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Quantitative trait loci affecting calving traits in Danish Holstein cattle
J R Thomasen1, B Guldbrandtsen, P Sørensen
1University of Aarhus, Faculty of Agricultural Sciences, Department of Genetics and Biotechnology, Research Center Foulum, DK-8830 Tjele, Box 50, Denmark. Jorn.RThomasen@agrsci.dk
Researchers identified quantitative trait loci (QTL) influencing calving traits in Danish Holsteins. These genetic markers, particularly on specific chromosomes, can aid selection for improved calving performance and reduced stillbirth.
Area of Science:
- Animal Genetics
- Reproductive Biology
- Quantitative Genetics
Background:
- Calving traits are critical for dairy cattle profitability and welfare.
- Identifying genetic factors influencing calving ease and stillbirth is essential for breeding programs.
- Understanding the genetic architecture of direct and maternal calving traits is complex.
Purpose of the Study:
- To detect quantitative trait loci (QTL) affecting direct and maternal calving traits in Danish Holsteins.
- To differentiate between pleiotropic and linked QTL impacting multiple traits.
- To identify QTL for stillbirth and calving difficulties, excluding calf size, for selection.
Main Methods:
- Genotyping of 2,297 progeny-tested bulls using 356 microsatellites across 29 autosomes.
- Utilizing a between-families linear regression model for QTL detection.
- Employing a variance component mapping approach to assess linkage and pleiotropy.
Main Results:
- Detected 27 significant QTL on 17 chromosomes affecting calving difficulty, stillbirth, and calf size.
- Identified pleiotropic QTL on chromosomes 12 and 25, and linked QTL on chromosomes 7 and 26.
- Chromosome 18 showed a QTL with pleiotropic effects on direct calving traits and linkage to maternal stillbirth.
Conclusions:
- Specific QTL on chromosomes 3, 4, 7, 10, 12, 18, 21, 24, 26, and 28 are valuable for selecting breeding candidates.
- These markers can improve calving performance and reduce calving difficulties in daughters.
- Distinguishing between pleiotropic and linked QTL provides a more nuanced understanding for genetic improvement.
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