Kalvningsintervall hos svenska köttkor : finns det genetisk variation som kan användas i avelsarbetet?
The Swedish beef cattle population is growing when the dairy cattle become fewer. The fertility of the beef cows is important for the profitability in beef cattle production. Today there is no genetic evaluation for female fertility in Swedish beef cows. The purpose of this study was to see if calvi...
| Autor principal: | |
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| Formato: | L3 |
| Lenguaje: | sueco Inglés |
| Publicado: |
SLU/Dept. of Animal Breeding and Genetics (until 231231)
2008
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| Materias: |
| _version_ | 1855571819871862784 |
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| author | Lennartsson, Maria |
| author_browse | Lennartsson, Maria |
| author_facet | Lennartsson, Maria |
| author_sort | Lennartsson, Maria |
| collection | Epsilon Archive for Student Projects |
| description | The Swedish beef cattle population is growing when the dairy cattle become fewer. The fertility of the beef cows is important for the profitability in beef cattle production. Today there is no genetic evaluation for female fertility in Swedish beef cows. The purpose of this study was to see if calving interval can be used in the genetic evaluation as a measure of female fertility in beef cows. For this purpose the variation in calving interval for beef cows of different breeds and ages registred in KAP was studied. Genetic parameters were calculated for charolais and hereford. Data from Svensk Mjölk were used. In the analyses purebred cows that calved between the years 1987 and 2005 were included.
The cows were divided into six different age classes, depending on age at the first calving in the interval. To seperate animals that calved for the first time from older cows it was asumed that calvings that happened when the animal was between 19 and 30 months old was the first calving of that animal.
Mean values for the length of the calving intervals were calculated for Angus, Blonde, Charolais, Hereford, Highland, Limousin and Simmental to see if there were any differences between them. The mean value was as a rule longer for animals that calved for the first time than for older cows. The calving interval then becomes shorter until age class 3-4. Afterwards it became somewhat longer again. There was variation between the breeds in the length of the calving intervals such that Angus and Hereford had the shortest intervals, whereas Highland and Blonde had the longest.
The variance components for calving interval in charolais and hereford were calculated with DMU package. A univariat analysis with repeated observations was done, where calving interval was seen as the same trait in each age class. A bivariate analysis was also done where age class 1 was seen as one trait and for the higher age classes it was seen as another trait. The heritabilities for calving interval in charolais and hereford were low, 0.01 for charolais and 0.02 for hereford in the univariate analysis. In the bivariate analysis the result was somewhat better for charolais in age class 1 (0.03), whereas the heritabilities for charolais in age class 2 6 and for hereford in all age classes were the same as in the univariate analysis. The estimated correlations between calving interval in age class 1 and calving interval in age class 2 6 were 0.76 for Charolais and 0.28 for Hereford.
The heritabilities in this study were low compared to earlier studies where the heritabilities ranged between 0.0125 and 0.10. The correlations between calving interval in age class 1 and age class 2 6 were below unit and calving intervals recorded both for younger and older cows should be taken into consideration in a genetic evaluation.
The next step in the evaluation of a good measurement of fertility for beef cattle is to estimate heritabilities and correlations for calving day. Then comparisons between calving day and calving interval need to be done to see which trait/traits are the best for Swedish purposes. More studies on correlations between fertility traits and other production traits are also needed. |
| format | L3 |
| id | RepoSLU11166 |
| institution | Swedish University of Agricultural Sciences |
| language | swe Inglés |
| publishDate | 2008 |
| publishDateSort | 2008 |
| publisher | SLU/Dept. of Animal Breeding and Genetics (until 231231) |
| publisherStr | SLU/Dept. of Animal Breeding and Genetics (until 231231) |
| record_format | eprints |
| spelling | RepoSLU111662017-09-26T11:09:28Z Kalvningsintervall hos svenska köttkor : finns det genetisk variation som kan användas i avelsarbetet? Lennartsson, Maria kalvningsintervall köttkor genetisk variation Charolais Hereford The Swedish beef cattle population is growing when the dairy cattle become fewer. The fertility of the beef cows is important for the profitability in beef cattle production. Today there is no genetic evaluation for female fertility in Swedish beef cows. The purpose of this study was to see if calving interval can be used in the genetic evaluation as a measure of female fertility in beef cows. For this purpose the variation in calving interval for beef cows of different breeds and ages registred in KAP was studied. Genetic parameters were calculated for charolais and hereford. Data from Svensk Mjölk were used. In the analyses purebred cows that calved between the years 1987 and 2005 were included. The cows were divided into six different age classes, depending on age at the first calving in the interval. To seperate animals that calved for the first time from older cows it was asumed that calvings that happened when the animal was between 19 and 30 months old was the first calving of that animal. Mean values for the length of the calving intervals were calculated for Angus, Blonde, Charolais, Hereford, Highland, Limousin and Simmental to see if there were any differences between them. The mean value was as a rule longer for animals that calved for the first time than for older cows. The calving interval then becomes shorter until age class 3-4. Afterwards it became somewhat longer again. There was variation between the breeds in the length of the calving intervals such that Angus and Hereford had the shortest intervals, whereas Highland and Blonde had the longest. The variance components for calving interval in charolais and hereford were calculated with DMU package. A univariat analysis with repeated observations was done, where calving interval was seen as the same trait in each age class. A bivariate analysis was also done where age class 1 was seen as one trait and for the higher age classes it was seen as another trait. The heritabilities for calving interval in charolais and hereford were low, 0.01 for charolais and 0.02 for hereford in the univariate analysis. In the bivariate analysis the result was somewhat better for charolais in age class 1 (0.03), whereas the heritabilities for charolais in age class 2 6 and for hereford in all age classes were the same as in the univariate analysis. The estimated correlations between calving interval in age class 1 and calving interval in age class 2 6 were 0.76 for Charolais and 0.28 for Hereford. The heritabilities in this study were low compared to earlier studies where the heritabilities ranged between 0.0125 and 0.10. The correlations between calving interval in age class 1 and age class 2 6 were below unit and calving intervals recorded both for younger and older cows should be taken into consideration in a genetic evaluation. The next step in the evaluation of a good measurement of fertility for beef cattle is to estimate heritabilities and correlations for calving day. Then comparisons between calving day and calving interval need to be done to see which trait/traits are the best for Swedish purposes. More studies on correlations between fertility traits and other production traits are also needed. Köttdjurspopulationen ökar i takt med att antal mjölkkor i landet minskar. Dikornas fertilitet är viktig för lönsamheten i köttdjursproduktionen. I Sverige sker idag ingen avelsvärdering för honlig fertilitet hos dikor. Syftet med denna studie var att se om kalvningsintervall kan användas i avelsvärderingen som ett mått på de svenska dikornas fertilitet. För detta ändamål studerades variationen i kalvningsintervall för dikor av olika raser och åldrar registrerade i KAP. Genetiska parametrar beräknades för raserna charolais och hereford. Datat som användes kom från Svensk Mjölk och innehöll kalvningar registrerade i KAP för de kor vars kalvar ingick i BLUP-avelsvärderingen hösten 2005. I analyserna ingick renrasiga kor som kalvade år 1987 till 2005. Korna delades in i sex åldersklasser beroende på ålder vid den tidigare kalvningen i intervallet I datasetet fanns ej information om kalvningsnummer och för att försöka skilja förstakalvare från äldre kor antogs kalvningar vid en ålder mellan 20 och 30 månader ske hos förstakalvare (åldersklass 1). För att få en överblick över kalvningsintervallen i de olika raserna och studera om det är några skillnader mellan dem beräknades medelvärden för angus, blonde, charolais, hereford, highland, limousin och simmental. Medelvärdet för kalvningsintervallets längd hos förstakalvare (åldersklass 1) visade att kalvningsintervallet i regel är något längre för förstakalvare än för äldre kor. Kalvningsintervallets längd sjönk successivt med någon dag fram till åldersklass 3-4. Därefter blev det något längre igen. Det var skillnader i längden på kalvningsintervallen mellan de olika raserna. Varianskomponenter för kalvningsintervall beräknades med hjälp av DMU programpaket för raserna charolais och hereford. En univariat analys med upprepade observationer gjordes där kalvningsintervall betraktades som samma egenskap i varje åldersklass. En bivariat analys gjordes också där kalvningsintervall i åldersklass 1 betraktades som en egenskap och kalvningsintervall i de senare åldersklasserna som en annan egenskap. Arvbarheterna för kalvningsintervall hos svensk charolais och hereford var låga, 0,01 för charolais och 0,02 för hereford i den univariata analysen. I den bivariata analysen var resultatet något högre för charolaisdjuren i åldersklass 1. Arvbarheten för dessa var 0,03. För hereford var resultatet oförändrat, liksom arvbarheten för övriga åldersklasser hos båda raserna. Korrelationen mellan djur i åldersgrupp 1 och äldre djur var lägre än 1, 0,76 för charolais och 0,28 för hereford. Arvbarheterna i denna studie var låga i jämförelse med tidigare gjorda studier där arvbarheterna legat mellan 0,0125 till 0,10. I den bivariata analysen var medelfelen höga för kalvningsintervall i åldersklass 1, vilket gör resultatet för denna åldersklass något osäkert. Kalvningsintervall bör dock, eventuellt tillsammans med något annat mått, kunna användas som ett mått på fertilitet i avelsarbetet. Då korrelationen mellan djur i åldersgrupp 1 och äldre djur inte var så hög bör man ta hänsyn till båda grupperna vid en eventuell avelsvärdering. Nästa steg i utvärderingen av ett bra fertilitetsmått på köttdjur är att se hur arvbarheter och korrelationer ser ut för kalvningsdag och sedan göra en jämförelse mellan detta mått och kalvningsintervall för att se vilket eller vilka mått som är användbara för de svenska förhållandena i praktiken. Fler analyser på korrelationer mellan fertilitetsegenskaper och andra produktionsegenskaper behövs också. SLU/Dept. of Animal Breeding and Genetics (until 231231) 2008 L3 swe eng https://stud.epsilon.slu.se/11166/ |
| spellingShingle | kalvningsintervall köttkor genetisk variation Charolais Hereford Lennartsson, Maria Kalvningsintervall hos svenska köttkor : finns det genetisk variation som kan användas i avelsarbetet? |
| title | Kalvningsintervall hos svenska köttkor : finns det genetisk variation som kan användas i avelsarbetet? |
| title_full | Kalvningsintervall hos svenska köttkor : finns det genetisk variation som kan användas i avelsarbetet? |
| title_fullStr | Kalvningsintervall hos svenska köttkor : finns det genetisk variation som kan användas i avelsarbetet? |
| title_full_unstemmed | Kalvningsintervall hos svenska köttkor : finns det genetisk variation som kan användas i avelsarbetet? |
| title_short | Kalvningsintervall hos svenska köttkor : finns det genetisk variation som kan användas i avelsarbetet? |
| title_sort | kalvningsintervall hos svenska köttkor : finns det genetisk variation som kan användas i avelsarbetet? |
| topic | kalvningsintervall köttkor genetisk variation Charolais Hereford |