A method for selecting chicken combining ability based on family heterosis rate

Abstract

The application provides a kind of selection method for selecting chicken combining force based on family heterosis rate, belongs to the technical field of breeding, the selection method is to use two or more matching system varieties, construct pure line subculture population, offspring determination population and combining force determination population, to determine the average weight of the offspring of the male of the combining force determination father line and the average weight of the offspring of the female of the combining force determination mother line, the mean value of the sum is used to construct family heterosis rate together with the average weight of the combining force determination population, then selection is carried out according to the family heterosis rate.The application provides a determination scheme for determining the combining force of pure line individuals, creates a method and evaluation index for quantifying combining force performance, establishes a new method for breeding and improving the combining force of pure line chicken population, eliminates the influence of the body weight difference of pure line individuals on the determination result of the combining force, so that the combining force of pure line population can be compared in the same dimension.

Description

Technical Field

[0001] This invention relates to the field of breeding technology, specifically a selection method for chickens based on the hybrid vigor rate of family lines to select combining ability. Background Technology

[0002] Heterosis refers to the phenomenon where offspring from a cross between two different varieties exhibit superior production and reproductive performance compared to their parents. The creation of hybrid breeding lines utilizing heterosis is widely applied in both animal and plant cultures, significantly improving agricultural and livestock production levels. However, the mechanisms underlying heterosis remain unclear. Currently, three main classical hypotheses are considered: the dominance hypothesis, the overdominance hypothesis, and the epistasis hypothesis. Generally, it is believed that the greater the genetic distance between varieties, the greater the heterosis produced during crosses.

[0003] After the breeding lines are determined, closed-group selection is required for the resulting pure-line populations to continuously improve the performance of the varietals. Based on the current mainstream theories of "micro-effect polygenic effect" and "gene-environment interaction," pure-line breeding is currently divided into two categories: pure-line breeding and hybridization breeding. Pure-line breeding aims to continuously enhance the additive effect of the pure-line population, indirectly improving the performance of the varietals. Hybridization breeding selects for non-additive effects between varieties or lines, i.e., the combining ability of the pure-line population, directly improving the production performance of the varietals.

[0004] In hybridization breeding, non-additive effects cannot be used with additive effect selection methods. While there has been much academic research on this topic, no practical schemes yet exist for commercial breeding. Therefore, it is necessary to create an index to quantify the combining ability of pure-line populations and to provide a suitable breeding scheme for commercial breeding. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides a selection method for chicken combining ability based on family heterosis rate, offering an index for evaluating the combining ability performance of purebred populations, enabling accurate assessment of the combining ability performance of purebred broilers, and providing new ideas and solutions for commercial broiler breeding.

[0006] To achieve the above objectives, this invention provides a set of methods for determining the progeny and combining ability of purebred chicken breeds, and establishes a method for selecting and improving the combining ability performance of individual breeds. Using a closed-loop broiler purebred breeding population, progeny and combining ability tests are conducted to obtain purebred performance and combining ability performance, calculate the heterosis rate of families, and select purebred breeds based on their combining ability performance, thereby continuously improving the production performance of the breeding lines. The technical solution adopted by this invention is as follows: A selection method for chickens based on pedigree heterosis rate, wherein the selection method uses two or more pedigrees to construct a purebred successor population, a progeny testing population, and a combining ability testing population. The average weight of the progeny of the paternal line and the maternal line of the combining ability testing population is combined with the average weight of the combining ability testing population to construct the pedigree heterosis rate. Then, selection is carried out based on the pedigree heterosis rate. Wherein, heterosis rate = (average body weight of the combining ability test population - mean of the sum of the average body weight of the paternal and maternal offspring of the combining ability test population) / mean of the sum of the average body weight of the paternal and maternal offspring of the combining ability test population. The mean of the sum of the average weight of the paternal and maternal descendants in the combining ability test is calculated as follows: (average weight of the paternal descendants in the combining ability test + average weight of the maternal descendants in the combining ability test) / 2.

[0007] Furthermore, the heterosis rate is divided into the heterosis rate of the paternal lineage and / or the heterosis rate of the maternal lineage; Wherein, the heterosis rate of the paternal line family = (average weight of roosters in the paternal rooster combining ability test group - the average of the sum of the average weight of the roosters in the paternal rooster descendant test group and ... The average weight of roosters descended from the paternal line and the average weight of roosters descended from the mated female line, as determined by the combining ability test, is calculated as follows: (average weight of roosters descended from the paternal line + average weight of roosters descended from the mated female line) / 2. Hybrid vigor rate of maternal lineage = (average weight of hens in the maternal lineage combining ability test group - average weight of hens in the offspring of the maternal lineage combined ability test group and average weight of hens in the offspring of the roosters bred in the combining ability test group) / average weight of hens in the offspring of the maternal lineage combined ability test group and average weight of hens in the offspring of the roosters bred in the combining ability test group. The mean of the sum of the average weight of the offspring of the maternal hens and the average weight of the offspring of the roosters used in the combining ability test is: (average weight of the offspring of the maternal hens + average weight of the offspring of the roosters used in the combining ability test) / 2.

[0008] Furthermore, the selection method includes the following specific steps: Choose a broiler breed that consists of two or more broiler lines, such as line A and line B. Select n male roosters and m female hen broilers of strain A from generation X, form a paternal lineage, and produce a purebred successor population P of generation X+1. A and the X+1 generation descendant population F A ; Select n male roosters and m female roosters of strain B from generation X, establish a maternal family line, and produce a purebred successor population P of generation X+1. B and the X+1 generation descendant population F B ; Select n male chickens of strain A from generation X and m female chickens of strain B from generation X to produce a population C for combining ability testing in generation X+1. Each chick is fitted with a wing tag to record pedigree information upon hatching; When the X+1 generation descendants are determined, the F group A and F B When the chickens in the combining ability test group C reached 6 weeks of age, the weight of each chicken was measured. The heterosis rate of the paternal lineage of strain A in generation X is calculated using the following formula: ; in, The hybrid vigor rate of the A-type rooster family representing Generation X. The average weight of roosters from group C, which were tested for combining ability in b batches of roosters of strain A. It is a population F that was tested for offspring of strain A roosters in batches b. A The average weight of roosters The progeny F of the breeding population of B-type hens mated with A-type roosters for combining ability testing. B Average weight of roosters. Generation X, A strain, same paternal lineage, successor population P. A All pedigrees have the same heterosis rate (i.e., the heterosis rate of the same rooster in generation X is the same as that of the purebred successor population P in generation X+1). A (The heterosis rate is the same). The heterosis rate of each rooster in the paternal lineage of strain A in generation X was calculated, and then selection was carried out based on the heterosis rate; And / or, calculate the pedigree heterosis rate of strain B hens in generation X, using the following formula: ; in, The hybrid vigor rate of the B strain hens representing Generation X. The average weight of group C hens in strain B was determined through b batches of combining ability testing. The progeny testing of B batches of B strain hens was conducted on population F. B The average weight of the hens The testing population F is the offspring of strain A roosters bred with strain B hens for combining ability testing. A Average weight of hens. Generation X, B strain, successor population P within the same maternal lineage. B All families have the same heterosis rate (i.e., the heterosis rate of the same hen in generation X is the same as that of the purebred successor population P in generation X+1). B (The heterosis rate is the same). The heterosis rate of each hen in the maternal lineage of the X generation B strain is calculated, and then selection is carried out based on the heterosis rate.

[0009] Furthermore, after calculating the heterosis rate of each rooster in the Xth generation A strain paternal lineage, the X+1 generation purebred successor population P produced in the A strain paternal lineage was compared according to the heterosis rate and feed conversion ratio. A Elimination will be carried out; among them, the pure lineage P of the X+1 generation produced in the paternal lineage of strain A will be eliminated. A All of them are roosters.

[0010] Furthermore, the P generation of purebred successors (X+1 generation) produced in the paternal lineage of the A strain will be eliminated. A The specific process is as follows: P, a pure lineage of the X+1 generation produced from the paternal line of strain A. A As candidate roosters, there are y roosters, and they are eliminated based on the heterosis rate (yn). r are selected as candidate roosters, resulting in a purebred group of remaining roosters to be eliminated; where r is the relative elimination weight of heterosis rate, and n is equal to the number of A-type roosters in generation X. Based on the feed conversion ratio, culling (yn) of the remaining purebred roosters to be culled is carried out. (1-r) candidate roosters, and finally n X+1 generation A lineage paternal pedigrees remain as breeding candidates; Where 1-r represents the relative elimination weight of feed conversion ratio; the sum of the relative elimination weight of heterosis rate and the relative elimination weight of feed conversion ratio is 1.

[0011] Furthermore, elimination (yn) The process of selecting r candidate roosters includes: Arrange the roosters in the X-generation A lineage paternal pedigree from high to low according to their heterosis rate; Based on the heterosis rate ranking, the pure-line successor population P produced from the paternal lineage of strain A in generation X, which has the lowest heterosis rate. A The process of elimination begins in the middle and continues until elimination (yn). r candidate roosters.

[0012] Furthermore, after calculating the heterosis rate of each hen in the Xth generation B strain maternal family, the X+1 generation purebred successor population P produced in the B strain maternal family was evaluated according to the heterosis rate and feed conversion ratio. B Elimination will be carried out; among them, the P generation of pure lineage successors of the X+1 generation produced in the maternal lineage of strain B will be eliminated. B All of them are hens.

[0013] Furthermore, the P generation of purebred successors (X+1 generation) produced in the maternal lineage of the B strain was eliminated. B The specific process is as follows: P, a purebred descendant of the X+1 generation produced in the maternal lineage of strain B. B As candidate hens, the number is u, and they are culled based on the heterosis rate (um). r candidate hens are selected to obtain the remaining purebred population of hens to be culled; where r is the relative culling weight of heterosis rate, and m is equal to the number of B-type hens in generation X. Based on the feed conversion ratio, cull the remaining purebred hens in the culled population (um). (1-r) candidate hens, and finally m X+1 generation A strain maternal pedigrees as the breeding candidate group; Where 1-r represents the relative elimination weight of feed conversion ratio; the sum of the relative elimination weight of heterosis rate and the relative elimination weight of feed conversion ratio is 1.

[0014] Furthermore, elimination (um) The process of selecting r candidate hens includes: Sort the hens in the X-generation A strain maternal lineage from high to low according to their heterosis rate; Based on the heterosis rate ranking, the pure-line successor population P produced from the maternal lineage of the X generation B strain with the lowest heterosis rate is... B The process begins with elimination and continues until it is completely phased out (um). r candidate hens.

[0015] The beneficial effects of the selection method for chicken combining ability based on the heterosis rate of family lines of the present invention are as follows: Based on commercial broiler breeding practices, this invention provides a method for measuring the combining ability of purebred individuals, creates a method and evaluation index for quantifying combining ability performance, establishes a new method for selecting and improving the combining ability of purebred flocks, eliminates the influence of individual body weight differences on the combining ability measurement results, and enables the combining ability of purebred groups to be compared on the same dimension. This solves the problem that traditional methods cannot accurately assess and select the combining ability of purebred groups, and provides a new approach for commercial broiler breeding. Attached Figure Description

[0016] Figure 1This is a schematic diagram of family formation in Embodiment 1 of the present invention. Detailed Implementation

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0018] Example 1: A method for selecting chickens based on hybrid vigor rate. This embodiment describes a selection method for chickens based on the heterosis rate of family hybrids to select for combining ability. Figure 1 As shown, the specific steps include: S1. Select a broiler breed consisting of two or more strains. This invention takes a two-line breeding system of strain A and strain B as an example. The primary trait for this breed is the weight at slaughter at age i. To balance breeding, the weight at slaughter for roosters is selected in strain A, and the weight at slaughter for hens is selected in strain B. The culling weight for weight at slaughter at age i in the combining ability test of strains A and B is r.

[0019] S2. Based on the primary breed selection target, select n roosters and m hens of breed A in generation X to form a paternal pedigree with a rooster-to-hen ratio of 1:m / n, and produce b batches of purebred successor population P. A (Right now Figure 1 The successor P in A The population consists of the X+1 generation and b batches of descendant population F. A (Right now Figure 1 Descendant determination F A The population is the X+1 generation; among them, the pure lineage of the X+1 generation P produced in the paternal lineage of strain A. A All were roosters; Select n male roosters and m female roosters of strain B from generation X to form a maternal family with a male-to-female ratio of 1:m / n, and produce b batches of purebred successor population P. B (Right now Figure 1 The successor P in B The population consists of the X+1 generation and b batches of descendant population F. B (Right now Figure 1 Descendant determination F B The population is the X+1 generation; among them, the pure lineage of the X+1 generation P produced in the maternal lineage of strain B. B All of them are hens.

[0020] S3. Select n male chickens of strain A in generation X and m female chickens of strain B in generation X. Pair the male chickens of strain A with the female chickens of strain B to form a combining ability testing family, and produce b batches of combining ability testing population C (i.e., Figure 1 The roosters in the combining ability test group C were from the b batches of the combining ability test group C in the process of calculating the heterosis rate of the A strain paternal lineage, and the hens were from the b batches of the combining ability test group C in the process of calculating the heterosis rate of the B strain maternal lineage, and were from generation X+1.

[0021] Each chick wears a wing tag upon hatching to record pedigree information.

[0022] S4, Wait until the X+1 generation descendants are measured in population F A and F B When the chickens in the combination ability test group C reached 6 weeks of age, the weight and feed conversion ratio of each chicken were measured.

[0023] S5. Calculate the heterosis rate of n paternal families of strain A in generation X using the following formula: ; in, The hybrid vigor rate of the A-type rooster family representing Generation X. The average weight of roosters from group C, which were tested for combining ability in b batches of roosters of strain A. It is a population F that was tested for offspring of strain A roosters in batches b. A The average weight of roosters The progeny F of the breeding population of B-type hens mated with A-type roosters for combining ability testing. B Average weight of roosters. Generation X, A strain, same paternal lineage, successor population P. A All pedigrees have the same heterosis rate (i.e., the heterosis rate of the same rooster in generation X is the same as that of the purebred successor population P in generation X+1). A (The heterosis rate is the same). S6. Calculate the heterosis rate of each rooster in the Xth generation A strain paternal line according to step S5. Then, based on the breeding plan, sequentially compare the heterosis rate and feed conversion ratio of the X+1 generation purebred successor population P produced in the A strain paternal line. A The process involves elimination to obtain a candidate population of paternal pedigrees for breeding of strain A. The specific steps are as follows: S61, P, a pure lineage of the X+1 generation produced from the paternal lineage of strain A. A As candidate roosters, there are y in number. According to the breeding plan, y roosters will be culled based on the heterosis rate (yn). r are candidate roosters; where r is the relative culling weight of heterosis rate, and n is equal to the number of A-type roosters in generation X; Elimination (yn) The process of selecting r candidate roosters includes: S611. Sort the roosters in the paternal lineage of strain A from high to low according to their heterosis rate (generation X). S612. According to the order of heterosis rate, the pure line successor population P produced from the paternal lineage of strain A in generation X, which has the lowest heterosis rate. A The process of elimination begins in the middle and continues until elimination (yn). r candidate roosters; It should be noted that the pure lineage successor population P of each paternal lineage of strain A A There is more than one rooster in the population. When culling based on heterosis rate, assuming that purebred successor population P in the paternal lineage of strain A in group q needs to be culled. A The paternal pedigrees of strain A in group q, ordered from highest to lowest heterosis rate, are q, q-1, q-2, ..., 1. Then, for the paternal pedigrees of strain A in groups 1, 2, 3...q-1, their corresponding pure lineage successor populations P... A All were eliminated; however, when it came to the last group, namely the qth group of A lineage paternal lineages, it might not be necessary to eliminate the corresponding pure lineage successor group P. A Eliminating them all would be enough (yn) If there are r roosters, then the pure lineage of the paternal lineage P of the qth group A will be used for succession. A The appropriate number of roosters can be randomly eliminated. Specifically: Calculate (yn) based on the average number of male chicks retained (where k is the number of male chicks retained). r only requires the number of sires of the candidate roosters to be eliminated (i.e., the number of roosters in the paternal lineage of the X generation A strain corresponding to the candidate roosters to be eliminated). The entire purebred successor population P produced from the q-1 X-generation A strain paternal roosters whose hybrid vigor rate was culled (q-1 roosters with the lowest hybrid vigor rate) A (i.e., elimination of (q-1)) (k roosters); then, from the qth rooster of the Xth generation A strain paternal lineage that has the lowest heterosis rate, the purebred successor population P is produced by... A Randomly selected from (yn) r-(q-1) k roosters were eliminated; in, Representative (yn) R / k rounded up is greater than or equal to (yn). The smallest integer value of r / k.

[0024] Complete (yn) The elimination of r candidate roosters results in a purebred group of remaining roosters to be eliminated.

[0025] S62. Based on the feed conversion ratio, cull (yn) from the remaining purebred rooster population to be culled. (1-r) candidate roosters, and finally n X+1 generation A strain paternal lineages are retained as breeding candidates for the next generation; Where 1-r represents the relative elimination weight of feed conversion ratio; the sum of the relative elimination weight of heterosis rate and the relative elimination weight of feed conversion ratio is 1.

[0026] S7. Calculate the heterosis rate of m hens of strain B in generation X using the following formula: ; in, The hybrid vigor rate of the B strain hens representing Generation X. The average weight of group C hens in strain B was determined through b batches of combining ability testing. The progeny testing of B batches of B strain hens was conducted on population F. B The average weight of the hens The testing population F is the offspring of strain A roosters bred with strain B hens for combining ability testing. A Average weight of hens. Generation X, B strain, successor population P within the same maternal lineage. B All families have the same heterosis rate (i.e., the heterosis rate of the same hen in generation X is the same as that of the purebred successor population P in generation X+1). B (The heterosis rate is the same). S8. Calculate the heterosis rate of each hen in the Xth generation B strain maternal family according to step S7. Then, based on the selection plan, sequentially evaluate the heterosis rate and feed conversion ratio of the X+1 generation purebred successor population P produced in the B strain maternal family. B The process involves elimination to obtain a candidate population of maternal pedigrees for breeding of strain B. The specific process is as follows: S81, a purebred descendant population P from generation X+1 b batches produced in the maternal lineage of strain B. B As candidate hens, the number is u, and they are culled (um) according to the hybrid vigor rate as needed for the breeding plan. r candidate hens are selected to obtain the remaining purebred population of hens to be culled; where r is the relative culling weight of heterosis rate, and m is equal to the number of B-type hens in generation X. Elimination (um) The process of selecting r candidate hens includes: S811. Sort the hens in the X-generation B lineage maternal lineage from high to low according to the heterosis rate of each hen; S812. According to the order of heterosis rate, the pure line successor population P produced from the maternal lineage of the X generation B strain with the lowest heterosis rate. B The process begins with elimination and continues until it is completely phased out (um). r candidate hens; It should be noted that the pure lineage successor population P of each B lineage maternal family B There are more than one hen in the population. When culling the last surviving hen based on heterosis rate, assume that the purebred successor population P in the maternal lineage of strain B in group h needs to be culled. B The maternal pedigrees of strain B in group h, ordered from highest to lowest heterosis rate, are h, h-1, h-2, ..., 1. Therefore, for the maternal pedigrees of strain B in groups 1, 2, 3...h-1, their corresponding pure lineage successor populations P... B All were eliminated; however, when it came to the last group, namely the h-th group of B lineage maternal pedigrees, it might not be necessary to eliminate the corresponding pure lineage successor group P. B Eliminating them all would be enough (um). If there are r hens, then the pure lineage of the hth group B lineage maternal pedigree, generation P, will be used. B The appropriate number of hens can be randomly eliminated. Specifically: Calculate (um) based on the average number of chicks retained by the mother (the number of chicks retained by the mother is t). r only requires the number of maternal hens corresponding to the candidate hens to be culled (i.e., the number of hens in the Xth generation B strain maternal lineage corresponding to the candidate hens to be culled). The entire purebred successor population P produced by culling h-1 X-generation B-type maternal hens with the reciprocal heterosis rate. B (i.e., elimination (h-1)) (t hens); then, the purebred successor population P produced from the hth generation X-type B-line maternal hen, which is at the bottom of the heterosis rate. B In, randomly select (um) r-(h-1) t hens were culled; in, Representative (um) R / t rounded up means greater than or equal to (um). The smallest integer value of r / t.

[0027] Complete (um) The culling of r candidate hens yields the remaining purebred population of hens to be culled.

[0028] S82. Based on the feed conversion ratio, cull (um) of the remaining purebred hens to be culled. (1-r) candidate hens, and finally m X+1 generation B strain maternal pedigrees are retained as breeding candidates for the next generation; Where 1-r represents the relative elimination weight of feed conversion ratio; the sum of the relative elimination weight of heterosis rate and the relative elimination weight of feed conversion ratio is 1.

[0029] Example 2: Application of Seed Selection Method This embodiment is a specific application of a selection method for chicken combining ability based on family heterosis rate. The selection method from Embodiment 1 is used, and the following details the selection process using data from fast-growing white-feathered broiler breeding: S1. There are two existing purebred populations of the 20th generation White Konish X1 strain (as the A strain X generation in the selection method of Example 1) and the 20th generation White Locke X3 strain (as the B strain X generation in the selection method of Example 1). The main selected trait for both strains is body weight at 6 weeks of age. The breeding goal for the X1 strain is to improve the body weight at 6 weeks of age for roosters with testing ability, and the breeding goal for the X3 strain is to improve the body weight at 6 weeks of age for hens with testing ability. The relative culling weight for body weight at 6 weeks of age for both the X1 and X3 strains is 30% (i.e., r=30%), and the relative culling weight for feed conversion ratio is 70% (i.e., 1-r=70%).

[0030] S2. Based on the primary strain selection target, select 80 male roosters (n=80) and 960 female roosters of the 20th generation X1 strain to form a paternal lineage with a male-to-female ratio of 1:12, and produce two batches of purebred successor population P. A (Generation 21) and two batches of progeny group F A (21st generation); Eighty male roosters and 960 female roosters (m=960) of the 20th generation X3 strain were selected to form a maternal family with a male-to-female ratio of 1:12, producing two batches of purebred successor population P. B (Generation 21) and two batches of progeny-tested population F B (21st generation).

[0031] S3. Select 80 male chickens of strain X1 and 960 female chickens of strain X3 to form a combining ability test family, generating two batches of combining ability test population C (21st generation).

[0032] When chicks hatch, they wear wing tags to record pedigree information.

[0033] S4, Wait until the 21st generation descendants are tested to determine the population F A and F B When the chickens in the combination ability test group C reached 6 weeks of age, the weight and feed conversion ratio of each chicken were measured.

[0034] S5. Calculate the heterosis rate of 80 paternal families in the X1 strain over 20 generations using the following formula: ; in, The hybrid vigor rate of the A-type rooster family representing Generation X. The average weight of roosters in group C, from two batches of X1 strain roosters, was used to determine their combining ability. Two batches of progeny testing were conducted on X1 strain roosters in population F. A The average weight of roosters The progeny F of the X1 strain roosters mated with the B strain hens used in the combining ability test were used to determine the combining ability of the roosters. B Average weight of roosters.

[0035] The successor group P within the same paternal lineage of the 20th generation A strain A All pedigrees have the same heterosis rate (i.e., the heterosis rate of the same rooster in the 20th generation is the same as that of the purebred successor population P in the corresponding 21st generation). A (The heterosis rate is the same). The following are the data for the three families with the highest and lowest heterosis rates among 80 paternal families in the X1 strain across generation 20: Table 1. Overview of heterosis rates in 80 paternal families of the X1 strain in Generation 20.

[0036] S6. According to the selection plan, based on heterosis rate and feed conversion ratio, eliminate the 21st generation purebred successor population P of the 20th generation of the X1 strain. A The details are as follows: 21st generation purebred successor group P A There are a total of 880 roosters (i.e., the number of candidate roosters is 880, y=880). Based on an average of 11 chicks per rooster (i.e., k=11), and according to the breeding plan, 240 candidate roosters need to be culled based on the heterosis rate (i.e., (yn)). r = (880 - 80) 30% = 240), sort the heterosis rates of 80 paternal families of the X1 strain from highest to lowest in the 20th generation, and eliminate 240 purebred successors in the 21st generation from approximately 22 paternal families of the X1 strain with the lowest heterosis rates in the 20th generation. A ; Among them, due to (yn) r / k≈21.82, i.e. q=22, therefore, all 21 generations of purebred successor populations P produced by the paternal lineages of the 20th generation X1 strain, which had the lowest heterosis rate among the 21 (i.e., q-1=21) strains, are eliminated. A That is, 231 birds were eliminated (i.e., (q-1)). (k=231) There are 9 candidate roosters needed (i.e., (yn)). r-(q-1) (k=9) Candidate roosters to be eliminated.

[0037] Then, the purebred successor population P produced from the 22nd paternal rooster of the X1 strain, which has the lowest heterosis rate, is... A Nine roosters were randomly selected and culled. At this point, the elimination of 240 purebred P-type Pokémon from Generation 21 was completed. A Then, based on the feed conversion ratio of all siblings, the 21st generation purebred successor population P was eliminated. A The highest meat-to-fat ratio was 560 (i.e., (yn)). (1-r)=560), and finally 80 breeding candidate roosters were left as experimental group T1, which were used to breed the 22nd generation of hybrid strains.

[0038] S7. Calculate the heterosis rate of the maternal family lineage in the X3 strain during the 20th generation. The calculation formula is as follows: ; in, The hybrid vigor rate of the B strain hens representing Generation X. The average weight of hens in group C, from two batches of X3 strain hens, was used to determine their combining ability. Two batches of progeny testing were conducted on X3 strain hens. B The average weight of the hens The F population is the progeny of X1 strain roosters bred for the testing of the combining ability of X3 strain hens. A Average weight of hens.

[0039] The successor group P within the same maternal lineage of the 20th generation X3 strain B All families have the same heterosis rate (i.e., the heterosis rate of the same hen in the 20th generation is the same as that of the corresponding purebred successor population P in the 21st generation). B (The heterosis rate is the same). The data for the three families with the highest and lowest heterosis rates in the X3 strain's maternal lineage are as follows: Table 2. Overview of heterosis rates in 80 paternal families of the X3 strain in the 20th generation.

[0040] S8. According to the selection plan, based on heterosis rate and feed conversion ratio, the 21st generation purebred successor population of the X3 strain produced in the 20th generation is eliminated in sequence for P. B The details are as follows: 21st generation purebred successor group P BThere are a total of 4800 (i.e., the number of candidate hens is 4800, u=4800). Based on an average of 5 chicks per hen (i.e., t=5), and according to the breeding plan, 1152 candidate hens need to be culled based on the heterosis rate (i.e., (um)). r = (4800 - 960) 30% = 1152), the heterosis rate of 80 hens from the 20th generation of the X3 strain was ranked from high to low, and 1152 purebred hens from the 21st generation were culled from the approximately 231 maternal families of the 20th generation X3 strain with the lowest heterosis rate. B ; Among them, due to (um) r / t=230.4, i.e., h=231, eliminating 230 (i.e., h-1=230) hybrid vigor ratios from the 20th generation X3 strain maternal families, producing all 21st generation purebred successor populations P. B That is, 1150 birds will be eliminated (i.e., (h-1)). (t=1150) Candidate hens, 9 more are needed (i.e., (um)). r-(h-1) t=2) Candidate hens to be culled.

[0041] Then, the purebred successor population P produced by the X3 strain maternal family hen, which ranked 231st in heterosis rate, was... B Two hens were randomly selected and culled. At this point, the elimination of 1152 purebred P-type Pokémon from Generation 21 was completed. B Then, based on the feed conversion ratio of all siblings, the 21st generation purebred successor population P was eliminated. B The highest feed-to-meat ratio was 2688 (i.e., (um)). (1-r)=2688), and finally 960 breeding candidate hens were left as experimental group T2, which were used to breed the 22nd generation of hybrid strains.

[0042] S9. As a control, a 21st generation purebred successor population P of strain X1 was generated using the same method. B (Roosters), and then based on the weight of the full-sibling roosters at 6 weeks of age, the 240 smallest roosters were culled, and based on the feed conversion ratio of the full-siblings, the 560 roosters with the highest feed conversion ratio were culled, leaving 80 roosters as breeding candidates, which served as the control group B1.

[0043] The same method was used to generate the 21st generation pure line successor population P of strain X3. B (Hens), and then based on the weight of the full-sibling hens at 6 weeks of age, the 1152 hens with the smallest weight were culled, and based on the feed conversion ratio of the full-siblings, the 2688 hens with the highest feed conversion ratio were culled, and finally 960 breeding candidate hens were left as the control group B2.

[0044] Selected groups from experimental groups T1 and T2 and control groups B1 and B2 underwent 6-week-old weight and progeny weight and cooperation tests, respectively. The test results for different groups are shown in the table below.

[0045] Table 3 Comparison of selection results between experimental and control groups

[0046] As shown in Table 3, the F-strain of the rooster offspring in the X1 strain experimental group was determined. A The average weight of the 6-week-old group was 3276g, lower than the control group by 156g. The combining ability of the experimental group roosters (Group C) was measured at an average weight of 3406g, higher than the control group by 118g. The heterosis rate of the experimental group's paternal line was 18.79%, higher than the control group by 4.43 percentage points. The F-strain of the offspring of the hens in the X3 strain experimental group was also measured. B The average weight of the experimental group at 6 weeks of age was 2965g, 91g lower than the control group. The average weight of the experimental group hens at 6 weeks of age, measured by combining ability testing, was 2979g, 158g higher than the control group. The heterosis rate of the experimental group's maternal lineage was 11.60%, 10.36 percentage points higher than the control group. Although the average weight of the offspring in both the X1 and X3 strains at 6 weeks of age was lower than the control group, the experimental group's weight and heterosis rate at 6 weeks of age, measured by combining ability testing, were significantly higher than the control group. Therefore, compared to traditional selection, pedigree heterosis selection can eliminate some individuals with high purebred performance but low combining ability, significantly improving their combining ability. This indicates that pedigree heterosis can accurately assess the combining ability of a strain, and using pedigree heterosis selection can improve strain combining ability, ultimately rapidly improving the production performance of the breeding lines.

[0047] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A selection method for chickens based on the heterosis rate of family hybrids to select combining ability, characterized in that, The selection method involves using two or more matching lines to construct a pure line succession population, a progeny testing population, and a combining ability testing population. The average weight of the progeny of the paternal line and the maternal line, which are used to determine the combining ability, is combined with the average weight of the combining ability testing population to construct the family heterosis rate. Then, selection is carried out based on the family heterosis rate. Wherein, heterosis rate = (average body weight of the combining ability test population - mean of the sum of the average body weight of the paternal and maternal offspring of the combining ability test population) / mean of the sum of the average body weight of the paternal and maternal offspring of the combining ability test population.

2. The selection method for chicken combining ability based on family hybrid vigor rate according to claim 1, characterized in that, The heterosis rate is divided into the heterosis rate of the paternal lineage and / or the heterosis rate of the maternal lineage; Wherein, the heterosis rate of the paternal line family = (average weight of roosters in the paternal rooster combining ability test group - the average of the sum of the average weight of the roosters in the paternal rooster descendant test group and ...) Hybrid vigor rate of maternal lineage = (average weight of hens in the maternal lineage testing population - average weight of hens in the offspring of the maternal lineage testing population and average weight of hens in the offspring of the roosters used in the testing population) / average weight of hens in the offspring of the maternal lineage testing population and average weight of hens in the offspring of the roosters used in the testing population) 3. The selection method for chickens based on pedigree heterosis rate according to claim 1 or 2, characterized in that, The seed selection method includes the following specific steps: Choose a broiler breed that consists of two or more broiler lines, such as line A and line B. Select n male chickens and m female chickens of strain A in generation X to form a paternal lineage and produce a purebred successor population of generation X+1 and a progeny population of generation X+1 for testing purposes. Select n male chickens and m female chickens of strain B in generation X to form a maternal pedigree and produce a purebred successor population of generation X+1 and a progeny population of generation X+1 for testing purposes. Select n male chickens of strain A from generation X and m female chickens of strain B from generation X to produce a population for combining ability testing in generation X+1. When the X+1 generation progeny test group and the combining ability test group reached 6 weeks of age, the weight of each chicken was measured. The heterosis rate of the paternal lineage of strain A in generation X is calculated using the following formula: ； in, The hybrid vigor rate of the A-type rooster family representing Generation X. It is the average weight of roosters in the A strain combining ability test group. It is the average weight of roosters in the A strain descendant population. The average weight of the roosters in the offspring population of the A strain roosters mated with the B strain hens was measured; the heterosis rate of the family lineage within the same paternal lineage of the X generation of the A strain was completely identical. The heterosis rate of each rooster in the paternal lineage of strain A in generation X was calculated, and then selection was carried out based on the heterosis rate; And / or, calculate the pedigree heterosis rate of strain B hens in generation X, using the following formula: ； in, The hybrid vigor rate of the B strain hens representing Generation X. It is the average weight of hens in the B strain combining ability test group. It is the average weight of hens in the B strain descendant population. The average weight of hens in the population bred with A-type roosters in the B-type hen combining ability test; the heterosis rate of the family lineage within the same maternal lineage of the X-generation B-type hen is completely the same; The heterosis rate of each hen in the maternal lineage of the X generation B strain is calculated, and then selection is carried out based on the heterosis rate.

4. The selection method for chicken combining ability based on family hybrid vigor rate according to claim 3, characterized in that, After calculating the heterosis rate of each rooster in the A-line paternal family of generation X, the purebred X+1 generation produced in the A-line paternal family was culled according to the heterosis rate and feed conversion ratio; among them, the purebred X+1 generation produced in the A-line paternal family were all roosters.

5. The selection method for chicken combining ability based on family hybrid vigor rate according to claim 4, characterized in that, The specific process for eliminating the X+1 generation of purebred successors produced in the paternal lineage of strain A is as follows: The X+1 generation of purebred roosters produced in the paternal lineage of strain A were selected as candidate roosters, with a number of y. They were eliminated based on the heterosis rate (yn). r are selected as candidate roosters, resulting in a purebred group of remaining roosters to be eliminated; where r is the relative elimination weight of heterosis rate, and n is equal to the number of A-type roosters in generation X. Based on the feed conversion ratio, culling (yn) of the remaining purebred roosters to be culled is carried out. (1-r) candidate roosters, and finally n X+1 generation A lineage paternal pedigrees remain as breeding candidates; Where 1-r represents the relative elimination weight of feed conversion ratio; the sum of the relative elimination weight of heterosis rate and the relative elimination weight of feed conversion ratio is 1.

6. The selection method for chicken combining ability based on family hybrid vigor rate according to claim 5, characterized in that, Elimination (yn) The process of selecting r candidate roosters includes: Arrange the roosters in the X-generation A lineage paternal pedigree from high to low according to their heterosis rate; According to the order of heterosis rate, the pure line successors produced from the paternal lineage of strain A in generation X with the lowest heterosis rate are eliminated, until elimination (yn). r candidate roosters.

7. The selection method for chicken combining ability based on family hybrid vigor rate according to claim 3, characterized in that, After calculating the heterosis rate of each hen in the X generation B lineage, the X+1 generation purebred successor population produced in the B lineage was culled according to the heterosis rate and feed conversion ratio; among them, the X+1 generation purebred successor population produced in the B lineage were all hens.

8. The selection method for chicken combining ability based on family hybrid vigor rate according to claim 7, characterized in that, The specific process for eliminating the X+1 generation of purebred successors produced in the maternal lineage of strain B is as follows: The X+1 generation of purebred hens produced in the maternal lineage of strain B were selected as candidate hens, numbered u, and culled based on the heterosis rate (um). r candidate hens are selected to obtain the remaining purebred population of hens to be culled; where r is the relative culling weight of heterosis rate, and m is equal to the number of B-type hens in generation X. Based on the feed conversion ratio, cull the remaining purebred hens in the culled population (um). (1-r) candidate hens, and finally m X+1 generation A strain maternal pedigrees as the breeding candidate group; Where 1-r represents the relative elimination weight of feed conversion ratio; the sum of the relative elimination weight of heterosis rate and the relative elimination weight of feed conversion ratio is 1.

9. The selection method for chicken combining ability based on family hybrid vigor rate according to claim 8, characterized in that, Elimination (um) The process of selecting r candidate hens includes: Sort the hens in the X-generation A strain maternal lineage from high to low according to their heterosis rate; According to the order of heterosis rate, the pure line successors produced from the maternal lineage of the X generation B strain with the lowest heterosis rate are eliminated, until elimination (um). r candidate hens.

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