• Login
    View Item 
    •   Home
    • Massey Documents by Type
    • Theses and Dissertations
    • View Item
    •   Home
    • Massey Documents by Type
    • Theses and Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Utilisation of marker assisted selection in the New Zealand dairy industry : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Animal Breeding and Genetics at Massey University

    Icon
    View/Open Full Text
    01_front.pdf (544.5Kb)
    02_whole.pdf (2.213Mb)
    Export to EndNote
    Abstract
    The genetic and economic benefits of marker assisted selection (MAS) to the New Zealand dairy industry were evaluated. The genetic marker was assumed to be the additive quantitative trait loci (QTL) itself and thus no recombination existed between the marker and QTL. Three sizes of QTL were evaluated; 0.1, 0.3 and 0.5 genetic standard deviations (σG), at three starting QTL frequencies; 0.01, 0.10 and 0.35. Three MAS strategies were evaluated and compared to the current New Zealand breeding scheme that had no genotypic knowledge of the QTL (control). The economic benefits, for the three MAS strategies, were calculated from the returns of extra milk produced, resultant from superior rates of increase in QTL frequency, less the costs of identifying the QTL linked genetic markers and subsequent genotyping. The size of the QTL had a major effect on the economic viability of the MAS strategies. For a 0.1 σG QTL, the most profitable strategy to utilise the QTL was to ignore it and continue with the current breeding scheme. For a single additive QTL of size 0.3 σG, it had to be at the 0.35 starting frequency for the MAS strategy of progeny testing only homozygous and heterozygous QTL bulls, to be more profitable than the current breeding scheme. This same MAS strategy at the 0.5 σG sized QTL was the most profitable for the range of QTL starting frequencies evaluated. The MAS strategy where only homozygous QTL bulls were progeny tested, was not economically viable for any of the QTL sizes and frequencies. This was due to the reduced selection differential on the cow to bull and bull to bull pathways. The third MAS strategy investigated utilised the current breeding scheme but included knowledge of the QTL genotype for the active cows and bulls. Superior rates of genetic gain were achieved at all QTL sizes and frequencies, but it was only economically profitable for a 0.5 σG QTL with a starting frequency of 0.35. Selection on large QTL with this strategy resulted in short-term genetic gain, but long-term loss. This was due to less selection intensity being applied to the quantitative background, in comparison to the control.
    Date
    1995
    Author
    Spelman, Richard John
    Rights
    The Author
    Publisher
    Massey University
    Description
    First page of bibliographical references missing (p. 63)
    URI
    http://hdl.handle.net/10179/5269
    Collections
    • Theses and Dissertations
    Metadata
    Show full item record

    Copyright © Massey University
    | Contact Us | Feedback | Copyright Take Down Request | Massey University Privacy Statement
    DSpace software copyright © Duraspace
    v5.7-2020.1-beta1
     

     

    Tweets by @Massey_Research
    Information PagesContent PolicyDepositing content to MROCopyright and Access InformationDeposit LicenseDeposit License SummaryTheses FAQFile FormatsDoctoral Thesis Deposit

    Browse

    All of MROCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsThis CollectionBy Issue DateAuthorsTitlesSubjects

    My Account

    LoginRegister

    Statistics

    View Usage Statistics

    Copyright © Massey University
    | Contact Us | Feedback | Copyright Take Down Request | Massey University Privacy Statement
    DSpace software copyright © Duraspace
    v5.7-2020.1-beta1