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| 2. |
- Eriksson, Susanne, et al.
(författare)
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Genetic trends for fertility, udder health and protein yield in Swedish red cattle estimated with different models
- 2017
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Ingår i: Journal of Animal Breeding and Genetics. - : Wiley. - 0931-2668 .- 1439-0388. ; 134, s. 308-321
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to estimate and compare genetic trends in Swedish Red cattle using a full multiple-trait (MT) model and trait-group-wise models for female fertility, udder health and protein yield. Field data for maiden heifers from 1989 and cows with a first and second lactation between 1990 and 2007 were included. (Co)variance components were estimated prior to prediction of breeding values. The estimated genetic trends were clearly favourable for protein yield and udder conformation, and in most cases neutral to favourable for clinical mastitis and calving to first insemination. In maiden heifers, the trends were neutral for number of inseminations per service period. Unfavourable genetic trends were estimated for number of inseminations in the first two lactations, but the trends seemed less unfavourable from evaluations within trait groups compared with when using the full MT model. Excluding maiden heifer data affected genetic trends less than using trait-group-wise analyses instead of a full MT model. Unfavourable genetic trends in functional traits may be missed unless the traits are evaluated in a MT model including traits under strong selection.
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| 3. |
- Hansen-Axelsson, Helen, et al.
(författare)
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Breakeven prices for recording of indicator traits to reduce the environmental impact of milk production
- 2015
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Ingår i: Journal of Animal Breeding and Genetics. - : Wiley. - 0931-2668 .- 1439-0388. ; 132, s. 30-41
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Tidskriftsartikel (refereegranskat)abstract
- A breeding scheme using genomic selection and an indicator trait for environmental impact (EI) was studied to find the most effective recording strategy in terms of annual monetary genetic gain and breakeven price for the recording of indicator traits. The breakeven price shows the investment space for developing a recording system for an indicator trait. The breeding goal consisted of three traits - milk production, functional trait and environmental impact - with economic values of Euro83, Euro82 and Euro-83, respectively. The first scenario included only breeding goal traits and no indicator traits (NoIT). The other scenarios included all three breeding goal traits and one indicator trait (IT) for EI. The indicator traits were recorded on a large scale (stayability after first lactation and stature), medium scale (live weight and greenhouse gases (GHG) measured in the breath of the cow during milking) or small scale (residual feed intake and total enteric methane measured in a respiration chamber). In the scenario with stayability, the genetic gain in EI was over 11% higher than it was in NoIT. The breakeven price of recording stayability was Euro8 per record. Stayability is easy to record in the national milk recording system, and its use as an indicator trait for EI would not generate any additional recording costs. Therefore, stayability would be a good indicator trait to use to mitigate EI. The highest genetic gain in EI (23% higher compared to NoIT) was achieved when the GHG measured in the breath of the cow was used as indicator trait. The breakeven price for this indicator trait was Euro29 per record in the reference population. Ideally the recording of a specific indicator trait for EI would take place when: (i) the genetic correlation between the IT and EI is high; and (ii) the number of phenotypic records for the indicator trait is high enough to achieve a moderately high reliability of direct genomic values.
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| 4. |
- Hansen-Axelsson, Helen
(författare)
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Breeding for sustainable milk production : from nucleus herds to genomic data
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The overall aim of the research reported in this thesis was to investigate ways to mitigate deterioration in functional traits and reduce the environmental impact of milk production. The more specific objectives were to obtain new information about the selection of bull dams for functional traits in an open nucleus herd, to monitor ongoing genetic trends in functional traits, and to examine a breeding program with genomic selection and contractor herds that records specific indicator traits correlated with environmental impact. A breeding scheme with expanded recording of functional traits in potential bull dams in a nucleus herd was simulated. The genetic trend in functional traits was found to be unfavourable in all scenarios. Improved recording of functional traits did not limit the unfavourable genetic response in fertility and udder health traits unless more economic weight was placed on functional traits in the breeding goal. Genetic trends in fertility and udder health traits were estimated in Swedish Red dairy cattle. The estimated genetic trend for number of inseminations in lactating cows was unfavorable. The choice of model to be used for genetic evaluation influences the estimate of genetic trend, indicating that unfavorable genetic trends may not be discovered unless the traits are evaluated in a multiple-trait model including both functional and production traits. Substantial genetic progress in breeding for environmentally friendly cows can be achieved by including environmental impact in the breeding goal, and by using phenotype records and genomic information on correlated indicator traits. The most valuable indicator traits are those with a strong genetic correlation with environmental impact that also have a high accuracy of direct genomic values. Breakeven prices for recording the indicator trait were calculated for all scenarios. They varied considerably from one scenario to another, depending on the number of phenotype records on indicator traits. Recording an indicator trait could be both genetically and economically advantageous where the genetic correlation between the trait in question and environmental impact is strong, the trait has an optimal number of phenotype records, and the reliability of direct genomic values is moderately high.
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| 5. |
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| 6. |
- Hansen-Axelsson, Helen, et al.
(författare)
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Genomic selection using indicator traits to reduce the environmental impact of milk production
- 2013
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Ingår i: Journal of Dairy Science. - : American Dairy Science Association. - 0022-0302 .- 1525-3198. ; 96, s. 5306-5014
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this simulation study was to test the hypothesis that phenotype information of specific indicator traits of environmental importance recorded on a small-scale can be implemented in breeding schemes with genomic selection to reduce the environmental impact of milk production. A stochastic simulation was undertaken to test alternative breeding strategies. The breeding goal consisted of milk production, a functional trait, and environmental impact (EI). The indicator traits (IT) for EI were categorized as large-, medium-, or small-scale, depending on how the traits were recorded. The large-scale traits were stayability and stature; the medium-scale traits were live weight and methane in the breath of the cow measured during milking; and the small-scale traits were residual feed intake and methane recorded in a respiration chamber. Simulated scenarios considered information for just one IT in addition to information for milk production and functional traits. The annual monetary genetic gain was highest in the large-scale scenario that included stayability as IT. The annual monetary gain in the scenarios with medium- or small-scale IT varied from €50.5 to 47.5. The genetic gain improvement in EI was, however, best in the scenarios where the genetic correlation between IT and EI was ≥0.30 and the accuracy of direct genomic value was ≥0.40. The genetic gain in EI was 26 to 34% higher when indicator traits such as greenhouse gases in the breath of the cow and methane recorded in respiration chamber were used compared with a scenario where no indicator trait was included. It is possible to achieve increased genetic gain in EI by using a highly correlated indicator trait, but it requires that the established reference population for the indicator trait is large enough so that the accuracy of direct genomic values will be reasonably high.
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| 9. |
- Rydhmer, Lotta, et al.
(författare)
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Avelsvärdering för svensk lammproduktion
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Syftet med detta projekt var att utveckla avelsvärderingen av får genom samlade avelsvärden som innefattar flera egenskaper, däribland de nya egenskaperna lammöverlevnad och tackans livslängd, att identifiera skillnader och likheter mellan får på konventionella och ekologiska gårdar ur ett avelsperspektiv samt att utveckla en bioekonomisk modell för att kombinera flera egenskaper i ett avelsvärde med ekonomiska vikter. Information om djuren kom från databasen Elitlamm och från KRAV kom information om besättningar i ekologisk produktion. Vi skattade genetiska parametrar för produktions- och reproduktionsegenskaper. Vi fann en tydlig skillnad mellan djur i ekologisk och konventionell produktion: tackorna i ekologiska besättningar får fler kullar. Baggarnas avelsvärde grundat på information från avkommor i ekologisk produktion skiljde sig från avelsvärdet grundat på information från avkommor i konventionell produktion. Den bioekonomiska modellen gav olika ekonomiska vikter för olika raser och för de två produktionssystemen.
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