The effect of dietary lipid saturation and antioxidant sources on performance and meat quality of lambs
| dc.contributor.advisor | Einkamerer, O. B. | |
| dc.contributor.advisor | Hugo, A. | |
| dc.contributor.advisor | Van Der Merwe, H. J. | |
| dc.contributor.author | Booyens, Käte Erna | |
| dc.date.accessioned | 2015-10-14T10:06:41Z | |
| dc.date.available | 2015-10-14T10:06:41Z | |
| dc.date.copyright | 2012-06-10 | |
| dc.date.issued | 2014-05-27 | |
| dc.date.submitted | 2012-06-10 | |
| dc.description.abstract | English: A study was conducted to investigate the influence of antioxidant source and fatty acid saturation in a standard finishing diet on apparent digestibility, production performance, fatty acid composition and oxidative stability of lamb. The four dietary treatments consisted of the same basal diet (187 g CP- and 355 g NDF/kg DM) differing in the lipid source (30 g/kg of either saturated beef tallow or unsaturated soyabean oil) and type of antioxidant included (125 g/ton of either a synthetic or natural antioxidant). Eighty-four S.A. Mutton Merino lambs (27.64 ± 1.72 kg) were randomly allocated to the four dietary treatments (n=21 lambs per treatment) and subdivided into seven replicates per treatment (n=3 lambs per replicate). After dietary adaptation of 8 days all lambs received the experimental diets for the remaining period (41 days). A digestibility study was conducted over a 12-day period (4-day adaptation to the faecal bags followed by an 8-day collection period). Seven lambs per treatment were randomly selected and slaughtered at completion of the production study. Physical carcass characteristics, muscle pH, muscle- and subcutaneous fatty acid composition, as well as meat oxidative- (malonaldehyde content) and colour stability was measured. The apparent NDF digestibility was reduced (P =0.0548) with the inclusion of unsaturated soyabean oil in the diet compared to saturated beef tallow. This was associated with a significant (P <0.05) lower digestible NDF and ME content in the experimental diet. No significant (P >0.05) differences in dry matter intake, daily gain and feed efficiency of lambs occurred. The addition of unsaturated soyabean oil significantly increased (P =0.0003) the efficiency of ME utilisation in the diet. Lipid saturation level in finishing diets for lambs did not influence (P >0.05) the physical carcass characteristics and meat pH of lambs. Saturated beef tallow increased (P <0.05) the monounsaturated palmitoleic- and oleic acid content of lamb subcutaneous and/or muscle tissue, whereas the more unsaturated soyabean oil increased (P <0.05) the polyunsaturated linoleic acid, α-linolenic acid and CLA content of both muscle fat and subcutaneous lipid tissue. Monounsaturated vaccenic acid was increased in lamb meat when unsaturated soyabean oil was included in combination with the natural antioxidant. The total PUFA, total n-6 fatty acid and PUFA:SFA ratio of lamb meat increased (P <0.05) with the inclusion of the more unsaturated soyabean oil in the diet. A higher (P <0.0001) n-6:n-3 ratio occurred in the intramuscular fat of lambs fed the unsaturated soyabean oil diet. Unsaturated soyabean oil negatively influenced (P <0.05) the oxidative stability of lamb meat on days 0 (fresh) and 90 (frozen), compared to saturated tallow. The inclusion of a synthetic compared to a natural antioxidant in the diet decreased (P =0.0672) the apparent digestibility of NDF, which was also associated with a significantly (P =0.0159) lower digestible NDF content of the experimental diet. The meat pH measured 45 minutes after slaughter was significantly (P =0.009) decreased when a synthetic antioxidant was added to the diet. Meat pH measured at 24 hours post slaughter was lower (P =0.0433) when a natural antioxidant was added to the diet. With the exception of the natural antioxidant that increased (P <0.05) the saturated palmitic- and monounsaturated palmitoleic acid content of subcutaneous and/or muscle fat, and decreased (P <0.05) the monounsaturated stearic acid content of intramuscular fat, dietary antioxidant type did not to effect (P >0.05) the fatty acid composition of lamb meat, neither the colour- nor oxidative stability. These results suggest that the fatty acid profile of lamb can be manipulated by the saturation level of the lipid source included in the diet. However, the replacement of saturated tallow with unsaturated soyabean oil did not result, from a human health point of view, in the desirable PUFA:SFA and n-6:n-3 ratios in muscle fat and subcutaneous lipid tissue. Therefore, the manipulation of the fatty acid content of finishing diets to achieve the desirable ratios within lamb meat, as well as the optimal inclusion level of a bioflavonoid antioxidant warrants further research. | en_ZA |
| dc.description.abstract | Afrikaans: ‘n Studie is uitgevoer om die invloed van antioksidant tipe en lipiedversadiging binne ‘n standaard afrondingsdieet op die skynbare verteerbaarheid van voedingstowwe, produksie van lammers, vetsuursamestelling asook oksidasie stabiliteit van lamsvleis te evalueer. Die vier proef diëte het uit dieselfde basale rantsoen bestaan (187 g RP- En 355 g NBV/kg DM) waarvan slegs die lipiedbron (30 g/kg versadigde beesvet of onversadigde sojaboonolie) en antioksidant tipe (125 g/ton sintetiese- of natuurlike antioksidant) verskil het. Vier-en-tagtig Suid-Afrikaanse Vleismerino lammers (27.64 ± 1.72 kg) is ewekansig aan vier behandelings (n=21 lammers per behandeling) toegeken, waarna elke behandeling verder in sewe herhalings (n=3 lammers per herhaling) verdeel is. Na ‘n aanpassingsperiode van agt dae is die proefdiëte vir ‘n verdere periode van 41 dae verskaf. ‘n Verteringstudie is vir ‘n periode van 12 dae uitgevoer (vier dae aanpassing aan missakke, gevolg deur ‘n agt dae kolleksie periode). Na voltooiing van die produksiestudie is 7 lammers per behandeling ewekansig geselekteer en geslag. Fisiese karkaseienskappe, spier pH, vetsuursamestelling van spier weefsel en onderhuidse vet, oksidasiestabiliteit (malonaldehiedinhoud) en kleur stabiliteit van vleis is bepaal. Die skynbare verteerbaarheid van neutraal-bestande vesel (NBV) binne die rantsoen het (P=0.0548) met die insluiting van onversadigde sojaboonolie teenoor versadige beesvet verlaag. Dienooreenkomstig het ‘n betekenisvolle verlaging (P<0.05) in die skynbaar verteerbare NBV- en metaboliseerbare energie (ME) inhoud van die sojaboonoliedieet voorgekom. Geen betekenisvolle verskille (P>0.05) in DMI, daaglikse toename en doeltreffendheid van voeromsetting van lammers het voorgekom nie. Die byvoeging van sojaboonolie het die doeltreffe ndheid van ME benutting in die diet betekenisvol verbeter (P=0.0003). Lipiedversadigtheidsvlak in afrondingsdiëte vir lammers het geen invloed (P>0.05) op die fisiese karkaseienskappe en pH van lamsvleis uitgeoefen nie. Versadigde beesvet het die mono-onversadigde palmitoleïensuur- en oleïensuur inhoud van spierweefsel en/of onderhuidse vetweefsel verhoog (P<0.05), terwyl die meer onversadigde sojaboonolie die poli-onversadigde linoleïensuur, α-linoleniese suur en gekonjugeerde linoleïensuur inhoud van beide spierweefsel en onderhuidse vetweefsel verhoog het (P<0.05). Mono-onversadige “vaccenic” suur is verhoog (P<0.05) in lamsvleis wanneer onversadige sojaboonolie in kombinasie met ‘n natuurlike antioksidant ingesluit is. Die totale poli-onversadigde vetsuur, totale n-6 vetsuur en poli-onversadigde tot versadigde vetsuurverhouding van lamsvleis het met die insluiting van meer onversadigde sojaboonolie in die diet verhoog (P<0.05). ‘n Hoër (P<0.0001) n-6 tot n-3 verhouding het voorgekom in die spierweefsel van lammers wat die sojaboonolie-dieet ontvang het. Onversadigde sojaboonolie het ‘n negatiewe invloed (P<0.05) op die oksidasiestabiliteit van lamsvleis op dag 0 (vars) en dag 90 (gevries) gehad teenoor die van versadigde beesvet. Die insluiting van ‘n sintetiese teenoor ‘n biologiese antioksidant in die diet het die skynbare NBV verteerbaarheid verlaag (P= 0.0672). Die binnespierse pH, 45 minute na slag was betekenisvol (P=0.009) laer wanneer ‘n sintetiese antioksidant ingesluit is. Die binnespierse pH, 24 uur na slag, was laer (P= 0.0433) wanneer ‘n natuurlike antioksidant in die diet bygevoeg is. Met uitsondering van die natuurlike antioksidant wat die versadigde palmititiensuur en mono-onversadigde palmitoleïensuur binne subkutaniese- en/of spierweefsel verhoog (P<0.05), en die versadige steariensuur inhoud van binnespierse vet laat afneem (P<0.05), blyk dit dat die antioksidant tipe geen effek (P>0.05) op die vetsuursamestelling van lamsvleis, vleiskleur of oksidasiestabiliteit uitgeoefen het nie. Die resultate toon dat die vetsuurprofiel van lamsvleis voordelig gemanipuleer kan word deur die insluiting van ‘n onversadigde lipiedbron in die dieet. Die vervanging van versadigde beesvet met onversadigde sojaboonolie in die dieet, het vanuit ‘n menslike gesondheidsoogpunt, nie die mees geskikte poli-onversadigde tot versadigde vetsuurverhouding en n-6 tot n-3 vetsuurverhouding in spierweefsel en onderhuidse lipiedweefsel tot gevolg gehad nie. Verdere navorsing rakende die manupilering van die vetsuurinhoud in afrondingsdiëte om die ideale verhoudings in lamsvleis te verkry, sowel as die optimale insluitingsvlak van ‘n bioflavonoid antioksidant is nodig. | af |
| dc.identifier.uri | http://hdl.handle.net/11660/1375 | |
| dc.language.iso | en | en_ZA |
| dc.publisher | University of the Free State | en_ZA |
| dc.rights.holder | University of the Free State | en_ZA |
| dc.subject | Dissertation (M.Sc. (Animal, Wildlife and Grassland Sciences))--University of the Free State, 2012 | en_ZA |
| dc.subject | Sheep -- Feeding and feeds | en_ZA |
| dc.subject | Meat -- Quality | en_ZA |
| dc.subject | Lamb (Meat) | en_ZA |
| dc.title | The effect of dietary lipid saturation and antioxidant sources on performance and meat quality of lambs | en_ZA |
| dc.type | Dissertation | en_ZA |