Thesis (M. A.)--University of Canterbury, 2007. / Typescript (photocopy). Includes bibliographical references (leaves 214-228). Also available via the World Wide Web.

Orientador: Angelo Berchieri Junior / Banca: Karin Werther / Banca: Antonio José Piantino Ferreira / Resumo: As criações de avestruzes vêm se desenvolvendo no Brasil e em outros países. De acordo com a literatura, Salmonella sp está envolvida na mortalidade de filhotes de avestruzes, sendo também importantes causadoras de toxinfecção alimentar em seres humanos. Apesar disso, existem poucos estudos envolvendo a pesquisa de Salmonella sp nesta espécie. Desse modo, elaborou-se o presente trabalho com o objetivo de pesquisar Salmonella sp em avestruzes de uma propriedade da região sudeste do Brasil. Para isso, foram realizados exames bacteriológicos, em 80 amostras de fezes de avestruzes (colhidas nas varias fases da criação), 90 ovos não eclodidos, 30 amostras de ração e em 30 amostras de fezes de roedores presentes na propriedade. Em seguida, investigou-se Salmonella sp em fezes, conteúdo cecal, fígado, baço e carcaça de 90 avestruzes abatidos. Aliado a isso, colheu-se o soro sanguíneo destes animais para a realização do "teste da Pulorose". Os exames microbiológicos demonstraram ausência de Salmonella sp em amostras de fezes de roedores e em fezes, ovos, conteúdo cecal, fígado, baço e carcaça dos avestruzes analisados. Por outro lado, Salmonella enterica subespécie enterica 4, 12: i:- foi isolada de uma amostra de ração e Salmonella Javiana de outras duas. O teste sorológico foi negativo nas 90 amostras. O sistema de criação, o bom manejo sanitário adotado na propriedade e a adoção dos programas de Boas Práticas de Fabricação (BPF) e Análise de Perigos e Pontos Críticos de Controle (APPCC) no abatedouro contribuíram para a ausência de Salmonella sp nas amostras examinadas. / Abstract: In recent years, the ostrich farming has expanded considerably in Brazil and all over the world. According to literature, Salmonella sp causes mortality in ostrich chicks, being also responsible for human food borne diseases. Even though, little research has focused on Salmonella in ostriches. This study was elaborated with the purpose to search for Salmonella sp in ostriches of a farm located on Brazilian southwest region. By conventional microbiological method, Salmonella sp was researched in 80 samples of ostrich's droppings, 90 eggs, 30 samples of feed and 30 samples of droppings from resident rodent population. In sequence, this bacterium was searched in droppings, caecal content, spleen, liver and carcass from 90 slaughtered ostriches. Also, blood serum of those animals were harvested and submitted to test for Pullorum Disease (Rapid Serum Blood Agglutination Test). No Salmonella sp was detected in eggs, caecal content, liver, spleen, carcass and droppings from ostriches, nor in droppings from rodents. On the other hand, Salmonella Javiana was isolated from two samples of feed and Salmonella enterica enterica 4, 12: i:- from another one. The serologic test was negative for all samples. The management of ostrich farming, the good sanitary management adopted on farm and the application of Hazard Analysis and Critical Control Point (HACCP) principles and Good Manufacturing Practices (GMP) during the slaughter process contributed for absence of Salmonella sp on samples assayed. / Mestre

Made available in DSpace on 2014-06-11T19:27:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-02-18Bitstream added on 2014-06-13T18:56:55Z : No. of bitstreams: 1 freitasneto_oc_me_jabo.pdf: 351713 bytes, checksum: 82c0d6bd573bc832444c3d0fe2427852 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / As criações de avestruzes vêm se desenvolvendo no Brasil e em outros países. De acordo com a literatura, Salmonella sp está envolvida na mortalidade de filhotes de avestruzes, sendo também importantes causadoras de toxinfecção alimentar em seres humanos. Apesar disso, existem poucos estudos envolvendo a pesquisa de Salmonella sp nesta espécie. Desse modo, elaborou-se o presente trabalho com o objetivo de pesquisar Salmonella sp em avestruzes de uma propriedade da região sudeste do Brasil. Para isso, foram realizados exames bacteriológicos, em 80 amostras de fezes de avestruzes (colhidas nas varias fases da criação), 90 ovos não eclodidos, 30 amostras de ração e em 30 amostras de fezes de roedores presentes na propriedade. Em seguida, investigou-se Salmonella sp em fezes, conteúdo cecal, fígado, baço e carcaça de 90 avestruzes abatidos. Aliado a isso, colheu-se o soro sanguíneo destes animais para a realização do “teste da Pulorose”. Os exames microbiológicos demonstraram ausência de Salmonella sp em amostras de fezes de roedores e em fezes, ovos, conteúdo cecal, fígado, baço e carcaça dos avestruzes analisados. Por outro lado, Salmonella enterica subespécie enterica 4, 12: i:- foi isolada de uma amostra de ração e Salmonella Javiana de outras duas. O teste sorológico foi negativo nas 90 amostras. O sistema de criação, o bom manejo sanitário adotado na propriedade e a adoção dos programas de Boas Práticas de Fabricação (BPF) e Análise de Perigos e Pontos Críticos de Controle (APPCC) no abatedouro contribuíram para a ausência de Salmonella sp nas amostras examinadas. / In recent years, the ostrich farming has expanded considerably in Brazil and all over the world. According to literature, Salmonella sp causes mortality in ostrich chicks, being also responsible for human food borne diseases. Even though, little research has focused on Salmonella in ostriches. This study was elaborated with the purpose to search for Salmonella sp in ostriches of a farm located on Brazilian southwest region. By conventional microbiological method, Salmonella sp was researched in 80 samples of ostrich’s droppings, 90 eggs, 30 samples of feed and 30 samples of droppings from resident rodent population. In sequence, this bacterium was searched in droppings, caecal content, spleen, liver and carcass from 90 slaughtered ostriches. Also, blood serum of those animals were harvested and submitted to test for Pullorum Disease (Rapid Serum Blood Agglutination Test). No Salmonella sp was detected in eggs, caecal content, liver, spleen, carcass and droppings from ostriches, nor in droppings from rodents. On the other hand, Salmonella Javiana was isolated from two samples of feed and Salmonella enterica enterica 4, 12: i:- from another one. The serologic test was negative for all samples. The management of ostrich farming, the good sanitary management adopted on farm and the application of Hazard Analysis and Critical Control Point (HACCP) principles and Good Manufacturing Practices (GMP) during the slaughter process contributed for absence of Salmonella sp on samples assayed.

Ostriches are an important commercial species in South Africa and are becoming increasingly so in other parts of the world. Fertility and hatchability of artificially incubated ostrich eggs, however, is generally regarded as low compared to other poultry species and to ostriches in the wild. Investigation into specific farming practices at present indicated scope for an overall improvement in productivity through a sound breeding strategy. This thesis investigated factors that affect egg production, fertility, and hatchability of artificially incubated eggs in the Little Karoo region of South Africa. Specific breeding pair combinations accounted for the major variations in egg weight, hatchability, chick production and offspring weight at slaughter age. An appreciable proportion of variation in reproductive traits was attributable to the repeatable nature of breeding pair performance from year to year, even from first breeding attempts, suggesting that selection of good breeding stock can be made from an early age. Artificially incubated eggs showed improved hatchability when eggs were collected two to three hours after lay rather than the following morning. Storing position of eggs did not significantly effect hatchability when eggs were stored for a maximum of one week. The critical zero temperature for ostrich eggs, below which no embryonical development takes place, was found to be ± 25°C and cooling eggs to temperatures below 20°C for complete cessation of embryonic development during storage resulted in better hatchabilities compared to eggs stored at 25°C room temperature. Hatchability decreased when incubator temperatures were raised from 36 to 37.3°C. Large temperature fluctuations and gradients, which encompass detrimental temperatures, persist within forced draught wooden incubators of the type most commonly in use in the Little Karoo region. The highest temperatures occurred at the top of these incubators and will consequently have a negative impact on hatchability. The ontogeny of ostrich egg metabolism showed an exponential increase during the first 70% of incubation followed by a decline to 75% of the peak value between days 31 and 38 of incubation. From peak levels of embryonic development it was calculated that single stage incubators needs an airflow of 54.4 1/egg.hour to maintain oxygen levels just below 21% and carbon dioxide levels below 0.5%. Lower embryonic mortalities were observed when eggs were turned twenty-four times/day in an electronic incubator compared to hand turning twice a day. Eggs rotated through increasing angles between 60 and 90° resulted in a linear improvement in hatchability. In incubators where turning angles were fixed at 60°, lower hatchabilities were overcome by incubating eggs for 2 - 3 weeks in a horizontal position before placing them vertically. No specific farming practice could be singled out as the main cause of low fertility or hatchability but rather a combination of certain practices applied wrongly.

Hierdie verhandeling is ‘n samestelling van verskeie studies, elk opgeskryf in die formaat en styl soos vereis deur die Suid-Afrikaanse Vereeniging vir Diereproduksie (South African Society of Animal Science). Hoofstuk 1 is ‘n literatuurstudie bestaande uit ‘n algemene inleiding wat agtergrond oor die studie verskaf en sluit die probleemstelling in, naamlik die swak oorlewing van volstruiskuikens wat onder kunsmatige toestande grootgemaak word. Hoofstukke 2, 3, 4 en 5 bestaan uit die eerste vier studies, waartydens sekere bestuurs-aspekte, wat moontlik oorlewing van volstruiskuikens kan verbeter (nl: populasiedigtheid, tipe vloer-oppervlak, die aanwending van broeipare en die aanwending van peetouers), ondersoek is. Hoofstukke 6, 7, 8 & 9 handel oor studies wat gerig is om voeding meer aanloklik te maak vir volstruiskuikens teneinde voedselinname te stimuleer en sodoende produksie en oorlewing te verbeter (nl: verskaffing van groenvoer, geur van voer, kleur van voer en beligting van voer). Die laaste hoofstuk bestaan uit ‘n algemene gevolgtrekking en aanbevelings. Alhoewel daar gepoog is om herhaling in hoofstukke te beperk, was dit onmoontlik om herhaling van sekere gedeeltes van hoofstukke te voorkom.

Thesis (MScAgric)--University of Stellenbosch, 2001. / ENGLISH ABSTRACR: Approximately 10 years ago South Africa, and specifically the Oudtshoorn region was the only place in the world that supplied ostrich products for the international market. Today, South Africa is only one of several countries with commercial ostrich farming. The largest concentration of ostrich farmers in the world is, however, still in the Oudtshoorn region. Increasing competition, limited possibilities to diversify and the so-called price cost squeeze put the emphasis on aspects such as higher productivity and lower production costs. The profitability of ostrich farming, especially in the Oudtshoorn region, should urgently be determined and evaluated as farmers rely heavily on this venture as an only source of income. Decreases in slaughter realisations and slaughtering numbers have necessarily negative financial implications for the farmers, as well as for the community as a whole. Diversification is often considered strategic to avoiding or minimising risk. However, the possibilities to diversify especially to existing alternatives, have proven limited. One sure solution is to increase productivity of ostrich farming. Production parameters like the number of day-old chicks per female, chick mortality and slaughtering realisations were found to vary considerable providing scope for improvement. It is evident that several factors that determine the generated income lie outside the sphere of influence of the individual ostrich farmer. The large variation in production performances renders the industry risky, especially for farmers with liquidity problems. Two questionnaires as well as group discussion techniques were used to evaluate the economics of ostrich farming. Income and costing budget models were constructed on Microsoft Excel to be able to do calculations to the level of gross margin. A complete representative ostrich-farming unit was constructed to do calculations to the level of net farm income. The budget models were applied to (1) representative ostrich production practices for each of the three phases in the production process of ostrich farming, and (2) the representative ostrich-farming unit. The effect of different critical factors on the gross margin and net farm income of ostrich farming were thereafter evaluated. Different scenarios were also evaluated. The results of these analyses are representative of ostrich farming in the Oudtshoorn region. A computer model was developed whereby ostrich farming can be evaluated economically. This model can also be applied to assist individual farmers with their planning.As no research results exist on the economics of ostrich farming at micro level, several questions regarding the economics of ostrich farming prompted this study. These questions were answered using the above-mentioned computer models. The survival of the ostrich industry in the Oudtshoom region with its limited resources depends on a secure lead in technology which will enable farmers to produce products of higher quality, but also at lower costs than the rest of the world. / AFRIKAANSE OPSOMMING: Sowat 10 jaar gelede was Suid-Afrika, en spesifiek die Oudtshoom-omgewing, die enigste gebied in die wereld wat volstruisprodukte aan die wereldmark verskaf het. Vandag is Suid-Afrika egter een van vele lande waar kommersiele volstruisboerdery voorkom. Die grootste konsentrasie van volstruisboere in die wereld word egter steeds in die Oudtshoom-omgewing aangetref. Toenemende mededinging, beperkte moontlikhede om te diversifiseer en die sogenaamde pryskoste-knyptang impliseer dat aspekte soos hoer produktiwiteit en laer produksiekoste aandag moet geniet. 'n Behoefte bestaan om die winsgewendheid van die volstruisvertakking, spesifiek in die Oudtshoomomgewing, nie net te bepaal nie, maar ook te evalueer. Voistruisboere in die Oudtshoom-omgewing steun swaar op die volstruisvertakking vir die generering van inkomste. 'n Verlaging in slagrealisasies en 'n inkorting van slaggetalle het dus noodwendig negatiewe finansiele implikasies tot gevolg, nie net vir die volstruisboere nie, maar ook vir die hele gemeenskap. 'n Strategie om risiko te vermy, mag wees om te diversifiseer, maar die moontlikhede om te diversifiseer, veral na die bestaande vertakkings wat reeds verbou word, blyk egter beperk te wees. 'n Oplossing kan wees om die produktiwiteit van volstruisboerdery te verhoog, met ander woorde om bestaande dinge beter te doen. Groot variasies kom onder andere voor in die getal dagoudkuikens per wyfie, vrektesyfer onder kuikens en ook slagresultate. Groot ruimte vir verbetering bestaan dus. Dit blyk dan ook dat daar heelwat faktore is wat buite die invloedsfeer van die indiwiduele volstruisboer val wat bepalend is vir die inkomste wat 'n slagvolstruis realiseer. Die groot variasies, soos genoem, impliseer verder dat die risiko van volstruisboerdery hoog kan wees, veral vir volstruisboere met likiditeitsprobleme. Twee vraelysopnames en die groepbesprekingstegniek is gebruik om volstruisboerdery ekonomies te kon evalueer. Inkomste- en kostebegrotingsmodelle is op Microsoft Excel gekonstrueer ten einde berekeninge tot op die vlak van bruto marge te kon doen. 'n Volledige verteenwoordigende volstruisboerdery-eenheid is vervolgens gekonstrueer om berekeninge ook tot op die vlak van netto boerdery-inkomste te kon doen. Die begrotingsmodelle is toegepas op (0 verteenwoordigende volstruisproduksiepraktyke vir elk van die drie fases in die produksieproses van volstruisboerdery en (2) die verteenwoordigende volstruisboerdery-eenheid. Die effek van verskillende kritieke faktore op die bruto marge en netto boerdery-inkomste van volstruisboerdery is vervolgens geevalueer. Verskillende scenarios is ook aan die hand van die verteenwoordigende boerderyeenheid beoordeel. Die resultate van hierdie ontledings is verteenwoordigend van volstruisboerdery in die Oudtshoom-omgewing. 'n Rekenaarmodel is in die proses ontwikkel om volstruisboerdery ekonomies te kan evalueer. Hierdie model kan ook aangewend word om indiwiduele volstruisboere met beplanning te help. Heelwat vrae oor die ekonomie van volstruisboerdery het aanleiding gegee tot die aanvang van hierdie studie. Navorsingsresultate oor die ekonomie van volstruisboerdery op mikrovlak bestaan dan ook nie. Deur gebruik te maak van die genoemde rekenaarmodelle is vrae oor die ekonomie van volstruisboerdery beantwoord. Die enigste behoud van die volstruisbedryf in die Oudtshoom-omgewing, met sy beperkte hulpbronne, is 'n stewige voorsprong in tegnologie om nie net beter nie, maar ook goedkoper as die res van die wereld te produseer.

Thesis (PhD)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: Although small, the South African ostrich industry contributes 60% to the total world production of slaughter ostriches. Ostrich leather contributes more than 50% of the R2.1 billion turnover of this industry. This study is the first structured investigation into the characteristics of ostrich leather focussing on factors such as age, nutrition, slaughter weight, and genetics, and the influence thereof on intrinsic leather traits. Large variation in terms of skin quality was found between producers, month of the year and production years. The effect of age suggested that leather thickness and tensile strength increased with age while the number of nodules declined by 2.8 for every month increase in slaughter age. Slit tear strength and tensile strength increased with heavier slaughter weights. Older ostriches had higher values for slit tear strength and skin thickness. Nodule diameter increased at a rate of 0.08mm per month increase in age. Nodules with an average diameter of more than 4.0mm were only obtained in the combination of old heavy birds, while nodule diameter of the other age-weight combinations ranged between 3.3mm and 3.5mm. Subjective assessment of nodule traits by participants with or without prior knowledge of age suggested that slaughter age accounted for 46% of the variation in estimated slaughter age. Nodule acceptability scores generally increased with an increase in slaughter age. Moderately acceptable scores were found in skins from birds 11 months and older. The effect of energy and protein concentrations of ostrich diets suggested that raw skin areas were 19.4% and 21.8% larger at slaughter for birds receiving a diet containing 10.5 MJ/ME and 12.0 MJ ME/kg DM respectively, compared to that of birds receiving a 9.0 MJ ME/kg DM diet. Leather thickness taken parallel to the spine was increased by 13% when birds were fed the higher energy diet. Dietary protein concentrations failed to influence skin weight, skin area or any physical leather properties. The genetic variation in nodule size measured at different sampling sites on the skin suggested that nodule size increased chronologically with age at the neck, back, upper leg, and flank and butt areas. Estimates of h² for nodule size ranged from 0.09 ± 0.07 on the flank region to 0.24 ± 0.10 on the upper leg region. Preliminary results seem to suggest that nodule size on different locations of the skin is not necessarily the same genetic trait. It was concluded that measurements at any specific site is unlikely to predict measurements at other sites with a high degree of accuracy due to the large variation that exists between measurement sites. This dissertation provides an insight into the complexity of ostrich leather quality, and the interaction of leather traits, such as nodule size and shape, leather thickness and tensile strength, that determine ostrich leather quality. / AFRIKAANSE OPSOMMING: Alhoewel klein, produseer die Suid-Afrikaanse volstruisbedryf 60% van die totale wêreldproduksie van slagvolstruise. Volstruisleer is verantwoordelik vir meer as 50% van die R 2.1 biljoen omset van die bedryf. Hierdie studie is die eerste gestruktureerde ondersoek na die intrinsieke eienskappe van volstruisleer en die invloed van ouderdom, voeding, slagmassa en genetika op hierdie eienskappe. Groot variasie t.o.v. leerkwaliteit is waargeneem tussen produsente, maande van die jaar en produksiejare. Die effek van ouderdom toon dat leerdikte en treksterkte verhoog het met toename in ouderdom, terwyl die aantal knoppies afneem met 2.8 vir elke maand toename in slagouderdom. Skeur- en treksterkte het verhoog met ʼn swaarder slagmassa (64kg vs. 99kg). Hoër waardes vir skeursterkte en veldikte is vir ouer voëls (384 dae vs. 234 dae ouderdom) verkry. Knoppie deursnit het teen ʼn tempo van 0.08mm per maand toename in ouderdom verhoog. Knoppies met ʼn gemiddelde deursit van groter as 4.0mm is slegs waargeneem in swaar-ou voëls, terwyl die knoppie deursnit van die ander massa-ouderdom kombinasies tussen 3.3mm en 3.5mm gewissel het. Die subjektiewe waarneming van 28 respondente, ingelig of oningelig oor die betrokke slagouderdom, dui daarop dat die werklike slagouderdom verantwoordelik is vir 46% van die variasie in geskatte slagouderdom. Die puntetoekenning vir knoppie-aanvaarbaarheid het verhoog met ‘n toename in slagouderdom. Aanvaarbare puntetoekenning vir knoppie-ontwikkeling is verkry vir voëls vanaf 11 maande en ouer. Die effek van energie- en proteïenkonsentrasies in volstruisdiëte toon dat die rouveloppervlakte onderskeidelik 19.4% en 21.8 % groter was met slagting vir voëls wat onderskeidelik ‘n 10.5 MJ/ME en 12.0 MJ ME/kg DM diëte gevoer is, in vergelyking met voëls wat ‘n 9.0 MJ ME/kg DM dieet ontvang het. Leerdikte, geneem parallel met die ruggraat, het met 13% toegeneem wanneer die hoër energie dieet gevoer is. Dieetproteïen konsentrasies het geen invloed op velmassa, veloppervlakte of enige fisiese leerkwaliteitseienskappe gehad nie. Die genetiese variasie in knoppiegrootte geneem op verskillende lokaliteite op die vel toon ʼn chronologiese toename met ouderdom in die nek-, rug-, boud-, sy- en stuitjie gebiede. Beraamde h² vir knoppiegrootte wissel vanaf 0.09±0.07 op die sye tot 0.24±0.10 op die boudgedeelte. Voorlopige resultate dui aan dat knoppiegrootte op verskillende lokaliteite nie noodwendig dieselfde genetiese basis het nie. Die gebruik van een lokaliteit vir die voorspelling van die eienskappe van ʼn ander, blyk nie sinvol te wees nie a.g.v. die groot variasie wat tussen verskillende lokaliteite bestaan. Hierdie studie verskaf insig oor die kompleksiteit van volstruisleerkwaliteit en die interaksie van leereienskappe soos knoppiegrootte en –deursnit, veldikte en treksterkte, in die bepaling van leerkwaliteit.

The aim of this research was to identify how farmers learn how to farm using pluriactive lifestyle block ostrich farmers who are part of the New Zealand ostrich industry as a case study. Ostrich farming is comparatively new to New Zealand farmers and the industry has attracted innovative individuals who have developed informal learning strategies. Ostrich farmers use other farmers as their main resource which is mainly facilitated through events organised by the New Zealand Ostrich Association (NZOA) and aimed at lifestyle block farmers. Ostrich farmers' community of practice is centred around their membership to the Association which enables farmers to come together to learn and socialise. For learning to effectively take place the key is social interaction, where ideas can be transferred between farmers. This thesis illustrates the important events and structure of the industry and how this has shaped farmer learning. Through semi-structured interviews and participant observation on a chick rearing farm I was able to gain a picture of how lifestyle block farmers balance full time off-farm employment while running stock, in an attempt to satisfy their version of the rural idyll. The industry is now in decline as most of the early players have exited the industry and it is now focused around New Zealand Ostrich Export (NZOE) goals. By exploring the period called the breeder phase which was characterised by some farmers making a fortune as ostrich farming was the 'next big thing' and the history since then, I have identified how these particular farmers have learned how to farm.

The South African ostrich industry is presently characterised by a drastic decline in the slaughter price of slaughter birds, due to the drop in the price of meat as well as leather. As a result, the economic viability of ostrich farming is severely hampered by these developments, and many generally accepted industry practices have to be reviewed. Among the practices under review is the possibility of slaughtering ostriches at an earlier age than the traditional slaughter age of 12 - 14 months, in order to minimise feed costs and the incidence of damage to the skin. However, little information is available on the effect of the slaughter age on the yield and quality of the economically important end-products. The effect of slaughter age on production and the economic viability of a commercially intensive ostrich production system was consequently evaluated in a completely randomised experimental design involving two batches (n= 81 and n= 94) of ostriches. The experiments took place at Kromme Rhee experimental farm of the Elsenburg Research Centre near Stellenbosch. The birds were subject to experimental treatment at the age of 4 months (n= 81, from May 2004 to March 2005) and 6 months (n= 94, from August 2004 to August 2005) respectively. The ostriches were randomly divided into 10 groups of between 16 and 20 birds per group. Standard production practices, as applied in an intensive ostrich production unit, were implemented. Clean drinking water and self-mixed grower diet (min 15 percent crude protein, 0.68 percent lysine and 11.4 MJ ME per kg feed) and finisher diet (min 14 percent crude protein, 0.55 percent lysine and 9.8 MJ ME per kg feed) were provided ad libitum to the birds. Birds were slaughtered at the ages of 8.5, 10.5, 12.5, 14.5, and 16.5 months respectively. Data on feed intake and yields of cold carcass, crust skin size, skin grade and total feathers was recorded for birds slaughtered at the respective ages. Data was analysed according to the analysis of variances. Values for meat yield, skin size yield and feed intake were predicted by regression analysis based on experimental values. Industry figures and norms were used as proxy for other production inputs and costs. A gross margin type analysis was performed to evaluate the effect of different slaughter ages on the profitability of each production system. There was a positive correlation between age and feed intake (r2= 0.40), slaughter weight (r2= 0.97), cold carcass yield (r2= 0.48), skin surface area (r2= 0.39), skin grade (r2= 0.19) and total yield of feathers (r2= 0.29). The dry skin grade showed deterioration as slaughter age was prolonged. Highly significant differences (P< 0.01) in slaughter weight, cold carcass yield, skin surface area, dry skin grade and total feathers were detected at the different slaughter ages. There were no significant differences (P> 0.05) with respect to gender for slaughter weight, skin surface area and dry skin grade within the different age groups. Males had significantly higher (P< 0.05) cold carcass yield and total feather yield than their female counterparts. From this study it can be concluded that an increase in slaughter age significantly increases feed intake, slaughter weight, cold carcass yield, and skin surface area. It is also clear that an increase in slaughter age can be detrimental to dry skin grade. The relative income contribution of the three main products (skin: meat: feathers) occurred in a ratio of 47:53:0, 52:47:1, 47:50:3, 44:51:5, 39:56:5 at the respective slaughter ages. Total income revealed an increase of 26 percent from 8.5 to 10.5 months slaughtering, an increase of 4 percent between 10.5 and 12.5 months, and an increase of 11 percent between 12.5 and 14.5 months. The income dropped by 0.3 percent between 14.5 and 16.5 months slaughtering. Total costs increased with slaughter age, particularly feed costs which showed an increase (at a decreasing rate) between the different slaughter ages. The margin above specified cost per bird was the highest for birds slaughtered at the age of 10.5 months. The margin above cost showed a steady decline as birds were slaughtered at higher ages. Slaughtering at 16.5 months revealed a negative margin. To compare the effect of differences in time span on different slaughter age regimes, margin above costs for each system over 5 years were discounted to a present value. In this study, with current feed costs and income from end products, slaughtering at 10.5 months revealed the highest present value for the margin above cost. Furthermore, slaughtering at 16.5 months revealed a negative present value on the margin above cost after 5 years. Financial viability calculations are relevant and valid for data obtained in this case study. Financial viability is however case-specific and may vary between producers, depending on their individual management practices, production systems and cost structures. Results from this study may be of significant value to managerial decision-making in the ostrich industry.

Thesis (PhD(Agric) Animal Sciences))--University of Stellenbosch, 1988. / Farming with ostriches became established as a new stock-farming activity in South Africa around 1863. Ostrich feathers were then the only commercial product of that activity and fifty years later still held fourth place on the list of exports from South Africa - after gold, diamonds and wool (Smit, 1963). However during the world depression of 1914 - 1945 the appeal of ostrich feathers vanished and the industry collapsed. Today commercial farming with domesticated ostriches (Struthi0 camelus var. domesticus), originating from a cross (Duerden, 1910; Smit, 1963, 1984) between the South African (Struthio camelus australis) and the North African ostriches (Struthio camelus camel us), is again a rapidly expanding activity in South Africa's Little Karoo. This is the only region in the world where farming with ostriches is still encountered at a commercial scale, and although relatively small in the general stock-farming scenario, it provides a livelihood for about 400 farmers who run some 150 000 ostriches. Feathers, together with ostrich leather and meat are all prominent export products that account for foreign exchange earnings of more than R30 million. In terms of monetary value the ostrich industry has grown by more than 300% over the past decade and by al most 100% in the 1ast 5 years. This high growth rate is primarily due to the steady development of the slaughter bird industry in which leather, meat and feathers account for more than 80% of the entire industry's turnover. Ostrich products, however, are primarily exclusive fashion products, of which more than 90% is exported. Because the world market is relatively small, expansion prospects for the industry are limited and sensitive to supply and demand. To ensure the industry's continued economic well-being, ostrich research pays particular attention to production techniques that will help to improve efficiency and result in better product quality and profitability. For the purpose of increased ostrich chick production, ostrich eggs are presently being incubated in large quantities (ca 200 000 eggs per annum). However, hatching success of ostrich eggs in incubators is considerably below that of natural nests, and Burger & Bertram (1981) suggested that it may be due to high humidities (63% relative humidity) commonly used in ostrich incubators. Investigations were undertaken to measure incubation temperatures and humidities during the complete course of 41 days of natural incubation in 6 ostrich nests. In addition, the water vapor conductance of the eggs was measured, as well as the incubation water loss which in other species averages 15% of the initial egg mass and has been proposed as an optimal condition for hatching success (Ar & Rahn, 1978; Rahn 1984). The natural incubation parameters measured during these experiments were adapted and applied to conditions of artificial incubation. This improved the realized hatchability from 50 to 75%. Furthermore the intensive production and finishing of slaughter birds on complete dry meal diets under feedlot conditions is a new development which contains exceptional possibilities for the industry (Swart & Kemm, 1985). Economically and biologically, efficient diet formulation has accordingly become essential for profitable slaughter bird production. The nutritional value of feed constituents for ostriches is, however, still unknown and without it effective least cost diet formulation and programming is not possible. Present growth and finishing diets for ostriches are based on energy values of the dietary components which have been derived from poultry (Blair, Daghir, Morimoto, Peter & Taylor, 1983; Du Preez, Duckitt & Paulse, 1986) and pig values (Kemm & Ras, 1981; NRC, 1973; IAFMM, 1985). This approach may, however, result in unreal estimation of the actual nutritional value of feed constituents for ostriches, so that quantification of their nutritional value has consequently become necessary. During 1985 a multi-disciplinary research programme on ostriches was initiated, the objective being to investigate the energy metabolism and the efficiency of energy utilization in growing farm ostriches. For the purpose of these experiments all ostrich chicks were incubated in an ostrich egg incubator, maintained at a dry bulb temperature of 36°C and a wet bulb temperature of 24,0 ± 1,0°C. These temperature settings were extrapolated from the natural incubation parameters measured in the six naturally incubated nests (Swart, Rahn & De Kock, 1987; Swart & Rahn, 1987). An important aspect of the studies on energy metabolism was to determine the extent to which plant fibre is digested in various segments of the gastrointestinal tract of growing ostriches and whether these birds utilize the end products of fibre digestion, namely volatile fatty acids such as acetic acid, efficiently. The possible use of metabolizable energy to evaluate feedstuffs for ostriches was an initial aim of this study. Subsequently the effect of crude fibre or energy concentration on the digestibility of gross energy, energy loss as methane, heat expenditure, and the effect on the efficiency of ME utilization were investigated. Finally accretion patterns and the partition of metabolizable energy during growth were studied in the young ostrich chick. The findings of the studies on incubation aspects (Section 1) are presented in Chapter 2 and 3 and that of the metabolism studies (Section 2) are presented in Chapters 4, 5, 6, 7 and 8 of this dissertation.