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dc.contributor.advisorEinkamerer, O. B.
dc.contributor.advisorHugo, A.
dc.contributor.advisorGreyling, J. P. C.
dc.contributor.authorDe Klerk, Inalene
dc.date.accessioned2018-01-16T06:38:38Z
dc.date.available2018-01-16T06:38:38Z
dc.date.issued2016-02
dc.identifier.urihttp://hdl.handle.net/11660/7610
dc.description.abstractEnglish: A study was conducted to investigate the effect of incrementally increasing NDF levels of finishing diets on apparent digestibility, production performance, FA composition, oxidative stability and tenderness of lamb. The five dietary treatments were formulated to contain a similar nutrient composition, differing only in respect to the NDF content as the primary parameter. The NDF content increased from low roughage (primarily lucerne hay as fibre source) inclusion to a high roughage inclusion rate representing a dose-response trial in the following order: 12.76% (T15), 17.69% (T30), 22.53% (T45), 27.48% (T60) and 32.40% (T75) NDF/kg DM, respectively. No rumen modifiers or buffers were added to the diet. Sixty (60) South African Mutton Merino wether lambs (29.3±1.8 kg) were randomly allocated to the five dietary treatments (n=12 lambs per treatment) and further subdivided into 12 animals per replicate (n=1 lamb per replicate). After dietary adaptation of 10 days all lambs received the experimental diets for the remaining period (51 days). Live weight and feed intake were recorded on a weekly basis. A digestibility study was conducted over a 12-day period (4-day adaptation to the faecal bags followed by an 8-day collection period) where seven lambs (mean 48.11±2.94 kg live weight; total of 35 lambs) were randomly allocated to each treatment (n=7 lambs/treatment). At the end of the production study all lambs were slaughtered. Physical carcass characteristics, muscle and subcutaneous FA composition, meat oxidation (malonaldehyde content), colour stability, as well as meat tenderness were measured. The data was subjected to analysis of variance (PROC ANOVA) of the SAS program, version 9.2 (SAS, 2008). Tukey’s honest significant difference (HSD) test was used to identify significant differences (P <0.05) between treatments. From the results of the present study it is apparent that an incremental increase in the NDF content of lamb finishing diets presented a significant decrease (P <0.05) in DM, OM, NSC, GE, CP and EE digestibilities, as well as ash solubility. In addition, the significant (P <0.05) decrease in digestible OM, NSC and EE dietary content were associated with diet digestibility and resulted in a significant decrease (P <.0001) in ME content following an increased NDF incremental inclusion. A high roughage inclusion in finishing diets for lambs (T75) resulted in a significant (P <0.05) reduction in MEI, ADG, FCR, and therefore cold carcass weight and dressing percentage. Increased dietary NDF content significantly (P <0.05) increased saturated stearic acid, and significantly (P <0.05) decreased monounsaturated oleic and vaccenic acid, polyunsaturated linoleic acid, as well as total PUFA, n-6, n-6:n-3 and PUFA:SFA ratios of both lamb meat and adipose tissue. Apart from the NDF content significantly (P <0.05) affecting the monounsaturated palmitoleic acid (decreased) and polyunsaturated CLA (C18:2c9t11;n-6) content of muscle tissue, as well as total SFA (increased) and MUFA (decreased) content of only adipose tissue, the effect of dietary treatment between lamb deposit sites seem to be similar. Neutral-detergent fibre content did significantly (P <0.05) affect meat colour stability stored for 7 days at 4oC. Neutral-detergent fibre content had no effect (P >0.05) on meat tenderness. These results suggest that the FA profile of lamb can be manipulated by altering the NDF content of the finishing diet. This however did not result, from a human health point of view, in the desirable PUFA:SFA and n-6:n-3 ratios in muscle and subcutaneous lipid tissue. It is proposed that, to increase the total UFA content and its desirable effect on the mentioned ratios of lamb meat, regression equations should be used to establish the optimum response at a given NDF inclusion. Further research attempting to manipulate specific FAs (single or total) or FA ratios of lamb meat via dietary means to meet consumers’ demands need further attention.en_ZA
dc.description.abstractAfrikaans: 'n Studie is uitgevoer om die invloed van inkrementeel toenemende neutral bestande vesel vlakke binne afrondingsdiëte op die skynbare verteerbaarheid, produksie, vetsuursamestelling, oksidasie stabiliteit en sagtheid van lamsvleis te evalueer. Vyf afrondingsdiëte is geformuleer om 'n soortgelyke voersamestelling te bevat, maar het slegs ten opsigte van die neutral bestande vesel inhoud as die primêre eienskap verskil. Die neutral bestande vesel inhoud het toegeneem vanaf ‘n lae ruvoer- (lusernhooi as ruvoerbron) tot 'n hoë ruvoer insluiting om 'n dosis-respons studie voor te stel met die volgende intervalle: 12.76% (T15), 17.69% (T30), 22.53% (T45), 27.48% (T60) en 32.40% (T75) neutral bestande vessel per kg droë materiaal, onderskeidelik. Geen rumen modifiseerders of buffers was bygevoeg tot enige dieët nie. Sestig (60) Suid-Afrikaanse Vleismerino hamellammers (lewnendige gewig van 29.3±1.8 kg) was ewekansig aan die vyf diëte toegeken (n=12 lammers per behandeling) en verder verdeel in 12 herhalings per behandeling (n=1 lam per herhaling). Na ‘n aanpassingperiode van 10 dae is die proefdiëte aan die lammers gevoer vir die oorblywende tydperk (51 dae). Lewende massa en voerinname is op ‘n weeklikse basis gemeet. ‘n Verteringstudie is vir ‘n periode van 12 dae uitgevoer (4-dae vir aanpassing tot die missakke, gevolg deur 'n 8-dae kolleksieperiode) waar sewe lammers (lewendige gewig van 48.11±2.94 kg; ‘n totaal van 35) ewekansig toegeken was aan elke behandeling (n=7 lammers per behandeling). Al die lammers was aan die einde van die produksiestudie geslag. Fisiese karkaseienskappe, vetsuursamestelling van spierweefsel en onderhuidse vet, oksidasiestabiliteit (malonaldehiedinhoud), kleurstabiliteit asook vleissagtheid is gemeet. Die data was onderworpe aan ‘n variansie analise (PROC ANOVA) van die SAS-program, weergawe 9.2 (SAS, 2008). Tukey se HSD toets was gebruik om betekenisvolle verskille (P <0.05) tussen behandelings te identifiseer. Uit die resultate van die huidige studie is dit duidelik dat 'n inkrementele toename in die NBV inhoud van ‘n lam afrondingsdieët 'n beduidende afname (P <0.05) in droë materiaal, organise materiaal, nie-strukturele koolhidrate, bruto energie, ru-proteien en eter ekstrak verteerbaarheid, sowel as oplosbare as het. Daarbenewens word die betekenisvolle (P <0.05) afname in verteerbare organise materiaal, nie-strukturele koolhidrate en eter ekstrak geassosieer met dieët verteerbaarheid wat gelei het tot 'n betekenisvolle afname (P <0.0001) in dieët ME inhoud soos NBV inkrementeel verhoog was. 'n Hoë ruvoer insluiting in die afrondingsdiëte vir lammers (T75) het gelei tot 'n betekenisvolle verlaging (P <0.05) in metabolise energie inname, gemiddelde daaglikse toename, voeromset verhouding, en daarom ook koue karkas gewig en uitslagpersentasie. ‘n Verhoogde dieët NBV inhoud het versadigde steariensuur betekenisvol (P <0.05) laat toeneem en mono-onversadigde oleien-, “vaccenic”- en poli-onversadigde linoleïensuur, sowel as totale poli-onversadigde vetsure, n-6, n-6:n-3 en poli-onversadigde vetsuur tot versadigde vetsuur verhoudings van beide spierweefsel en onderhuidse vet het betekenisvol (P <0.05) verlaag. Afgesien van die neutral bestande velsel inhoud wat ‘n betekenisvolle effek (P <0.05) op die mono-onversadigde palmitoleïen suur (afgeneem) en poli-onversadigde gekonjugeerde linoleiensuur (C18:2c9t11;n-6) inhoud van spierweefsel, asook die totale versadigde vetsure (toegeneem) en totale mono-onversadigde vetsure inhoud (afgeneem) van slegs onderhuidse vet gehad het, blyk die effek van dieët tussen die deponerings areas soortgelyk te wees. Neutraal-bestande veselinhoud het ‘n betekenisvolle (P <0.05) effek op kleurstabiliteit van vleis gehad wat gestoor was vir 7 dae by 4°C. Neutraal-bestande veselinhoud het geen effek (P >0.05) op vleissagtheid gehad nie. Hierdie resultate dui daarop dat die vetsuurprofiel van lamsvleis gemanipuleer kan word deur ’n verandering in die NBV inhoud van ‘n afrondingsdieët. Die resultate het egter nie die wenslike poli-onversadigde vetsuur tot versadigde vetsuur en n-6:n-3 verhoudings in die spierweefsel en onderhuidse vet uit ‘n menslike gesondheids oogpunt tot gevolg gehad nie. Daar word voorgestel dat, om die totale onversadigde vetsuur inhoud te verhoog met ‘n wenslike effek op die genoemde verhoudings van lamsvleis, regressie vergelykings gebruik moet word om die optimum reaksie op 'n gegewe neutral bestande vesel inhoud te bevestig. Verdere navorsing om spesifieke vetsure van lamsvleis (enkel of totale) of verhoudings daarvan te probeer manipuleer deur die dieëtsamestelling om in verbruikers se behoeftes te voldoen, verdere aandag verg.af
dc.description.sponsorshipCentre for Research Development of the University of the Free Stateen_ZA
dc.description.sponsorshipNational Research Foundation (NRF)en_ZA
dc.description.sponsorshipFaculty of Natural and Agricultural Sciences of the University of the Free Stateen_ZA
dc.language.isoenen_ZA
dc.publisherUniversity of the Free Stateen_ZA
dc.subjectLamb (Meat)en_ZA
dc.subjectMeat -- Qualityen_ZA
dc.subjectSheep -- Feeding and feedsen_ZA
dc.subjectDissertation (M.Sc.Agric. (Animal, Wildlife and Grassland Sciences))--University of the Free State, 2016en_ZA
dc.titleThe effect of NDF content in finishing diets on performance and meat quality of lambsen_ZA
dc.typeDissertationen_ZA
dc.rights.holderUniversity of the Free Stateen_ZA


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