Dystocia in Swedish beef cattle : effects of different scoring systems on the genetic evaluation
In Swedish beef cattle breeding, the genetic evaluation comprises calving traits, carcass traits and growth traits. For the calving traits stillbirth, birth weight and dystocia severity grade are recorded. The genetic evaluation for dystocia is divided into four traits; maternal and direct effect wh...
| Main Author: | |
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| Format: | H2 |
| Language: | Inglés Swedish |
| Published: |
SLU/Dept. of Animal Breeding and Genetics (until 231231)
2019
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| Subjects: |
| _version_ | 1855572537663029248 |
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| author | Nilsson, Filip |
| author_browse | Nilsson, Filip |
| author_facet | Nilsson, Filip |
| author_sort | Nilsson, Filip |
| collection | Epsilon Archive for Student Projects |
| description | In Swedish beef cattle breeding, the genetic evaluation comprises calving traits, carcass traits and growth traits. For the calving traits stillbirth, birth weight and dystocia severity grade are recorded. The genetic evaluation for dystocia is divided into four traits; maternal and direct effect when the mother is a primiparous cow, and maternal and direct effect when the mother is a multiparous cow.
The system for reporting the grade of dystocia changed in May 2012 from a three-graded scale to a four-graded scale. The distribution of the dystocia grades became mark-edly different, which affected the breeding values in a way that several extremely low values have occurred.
This report examines different genetic evaluations with alternative normal scores in-stead of the old scores corrected for heterogeneous variance. Also some genetic correla-tions that had been put to zero to avoid extremely low breeding values were again added to the genetic evaluation to examine their effect on the breeding values.
In the current reporting system there are examples of negative breeding values, while in the old reporting system the breeding values were not that extreme. The breeding values seem to be more normally distributed when using the transformed normal scores com-pared to the old scores. There are also less extremely low breeding values. When adding the genetic correlations between the traits, the breeding values changed a little bit. Overall the results indicate that the genetic evaluation is more influenced by changes in the scores system than by the genetic correlation. |
| format | H2 |
| id | RepoSLU15185 |
| institution | Swedish University of Agricultural Sciences |
| language | Inglés swe |
| publishDate | 2019 |
| publishDateSort | 2019 |
| publisher | SLU/Dept. of Animal Breeding and Genetics (until 231231) |
| publisherStr | SLU/Dept. of Animal Breeding and Genetics (until 231231) |
| record_format | eprints |
| spelling | RepoSLU151852019-11-08T15:16:05Z Dystocia in Swedish beef cattle : effects of different scoring systems on the genetic evaluation Kalvningssvårigheter hos svenska nötköttsraser : påverkan på avelsvärderingen av olika graderingssystem Nilsson, Filip Swedish beef cattle residuals genetic evaluation normal score beef breeding In Swedish beef cattle breeding, the genetic evaluation comprises calving traits, carcass traits and growth traits. For the calving traits stillbirth, birth weight and dystocia severity grade are recorded. The genetic evaluation for dystocia is divided into four traits; maternal and direct effect when the mother is a primiparous cow, and maternal and direct effect when the mother is a multiparous cow. The system for reporting the grade of dystocia changed in May 2012 from a three-graded scale to a four-graded scale. The distribution of the dystocia grades became mark-edly different, which affected the breeding values in a way that several extremely low values have occurred. This report examines different genetic evaluations with alternative normal scores in-stead of the old scores corrected for heterogeneous variance. Also some genetic correla-tions that had been put to zero to avoid extremely low breeding values were again added to the genetic evaluation to examine their effect on the breeding values. In the current reporting system there are examples of negative breeding values, while in the old reporting system the breeding values were not that extreme. The breeding values seem to be more normally distributed when using the transformed normal scores com-pared to the old scores. There are also less extremely low breeding values. When adding the genetic correlations between the traits, the breeding values changed a little bit. Overall the results indicate that the genetic evaluation is more influenced by changes in the scores system than by the genetic correlation. I köttaveln på nötkreatur i Sverige avelsvärderas djuren för kalvningsegenskaper, slakt-kroppsegenskaper och tillväxtegenskaper. För kalvningsegenskaper är det två egenskaper som ingår i avelsvärderingen; födelsevikt och kalvningssvårighet. Avelsvärderingen för kalvningssvårigheter är uppdelad på fyra egenskaper, maternell effekt då modern är förs-takalvare, direkt effekt då modern är förstakalvare, maternell effekt då modern är en äldre ko, och direkt effekt då modern är en äldre ko. Rapporteringssystemet för kalvningssvårigheter ändrades i maj 2012 från en tregradig skala till en fyrgradig. Fördelningen mellan de rapporterade klasserna för kalvningssvårig-het ändrades markant, vilket påverkade avelsvärdena så att avelsvärdena för en del djur blev extremt låga. Denna rapport utvärderar olika sätt att hantera olika grader av kalvningssvårighet i avelsvärderingen med alternativa så kallade ’normal scores’ istället för de värden som används idag tillsammans med korrektion för heterogen varians. Några genetiska korrelat-ioner som tidigare har satts till noll, på grund av de extremt låga avelsvärdena, återinför-des i denna rapport för att utvärdera deras påverkan på avelsvärdena. Dagens rapporteringssystem och avelsvärdering ger upphov till en del negativa avels-värden, medan det med det gamla rapporteringssystemet inte fanns lika extrema avels-värden. Avelsvärdena verkar vara mer normalfördelade när man använder de transfor-merade ’normal scores’ jämfört med de värden som används idag. Det ger dessutom mindre extremt låga avelsvärden. När korrelationerna återinfördes så ändrades avelsvär-dena något. Överlag indikerar resultaten att avelsvärderingen påverkas mer av om ’nor-mal scores’ används än av om dessa korrelationer utelämnas eller inte. SLU/Dept. of Animal Breeding and Genetics (until 231231) 2019 H2 eng swe https://stud.epsilon.slu.se/15185/ |
| spellingShingle | Swedish beef cattle residuals genetic evaluation normal score beef breeding Nilsson, Filip Dystocia in Swedish beef cattle : effects of different scoring systems on the genetic evaluation |
| title | Dystocia in Swedish beef cattle : effects of different scoring systems on the genetic evaluation |
| title_full | Dystocia in Swedish beef cattle : effects of different scoring systems on the genetic evaluation |
| title_fullStr | Dystocia in Swedish beef cattle : effects of different scoring systems on the genetic evaluation |
| title_full_unstemmed | Dystocia in Swedish beef cattle : effects of different scoring systems on the genetic evaluation |
| title_short | Dystocia in Swedish beef cattle : effects of different scoring systems on the genetic evaluation |
| title_sort | dystocia in swedish beef cattle : effects of different scoring systems on the genetic evaluation |
| topic | Swedish beef cattle residuals genetic evaluation normal score beef breeding |