Detection and utilisation of quantitative trait loci in dairy cattle

R.J. Spelman

Research output: Thesisinternal PhD, WU

Abstract

<p>The focus of the thesis is on the detection of quantitative trait loci (QTL) in dairy cattle and their utilisation in breeding programmes. Analysis of one bovine chromosome for quantitative trait loci for milk production traits is described and a QTL for protein percent was identified that was significant at the 1% level.</p><p>When analysing the chromosome it was observed that the degree of precision in estimating QTL location and size (or variance) is poor. Through stochastic simulation, the effect of incorrect parameter estimates for quantitative trait locus effect, and position on genetic response from marker assisted selection is investigated.</p><p>From this study it was concluded that studies should be undertaken to verify estimates of QTL and location to enable optimal use of marker assisted selection. Strategies to confirm the existence and size of quantitative trait loci identified in a genome scan are outlined. Also through stochastic simulation the effect of reducing flanking-marker bracket size was found to increase the genetic response from marker assisted selection.</p><p>Simulation is used to estimate improvements in rate of genetic gain from marker assisted selection for two scenarios, the current situation and a futuristic setting. The increase in rate of genetic gain with marker assisted selection is some 5% in the current situation with the potential of 30% with improvements in level of genetic variance identified and the identified loci being in disequilibrium with marker alleles.</p><p>The general discussion of this thesis addresses the use of significance levels in quantitative trait loci detection, experimental designs to identify further quantitative trait loci in the New Zealand dairy industry, and the current and possible future application of marker assisted selection in dairy breeding programmes.</p>
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
Supervisors/Advisors
  • Brascamp, E.W., Promotor, External person
  • Garrick, D.J., Promotor, External person
  • van Arendonk, J.A.M., Promotor
Award date4 Sep 1998
Place of PublicationS.l.
Publisher
Print ISBNs9789054858966
Publication statusPublished - 1998

Keywords

  • dairy cattle
  • selective breeding
  • genetic markers
  • quantitative traits
  • genetic variation
  • chromosomes
  • simulation

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