Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2011. / Includes bibliography. / ENGLISH ABSTRACT: The ostrich industry has overcome many challenges since it originated. However, it is still vulnerable
to sudden changes in customer preferences and economic cycles. As feed costs are the greatest
expense in ostrich production, optimising feed formulations is vital. This will be possible if the growth
and development of the ostrich can be simulated by modelling software. Various studies were
conducted to describe ostrich growth in the form of equations that can be used in modelling software
to increase the accuracy of predictions.
In the first study, birds were given the choice of four diets with varying energy (8.5 or 13.5 MJ ME/kg
feed) and protein (180 or 120 g/kg feed) levels. The birds preferred the high density diet (high energy
and protein) in each growth phase. A growth curve of assumed optimal growth was constructed. The
chemical fractions of the body were shown to increase non-linearly with advancing age and equations
were established to predict the change of the body composition over time.
In the second trial, birds received a formulated growth diet and were fed according to their nutrient
requirements. Growth data was collected on the separate body components of maturing birds.
Feather and skin nodule growth was defined for birds hatched in the summer. Allometric equations
were set up to determine, predict and model the ostrich skin size and skin weight, some bones, some
organs and the commercially valuable muscles through the growth cycle.
The final trial was conducted to determine the effect of diet density (energy and amino acid level) on
the growth of ostrich body components. A four-stage, 3 x 5 (energy x protein) factorial design was
developed with varying energy and protein feeding regimes. Protein (amino acid) level had no
influence on body component growth. Energy level had no effect on feather growth, skin nodule growth, bone and organ growth and muscle growth. Increased levels of dietary energy increased the
skin size and skin weight. Increasing the dietary energy level also had a significant effect on the total
body fat of the birds. Allometric equations were set up for each variable to predict the effect of diet on
ostrich growth.
Results in this study provide a framework for simulation modelling. Predicting ostrich growth and
development is paramount to accurate diet formulations and lower feeding costs. / AFRIKAANSE OPSOMMING: Die volstruisindustrie het reeds vele struikelblokke oorkom, maar bly steeds kwesbaar vir skielike
veranderinge in die ekonomiese klimaat asook in die voorkeure van die verbruiker. Een van die
belangrikste insetkostes in volstruisproduksie is voer en daarom is dit noodsaaklik om
voerformulerings te optimiseer. Die doel van hierdie tesis was om by te dra tot die ontwikkeling van
modellering sagteware wat die groei en ontwikkeling van die volstruis naboots. Die spesifieke doel
was om volstruisgroei te bestudeer en te bespreek deur middel van vergelykings wat gebruik kan
word om die akkuraatheid van die simulasiemodelle te verhoog.
Tydens die eerste studie is die voëls die keuse van vier diëte gegee waarvan die energie- (8.5 of 13.5
MJ ME/kg voer) en proteïen- (180 of 120 g/kg voer) vlakke verskil het. Die voëls het in die hoëdigtheid
voer (hoog in energie en proteïen) in elke groeifase gekies. Uit hierdie data, wat aanvaar is
om optimale groei te verteenwoordig, is ‘n groeikurwe gekonstrueer wat getoon het dat die chemise
komponente van die liggaam nie-linieêr toegeneem het oor tyd. Vergelykings is hieruit afgelei wat die
verandering in die liggaamsamestelling oor tyd kan voorspel.
In die tweede studie het die voëls ʼn vier-fase geformuleerde groeidieët ontvang en is na gelang van
hulle voedings behoeftes gevoer. Groeidata is ingesamel van die individuele liggaams-komponente
van die groeiende volstruise. Veer- en velgroei is gedefinieer vir die voëls wat in die somer uitgebroei
het. Allometriese vergelykings is opgestel om te bepaal hoe die volstruis se velgrootte, velgewig,
sekere bene en organe, asook die kommersiële belangrike spiere gedurende die groei-siklus
verander.
Die finale studie is uitgevoer om die effek van voedingsvlak (energie- en aminosuurvlak) op die groei
van die volstruis se liggaamskomponente te bepaal. ʼn Vier-fase, 3 x 5 (energie x proteïen) faktoriale
ontwerp is gebruik met veranderende energie- en proteïenvlakke. Proteïen- (aminosuur) vlakke het
geen invloed op die groei van die liggaamskomponente gehad nie. Energievlak het geen effek op die
veer-, vel-, velknoppie-, been-, organe- en spiergroei gehad nie. Toenemende vlakke van energie het
wel gelei tot ʼn toename in die velgrootte en massa. Die toename in voedingsengergie-vlakke het ook
ʼn betekenisvolle effek op die totale liggaamsvet van die voëls gehad. Allometriese vergelykings is
opgestel vir elk van die veranderlikes om die effek van dieët op elke komponent van die volstruis te
bepaal.
Die resultate van hierdie studies verskaf ‘n raamwerk vir die simulering en modellering van die groei
en ontwikkeling van die volstruis. Akkurate voorspellings van die groei en ontwikkeling van die
volstruis is noodsaaklik vir akkurate dieëtformulering en verlaagde voedingskostes.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/6469 |
| Date | 03 1900 |
| Creators | Kritzinger, Werne Jacobus |
| Contributors | Brand, T. S., Hoffman, L. C., Mellett, F. D., 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 | 142 p. : ill. |
| Rights | University of Stellenbosch |
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