The effect of intensive feeding duration on the authenticity of Karoo lamb

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dc.contributor.advisorStrydom, P. E.en_ZA
dc.contributor.advisorHoffman, L. C.en_ZA
dc.contributor.advisorMarais, Jeannineen_ZA
dc.contributor.advisorVan Zyl, Johan Hendrik Combrinken_ZA
dc.contributor.authorBoden, Jarryd Michaelen_ZA
dc.contributor.otherStellenbosch University. Faculty of AgriSciences. Dept. of Animal Science.en_ZA
dc.date.accessioned2024-02-22T09:03:22Z
dc.date.accessioned2024-04-26T12:57:20Z
dc.date.available2024-02-22T09:03:22Z
dc.date.available2024-04-26T12:57:20Z
dc.date.issued2024-03
dc.descriptionThesis (MScAgric)--Stellenbosch University, 2024. en_ZA
dc.description.abstractENGLISH ABSTRACT: Present climatic conditions such as droughts are becoming more frequent and may affect the future production of authentic Karoo lamb. To mitigate the effect of these possible climatic events on authentic Karoo lamb production, production practices need to be updated or modified. Although a supplementary feeding protocol is currently in place, establishing an intensive feeding protocol that affords all certified Karoo lamb producers the option to intensively feed for a limited duration, prior to unfavourable climatic conditions, is required. Additionally, as the sensory profile of Karoo lamb is its unique quality, changing the production practices, associated with the feeding regime, may influence the authenticity of Karoo lamb. During this investigation, free-ranging Dorper ram lambs from the Karoo region were intensively fed in a feedlot for 0, 21, 28 and 35 days on the same diet. During this period, the performance, carcass quality and profitability were evaluated. Feedlotting increased feed costs and is an uncharacteristic production system for an origin-based and region-specific meat product, such as Karoo lamb. However, when climatic conditions dictate feedlotting, the Dorper breed when raised and weaned on an extensive production system performs well. Following the initial investigation, the retail shelf-life of lamb chops was evaluated by measuring colour changes and lipid oxidative capacity over a seven-day shelf-life trial. Additionally, the proximate composition and physical characteristics of lamb meat were evaluated. The feeding system appeared to be responsible for the variations in lamb meat colour attributes and lipid oxidative capacity. Lambs slaughtered directly off pasture had better colour stability and lipid oxidative capacity than those placed in a feedlot. Overall, the colour, physical meat characteristics and lipid oxidative capacity of the lamb meat in the current investigation would be considered acceptable across all groups. To measure meat compositional changes, the fatty acid composition and carbon and nitrogen isotopic ratio of lamb meat influenced by intensive feeding duration was evaluated. Fatty acid and stable isotope compositional changes were apparent due to intensive feeding. However, key FAs were still within beneficial bounds and isotope ratios within previously defined isotopic ratios for free-ranging Dorper lambs from the Karoo region. Lastly, the effect of intensive feeding duration on the sensory profile of previously free-ranging Dorper ram lambs was investigated. The “herbaceous” quality was not surrendered during intensive feeding, however the subsequent increase in pastoral aromas diluted and modified the unique aroma and flavour. A diet devoid of feedstuffs known to promote negative aromas and flavours is postulated to be more appropriate for maintaining the unique Karoo lamb meat aroma and flavour during a period of intensive feeding. It is difficult to conclude whether the authentic nature of Karoo lamb was indeed preserved or not. However, the overall quality of Karoo lamb as a meat product changed during an intensive feeding period and thus it is the opinion of the author, that considering everything, the authentic quality of Karoo lamb was not preserved.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Huidige klimaatstoestande soos droogtes kom meer gereeld voor en kan die toekomstige produksie van outentieke Karoo-lam beïnvloed. Om die effek van hierdie moontlike klimaatsgebeure op Karoo- lam produksie te beperk, moet produksiepraktyke opgedateer of gewysig word. Alhoewel 'n aanvullende voedingsprotokol vir die produkise van Karoo-lam tans in plek is, word die daarstelling van 'n intensiewe voedingsprotokol wat aan alle gesertifiseerde Karoo-lam produsente die opsie bied om intensief te voer (zero beweiding) vir 'n beperkte duur tydens ongunstige klimaatstoestande, vereis. Aangesien die sensoriese profiel van Karoo-lam ‘n unieke kwaliteit is, kan die verandering van die produksiepraktyke, wat met die voedingsregime geassosieer word, die egtheid van Karoo-lam beïnvloed. Tydens hierdie ondersoek is vrylopende Dorper-ramlammers uit die Karoo-streek intensief in 'n voerkraal gevoer vir 0, 21, 28 en 35 dae op dieselfde dieet. Gedurende hierdie tydperk is die groeiprestasie, karkaskwaliteit en winsgewendheid geëvalueer. Voerkraalvoeding behels verhoogte voerkoste en is 'n onkenmerkende produksiestelsel vir 'n oorspronggebaseerde en streekspesifieke vleisproduk, soos Karoo-lam. Wanneer klimaatstoestande aanpassings vereis, presteer die Dorper-ras goed wanneer dit grootgemaak en gespeen word op 'n uitgebreide produksiestelsel wat voerkraalvoeding uinsluit. Ten einde die effek van voerkraalvoeding op kwlaiteit te ondersoek is die kleinhandel-raklewe van lamtjops geëvalueer deur kleurveranderinge en lipiedoksie oor 'n sewe dae lange rakleweproef gemeet. Daarbenewens is die samestelling en fisiese eienskappe van lamsvleis geëvalueer. Die voedingstelsel blyk verantwoordelik te wees vir die variasies in lamvleiskleurkenmerke en lipiedoksidatiewe kapasiteit. Lammers wat direk van weiding geslag is, het beter kleurstabiliteit en lipiedoksidatiewe kapasiteit gehad as dié wat in 'n voerkraal geplaas is. Oor die algemeen sal die kleur, fisiese vleiseienskappe en lipiedoksidatiewe kapasiteit van die lamsvleis in die huidige ondersoek egter as aanvaarbaar in alle groepe beskou word. Om vleissamestellingveranderinge te meet, is die vetsuursamestelling (VS) en koolstof- en stikstofisotopiese verhouding van lamsvleis wat deur intensiewe voedingsduur beïnvloed is, geëvalueer. Vetsuur en stabiele isotoop samestellingsveranderinge was duidelik as gevolg van intensiewe voeding. Sleutel VS’e was egter steeds binne voordelige grense en isotoopverhoudings binne voorheen-gedefinieerde isotopiese verhoudings vir vrylopende Dorper-lammers uit die Karoo- streek. Laastens is die effek van intensiewe voedingsduur op die sensoriese profiel van voorheen vrylopende Dorper- ram lamme ondersoek. Die “kruidagtige”-kwaliteit het nie tydens intensiewe voeding verdwyn of vervaag nie, maar die toename in “gras-“ of “weidings-“ geassosieerde aromas het die unieke aroma en geur verdun en verander. 'n Dieet sonder voer wat bekend is om negatiewe aromas en geure te bevorder, word gepostuleer as meer geskik vir die handhawing van die unieke Karoo-lam vleisaroma en -geur gedurende 'n tydperk van intensiewe voeding. Dit is moeilik om tot die gevolgtrekking te kom of die outentieke aard van Karoo-lam wel bewaar is of nie. Die algehele kwaliteit van Karoo-lam as vleisproduk het egter gedurende 'n intensiewe voedingsperiode verander en dus is dit die mening van die skrywer, dat met inagneming van alles, die outentieke kwaliteit van Karoo-lam nie behoue gebly het nie.af_ZA
dc.description.versionMastersen_ZA
dc.identifier.urihttps://scholar.sun.ac.za/handle/10019.1/130310
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subject.lcshLambs -- South Africa -- Karooen_ZA
dc.subject.lcshClimatic changes -- South Africa -- Karooen_ZA
dc.subject.lcshLambs -- Feeding and feeds -- Economic aspectsen_ZA
dc.subject.lcshDroughtsen_ZA
dc.subject.lcshLamb (Meat) -- Evaluationen_ZA
dc.subject.nameUCTDen_ZA
dc.titleThe effect of intensive feeding duration on the authenticity of Karoo lamben_ZA
dc.typeThesisen_ZA
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