Estimation of genetic variability and selection response for clutch length in dwarf brown-egg layers carrying or not the naked neck gene
<p>Abstract</p> <p>In order to investigate the possibility of using the dwarf gene for egg production, two dwarf brown-egg laying lines were selected for 16 generations on average clutch length; one line (L1) was normally feathered and the other (L2) was homozygous for the naked ne...
| Main Authors: | , |
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| Format: | Article |
| Language: | deu |
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BMC
2003-03-01
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| Series: | Genetics Selection Evolution |
| Subjects: | |
| Online Access: | http://www.gsejournal.org/content/35/2/219 |
| _version_ | 1818788035268968448 |
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| author | Tixier-Boichard Michèle Chen Chih-Feng |
| author_facet | Tixier-Boichard Michèle Chen Chih-Feng |
| author_sort | Tixier-Boichard Michèle |
| collection | DOAJ |
| description | <p>Abstract</p> <p>In order to investigate the possibility of using the dwarf gene for egg production, two dwarf brown-egg laying lines were selected for 16 generations on average clutch length; one line (L1) was normally feathered and the other (L2) was homozygous for the naked neck gene NA. A control line from the same base population, dwarf and segregating for the NA gene, was maintained during the selection experiment under random mating. The average clutch length was normalized using a Box-Cox transformation. Genetic variability and selection response were estimated either with the mixed model methodology, or with the classical methods for calculating genetic gain, as the deviation from the control line, and the realized heritability, as the ratio of the selection response on cumulative selection differentials. Heritability of average clutch length was estimated to be 0.42 ± 0.02, with a multiple trait animal model, whereas the estimates of the realized heritability were lower, being 0.28 and 0.22 in lines L1 and L2, respectively. REML estimates of heritability were found to decline with generations of selection, suggesting a departure from the infinitesimal model, either because a limited number of genes was involved, or their frequencies were changed. The yearly genetic gains in average clutch length, after normalization, were estimated to be 0.37 ± 0.02 and 0.33 ± 0.04 with the classical methods, 0.46 ± 0.02 and 0.43 ± 0.01 with animal model methodology, for lines L1 and L2 respectively, which represented about 30% of the genetic standard deviation on the transformed scale. Selection response appeared to be faster in line L2, homozygous for the NA gene, but the final cumulated selection response for clutch length was not different between the L1 and L2 lines at generation 16.</p> |
| first_indexed | 2024-12-18T14:17:16Z |
| format | Article |
| id | doaj.art-f984f3f2f8be405786d818d41db08732 |
| institution | Directory Open Access Journal |
| issn | 0999-193X 1297-9686 |
| language | deu |
| last_indexed | 2024-12-18T14:17:16Z |
| publishDate | 2003-03-01 |
| publisher | BMC |
| record_format | Article |
| series | Genetics Selection Evolution |
| spelling | doaj.art-f984f3f2f8be405786d818d41db087322022-12-21T21:04:59ZdeuBMCGenetics Selection Evolution0999-193X1297-96862003-03-0135221923810.1186/1297-9686-35-2-219Estimation of genetic variability and selection response for clutch length in dwarf brown-egg layers carrying or not the naked neck geneTixier-Boichard MichèleChen Chih-Feng<p>Abstract</p> <p>In order to investigate the possibility of using the dwarf gene for egg production, two dwarf brown-egg laying lines were selected for 16 generations on average clutch length; one line (L1) was normally feathered and the other (L2) was homozygous for the naked neck gene NA. A control line from the same base population, dwarf and segregating for the NA gene, was maintained during the selection experiment under random mating. The average clutch length was normalized using a Box-Cox transformation. Genetic variability and selection response were estimated either with the mixed model methodology, or with the classical methods for calculating genetic gain, as the deviation from the control line, and the realized heritability, as the ratio of the selection response on cumulative selection differentials. Heritability of average clutch length was estimated to be 0.42 ± 0.02, with a multiple trait animal model, whereas the estimates of the realized heritability were lower, being 0.28 and 0.22 in lines L1 and L2, respectively. REML estimates of heritability were found to decline with generations of selection, suggesting a departure from the infinitesimal model, either because a limited number of genes was involved, or their frequencies were changed. The yearly genetic gains in average clutch length, after normalization, were estimated to be 0.37 ± 0.02 and 0.33 ± 0.04 with the classical methods, 0.46 ± 0.02 and 0.43 ± 0.01 with animal model methodology, for lines L1 and L2 respectively, which represented about 30% of the genetic standard deviation on the transformed scale. Selection response appeared to be faster in line L2, homozygous for the NA gene, but the final cumulated selection response for clutch length was not different between the L1 and L2 lines at generation 16.</p>http://www.gsejournal.org/content/35/2/219dwarf chickennaked neck geneclutch lengthgenetic variabilityselection response |
| spellingShingle | Tixier-Boichard Michèle Chen Chih-Feng Estimation of genetic variability and selection response for clutch length in dwarf brown-egg layers carrying or not the naked neck gene Genetics Selection Evolution dwarf chicken naked neck gene clutch length genetic variability selection response |
| title | Estimation of genetic variability and selection response for clutch length in dwarf brown-egg layers carrying or not the naked neck gene |
| title_full | Estimation of genetic variability and selection response for clutch length in dwarf brown-egg layers carrying or not the naked neck gene |
| title_fullStr | Estimation of genetic variability and selection response for clutch length in dwarf brown-egg layers carrying or not the naked neck gene |
| title_full_unstemmed | Estimation of genetic variability and selection response for clutch length in dwarf brown-egg layers carrying or not the naked neck gene |
| title_short | Estimation of genetic variability and selection response for clutch length in dwarf brown-egg layers carrying or not the naked neck gene |
| title_sort | estimation of genetic variability and selection response for clutch length in dwarf brown egg layers carrying or not the naked neck gene |
| topic | dwarf chicken naked neck gene clutch length genetic variability selection response |
| url | http://www.gsejournal.org/content/35/2/219 |
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