Thesis (MScAgric)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The first study (Chapter 3) evaluated the growth response of ostrich chicks on diets
containing three different levels of protein and amino acids. Linear and nonlinear models
were fitted to the data and compared by using Akaike’s information criterion (AIC). The
linear polynomial of the third degree had the lowest AIC value for all three treatments thus
making it the most suitable model for the data. Significant differences were found between
treatments for growth data. The results from this study can aid in describing the growth of
ostriches subjected to assumed optimum feeding conditions.
In the second study (Chapter 4), a range of diets was formulated for the five growth
stages of ostriches (pre-starter, starter, grower, finisher and maintenance) according to their
nutrient requirements. The diets were diluted with wheat straw. Three dilution levels (0%,
10% and 20%) were used for the pre-starter and starter phases, five dilution levels (0%, 15%,
30%, 45% and 60%) were used for the grower and the finisher phases, and five dilution levels
(0%, 20%, 40%, 60% and 80%) were used for the maintenance phase. Weekly intake data
were collected throughout each phase. Feed bulk restricted intake by 21% and 52% at the
10% and 20% dilution level, respectively (P < 0.05) in the pre-starter phase, whereas intake
was not restricted during the starter phase(P > 0.05). Intake was constrained by 39% and 42%
at the 45% and 60% dilution levels in the grower phase, respectively (P < 0.05), and by 17%
and 39% at the 45% and 60% dilution levels (P < 0.05) in the finisher phase, respectively.
Feed bulk restricted intake by 60% and 69% for the 60% and 80% dilution levels (P < 0.05),
respectively, in the maintenance phase. Defining the bulk density that will constrain feed
intake, as established in this study, will aid in least-cost feed formulations, feed intake
modelling and growth predictions. In the third study (Chapter 5) the effect of three different dietary protein (with a
specific associated amino acid content) concentrations on certain production parameters in
growing ostriches were investigated. Significant differences were found for the final live
weight of birds, cold carcass weight, thigh weight as well as for most of the weighed muscles
at slaughter (350 days old). Concerning the growth and feed related parameters, only average
daily gain (ADG) was influenced by dietary treatment (P < 0.05). Results indicated that birds
on the diet with the medium protein performed optimally. One exception is the starter phase
(26 – 47 kg) where chicks on the high protein diet outperformed those on the medium protein
diet. In the fourth study (Chapter 6) the effects of different dietary energy concentrations
on ostrich production parameters were examined in two different trials. The first trial
included measurements from the pre-starter phase through the starter phase until the grower
phase. The second trial was based on the finisher phase per se. Overall dietary levels
provided in the pre-starter, starter and grower phases indicated better growth, FCR, skin size
and grade, thigh weight, live weight, and carcass weight for the birds fed the medium energy
diet. Dietary energy levels provided during the finisher phase indicated that the energy level
above the medium level used improved growth rate and tanned skin size. The gender of the
birds influenced carcass weight, growth rate, and certain feather parameters (P < 0.05).
In the fifth study (Chapter 7) the effect of feather clipping at six to eight months of
age on the production parameters of ostrich chicks were investigated. The study was
conducted in three different trials. In each of the trials the feathers of half the amount of birds
were clipped at six to eight months of age. Significant differences (P < 0.05) were found for
the feed conversion ratio (FCR), the average daily gain (ADG) and for the quantity of
valuable feathers. Results indicated that the growth rate and FCR was better for the birds
which had their feathers clipped at six to eight months of age. Results also showed that the
quantity of feathers with commercial value were significantly higher for the clipped group.
This study showed that there may be an advantage for ostrich producers concerning
the harvesting of feathers at six to eight months of age.
The work in this thesis is a follow up on the framework set by Kritzinger (2011) and
is part of the same project. Most of the results obtained in these studies will be incorporated
in to the mathematical optimisation model of Gous and Brand (2008) for more accurate
predictions concerning feed intake and other production parameters that may lower feeding
costs. / AFRIKAANSE OPSOMMING: Die eerste studie (Hoofstuk 3) evalueer die groei van volstruiskuikens op diëte met drie
verskillende vlakke van proteïene en aminosure. Liniêre en nie-liniêre regressiemodelle is op
die data gepas en met Akaike se inligting kriterium (AIC) vergelyk. Die liniêre polinoom van
die derde graad het die laagste AIC waarde vir al drie behandelings gehad. Daarom is die
voorspellings van hierdie model gebruik om die groeidata te interpreteer. Beduidende
verskille tussen behandelings vir groeidata (P < 0.05) is gevind. Die resultate van hierdie
studie kan help met die beskrywing van die groei van volstruise, onderworpe aan
aangeneemde optimale voedingsbehoeftes.
In die tweede studie (Hoofstuk 4) is 'n verskeidenheid diëte geformuleer vir die vyf
groeistadiums van volstruise (voor-aanvangs, aanvangs, groei, afronding en onderhoud)
volgens hul voedingsbehoeftes. Die diëte is verdun met koringstrooi. Drie verdunningsvlakke
(0%, 10% en 20%) is gebruik vir die voor-aanvangs- en aanvangsfase, vyf verdunningvlakke
(0%, 15%, 30%, 45% en 60%) is gebruik vir die groei- en die afrondingsfase en vyf
verdunningsvlakke (0%, 20%, 40%, 60% en 80%) is gebruik vir die onderhoudsfase.
Weeklikse inname-data is ingesamel gedurende elke fase. In die voor-aanvangsfase het
voerlywigheid (verhoging van ruvesel) inname beperk met 21% en 52% vir die 10% en 20%
verdunningsvlakke (P < 0.05) onderskeidelik, terwyl inname nie beperk is gedurende die
aanvangsfase nie (P > 0.05). Inname is beperk met 39% en 42% op die 45% en 60%
verdunningsvlakke in die groeifase (P < 0.05) onderskeidelik, en met 17% en 39% op die
45% en 60% verdunningsvlakke in die afrondingsfase (P < 0.05), onderskeidelik.
Voerdigtheid het inname beperk met 60% en 69% vir die 60% en 80% verdunningsvlakke,
onderskeidelik, in die onderhoudsfase (P < 0.05). Die definiëring van die digtheid of
ruvoerinhoud van voer wat inname beperk, soos in die studie bepaal, sal help met die
optimering van voerformulasies, voerinname-modellering en groeivoorspellings.
In die derde studie (Hoofstuk 5) is die effek van drie verskillende
dieëtproteïenkonsentrasies (met 'n spesifieke gepaardgaande aminosuurinhoud) op sekere
produksieparameters in die groei van volstruise ondersoek. Beduidende verskille is gevind vir
die finale lewende gewig, koue karkasmassa, boudgewig sowel as vir die meeste van die
geweegde spiere van voëls op slagouderdom (350 dae oud). Met betrekking tot die groei en
voedingsverwante parameters, is slegs die gemiddelde daaglikse toename (GDT) beïnvloed
deur die dieet (P < 0.05). Resultate het aangedui dat voëls op die medium-proteïendieet optimaal presteer. Een uitsondering is die aanvangsfase (26 – 47 kg), waar kuikens op die
hoë-proteïendieet beter gevaar het as die voëls wat die medium-proteïendieet ontvang het.
In die vierde studie (Hoofstuk 6) is die invloed van verskillende dieet-energiekonsentrasies
op volstruis-produksieparameters in twee verskillende proewe ondersoek. Die
eerste proef het gestrek vanaf die voor-aanvangsfase, deur die aanvangsfase tot en met die
einde van die groeifase. Die tweede proef is gedoen vir die afrondingsfase.
In die voor-aanvangs-, aanvangs- en groeifase is beter groei, voeromsetverhouding
(VOV), velgrootte en -graad, boudgewig, lewende gewig en karkasgewig verkry vir die voëls
wat die standaard-energie dieet ontvang het (P < 0.05). Dieet-energievlakke wat tydens die
afrondingsfase fase verskaf is, het aangedui dat die energievlak bo die medium-vlak
verbeterde groeitempo en gelooide velgrootte tot gevolg het (P < 0.05). Die geslag van die
voëls het ’n invloed gehad op karkasgewig, groei, en sekere veerparameters.
In die vyfde studie (Hoofstuk 7) is die effek van die knip van vere, op die ouderdom
van ses tot agt maande, op die produksieparameters van volstruiskuikens ondersoek. Die
studie is uitgevoer in drie verskillende proewe. In elk van die proewe is die vere van die
helfte van die hoeveelheid voëls geknip op ses tot agt maande ouderdom. Beduidende
verskille is gevind vir die VOV, die gemiddelde daaglikse toename (GDT) en vir die
hoeveelheid waardevolle vere (P < 0.05). Die groeitempo en VOV was beter vir die voëls
waarvan die vere op ses tot agt maande ouderdom geknip is (P < 0.05). Resultate het ook
getoon dat die hoeveelheid waardevolle vere aansienlik hoër was vir die groep waarvan die
vere op ses tot agt maande ouderdom geknip is (P < 0.05). Hierdie studie het getoon dat daar
'n voordeel mag wees vir volstruisprodusente indien vere geknip word op die ouderdom van
ses tot agt maande.
Die werk in hierdie tesis volg op die raamwerk van Kritzinger (2011) en was deel van
dieselfde projek. Die meeste van die resultate wat verkry is in die studies sal in die
wiskundige optimeringsmodel van Gous en Brand (2008) geïnkorporeer word vir meer
akkurate voorspellings van voerinname en produksieparameters wat die voerkostes kan
verlaag.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/85639 |
| Date | 12 1900 |
| Creators | Carstens, Petrus Daniel |
| Contributors | Brand, T. S., Hoffman, L. C., 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 |
| Rights | Stellenbosch University |
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