Thesis (MScAgric)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: This research study consists of three investigations with regard to ostrich (Struthio camelus var.
domesticus) production, meat quality and the processing of ostrich meat into a value added meat
product.
The first study was conducted in order to establish whether the gradual replacement of soybean
oilcake meal with cottonseed oilcake meal (CSOCM) as a protein source in the diet of slaughter
ostriches would affect ostrich growth performance and meat quality. A total of 105 ostriches were
divided into five feeding groups according to the CSOCM inclusion level: Control (0% CSOCM),
3%, 6%, 9% and 12% CSOCM, and fed with experimental diets from 6 to 13 months of age. As a
result of feeding CSOCM, the final live weight and the average daily gain significantly increased in
the 12% CSOCM group compared to the other treatment diets. The proximate composition,
cholesterol content, mineral and fatty acid profile of the meat remained unaffected. Considering all
the results, CSOCM may be used as an alternative protein source to soybean oilcake meal in
ostrich nutrition, resulting in decreased feed costs.
Secondly, a descriptive sensory analysis, together with chemical and physical measurements, was
performed to determine whether the manipulation of the fatty acid composition in the fan fillet
(Iliofibularis muscle) as a result of feeding CSOCM would be detected on a sensory level. Two
levels of CSOCM were investigated; 0% as a control and 9% CSOCM. No significant differences
were found for the physical measurements (cooking loss (%) and shear force) as well as for the pH
and proximate composition of the raw fan fillet. The Control group presented a higher (P<0.05)
mono-unsaturated fatty acid (MUFA) content in the cooked fan fillet whereas the 9% CSOCM
group showed a favourable increased (P<0.05) poly-unsaturated fatty acid (PUFA) content when
compared to the cooked Control samples. As a result, the poly-unsaturated:saturated fatty acid
(PUFA:SFA) ratio in the 9% CSOCM group was also higher (P<0.05). No differences (P>0.05)
were found between the treatments for the n-6:n-3 (omega 6 to omega 3) ratio. The 9% CSOCM
group had a more intense beef aroma, had a higher level of initial and sustained juiciness as well
as increased tenderness (P<0.05). Inclusion of 9% CSOCM resulted in a favourable cooked ostrich
fan fillet.
Finally, the effect of feeding CSOCM on a processed ostrich meat product was investigated. Fan
fillet (Iliofibularis muscle) from 13 month old birds receiving no cottonseed oilcake meal (Control) or
9% cottonseed oilcake meal (9% CSOCM) was used. Olive oil was used as a replacement for
pork fat, and warthog (Phacochoerus africanus) meat was used to replace commercial pork meat
in the production of a semi dry sausage, cabanossi. Olive oil was included at three levels (0%, 1%
and 2%). Six treatments were investigated: Control 0% olive oil, Control 1% olive oil, Control 2%
olive oil, 9% CSOCM 1% olive oil, 9% CSOCM 2% olive oil en 9% CSOCM 2% olive oil. The
Control and 9% CSOCM ostrich meat did not differ significantly in chemical composition nor fatty
acid profile. After smoking and drying the fat content in the cabanossi containing 0%, 1% and 2% olive oil averaged 7.2%, 7.45% and 8.65% respectively. Processed meat products containing less
than 10% fat are classified as a low-fat meat product. Olive oil is a mono-unsaturated vegetable oil
containing mainly Oleic acid (C18:1n9c), and low quantities of saturated fatty acids and
polyunsaturated fatty acids. Total mono unsaturated fatty acids in the cabanossi increased from
47.0% to 73.0% of total fat, whilst total saturated fatty acids and total polyunsaturated fatty acids
decreased from 40.6% to 19.9% and 11.6% to 6.6% respectively as olive oil increased from 0% to
2%. The inclusion of olive oil at 2% resulted in cabanossi with increased (P<0.05) tenderness,
juiciness and cured red meat colour, all factors that appeal greatly to the consumer. Overall flavour
was not adversely affected by the inclusion of olive oil.
This investigation indicated that the use of CSOCM had no negative effect on the production
performance of ostriches whilst a 9% CSOCM inclusion level resulted in meat that was found to be
favourable by a trained sensory panel. Furthermore, the use of CSOCM as a feed component also
had no negative effect on a processed product (cabanossi) derived from the meat obtained from
the birds fed this feed component. The CSOCM used in this investigation had low levels of
gossypol (10 to 20ppm) and more research is required on the effect of the use of CSOCM with
higher levels of gossypol on the production performance of ostriches. / AFRIKAANSE OPSOMMING: Die studie het bestaan uit drie ondersoeke met betrekking tot volstruis (Struthio camelus var.
domesticus) -produksie, -vleiskwaliteit en die vervaardiging van waarde-toegevoegde
geprosesseerde volstruis-vleisprodukte.
Die doel van die eerste studie was om vas te stel of die geleidelike vervanging van sojaboonoliekoekmeel
met katoensaad-oliekoekmeel (CSOCM) as ‘n proteïenbron in die voeding van
volstruise, die groeipersentasie en vleiskwaliteit van die Iliofibiularis spier (fan fillet) sal affekteer. ‘n
Totaal van 105 volstruise is verdeel in vyf voedingsgroepe volgens die katoensaad oliekoekmeel
insluitingsvlak: Kontrole (0% CSOCM), 3%, 6%, 9% en 12% CSOCM. Die onderskeie
voedingsgroepe was van ses tot 13 maande ouderdom op die eksperimentele voere geplaas. Die
resultate het aangedui dat die voëls in die 12% CSOCM behandelingsgroep ‘n betekenisvolle
(P<0.05) toename in finale lewende massa asook gemiddelde daaglikse toename gehad het. Die
proksimale samestelling, cholesterol-inhoud, mineraal- en vetsuursamestelling van die vleis was
nie geaffekteer deur die insluiting van CSOCM nie. Die CSOCM kan dus wel as ‘n alternatiewe
proteïenbron in die voeding van volstruise gebruik word. Laasgenoemde bevinding kan ook lei tot
verlaagde voerkostes, aangesien CSOCM heelwat goedkoper is as sojaboon-oliekoekmeel.
Die tweede deel van die studie was van ‘n chemiese asook sensoriese aard. ‘n Beskrywende
sensoriese analiese is uitgevoer om vas te stel of die manipulering van die vetsuursamestelling in
die volstruis fan fillet as gevolg van die CSOCM sensories waargeneem kan word. Die chemiese
en fisiese eienskappe van die vleis is ook ondersoek. Twee vlakke van CSOCM inhoud is
ondersoek; 0% (as kontrole) en 9% CSOCM. Geen betekenisvolle verskille is gevind vir die fisiese
vleiskwaliteit (kookverliespersentasie en taaiheid), asook vir die proksimale samestelling en pH
van die fan fillet nie. Die gekookte fan fillet van die Kontrole behandeling het ‘n betekenisvolle
(P<0.05) toename in mono-onversadigde vetsure (MUFA) getoon en die 9% CSOCM het ‘n
voordelige toename in poli-onversadigde vetsuur-inhoud (PUFA) gehad. Die poli-onversadigde tot
versadigde vetsuurverhouding (PUFA:SFA) was as ‘n gevolg ook betekenisvol hoër. Geen
verskille (P>0.05) is opgemerk in die omega-6 tot omega-3 poli-onversadigde vetsuurverhouding
(n-6:n-3) nie. Met betrekking tot die sensoriese eienskappe het die 9% CSOCM ‘n meer
opvallende beesvleis aroma, hoër vlakke van aanvanklike sappigheid en ook sagter vleis in
vergelyking met die kontrole behandeling gehad (P<0.05). Insluiting van 9% CSOCM het gelei tot
‘n gekookte volstruis fan fillet van voornemende kwaliteit.
Laastens is daar ondersoek ingestel op die vervanging van varkvet met olyfolie in die
vervaardiging van ‘n volstruis cabanossi. Chemiese asook sensoriese analises is uitgevoer op die
gedroogde en gerookte volstruis cabanossi. Vir die vervaardiging van laasgenoemde produkte is
die fan fillet van 13 maande oue voëls van die Kontrole (0% CSOCM) en 9% CSOCM
behandelings gebruik. Addisioneel tot die volstruisvleis is daar ook vlakvarkvleis (Phacochoerus
africanus) gebruik om die kommersiële varkvleis te vervang. Olyfolie was ingesluit teen drie vlakke (0%, 1% en 2% van die totale mengsel). Ses behandelings was ondersoek: Kontrole 0% olyfolie,
Kontrole 1% olyfolie, Kontrole 2% olyfolie, 9% CSOCM 1% olyfolie, 9% CSOCM 2% olyfolie en 9%
CSOCM 2% olyfolie. Daar was geen verskille (P>0.05) in die chemiese en vetsuursamestellings
van die Kontrole en 9% CSOCM volstruisvleis nie. Na die droging en rooksiklus was die
gemiddelde vet-inhoud van die 0%, 1% en 2% olyfolie cabanossi monsters onderskeidelik 7.2%,
7.45% en 8.65%. Geprosesseerde vleisprodukte met ‘n vet-inhoud van minder as 10% word in die
kommersiële vleisindustrie na lae vet vleisprodukte verwys. Olyfolie is baie ryk aan MUFA, veral
Oleïensuur (C18:1n9c) en dit bevat ook lae hoeveelhede SFA en PUFA. Die totale MUFA inhoud
in die cabanossi het toegeneem van 47.0% tot 73.0% terwyl die totale SFA en PUFA
onderskeidelik afgeneem het van 40.6% tot 19.9% en 11.6% tot 6.6%, met ‘n olyfolie toename van
0% tot 2%. Die insluiting van olyfolie teen 2% het gelei tot ‘n sagter cabanossi wat meer sappig
was met ‘n meer opvallende rooi gekuurde vleiskleur, wat almal eienskappe is wat dié produk
meer aantreklik maak vir die verbruiker.
Hierdie studie het aangedui dat CSOCM geen negatiewe effek gehad het op die produksie van
volstruise nie. Volstruisvleis van die behandelingsgroep wat CSOCM teen 9% van die dieet
ontvang het, het wel vleis geproduseer wat as aanvaarbaar aanskou was deur ‘n opgeleide
sensoriese paneel. Die gebruik van CSOCM as ‘n voerbestandeel het ook geen negatiewe effek
gehad op ‘n geprosesseerde produk (cabanossi) gemaak van die volstruisvleis nie. Die CSOCM
wat in die huidige studie gebruik is, het baie lae vlakke van gossypol (10 – 20dpm) gehad en
verdere ondersoek is noodsaaklik om die effek van CSOCM met hoër vlakke van gossypol op die
produksie van volstruise te bevestig.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/71847 |
| Date | 12 1900 |
| Creators | Schoon, Katryn |
| Contributors | Hoffman, L. C., Brand, T., Dalle Zotte, A., Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 125 p. : ill. |
| Rights | Stellenbosch University |
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