• 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.

    Investigations into procedures for the implementation of a multiple ovulation and embryo transfer scheme using ewe lambs: a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University

    Icon
    View/Open Full Text
    02_whole.pdf (6.054Mb)
    01_front.pdf (584.7Kb)
    Export to EndNote
    Abstract
    Three trials using 6-7 month-old Romney ewe lambs and adult ewes were conducted to evaluate the feasibility of implementing a juvenile MOET scheme. Older lambs were used to evaluate ways of improving the ovulation rates in 3 additional trials, one of them involved Booroola-cross lambs. Studies were also carried out to develop and evaluate a technique for splitting sheep embryos, and these were transferred to recipient ewes. In the three trials involving superovulation and transfer a range of gonadotrophin treatments were used. The more highly purified preparations (FSH-P, Ovagen) gave lower responses compared with PMSG (1.78, 1.06 vs 4.18 respectively in Trial 3, P<0.01). Ovulation rate of ewe lambs relative to adult ewes in the 3 trials were respectively 1.20 vs 2.00 (P<0.01), 4.18 vs 6.35 and 1.61 vs 3.15. Overall, administration of GnRH did not significantly increase the ovulation rates, although lambs treated with PMSG + GnRH tended to give higher responses. Egg recovery was higher in most cases in adults than in lambs (91% vs 55%, P<0.01; 72% vs 47%. P<0.01; 34% vs 43%, for trials 1, 2 and 3 respectively). Fertilization rate in trial 1 was lower in lambs than in adults (50% vs 82%, P<0.05) but not different in trials 3 and 5, probably due to the use of intrauterine insemination. Ovulation rate was not improved by treating lambs at 8-9 months of age or by administering PMSG 2 or 4 days before sponge removal. Ovulation rates following gonadotrophin stimulation were higher in androstenedione-immunized ewe lambs than in non-immunized ewe lambs (2.22 vs 1.59. P<0.05). Booroola-cross lambs treated at 6-7 months of age gave considerably higher ovulation rates compared to those recorded in Romney lambs from another experiment conducted at the same time (3.79 vs 1.61). Lower embryo survival and incidence of twins were found for demi-embryos generated from 9-10 month-old lambs compared to those obtained from 24 months or older animals. Higher pregnancy rate and demi-embryo survival were found when bisecting blastocysts rather than morulae harvested in the same flush. A deterministic model incorporating parameters provided by the study showed that the limited number of lambs generated from lamb donors restricted the improvement in genetic progress.
    Date
    1991
    Author
    Rangel-Santos, Raymundo
    Rights
    The Author
    Publisher
    Massey University
    URI
    http://hdl.handle.net/10179/3103
    Collections
    • Theses and Dissertations
    Metadata
    Show full item record

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

     

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