Thesis (MScAgric)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: This study quantified the growth performance, carcass and meat characteristics of South
African slow-growing chicken lines. Two slow-growing lines developed outside South Africa,
the Black Australorp and New-Hampshire, two native lines including the Naked-Neck and
Potchefstroom Koekoek, as well as a hybrid between a Cobb 500 broiler and Potchefstroom
Koekoek were evaluated. Fifty birds of each line were randomly allocated to cages of five
birds per cage where they were fed a standard broiler diet ad libitum to an average weight of
2kg. Twenty cockerels of each line were then slaughtered for further analyses. For the
carcass characteristics: live weight at slaughter, hot carcass weight, and chilled carcass
weight were determined. Portion yields and dissection characteristics were measured, and
the deboned meat from the breast, thigh and drumstick analysed for proximate analysis and
fatty acids.
Average daily gain (ADG), feed conversion ratio (FCR), and European Production Efficiency
Factor (EPEF) were calculated and analyzed for line differences. No significant differences
were observed between the indigenous lines with regards to feed intake ADG (~22g), FCR
(~3.65), and EPEF (~57). The Hybrid outperformed the indigenous lines for all of the growth
performance parameters measured. No differences were observed for dressing %. The breast yield obtained by the Hybrid was
significantly higher (45.56%) than that of the indigenous lines which had similar breast yield
values (~41%). The naked-Neck had the highest thigh yield and the lowest drumstick
percentage yield, 27.7% and 17.3%, respectively. A similar pattern was observed for
drumstick yield with the Australorp, New-Hampshire and Koekoek lines having significantly
higher yields than those of the Hybrid. For the tissue characteristics, similar values were
seen for breast skin (~20%), breast bone (~22%), drumstick skin (~4.3%), and drumstick
muscle (~27%). The Hybrid had significantly higher breast muscle, thigh muscle, and total
muscle percentage yield (22.67%, 26.17% and 43.51%, respectively).
Proximate chemical composition of the breast samples did not differ (P>0.05) for any
parameters. Differences (P<0.05) were recorded for thigh moisture, protein and ash
content. The Naked-Neck recorded the lowest moisture (72.3%) and the highest protein
(18.6%) and ash (1.1%) values. Differences were also recorded for drumstick moisture
protein and fat. The highest moisture content was measured for the Hybrid (75.9%) and the
lowest for the Naked-Neck (73.6%). The indigenous lines had higher protein content
(~19.5%) when compared to the Hybrid (18.9%). The drumstick fat content for the Nakednecks
(4.4%) was higher than the remaining lines. Differences were observed for the fatty acid profile. Total PUFA differed (P<0.05) with the
Australorp (28.2%) showing the highest proportion. The relative contributions of total SFA,
total MUFA and TUFA did not differ significantly between lines. The ratio of polyunsaturated
and saturated fatty acids, the proportion of n-6 fatty acids and the ratio of n-6/n-3 differed,
higher values were recorded for the indigenous lines. The proportion of n-3 fatty acids did
not differ.
The Hybrid performed significantly better than the indigenous lines but did not reach the
performance potential expected for commercial broilers. Despite this, the Hybrid does show
potential for use in alternative practices that make use of slower growing lines. / AFRIKAANSE OPSOMMING: Hierdie studie het die groei-prestasie, karkas- en vleiskwaliteitseienskappe van Suid
Afrikaanse inheemse hoenders gekwantifiseer. Vier plaaslike lyne, die Swart Ostralorp, New
Hampshire, Kaalnek en Potchefstroomse Koekoek, sowel as ʼn kruising van die Koekoek
henne met Cobb 500 braaikuikenhane is evalueer. Vyftig voëls van elke genotipe is
ewekansig ingedeel in hokke met vyf voëls per hok. ʼn Standaard braaikuiken dieet is
gevoer totdat die gemiddelde massa van die kuikens 2kg bereik het. Daarna is 20 hane van
elke genotipe geslag vir verdere analise. Vir karkaseienskappe is lewendige massa voor
slag, warm karkasmassa en koue karkasmassa bepaal. Daarna is porsie opbrengs en
disseksie eienskappe bepaal en, en die ontbeende vleis van die bors, dy en been is ontleed
vir proksimale en vetsuur analises.
Gemiddelde daaglikse toename (GDT), voeromsetverhouding (VOV), en Europese
produksie effektiwiteits faktor (EPEF) is vir die verskillende genotipes bereken en getoets vir
verskille. Geen betekenisvolle verskille is waargeneem vir inname, GDT (~22g), VOV
(~3.65), en EPEF (~57) nie. Die kruisras het in alle gevalle beter produksieparameters
gelewer as die plaaslike lyne. Geen verskille is opgemerk vir uitslagpersentasie nie. Die borsopbrengs van die kruisras
was betekenisvol hoër (45.66%) as die van die plaaslike lyne (~41%). Die Kaalnek het die
hoogste dyopbrengs (27.7%) en die laagste beenopbrengs (17.3%) gelewer. ʼn Soortgelyke
patroon is waargeneem vir die beenopbrengs van Australorp, New-Hampshire en Koekoek
met betekenisvol hoër opbrengste as dié van die kruisras. Weefsel eienskappe het
dieselfde opbrengs gelewe vir die plaaslike lyne met borsvel (~20%), borsbeen (~22%),
beenvel (~4.3%) en beenspier (~27%). Die kruisras het betekenisvol meer borsvleis,
dyspier en totale spierpersentasie gelewer as al die ander genotipes (onderskeidelik
22.67%, 26.17% en 43.51%). Proksimale analise van die borsmonsters het geen verskille (P>0.05) gelewer vir enige van
die parameters wat bepaal is nie. Verskille is opgemerk vir die vog-, proteïen- en asinhoud
van die dyspier. Die Kaalnek het die laagste voginhoud (72,3%) en die hoogste
proteïen- (18.6%) en as-inhoud (1.1%) gehad. Verskille is ook opgemerk vir been vog-,
proteïen- en vetinhoud. Die hoogste voginhoud is gemeet in die kruisras (75.9%) en die
laagste in die Kaalnek (73.6%). Die plaaslike lyne het ʼn hoër proteïeninhoud (~19.5%) as
die kruisras (18.9%) gehad. Die vetinhoud van die beenspier was ook die hoogste vir die
Kaalnek (4.4%).
Verskille is waargeneem vir die vetsuurprofiele van vleis. Die PUFA het verskil, met die
hoogste persentasie waargeneem vir die Australorp (28.2%). Die verhoudelike bydrae van
die totale SFA, totale MUFA en TUFA het nie betekenisvol tussen genotipes verskil nie. Die
verhouding van n-3 vetsure het ook nie verskil nie. Die verhouding van die PUFA:SFA, die
verhouding van n-6 vetsure en die verhouding van n-6/n-3 vetsure het verskil, met hoër
waardes vir die plaaslike lyne. Die verhouding van n-3 vetsure het nie verskil nie.
Die kruisras het oor die algemeen betekenisvol beter gevaar as die plaaslike lyne, maar het
steeds nie die produksie potensiaal van die kommersiële braaikuiken bereik nie.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/86211 |
| Date | 04 1900 |
| Creators | Packard, Russel |
| Contributors | Pieterse, Elsje, Hoffman, Louw, 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 | x, 75 p. : col. ill. |
| Rights | Stellenbosch University |
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