Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2011. / Includes bibliography. / ENGLISH ABSTRACT: A study was conducted to characterize the three ostrich breeds available as genetic resource in South
Africa, namely the South African Black (SAB), Zimbabwean Blue (ZB) and the Kenyan Redneck (KR), and
their respective crosses. Growth, slaughter traits and reproduction of these ostriches were recorded at
Oudtshoorn Research Farm in the Western Cape of South Africa. Individual non-linear regressions
(Gompertz) were fitted to the data of 390 purebred and 41 crossbred ostriches, using the SAS NLIN function.
Heterosis was estimated for each parameter of the Gompertz model. The estimated adult weight (Aparameter)
of the ZB (147 kg) and the KR breeds (148 kg) were higher than that of the SAB breed (129 kg).
The overall growth rate (B-parameter) of the ZB breed (0.0075) and the SAB breed (0.0080) was lower than
that of the KR (0.0150). The age at maximum weight gain (C-parameter) was higher for the ZB breed (226
days) compared to the SAB (198 days) and the KR (194 days). Heterosis for the A-parameter was estimated
at -6.2% and at -12% for the C-parameter. The slaughter traits studied were slaughter weight (SLW), carcass
weight (CW), dressing percentage (DP), fan fillet weight (FFW), pH0, pH24, drip loss % (DL%), cooking loss
% (CL%), tenderness and meat colour traits. Differences were observed between the means for SLW of the
SAB (86.5 kg) and ZB (93.9 kg). Mean DP of the KR breed (52.5%) was increased relative to the low DP of
their SAB contemporaries (48.8%). The sire lines (ZB and KR) and crosses were heavier than the SAB (dam
line), whereas the crosses resembled the dam line for meat quality traits. Means for pH24 also differed, with
higher values for the sire lines (ZB – 6.36; KR – 6.4) relative to the SAB (5.85). The instrumental b* colour
value also differed between the SAB (9.4) and KR (6.9). Records used for assessing the reproduction and
body measurements of purebred and crossbred dams were 428 in total. Traits analyzed were, total egg
production (TEP), the number of fertile eggs, number dead in shell chicks, hatchability and chick production
(CP), the time to lay, live weight, front chest circumferences as well as tail circumference. The ZB and KR
were heavier in live weight and of larger body measurements than the SAB, whereas the SAB exhibited
superior reproduction performance in comparison with the ZB and KR breeds. Derived heterosis estimates
amounted to 2.2% for tail circumference, 12% for TEP, 12% for hatchability and 19% for CP. Genetic
variation between and within the breeds were determined utilizing 19 microsatellite markers. Significant
molecular genetic differences were observed between the three breeds. The SAB and ZB (Fst = 0.10 and
Nei = 0.49) were genetically most similar, whereas the genetic distance between the KR and ZB breeds were
furthest (Fst = 0.13 and Nei = 0.61). The SAB breed exhibited the highest heterozygosity within its population
and the ZB the lowest heterozygosity. These results contribute to a better understanding of the utilization of
the distinct ostrich breeds for commercial production. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die verskille tussen drie volstruisrasse wat tans in Suid Afrika mee
geboer word te karakteriseer, naamlik die “South African Black” (SAB), “Zimbabwean Blue” (ZB) en die
“Kenyan Redneck” (KR) en hulle onderskeie kruisse. Rekords van die groei-, slag- en reproduksie
eienskappe van die volstruise was by Oudtshoorn Navorsingsplaas in die Wes-Kaap aangeteken. Individuele
nie-lineêre regressies (Gompertz) is op die data van 390 suiwerras en 42 kruisgeteelde volstruise gepas,
met die gebruik van die “NLIN” prosedure van SAS, (2006). Heterose is beraam vir elke parameter van die
Gompertz model. Die beraamde volwasse gewig (A-parameter) van die ZB (147 kg) en die KR ras (148 kg)
was hoër as die van die SAB ras (129 kg). Die totale groeitempo (B-parameter) van die ZB ras (0.0075) en
die SAB ras (0.0080) was laer as die van die KR (0.0150). Die ouderdom by maksimum groei (C-parameter)
was hoër vir die ZB ras (226 dae) in vergelyking met die SAB (198 dae) en die KR (194 dae). Heterose vir
die A-parameter was beraam teen -6.2% en teen -12% vir die C-parameter. Die slageienskappe wat
ondersoek was, was slagmassa (SLW), karkasmassa (CW), uitslag persentasie (DP), “fan fillet” massa
(FFW), pH0, pH24, drupverlies % (DL%), kookverlies % (CL%), sagtheid en kleureienskappe.
Beduidendende verskille is waargeneem tussen die gemiddeldes vir SLW vir die SAB (86.5 kg) en ZB (93.9
kg). Gemiddelde DP van die KR ras (52.5%) was beter as die van die SAB ras (48.8%). Die mannetjielyne
(ZB en KR) en die kruisse was swaarder as die SAB (wyfielyn), en die kruise was vergelykbaar met die
wyfielyn vir vleiskwaliteit eienskappe. Gemiddeldes vir die pH24 het verskil, met hoër waardes vir die vaar
lyne (ZB – 6.36; KR – 6.4) relatief tot die SAB (5.85). Die instrumentale b* kleurwaarde het ook verskil tussen
die SAB (9.4) en KR (6.9). ‘n Totaal van 428 rekords is gebruik om reproduksie en liggaamsmetings van die
suiwer en kruisteelwyfies te ondersoek. Reproduksie eienskappe ge-analiseer was: die aantal broeisels,
totale eierproduksie (TEP), die aantal vrugbare eiers, die aantal kuikens dood in dop, uitbroeibaarheid,
kuiken produksie (CP), tyd tot produksie van die eerste eier, volwasse gewig, voorbors omtrek, sowel as,
kruisomtrek. Die ZB en KR rasse was swaarder as die SAB, en het groter liggaamsmetings gehad. Die SAB
het beter reproduksie in vergelyking met die ZB- en KR rasse gehad. Heterose beramings was 2.2% vir
kruisomtrek, 12% vir TEP, 12% vir uitbroeibaarheid en 19% vir CP. Genetiese variasie tussen en binne die
rasse was vasgestel deur die gebruik van 19 mikrosatelliete merkers. Beduidende genetiese verskille op ‘n
molekulêre vlak was waargeneem tussen die drie rasse. Die SAB en ZB (Fst = 0.10 en Nei = 0.49) was
geneties meer gelyk terwyl die KR en ZB genetiese verder verwyder is (Fst = 0.13 en Nei = 0.61). Die SAB
ras het die hoogste heterosigositeit binne populasie getoon, en die ZB die laagste. Hierdie resultate dra by
tot ‘n beter begrip van die gebruik van die drie rasse in kommersïele produksie.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/6632 |
| Date | 03 1900 |
| Creators | Davids, Annelin Henriehetta |
| Contributors | Cloete, Schalk, Dzama, Kennedy, University of Stellenbosch. Faculty of AgriSciences. Dept. of Animal Sciences. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 82 p. |
| Rights | University of Stellenbosch |
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