mating of full siblings, and make the number of ewes mated with each ram equal;
[0017] In the later stage of closed breeding and selection, implement complete random mating, without any restriction on the degree of inbreeding, and let excellent rams mate with more ewes;
[0018] During the process of closed breeding and selection, achieve the selection of beneficial traits for the meat sheep in each generation through homogenous mating.
[0019] Further, during the process of selecting the basic population and closed breeding and selection, use the MBLUP genetic evaluation method to select the rams and ewes for breeding and mating. The MBLUP genetic evaluation method specifically includes:
[0020] In the ram and ewe models, the effects of genes are divided into the effects of mapped QTLs and the effects of unknown genes, and the information of molecular markers is used to infer the probabilities of QTL genotypes or QTL alleles. The total breeding value of an individual is the sum of the QTL breeding value and the remaining polygenic breeding value. The breeding model of MBLUP is:
[0021] Y = Xβ + Zu + Wv + e
[0022] where Y is the vector of phenotypic values; β is the vector of fixed effects; u is the random vector of polygenic values; v is the vector of QTL alleles; e is the vector of residual effects; and X, Z, and W are the incidence matrices of β, u, and v, respectively.
[0023] Furthermore, in the MBLUP genetic evaluation method, the expectations and variances of β, u, and v are:
[0024]
[0025] where A is the relationship matrix of additive effects; G is the incidence matrix of QTL genotypes, and its mixed equations are:
[0026]
[0027] where k 1 and k 2 are respectively and and the rank correlation coefficient is obtained as d is the difference between the true value and the estimated value, and n is the number of individuals.
[0028] Furthermore, the crossbreeding patterns of rams and ewes include simple two-way progressive crossbreeding, simple two-way crossbreeding, complex three-way or more breeding crossbreeding, and four-way crossbreeding;
[0029] Simple two-way progressive crossbreeding means advancing the male parent to the second generation or higher and selecting the ideal type;
[0030] Simple two-way crossbreeding means crossing in both directions to the third generation or higher and selecting the ideal type;
[0031] Complex three-way or more breeding crossbreeding means selecting the ideal type after three to four generations of backcrossing, or selecting the ideal type in the second generation;
[0032] Four-way crossbreeding means first performing a two-way cross, then crossing their F1s with each other, and then selecting the ideal type in the F2 generation; or using the F1 generation to cross with another male parent separately, and then selecting the ideal type in the F3 generation after crossing the produced F2 generations.
[0033] The beneficial effects of the present invention are:
[0034] The present invention hybridizes excellent domestic and foreign meat sheep breeds to obtain first-generation hybrid meat sheep, selects the first-generation female sheep for further breeding, and then hybridizes with excellent foreign breed rams to select second-generation hybrid female sheep. The second-generation and first-generation hybrid female sheep are again hybridized with excellent foreign breed rams to produce third-generation meat sheep. Rams are selected at a retention rate of less than 8%, and ewes are selected at a retention rate of less than 20% to form a basic herd, and the basic herd is closed for breeding for 4 to 5 generations to form a new strain of high-quality meat sheep. When the strain is developed, the traits of the meat sheep are prominent, the uniformity is good, and the average level of the population is high. The cultivation method is simple and easy to implement, the required size of the livestock herd is not large, based on certain modern quantitative genetics theories, the strain establishment speed is fast, it is suitable for improving traits with high and medium heritability, and the quality at the time of strain establishment is relatively easy to guarantee, and the average level of the main traits will surely exceed the basic herd. BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Figure 1 It is a schematic flow chart of the cultivation method of the new strain of high-quality meat sheep of the present invention.
[0036] The realization of the object, functional characteristics and advantages of the present invention will be further described in conjunction with the embodiments with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0037] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.
[0038] As Figure 1 shown, a cultivation method of a new strain of high-quality meat sheep includes:
[0039] S1. Select 25 to 45 domestic excellent breed ewes with no less than 8 different bloodlines to form 4 to 7 mating groups;
[0040] S2. Introduce 12 to 18 rams of excellent foreign breeds with 4 to 7 different bloodlines, and hybridize them with the ewes in the mating groups respectively to produce first-generation hybrid meat sheep;
[0041] S3. Select first-generation hybrid ewes from the first-generation hybrid meat sheep at a retention rate of less than 20%;
[0042] S4. Introduce 5 to 10 rams of excellent foreign breeds belonging to different bloodlines, and breed and hybridize the introduced 5 to 10 rams of excellent foreign breeds with the first-generation hybrid ewes to produce second-generation hybrid meat sheep;
[0043] Among them, there is no consanguinity between the 5 to 10 rams of excellent foreign breeds and the 12 to 18 rams of 4 to 7 different bloodlines of excellent foreign breeds introduced.
[0044] S5. Select second-generation hybrid ewes from the second-generation hybrid mutton sheep with a seed retention rate of not less than 20%;
[0045] S6. Introduce 12 to 22 rams of excellent breeds from foreign countries with 6 to 11 different bloodlines, and use the introduced 12 to 22 rams of excellent breeds from foreign countries with 6 to 11 different bloodlines to breed and crossbreed with first-generation hybrid ewes and second-generation hybrid ewes, respectively, to produce third-generation hybrid mutton sheep;
[0046] In the above steps S1-S6, the hybridization modes of rams and ewes include simple binary progressive hybridization, simple binary hybridization, complex breeding hybridization of three or more, and four-way hybridization;
[0047] Simple binary progressive hybridization, that is, the male parent is advanced to more than two generations to select the ideal type;
[0048] Simple binary hybridization, forward and reverse crosses for more than three generations, and selection of ideal types;
[0049] Complex breeding of three or more varieties of hybrids, selecting the ideal type in three to four generations, or selecting the ideal type in the second generation;
[0050] In four-way hybridization, binary hybridization is first performed, and then the F1 generations are hybridized with each other, and then the ideal type is selected from the F2 generation; or the F1 generation is cross-hybridized with another male parent, and the F2 generations are hybridized and then the ideal type offspring is selected from the F3 generation.
[0051] S7. From the first-generation hybrid mutton sheep, the second-generation hybrid mutton sheep and the third-generation hybrid mutton sheep, rams with a seed retention rate of less than 8% and ewes with a seed retention rate of less than 20% are selected to form the basic group; in the process of selecting the basic group, the domestic excellent breed ewes and foreign excellent breed rams are selected from breeding farms without germplasm exchange between each other.
[0052] S8. Carry out closed breeding of the basic group for 4 to 5 generations without introducing foreign blood in the middle, so that the average inbreeding coefficient of the group will increase naturally, the gene homozygosity of the main selected traits and the genetic similarity between individuals will be improved, the main selected traits will achieve annual genetic progress, and the genetic level will exceed that of the basic group, thereby forming a new breed of high-quality mutton sheep with beneficial traits.
[0053] In the early stage of closed breeding, emphasis is placed on genetic recombination, random mating is carried out to avoid full-sibling mating, and the number of rams and ewes is equal.
[0054] In the later stage of closed breeding, emphasis is placed on achieving genetic homozygosity, implementing completely random mating, without any restrictions on the degree of inbreeding, and using more excellent rams to mate with ewes.
[0055] In the closed breeding process, beneficial traits are selected for each generation of meat sheep through homogeneous selection.
[0056] When the strain was developed, the meat sheep had prominent traits, good uniformity, and a high average population level. The average inbreeding coefficient of the population reached 10% - 13%, with a maximum not exceeding 15%. The average coefficient of relationship was above 20%. This means that on average, the genetic similarity between individuals is equivalent to that between half-siblings. At the same time, the coefficient of relationship between any two randomly selected individuals is above 10%, indicating a genetic similarity at least as high as that between first cousins. The breeding method is simple and easy to implement, requires a small herd size, is based on certain modern quantitative genetic theories, has a fast line establishment speed, is suitable for improving traits with high and medium heritability, and it is relatively easy to ensure the quality when the strain is developed. The average level of the main traits exceeds that of the base population.
[0057] During the selection of the base population and the process of closed breeding and selection, the MBLUP (Marker - assisted BLUP, Marker - assisted Best Linear Unbiased Prediction method) genetic evaluation method is used to select the rams and ewes for breeding. The MBLUP method is a new technology in modern breeding science, an extension of the conventional BLUP method. It simultaneously utilizes phenotypic pedigree and DNA marker information to conduct genetic evaluation of individuals, improving the accuracy of breeding value estimation and thus enhancing the accuracy and efficiency of breeding selection.
[0058] The MBLUP genetic evaluation method specifically includes:
[0059] In the ram and ewe models, the effects of genes are divided into the effects of mapped QTLs and unknown gene effects, and molecular marker information is used to infer the probabilities of QTL genotypes or QTL alleles. The total breeding value of an individual is the sum of the QTL breeding value and the remaining polygenic breeding value. The breeding model of MBLUP is:
[0060] Y = Xβ + Zu + Wv + e
[0061] Where Y is the vector of phenotypic values; β is the vector of fixed effects; u is the random vector of polygenic values; v is the vector of QTL alleles; e is the vector of residual effects; X, Z, and W are the incidence matrices associated with β, u, and v respectively.
[0062] The expectations and variances of β, u, and v are:
[0063]
[0064] Where A is the relationship matrix of additive effects; G is the incidence matrix of QTL genotypes, and its mixed equations are:
[0065]
[0066] Where, in k 1 and k 2 are respectively and and the rank correlation coefficient is obtained as where d is the difference between the true value and the estimated value, and n is the number of individuals. The higher the heritability of the observed trait, the smaller the QTL variance, or the smaller the map distance between two adjacent markers, the higher the accuracy of MBLUP estimation under the model. On the contrary, when the heritability of the trait is low, the QTL variance is large, or the map distance between two adjacent markers is large, the accuracy of MBLUP estimation by the model is low.
[0067] It should be noted that in this article, the terms "including", "comprising", or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, device, article, or method including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such a process, device, article, or method. Without further limitations, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, device, article, or method including that element.
[0068] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.
Claims
1. A method for breeding a new strain of high-quality mutton sheep, characterized in that: include: S1. Select 25 to 45 ewes of no less than 8 different bloodlines and excellent domestic breeds to form 4 to 7 breeding groups; S2. Introduce 12 to 18 rams of 4 to 7 different bloodlines and excellent breeds from foreign countries, and cross them with ewes in the breeding group to produce the first generation of hybrid meat sheep; S3. Selecting first-generation hybrid ewes from the first-generation hybrid mutton sheep with a seed retention rate of less than 20%; S4. Introduce 5 to 10 foreign rams of different pedigrees, and use the imported 5 to 10 foreign rams to breed and crossbreed with the first-generation hybrid ewes to produce the second-generation hybrid mutton sheep; S5. Select second-generation hybrid ewes from the second-generation hybrid mutton sheep with a seed retention rate of not less than 20%; S6. Introduce 12 to 22 rams of excellent breeds from foreign countries with 6 to 11 different bloodlines, and use the introduced 12 to 22 rams of excellent breeds from foreign countries with 6 to 11 different bloodlines to breed and crossbreed with first-generation hybrid ewes and second-generation hybrid ewes, respectively, to produce third-generation hybrid mutton sheep; S7. From the first-generation hybrid mutton sheep, the second-generation hybrid mutton sheep and the third-generation hybrid mutton sheep, rams with a seed retention rate of less than 8% and ewes with a seed retention rate of less than 20% are selected to form a basic group; S8. Carry out closed breeding on the basic group for 4 to 5 generations without introducing foreign blood, so as to form a new breed of high-quality mutton sheep with beneficial traits.
2. The method for breeding a new strain of high-quality mutton sheep according to claim 1, characterized in that: In step S4, the 5 to 10 rams of foreign excellent breeds and the introduced 12 to 18 rams of foreign excellent breeds of 4 to 7 different bloodlines are not related to each other.
3. The method for breeding a new strain of high-quality mutton sheep according to claim 1, characterized in that: In the process of selecting the basic group, the domestic high-quality ewes and foreign high-quality rams are selected from breeding farms with no germplasm exchange between them.
4. The method for breeding a new strain of high-quality mutton sheep according to claim 1, characterized in that: In step S8, in the early stage of closed breeding, random mating is avoided to avoid full-sibling mating, and the number of rams mated with ewes is equal; In the later stage of closed breeding, completely random mating is implemented without any restrictions on the degree of inbreeding, and excellent rams are mated with more ewes; In the closed breeding process, beneficial traits are selected for each generation of meat sheep through homogeneous selection.
5. The method for breeding a new strain of high-quality mutton sheep according to claim 1, characterized in that: In the process of selecting the basic group and closed breeding, the MBLUP genetic evaluation method is used to select the rams and ewes for breeding. The MBLUP genetic evaluation method specifically includes: In the ram and ewe models, the effects of genes are divided into located QTL effects and unknown gene effects, and the probability of QTL genotypes or QTL alleles is inferred with the help of molecular marker information. The total breeding value of an individual is the sum of the QTL breeding value and the remaining polygenic breeding value. The breeding model of MBLUP is: Y=Xβ+Zu+Wv+e Among them, Y is the phenotypic value vector; β is the fixed effect vector; u is the random vector of polygenic values; v is the QTL allele vector; e is the residual effect vector; X, Z, W are the association matrices of β, u, and v, respectively.
6. The method for breeding a new strain of high-quality mutton sheep according to claim 5, characterized in that: In the MBLUP genetic evaluation method, the expectations and variances of β, u, and v are: Among them, A is the relationship matrix of additive effects; G is the association matrix of QTL genotypes, and its mixed equation system is: Among them, k1 and k2 are and And the rank correlation coefficient is obtained as d is the difference between the true value and the estimated value, and n is the number of individuals.
7. The method for breeding a new strain of high-quality mutton sheep according to claim 1, characterized in that: The hybridization patterns of rams and ewes include simple binary progressive hybridization, simple binary hybridization, complex breeding hybridization of three or more, and four-way hybridization; Simple binary progressive hybridization, that is, the male parent is advanced to more than two generations to select the ideal type; Simple binary hybridization, forward and reverse crosses for more than three generations, and selection of ideal types; Complex breeding of three or more varieties of hybrids, selecting the ideal type in three to four generations, or selecting the ideal type in the second generation; In four-way hybridization, binary hybridization is first performed, and then the F1 generations are hybridized with each other, and then the ideal type is selected from the F2 generation; or the F1 generation is cross-hybridized with another male parent, and the F2 generations are hybridized and then the ideal type offspring is selected from the F3 generation.