The influence of superstimulation protocol on oocyte developmental competence in dairy cattle

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dc.contributor.advisorLambrechts, Heleten_ZA
dc.contributor.advisorVan Zyl, Johan Hendrik Combrinken_ZA
dc.contributor.authorGrobler, Barend Jacobusen_ZA
dc.contributor.otherStellenbosch University. Faculty of AgriSciences. Dept. of Animal Science.en_ZA
dc.date.accessioned2024-03-04T09:17:26Z
dc.date.accessioned2024-04-26T08:46:07Z
dc.date.available2024-03-04T09:17:26Z
dc.date.available2024-04-26T08:46:07Z
dc.date.issued2024-03
dc.descriptionThesis (MScAgric)--Stellenbosch University, 2024. en_ZA
dc.description.abstractENGLISH ABSTRACT: The increasing demand for dairy products globally, places increasing pressure on dairy producers to select animals for higher milk yield. In South Africa, market forces and the resulting economic pressure have resulted in a decline in the number of dairy producers, which necessitates that existing producers need to increase the average herd size and select dairy animals for a high milk yield, to remain sustainable in the South African dairy sector and to meet the ever-increasing demands of the consumer. The negative impact of selecting dairy animals for high milk yield is reflected in the decline in fertility of dairy animals, not only in South Africa, but globally. The purpose of this study was to evaluate the effects that age, lactation stage, and superstimulation program have on the fertility of Holstein dairy cows. The effect these factors have on fertility was assessed by looking at oocyte developmental competence in an in vitro embryo production system. The selection of the Holstein breed as donor animals, is based on the substantial representation of this dairy breed in the dairy industry. Twelve Holstein cows were selected as oocyte donors and allocated to three different age categories, i.e.3-4 years, 5-8 years, and 10-11 years; and according to stage of lactation, i.e. dry (non-lactating), early lactation (<120 Days in milk) and mid-lactation (>120 Days in milk). The donor animals were then randomly allocated into four different FSH-concentration superstimulation treatment groups (i.e. Control: 0 mg, Low: 150 mg, Medium: 180 mg, High: 240 mg). The superstimulation program and transvaginal oocyte retrieval (TVOR) were repeated every 28 Days, for four repetitions, to ensure that each donor was subjected to each treatment. In this study, the age of the donor and the FSH concentration had no significant effect on follicular wave response, oocyte developmental competence, or embryo yield in an in vitro embryo production system. Lactation stage, although not having a significant effect on follicular wave response, significantly influenced the number of embryos, with non-lactating cows producing 5.63 ± 0.76 embryos, compared to early-lactation cows (2.96 ± 0.53 embryos), and mid-lactation cows (1.97 ± 0.72 embryos). The findings from this study highlighted the impact of dairy cow nutrition on the quality of oocytes, which was more pronounced than the influence of cow age and FSH treatment. The high demand for nutrients in lactating animals disrupts the delicate physiological balance that is required to ensure oocyte developmental competence, in vivo as well as in vitro. The negative impact of lactation on oocyte developmental competence, and the partitioning of nutrients in favour of milk production at the cost of reproduction is clearly highlighted in this study.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Die toenemende aanvraag na melk en melk-produkte wêreldwyd, plaas suiwelprodusente onder druk om diere te selekteer vir hoër melkproduksie. In Suid-Afrika, het markkragte en ‘n verwante toenemende ekonomiese druk op suiwelprodusente tot ʼn afname in die aantal -produsente gelei, wat tot gevolg dat bestaande suiwelprodusente gedwing word om hulle kuddes te vergroot en diere te selekteer vir hoër melkproduksie, om ekonomies volhoubaar te bly en om aan die toenemende aanvraag vir suiwelprodukte te voldoen. Die benadering in die suiwelbedryf om diere met ʼn hoër melkproduksie te selekteer, het ʼn negatiewe invloed op melkbees vrugbaarheid in Suid-Afrika, sowel as in die res van die wêreld. Die doel van hierdie studie was om die effek van ouderdom, laktasie stadium en superstimulasie program op die vrugbaarheid van Holstein melkkoeie, te evalueer. Die effek wat die onderskeie faktore op vrugbaarheid het, is bepaal deur na oösiet ontwikkelingsvermoë in 'n in vitro embrio produksie program te kyk. Die keuse van die Holstein ras as skenkers is gebaseer op die aansienlike verteenwoordiging van hierdie beesras in die suiwelbedryf. Twaalf Holstein melkkoeie is as oösietskenkers geselekteer en in drie verskillende ouderdomskategorieë, d.i. 3-4 jaar, 5-8 jaar en 10-11 jaar en ook volgens stadium van laktasie, d.i. droog (nie- lakterend), vroeë laktasie (<120 dae in melk) en mid-laktasie (>120 dae in melk), ingedeel. Die skenkerdiere is toe ewekansig in vier verskillende FSH-konsentrasie superstimulerings-behandelingsgroepe verdeel (d.i. Kontrole: 0 mg, Laag: 150 mg, Medium: 180 mg, Hoog: 240 mg). Die superstimulasie program en transvaginale oösietherwinning (TVOR) is elke 28 dae, vir vier herhalings, herhaal om te verseker dat elke skenker aan elke behandeling onderwerp is. In hierdie studie het die ouderdom van die skenker en die FSH-konsentrasie geen betekenisvolle effek op follikulêre golfrespons, oösiet ontwikkelingsvermoë of aantal embrio’s in 'n in vitro embrio produksie program gehad nie. Laktasie stadium, hoewel dit nie 'n beduidende effek op follikulêre golfreaksie gehad het nie, het die aantal embrio's beduidend beïnvloed, met nie-lakterende koeie wat 5.63 ± 0.76 embrio's geproduseer het, in vergelyking met vroeë laktasie koeie (2.96 ± 0.53 embrio's), en mid-laktasie koeie (1,97 ± 0,72 embrio's). Die bevindinge van hierdie studie het die belang van melkkoei voeding op die kwaliteit van oösiete uitgelig, wat ‘n groter invloed as koei-ouderdom en FSH-behandeling, gehad het. Die hoë aanvraag na voedingstowwe in lakterende diere versteur die delikate fisiologiese balans wat oösiet ontwikkelingsvermoë beide op ‘n in vivo en in vitro vlak, sal verseker. Die negatiewe invloed van laktasie op oösiet ontwikkelingsvermoë en die verdeling van voedingstowwe ten gunste van melkproduksie, ten koste van reproduksie, word duidelik in hierdie studie uitgelig.af_ZA
dc.description.versionMastersen_ZA
dc.format.extent127 pages : illustrations (some color)en_ZA
dc.identifier.urihttps://scholar.sun.ac.za/handle/10019.1/130195
dc.language.isoen_ZAen_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subject.lcshDairy cattle breeds -- South Africaen_ZA
dc.subject.lcshHolsteins -- Growthen_ZA
dc.subject.lcshDairy cattle -- Fertilityen_ZA
dc.subject.lcshDairy cattle -- Feeding and feeds -- Nutrition -- Requirementsen_ZA
dc.subject.lcshLactation -- Evaluationen_ZA
dc.subject.lcshOocyte -- Development -- Evaluationen_ZA
dc.subject.nameUCTDen_ZA
dc.titleThe influence of superstimulation protocol on oocyte developmental competence in dairy cattleen_ZA
dc.typeThesisen_ZA
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