Thesis (MScAgric)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Grapevine performance and wine quality are influenced by various factors, two of the most important being the availability and quality of irrigation water. In relatively dry countries such as South Africa the conservation and effective use of water is of utmost importance. Expected increases in temperature and decreases in rainfall in the future due to climate change impacts highlights the importance of water conservation. This inspired investigations into possible alternative irrigation water sources and therefore the possibility of vineyard irrigation using winery wastewater is of utmost importance for the sustainability of the wine industry. Winery wastewater contains higher concentrations of certain elements other than water generally used for vineyard irrigation, the most important differences being Na and K levels. Furthermore, winery wastewater contains larger populations of microorganisms such as yeasts, lactic acid bacteria and acetic acid bacteria, typical associated with wine production. If irrigation using winery wastewater affects the uptake of certain elements or alters grapevine water status, it may affect grapevine growth, juice and wine composition. Furthermore, if juice and wine composition is affected wine composition and sensorial quality may be affected. Cabernet Sauvignon/99R grapevines, growing in a sandy soil in the Breede River Valley, were subjected to eight irrigation treatments using augmented winery wastewater in addition to irrigation using raw river water as control. The study was carried out during the 2010/11 and 2011/12 seasons. The various wastewater irrigation treatments were made up by augmenting winery wastewater with raw river water to obtain a target chemical oxygen demand (COD) concentration. In this study, the level of COD in the irrigation water is a direct indication of water quality, the two being indirectly proportional. The eight wastewater irrigation treatments ranged from 100 mg/L COD up to 3000 mg/L COD. The first objective of the study was to determine the effect of irrigation using augmented winery wastewater on grapevine response, with regards to vegetative growth, berry development and berry composition. The various wastewater irrigation treatments did not affect grapevine vegetative growth or reproductive growth, including yield, throughout berry development up to harvest. Berry sugar accumulation and evolution in acid concentrations were also not affected. An increase in berry juice pH was observed with an increase in the level of COD in the augmented winery wastewater only in the second season. The amount of elements, ions and heavy metals in juice was not affected by wastewater irrigation, indicating that there was no absorption by the grapevines. Berry skin thickness, colour and phenolic content as well as yield and its associated components were not affected by irrigation using augmented winery wastewater. The second objective of the study was to determine the effect of irrigation using augmented winery wastewater on wine microbial and chemical composition, fermentation performance and wine sensorial characteristics. The natural yeast and bacteria flora of juice was not affected by the various wastewater irrigation treatments. In addition, the ability of the inoculated yeast and lactic acid bacteria strains to conduct their respective fermentation processes were not affected. With the exception of total titratable acidity (TTA) and pH, irrigation using augmented winery wastewater did not affect wine chemical composition with regards to basic wine parameters as well as colour, phenolic and tannin composition. Similar to juice, phosphorus and selected ions were not affected. None of the measured wine sensorial characteristics were affected by irrigation using augmented winery wastewater. The third objective of the study was to investigate the effect of direct contact between berries and winery wastewater on wine sensorial characteristics. The study focussed on the transference of off-flavours from the wastewater into the wine and the occurrence of off-flavours as a response to contact with winery wastewater. Wine colour and general sensory wine descriptives were not affected by direct contact with winery wastewater. The presence of a winery wastewater-like off-odour and volatile acidity was, however, more detectable in wines made from berries that were in contact with the most concentrated wastewater. Therefore, it may be possible for off-odours to be transferred from the winery wastewater into the wines, or that off-odours are formed as a direct or indirect result of contact with winery wastewater. Under the given conditions, results obtained in this two seasons of the study suggest that irrigation using augmented winery wastewater does not affect grapevine performance or wine quality substantially. The major impact that was observed was an increase in wine pH and a decreasing trend in TTA. Both these parameters could be rectified by simply adding acid to the wines. Therefore, irrigation using augmented winery wastewater may be considered as a possible future alternative source for vineyard irrigation. It is, however, important to remember that some of the effects of wastewater irrigation may be cumulative and could possibly arise only after several years. Furthermore, different field conditions and cultivars may respond differently. / AFRIKAANSE OPSOMMING: Wingerd prestasie en wyngehalte word deur verskeie faktore beïnvloed waarvan twee van die belangrikste die beskikbaarheid en gehalte van besproeiingswater is. In relatiewe droë lande soos Suid Afrika is waterbesparing en die effektiewe benutting van water hulpbronne van uiterste belang. Die verwagte toename in temperatuur en afname in reënval in die toekoms as gevolg van klimaatsveranderinge plaasdieklem op op die belangrikheid van waterbesparing. Dit het navorsing om moontlike alternatiewe vorme van besproeiingswater te ontdek geïnspireer. Na aanleiding van hierdie faktore word daar toenemend gefokus op navorsing oor die moontlikheid om kelder afvalwater as alternatiewe bron van besproeiings water vir wingerde te benut. Kelder afvalwater bevat hoër konsentrasie van sekere elemente as water wat onder normale omstandighede gebruik word vir die besproeiing van wingerde, die belangrikste verskille was die vlakke van Na en K. Benewens die hoër konsentrasie van sekere elemente bevat kelder afvalwater ook groot populasies van mikroörganismes soos giste, melksuurbakterieë en asynsuurbakterieë, tipies geassosieerd met wynbereiding. Indien besproeiing met kelder afvalwater die opname van sekere elemente of die plant water status beϊnvloed, mag wingerd groei, sap en wyn samestelling beϊnvloed word. Daar benewens, indien die mikrobiese samestelling van die sap en wyn beϊnvloed word sal die samestelling en sensoriese gehalte van die wyn moontlik beϊnvloed word. Cabernet Sauvignon/99R wingerde, geleë in sanderige grond in die Breede Rivier Vallei, is onderwerp aan besproeiing met agt verskillende konsentrasies van verdunde kelder afvalwater, bykomend tot besproeiing met onbehandelde rivier water wat as kontrole gedien het. Hierdie studie is uitgevoer gedurende die 2010/11 en 2011/12 seisoene. Die teiken besproeiings konsentrasies is verkry deur kelder afvalwater met onbehandelde rivier water te verdun tot ‘n sekere chemiese suurstofbehoefte (CSB) konsentrasie bereik is. Die CSB is in hierdie studie ‘n direkte aanduiding van watergehalte, die twee was indirek eweredig tot mekaar. Die agt CSB konsentrasies waarteen die afvalwater besproei is wissel tussen 100 mg/L CSB en 3000 mg/L CSB. Die eerste doelwit van die studie was om te bepaal wat die effek van besproeiing met verdunde kelder afvalwater op wingerdprestasie, met spesifieke verwysing na vegetatiewe groei, korrelontwikkeling en korrelsamestelling is. Wingerd vegetatiewe en reproduktiewe groei, insluitende opbrengs, is op geen stadium tydens korrelontwikkeling tot en met oes beïnvloed nie. Die laai van suikers gedurende rypwording, sowel as verskuiwings in suurkonsentrasie, is nie deur besproeiing met kelder afvalwater beïnvloed nie. In die tweede seisoen is ‘n toename in sap pH waargeneem soos die CSB konsentrasie van die besproeiings water toegeneem het. Die element, ioon en swaar metaal samestelling van sap was nie beïnvloed deur besproeiing met afvalwater nie wat aandui dat daar geen opname was deur die wingerd nie. Die dikte, kleur en fenoliese samestelling van druifdoppe is ook nie beïnvloed nie. Die tweede doelwit van die studie was om te bepaal wat die effek van besproeiing met verdunde kelder afvalwater op wyn mikrobiese en chemiese samestelling, fermentasie effektiwiteit en wyn sensoriese eienskappe is. Die verskeie afvalwater besproeiings behandelings het geen effek op die natuurlike gis of bakterieë flora van die sap gehad nie. Die vermoë van die geïnokuleerde gis en melksuurbakterieë om hul afsonderlike fermentasie prosesse te voltooi is ook nie beïnvloed nie. Met die uitsondering van totale titreerbare suur (TTS) en pH, is die chemiese samestelling van wyne met betrekking tot basiese wyn parameters, kleur, fenole en tanniene nie beïnvloed nie. Soortgelyk aan sap is wyn fosfor en geselekteerde ioon samestelling nie geaffekteer nie. Die sensoriese karakteristieke was eenders vir wyne van alle behandelings. Die derde doelwit van die studie was om te bepaal wat die effek wat direkte kontak van kelder afvalwater met druiwekorrels op wyn sensoriese eienskappe het. Hierdie studie het gefokus op die oordrag van afgeure vanaf kelder afvalwater na die wyne sowel as die voorkoms van afgeure as ‘n reaksie op kontak met kelder afvalwater. Wyn kleur en algemene sensoriese eienskappe is nie geaffekteer deur kontak tussen druiwe en kelder afvalwater nie. Kelder afvalwater-geassosieerde afgeure en vlugtige suur was meer duidelik waarneembaar in wyne wat gemaak is van druiwe wat in kontak was met die meer gekonsentreerde afvalwater. Dit mag dus moontlik wees dat afgeure vanaf kelder afvalwater oorgedra word na wyne, of dat sekere afgeure gevorm word as ‘n direkte of indirekte reaksie op kontak met kelder afvalwater. Onder die gegewe toestande oor die twee jaar studie periode het resultate getoon dat besproeiing met verdunde kelder afvalwater nie wingerdprestasie en wyn gehalte aansienlik beïnvloed nie. Die grootste impak wat afvalwater besproeiing gehad het, was om ‘n toename in wyn pH en ‘n tendens tot afname in TTS te veroorsaak. Deur eenvoudig suur by die wyn te voeg kan albei hierdie probleme reg gestel word. Op grond van hierdie bevindings kan besproeiing met verdunde kelder afvalwater moontlik as toekomstige bron vir addisionele wingerdbesproeiing dien. Dit is egter belangrik om te onthou dat die effekte van besproeiing met kelder afvalwater mootlik kumulatief kan wees en dat probleme moontlik eers na etlike jare na vore kan kom. Ander kultivars en veldkondisies mag ook lei tot ander resultate.

Thesis (MSc) -- Stellenbosch University, 1975. / No abstract available

Thesis (MScAgric)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Thompson Seedless and Regal Seedless are two white seedless table grape cultivars widely produced in South Africa. Both cultivars are susceptible to berry browning, especially Regal Seedless. Browning leads to annual financial losses for table grape growers. Although a correlation between harvest maturity and the occurrence of browning seems to exist, it is still unclear whether maturity levels are the actual contributing factor. The aim of the study was to establish if harvest maturity and crop load could influence the occurrence of browning of both cultivars. The impact of harvest maturity and crop load on phenolic compound concentration in the berry skin of both cultivars was also investigated. Total external browning of Regal Seedless and Thompson Seedless occurred in much higher percentages than internal browning. Regal Seedless showed a tendency to decreased total external browning with harvest maturity. The main reason for this is that net-like browning, which is the greatest contributor to total external browning, decreased with harvest maturity, in all three seasons. External browning of Thompson Seedless increased with harvest maturity in both seasons. Contact browning was the greatest contributor to total external browning of Thompson Seedless. Crop load did not significantly influence berry browning of Regal Seedless or Thompson Seedless grapes. The flavan-3-ol concentration (catechin, epicatechin, procyanidin B1 and procyanidin B2) in Regal Seedless generally increased with harvest maturity, whereas in Thompson Seedless the general tendency was a decrease in the flavan-3-ol concentration with harvest maturity. The development of phenolic compound concentration with maturity could not be correlated with the occurrence of berry browning. Crop load did not affect flavan-3-ol concentration. When the flavan-3-ol concentration of Regal Seedless and Thompson Seedless were compared at different harvest maturities the concentrations of flavan-3-ols were clearly much higher in the skin of Regal Seedless than in the skin of Thompson Seedless (for both the 2008 & 2009 seasons). Comparison of the browning incidence with harvest maturity for these two cultivars (see above) clearly reveals that external browning of Regal Seedless occurred in much higher percentages than on Thompson Seedless. Regal Seedless had much higher levels of external browning than Thompson Seedless. The concentration of flavan-3-ols in the skin of white seedless cultivars may be an indication of the cultivar’s susceptibility to external browning. / AFRIKAANSE OPSOMMING: Thompson Seedless en Regal Seedless is twee wit pitlose tafeldruif kultivars wat ekstensief in Suid-Afrika verbou word. Verbruining kan ‘n probleem wees by beide kultivars, spesifiek Regal Seedless. Die faktore wat aanleiding gee tot verbruining is nog nie duidelik bepaal nie. Alhoewel dit lyk of daar ‘n korrelasie tussen rypheidsgraad van die oes en verbruining kan wees is dit steeds onduidelik of oesrypheidsvlakke die werklike oorsaak van verbruining is. Die doel van die studie was om vas te stel of die rypheidsgraad van die oes en oeslading verbruining van beide kultivars kan beïnvloed. Die effek van oes rypheidsgraad en oeslading op konsentrasie van fenoliese verbindings in die korrelskil van beide kultivars is ook ondersoek. Totale eksterne verbruining van Regal Seedless en Thompson Seedless het in baie hoër persentasies voorgekom as interne verbruining. Daar was ‘n tendens by Regal Seedless dat totale eksterne verbruining verminder het soos die oes ryper geraak het as gevolg van netagtige verbruining, wat die grootste bydrae tot totale eksterne verbruining veroorsaak het. Netagtige verbruining se voorkoms het verminder oor al drie seisoene. Eksterne verbruining van Thompson Seedless het toegeneem met oes rypheid in beide seisoene. Kontak verbruining het grootste byrdae gelewer tot totale eksterne verbruining van Thompson Seedless. Oeslading het nie ‘n betekenisvolle invloed op verbruining van Regal Seedless en Thompson Seedless gehad nie. Die flavan-3-ol (katesjien, epikatesjien, prosianidien B1 en prosianidien B2) konsentrasie van Regal Seedless het met oes rypheid toegeneem. By Thompson Seedless was daar ‘n afname in die flavan-3-ol konsentrasie met oes rypheid. Daar was geen korrrelasie tussen die konsentrasie van fenoliese verbinding en die voorkoms van verbruining vir beide kultivars. Oeslading het nie ‘n betekenisvolle effek op die konsentrasie van fenoliese verbindings gehad nie. Vergelyking van die flavan-3-ol konsentrasie van Regal Seedless en Thompson Seedless by verskillende rypheidsgrade wys dat die konsentrasie baie hoër in die korrel skil van Regal Seedless as in die van Thompson Seedless (vir beide 2008 & 2009 seisoene). Die vergelyking van die voorkoms van verbruining met oesrypheid van beide kultivars wys duidelik dat eksterne verbruining van Regal Seedless in baie hoër persentasies voorkom as in Thompson Seedless. Flavan-3-ol konsentrasie in die skil van wit pitlose kultivars kan ‘n aanduiding wees van die kultivar se moontlike risiko vir die voorkoms van eksterne verbruining.

Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The wildlife industry in Namibia continues to grow as the production and consumption of game meat increases. However, the health risks posed by the trade in wildlife and related by-products to livestock and humans have not been fully assessed. The main objective of this study was to investigate the potential health risks related to the increased consumption of game meat and relevant by-products by assessing the quality of game meat, as well as determine the role of game meat species in the transmission of zoonoses. The microbiological quality and safety of export game meat was assessed. No differences in the aerobic plate count (APC) were observed between the years (2009 and 2010), but the mean Enterobacteriaceae count was 1.33±0.69log10 cfu/cm2 compared to 2.93±1.50log10 cfu/cm2 between the years. Insignificant heterotrophic plate count (HPC) levels were detected in 9/23 field water samples, while faecal bacteria (coliforms, Clostridium perfringens and enterococci) were not isolated in all samples. Seven serogroups, with the exception of O26, were detected in exotic species. A white tailed deer sample had a serotype belonging to O45 which confirmed positive for stx1 gene. In springbok, 5/15 pools of faecal samples tested positive for the intimin gene. No Salmonella spp were isolated, and all E. coli isolates from the meat samples were negative for STEC virulence genes (i.e. stx1, stx2, eae and hlyA). A linear regression analysis was conducted on selected variables to identify the main predictors and their interactions affecting pH of meat 4 hours post-slaughter. In an increasing order of magnitude during winter time, the pH reached at 16-36hr post slaughter in springbok heart, liver, spleen, kidney and lungs was significantly higher than pH 6.0, while no significant differences were observed from the regulatory reference (pH 6.0) in the heart. There was a positive association between the pH of game meat 4hr post-slaughter, and liver congestion. The pH of game meat 4hr post slaughter, increased by 0.11 units per mL increase in liver congestion, and decreased by 0.04 units per minute increase in the shooting to bleeding interval, irrespective of the species. Worm eggs of strongylids, Strongyloides papillosus, Toxocara spp, Trichuris spp and coccidia were found in variable numbers in both springbok and gemsbok faeces, indicating a potential risk of transmission to other species in the ecosystem. On examination of carcasses, a novel parasite, Skjabinodera kuelzii, was identified and noted to be associated with inguinal fascia and renal fat, but the public health significance remains unclear. Nevertheless, S. kuelzii should be considered as of potential significance during routine game meat inspection. A total of 12 310 springbok were harvested from 26 commercial farms over a period of two years. Tissue samples (i.e. 60 livers, 41 kidneys and 52 hindquarter muscles) were collected from randomly selected healthy animals. The mean values (i.e. above the detection limit) of cadmium (Cd) and lead (Pb) were 0.10±0.05mg/kg and 1.04±0.21mg/kg in the liver, respectively; and 0.33±0.22mg/kg and 0.905±0.51mg/kg in the kidney of springbok, respectively. The levels of cadmium and lead in the hindquarter muscles were below the detection limit. Serum samples (n=1692) collected from sheep, goats and cattle from four presumably at-risk farms, and 900 springbok (Antidorcas marsupialis) serum samples collected from 29 mixed farming units, were screened for Brucella antibodies by using the Rose-Bengal test (RBT). Positive cases were confirmed by complement fixation test (CFT). To assess the prevalence of human brucellosis, 137 abattoir employees were tested for Brucella antibodies using the standard tube agglutination test (STAT), and the enzyme linked immunosorbent assay (ELISA). Cattle and sheep from all four farms were negative by RBT and CFT, but two of the four farms carried 26/42 and 12/285 seropositive goats, respectively. Post mortem examination of seropositive goats revealed no gross pathological lesions. Culture for brucellae from organs of seropositive animals was negative. None of the wildlife sera tested positive by either RBT or CFT. Occurrence of confirmed brucellosis in humans was linked to the consumption of unpasteurized goat milk, home-made goat cheese and coffee with raw milk and prior contact with goats. All abattoir employees (n=137) tested negative by STAT, but 3 were positive by ELISA. The three abattoir workers were clinically normal, and lacked historical connections with clinical cases. This study illustrates the importance of microbiological, parasitic and residue monitoring as critical components of a hazard analysis and critical control point based system for game meat. The study also provides the basis for increased integrated health research, surveillance and meat safety risk analysis. / AFRIKAANSE OPSOMMING: Die Namibiese wildbedryf raak toenemend groter soos die produksie en verbruik van wildsvleis toeneem. Die verwante gesondheidsrisiko’s wat die gebruik van wildsvleis en verwante produkte vir mens en dier inhou, is nog nie volledig geassesseer nie. Die doelwit van die studie was om ondersoek in te stel na die potensiële gesondheidsrisiko's wat wildsvleis en verwante neweprodukte vir mens en dier inhou deur middel van die assessering van vleisgehalte en die bepaling van die rol van die wildsvleis spesies in die oordrag van soönoses. Die mikrobiologiese gehalte en veiligheid van uitvoer wildsvleis was geassesseer. Geen verskille in die aerobiese plaat telling (APC) vir monsters versamel tydens 2009 en 2010 is aangeteken nie. Die gemiddelde Enterobacteriaceae telling was 1.33± 0.69log10 cfu/cm2 in vergelyking met 2.93±1.50log10 cfu/cm2 tussen die jare. Onbeduidende heterotrofe plaattelling (HPC) vlakke is waargeneem in 9/23 water monsters, terwyl fekale bakterieë (d.i. kolivorme, Clostridium perfringens en enterokokke) nie in enige van die monsters geïsoleerd is nie. Sewe serogroepe, met die uitsondering van O26, is aangeteken vir die eksotiese spesies. Monsters verky van ʼn white tailed deer is as positief vir 'n serotipe van O45 getoets, en die teenwoordigheid van die stx1 geen is bevestig. In springbok het 5/15 poele van fekale monsters positief getoets vir die intimien geen. Geen Salmonella spp is geïsoleer nie en alle E. coli geïsoleer in die vleismonsters was negatief vir die Stec virulensie geen (d.i. stx1, stx2, EAE en hlyA). ʼn Liniêre regressie-analise is op geselekteerde veranderlikes wat as die belangrikste indikators kan dien, en enige moontlike interaksie wat die pH van wildsvleis 4 uur na-slag kan beïnvloed, uitgevoer. In 'n toenemende orde van grootte gedurende die winter tyd, die pH teen 16-36hr na slagting in springbok hart, lewer, milt, niere en longe was aansienlik hoër as die pH 6.0, terwyl geen beduidende verskille waargeneem is wanneer dit met die regulasie verwysingswaarde van die hart (pH 6.0) vergelyk is nie. Daar was 'n positiewe assosiasie tussen die pH van wildsvleis 4 uur na-slag en mate van aansameling in die lewer. Die pH van wildsvleis 4 uur na-slag, het toegeneem met 0.11 eenhede per mL toename in lewer aansameling en afgeneem met 0.04 eenhede per minuut toename in die skiet tot uitbloei interval, ongeag die spesie. Wurmeiers van rondewurms, Strongyloides papillosus, Toxocara spp, Trichuris spp en koksidia het in verskillende ladings in die mis van beide springbok en gemsbok ontlasting, voorgekom. Dit dui op 'n potensiële risiko van oordrag na ander spesies in die ekosisteem. Die voorkoms van ʼn nuwe parasiet, Skjabinodera kuelzii, in wildskarkasse is aangeteken en was geassosieer met inguinale fascia en renale vet, maar die openbare gesondheidsrisiko bly onduidelik. Daar word aanbeveel dat dié parasiet as ʼn potensiële risiko faktor tydens roetine vleisinspeksies beskou moet word. ʼn Totaal van 12 310 springbokke is oor 'n tydperk van twee jaar van 26 kommersiële plase geoes. Weefselmonsters (d.i. 60 lewers, 41 niere en 52 agterkwart spiere) is ewekansig versamel van gesonde diere. Die gemiddelde waardes (d.i. hoër as die opsporingslimiet) van kadmium (Cd) en lood (Pb) was 0.10 ± 0.05mg/kg en 1.04 ± 0.21mg/kg in die lewer onderskeidelik en 0.33 ± 0.22mg/kg en 0.905 ± 0.51mg/kg in die niere van springbok, onderskeidelik. Die vlakke van kadmium en lood in die agterkwart spiere was laer as die opsporingslimiet. Serum monsters (n=1692) is van skape, bokke en beeste van vier vermoedelik hoë risiko plase en springbok (Antidorcas marsupialis, n=900) van 29 gemengde boerdery sisteme versamel en getoets vir die teenwoordigheid van Brucella teenliggaampies deur middel van die Rose-Bengal-toets (RBT). Positiewe gevalle is bevestig deur die komplement binding toets (CFT). Die voorkoms van menslike brusellose is bepaal deur 137 abattoir werknemers te toets vir Brucella teenliggaampies deur gebruik te maak van die standaard buis agglutinasie toets (STAT) en die ensiembinding immunosorberende toets (ELISA). Beeste en skape van die vier hoë risiko plase het negatief getoets met die RBT en CFT metodes, maar bokke van twee van die vier plase het seropositief getoets (26/42 en 12/285 onderskeidelik). Nadoodse ondersoek van seropositief bokke het geen patologiese letsels aangedui nie. Die kultuur van orgaanmonsters van seropositief diere vir Brucellae was negatief. Die monsters versamel van wild het negatief getoets deur middel van die RBT en CFT toets metodes. Die voorkoms van brusellose in mense in die studie was geassosieer met die gebruik van ongepasteuriseerde melk, tuisgemaakte bokmelkkaas en koffie met ongepasteuriseerde melk, asook direkte kontak met bokke. Alle abattoir werknemers (n=137) het negatief getoets met die STAT metode, maar drie werknemers het positief getoets met die ELISA metode. Die drie abattoir werkers was klinies normaal en het nie vorige kontak met bevestigde kliniese gevalle gehad nie. Hierdie studie bevestig die belang van mikrobiologiese, parasitiese en residu monitering as kritieke komponente van 'n gevaar-analise en kritiese kontrolepunt gebaseerde stelsel vir die produksie en verbruik van wildsvleis. Die studie verskaf ʼn basis vir toekomstige navorsing gefokus op ʼn geïntegreerde benadering van mens- en diergesondheid, monitering en vleis veiligheid risiko-analises.

Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: In this study, five trials were conducted to examine in vitro and in vivo degradation, excretion and absorption parameters of melamine (MEL) in dairy cows that have not been studied before or where limited information is available. The first two trials were in vitro studies conducted to determine the extent of MEL degradation in rumen liquor and the effects of MEL on ruminal ammonia (NH3) and volatile fatty acid (VFA) concentrations. For both trials, rumen liquor was collected from ruminally cannulated lactating Holstein cows. For the first and second trial, rumen liquor was collected from three and two cows, respectively. For both trials, Erlenmeyer flasks contained 1 g substrate and 100 mL incubation medium consisting of 20 mL rumen liquor and 80 mL reduced buffer solution. In the first trial, each flask contained 100 mg of MEL, resulting in an initial MEL concentration of 1000 mg/L. The flasks were incubated at 39° C for 0 (Control), 6, 24 or 48 hours under strictly anaerobic conditions. In all the trials, MEL concentrations were determined by LC/MSMS. MEL degradation was low after 6 and 24 h of incubation (3.2 and 5.5%, respectively) and increased to 13.6% after 48 h of incubation. In the second trial where VFA and NH3 concentrations were determined, the flasks contained either 0 (Control), 0.2 (T1) or 0.4 mg (T2) of MEL. The flasks were incubated for 6, 24 or 48 h. Treatment had no effect on individual or total VFA concentrations or NH3 concentrations at 6 and 48 h. At 24 h, T2 resulted in an inexplicable higher NH3 concentration. This study showed that the addition of melamine would not result increased rumen NH3 concentrations in vitro. Melamine would also not affect the production of different VFA’s. Therefore, it was concluded that the rumen micro-organisms present in rumen liquor would be unable to utilize MEL as a source of nitrogen and that the microbial production of VFA’s remains unaffected by the presence of MEL. In the third trial, MEL excretion in lactating cows was determined. Five cows were randomly allocated to treatments according to a 5 x 5 Latin square design. Cows received the treatment diets for 7 d followed by 8 d of MEL withdrawal during each of the five periods. The experimental treatments were formulated to provide a daily MEL intake of 0 (M0), 500 (M1), 1000 (M2), 5000 (M3) or 10000 mg (M4) via 15 kg of dairy concentrate pellets. Calculations based on the work of Newton & Utley (1978) suggested that a melamine intake of 0.16 g/kg of live weight would not result in detrimental health effects of ruminant animals. Therefore, a 600 kg lactating dairy cow should not be at risk when consuming 100 g of melamine. In this trial, the highest melamine treatment (M4 = 10 g/d) included a 10-fold safety factor from the suggested safe amount from the work of Newton & Utley (1978) and should not pose a health risk to the cows. Treatments had no effect on DMI, milk yield or milk composition. MEL was detected in the milk 8 h after initial MEL ingestion, increased rapidly and peaked on d 3 and was undetectable after 8 d. Treatments had no effect on MEL excretion efficiencies which ranged from 1.5 to 2.1%. The mean apparent digestibility of MEL was 78%. Mean faecal and urinary MEL excretions were 22 and 54 % of ingested MEL, respectively. Higher milk, urine and faecal MEL concentrations were observed with higher levels of dietary MEL. It was concluded that MEL appeared in the milk soon after first ingestion and a withdrawal period of 8 d was required for all milk, faecal and urine samples to reach undetectable levels of MEL. Urine and faeces were the primary routes for MEL excretion. The fourth trial was conducted to determine MEL absorption by the mammary gland in lactating dairy cows through arterio-venous (A-V) difference. Five cows received 10 g of MEL/d for three consecutive days. Day 3 of the trial was selected for commencement of blood sampling as previous studies (Cruywagen et al., 2009; Shen et al., 2010; Sun et al., 2011) reported the milk melamine concentration to reach a peak on d 3 of continuous melamine consumption by dairy cows. Early on d 3, catheters were inserted into the caudal superficial epigastric vein (milk vein) and caudal auricular artery. The blood sampling period commenced after residual milk removal from the udder following oxytocin administration. Blood from both locations were collected hourly for 9 hours. Following the final blood collection, oxytocin was administered again, catheters were carefully removed and cows were milked immediately thereafter. All blood samples were centrifuged and the decanted plasma was analysed for MEL, as well as for amino acid contents to calculate mammary blood flow. The positive MEL flux (calculated from A-V difference) confirmed net absorption of MEL into the mammary gland with an efficiency of absorption of 0.29%. Melamine excretion into milk was 5.63 mg/h. The mean plasma and milk MEL concentrations were 5.2 and 3.9 mg/kg, respectively. Melamine excretion efficiency to milk, expressed as percentage of the ingested amount, was 1.47%. It was concluded that melamine ingested by cows will result in net MEL absorption by the mammary gland, but that the absorption efficiency is low. The final trial of the study aimed to determine the effects that fermentation processes during the manufacturing of cheese, yoghurt and kefir would have on their MEL content if these products were made from MEL contaminated milk. Another objective was to determine if MEL in cheese would be degraded during the curing process. Cheese, yoghurt and kefir were made from milk with a MEL content of 6.77 mg/kg. The cheese was then cured for 2 wk at 6° C. The MEL contents of the yoghurt and kefir were 6.76 and 6.78 mg/kg, respectively, indicating that the different fermentation processes used in yoghurt and kefir production had no effect on their MEL content and that MEL was not degraded during the short fermentation periods. The percentage of milk MEL partitioned to whey and cheese were 97.4 and 6.5 %, respectively. It was concluded that the different fermentation processes involved during the manufacturing of yoghurt and kefir from MEL tainted milk did not decrease the MEL concentration. The milk MEL was predominantly partitioned to whey, with little MEL transferred to cheese. It was also concluded that MEL was not degraded in cheese during a 2-wk curing period. It was finally concluded that dietary MEL is readily absorbed by dairy cows and mainly excreted via the urine. The mammary gland has a low affinity for MEL absorption and approximately 2% of ingested MEL is excreted in the milk. When cheese is made from MEL tainted milk, the majority of MEL will concentrate in the whey fraction and only 6.5% will be present in the cheese. / AFRIKAANSE OPSOMMING: Vyf proewe is gedoen om in vitro- en in vivo-degradering, uitskeiding en absorpsie parameters van melamien (MEL) na te gaan waaroor daar min of geen inligting bekend was nie. Die eerste twee proewe was in vitro-studies, uitgevoer om die mate van MEL degradeerbaarheid in rumenvloeistof na te gaan, asook die invloed van MEL op rumen-NH3 en vlugtige vetsuur (VVS)-konsentrasies. Vir beide proewe is rumenvloeistof van lakterende, rumengekannuleerde Holsteinkoeie verkry. Vir die eerste en tweede in vitro-studies, was rumenvloeistof verkry vanaf drie en twee koeie, onderskeidelik. In albei proewe is 1 g substraat in Erlen-meyerflessies afgeweeg en 100 mL inkubasiemedium bygevoeg wat uit 20 mL rumenvloeistof en 80 mL van ‘n buffermedium bestaan het. In die eerste proef is 100 mg MEL by die substraat gevoeg, sodat die aanvanklike MEL konsentrasie in die flessies 1000 mg/L was. Die flessies is by 39° C geïnkubeer vir 0 (Kontrole), 6, 24 of 48 ure, onder streng anaerobiese kondisies. Met die beïndiging van die inkubasieperiode is 100 mL van ‘n 0.2 M perchloorsuuroplossing bygevoeg om enige melamien wat nie gedegradeer was nie, op te los. In al die proewe is melamienbepalings by wyse van LC/MSMS gedoen. Melamiendegradering was laag na 6 en 24 h inkubasie (3.2 en 5.5%, respektiewelik) en teen 48 h inkubasie het dit toegeneem tot 13.6%. In die tweede proef het die flessies 0 (Kontrole), 0.2 (T1) of 0.4 mg (T2) melamien bevat. Behandeling het geen invloed op individuele of totale VVS-konsentrasies by enige van die inkubasietye gehad nie en ook nie op NH3-konsentrasies by 6 en 48 h nie. Om een of ander onverklaarbare rede het die T2-behandeling gelei tot hoër NH3-konsentrasies by 24 h. Die gevolgtrekking is gemaak dat die byvoeging van MEL geen effek op rumen NH3-konsentrasies het nie en dat die mikroorganismes in die rumen nie daartoe in staat sal wees om MEL as ‘n stikstof-bron sal kan benut nie. In die derde proef is die uitskeiding van MEL in melkkoeie ondersoek. Vyf lakterende Holsteinkoeie is ewekansig aan vyf behandelings toegeken in ‘n 5 x 5 Latynsevierkantontwerp. Gedurende elke periode het koeie die behandelings vir 7 d ontvang, gevolg deur ‘n 8 d MEL-onttrekkingsperiode. Die eksperimentele diëte is geformuleer om ‘n daaglikse MEL-inname van 0 (M0), 500 (M1), 1000 (M2), 5000 (M3) of 10000 mg (M4) per koei/dag te verseker, toegedien via 15 kg/d van ‘n suiwelkonsentraat in pilvorm. Berekeninge gebasseer op die werk van Newton & Utley (1978) stel voor dat ‘n MEL inname van 0.16 g/kg lewende massa, geen negatiewe effek op herkouers se gesondheid sal hê nie. Dus, ‘n koei wat 600 kg weeg, sal geen skade lei deur die inname van 100 g MEL nie. In hierdie proef was die hoogste MEL behandeling (M4 = 10g/d) tien keer laer as die voorgestelde veiligheidsvlak van Newton & Utley (1978). Behandeling het geen invloed op DMI, melkopbrengs of melksamestelling gehad nie. Melamien is so gou as 8 h na eerste inname in die melk waargeneem, waarna die konsentrasie vinnig toegeneem het en ‘n piek na 3 d bereik het. Behandeling het geen invloed op die uitskeidingsdoeltreffendheid van melamien in melk gehad nie en waardes het gewissel van 1.5 tot 2.1%. Die gemiddelde skynbare verteerbaarheid van MEL was 78%. Die gemiddelde mis- en uriene-MEL-konsentrasies was 22 en 54%, onderskeidelik. Hoër melk-, mis- en uriene-MEL-konsentrasies is waargeneem namate die MEL-inhoud van die diëte gestyg het. Die gevolgtrekking is gemaak dat MEL spoedig na eerste inname in die melk verskyn en dat ‘n onttrekkingsperiode van 8 d benodig word voordat melk-, mis- en uriene-MEL onwaarneembare vlakke bereik. Uriene en mis is die primêre uitskeidingsroetes van ingenome MEL. Die vierde proef is onderneem om MEL-absorpsie in die melkklier met behulp van arterio-veneuse (A-V) verskille te ondersoek. Vyf koeie het elk 10 g MEL/d vir drie agtereen-volgende dae ontvang. Dag 3 van die proef is gekies vir bloedkolleksies aangesien vorige studies (Cruywagen et al., 2009; Shen et al., 2010; Sun et al., 2011) gewys het dat melk MEL op dag 3 van MEL inname, piek konsentrasies beryk. Vroeg gedurende die oggend van d 3 is kateters in die kaudale oppervlakkige epigastriese aar (melkaar) en die kaudale aurikulêre slagaar geplaas. Die bloedtrekkingsperiode het ‘n aanvang geneem direk nadat die koeie volledig uitgemelk is na toediening van oksitosien om te verseker dat soveel as moontlik residuele melk verwyder word. Monsters van veneuse-, sowel as arteriële bloed, is 9-uurliks geneem. Na die finale bloedtrekking is oksitosien weer toegedien, die kateters is versigtig verwyder en die koeie is direk daarna weer gemelk. Al die bloedmonsters is gesentrifugeer en plasmamonsters is ontleed vir MEL, asook vir aminosuursamestelling ten einde bloedtoevoer na die uier te bereken. Die positiewe fluks (bereken van A-V verskil) het bevestig dat netto MEL absorpsie in die melkklier plaasvind, met ‘n doeltreffendheid van 0.29%. Melamienuitskeiding in die melk was teen ‘n tempo van 5.63 mg/h. Die gemiddelde plasma- en melk-MEL konsentrasies was 5.2 en 3.9 mg/kg, onderskeidelik. Die uitskeidingsdoeltreffendheid van MEL na melk, uitgedruk as persentasie van ingenome MEL, was 1.47%. Die gevolgtrekking is gemaak dat MEL wat deur koeie ingeneem word, tot netto MEL-absorpsie in die melkklier sal lei, maar dat die absorpsiedoeltreffendheid baie laag is. In die finale proef is daar gepoog om die invloed van fermentasieprosesse gedurende die vervaardiging van kaas, joghurt en kefir op die produkte se melamieninhoud na te gaan indien die produkte van melamienbevattende melk gemaak sou word. ‘n Tweede doel van hierdie proef was om te bepaal of MEL in kaas gedegradeer kan word tydens rypwording. Kaas, joghurt en kefir is gemaak van melk wat ‘n MEL-inhoud van 6.77 mg/kg gehad het. Die kaas is vervolgens vir twee weke by 6° C rypgemaak. Die MEL-inhoud van die joghurt en kefir was 6.76 en 6.78 mg/kg, onderskeidelik, wat daarop dui dat die onderskeie fermentasieprosesse wat tydens die bereiding van joghurt en kefir plaasvind, geen invloed op hul MEL-inhoud gehad het nie en dat MEL nie gedurende hierdie kort fermentasieperiodes gedegradeer is nie. Die persentasie MEL na wei en kaas versprei was 97.4 en 6.5%, onderskeidelik. Die gevolgtrekking is gemaak dat die verskillende fermentasieprosesse betrokke tydens die vervaardiging van joghurt en kefir wat van melamienbesmette melk gemaak word, nie die MEL-konsentrasie verlaag het nie. Tydens die vervaardiging van kaas, word die MEL hoofsaaklik na die weikomponent versprei en baie min na kaas. Melamien word ook nie in kaas afgebreek gedurende ‘n verouderingsproses van twee weke nie. Die finale gevolgtrekkings is gemaak dat MEL maklik deur melkkoeie geabsorbeer word en dat die hoof uitskeidingsroete via urine is. Die uier het ‘n lae affiniteit vir MEL absorpsie en ongeveer 2% van ingenome MEL is in die melk uitgeskei. Wanneer kaas van MEL besmette melk gemaak word, sal die meerderheid van die MEL in die weifraksie konsentreer, met slegs 6.5% teenwoordig in die kaas. / The Hennie Steenberg Trust Fund, the Ernst and Ethel Erickson Trust and the National Research Foundation (NRF) for their financial support

Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The ostrich industry is a predominantly quantitative industry; focused mainly on the production of large numbers of slaughter birds for maximum meat and leather yield. Competing in the international market in the current economic environment necessitates a more qualitative approach. Productivity and product quality are aspects that need to be improved in order to stay competitive and economically viable. Genetic parameters for ostrich slaughter traits are lacking, however, and breeding programs are yet to be developed. Data on quantitative and qualitative production and slaughter traits from a commercial ostrich breeding flock was consequently analysed to establish the relative importance of genetic and non-genetic influences on these traits. Genetic and environmental (co)variances as well as estimates of heritability, genetic and phenotypic correlations were estimated for and among the various traits using standard software for multi-trait genetic analyses. Substantial variation, high and favourable genetic correlations as well as moderate to high heritability estimates were found among, and for distinguished body weight traits of growing ostriches. Heritability estimates of 0.14, 0.22, 0.33, 0.43 and 0.43 for 1-month, 4-month, 7-month, 10-month and 13-month-old ostrich weights were estimated in a five-trait animal model analysis. All carcass component weight traits, with the exception of the weight of the liver, showed significant genetic variation. No significant maternal permanent environmental variance was evident for these traits. Heritability estimates ranged from 0.21 (for subcutaneous fat weight) to 0.45 (for neck weight) in multi-trait analyses. The only potentially unfavourable correlation was a high genetic correlation between live weight and subcutaneous fat weight, as fat is considered as a waste product in the present system. The heritability estimates for individual muscle weights ranged from 0.14 to 0.43, while the genetic correlation between these weights and pre-slaughter live weight were all positive, ranging from 0.59 to 0.82. When meat quality traits were analysed it was evident that lightness (L*) and ultimate pH (pHu) showed significant genetic variation, with heritability estimates of 0.37 and 0.42, respectively. L* and pHu were negatively correlated (-0.65 ± 0.19). Since pH is an indicator of various meat quality parameters, it could be considered as an appropriate selection criterion for enhanced meat quality. With the exception of skin grading and crown length, all quantitative and qualitative skin traits showed significant genetic variation. Nodule traits were accordingly moderate to highly heritable. A negative, but favourable, correlation between weight and hair follicle score was ascertained, as hair follicles is a defect that should be selected against. This study demonstrated that sufficient genetic variation exists for most slaughter traits to allow sustained genetic progress for these traits, should it be desired as part of the overall selection objective. Combining some of the current economically important slaughter traits in a provisional selection index, it was clear that weight and crust skin size contributed most to monetary gain (approximately 54 and 38%, respectively). It was also demonstrated with this simple index that monetary gains in slaughter bird production should be easy to achieve at all levels of production performance and data recording. / AFRIKAANSE OPSOMMING: Die volstruisbedryf is hoofsaaklik ‘n kwantitatiewe bedryf wat meerendeels fokus op die produksie van groot getalle slagvolstruise vir die produksie van vleis en leer. Siende dat die bedryf hoofsaaklik op uitvoere fokus, word aanvaar dat ‘n verandering in strategie na ‘n meer kwalitatiewe benadering nodig is, in ag geneem die huidige ekonomiese situasie en marktoestande. Produktiwiteit sowel as produkgehalte moet in ag geneem word vir die bedryf om lewensvatbaar te bly. Daar is egter ‘n gebrek aan genetiese parameters vir volstruisslageienskappe, terwyl doeltreffende teeltstelsels nog ontwikkel moet word. Data van kwantitatiewe en kwalitatiewe produksie- en slageienskappe is gevolglik van ‘n kommersiële volstruis teeltkudde verkry en ontleed om die relatiewe belang van genetiese en nie-genetiese effekte op die eienskappe te kwantifiseer. Genetiese- en omgewings (ko)variansies, asook beramings van oorerflikheid sowel as genetiese en fenotipiese korrelasies, is vervolgens vir en tussen die onderskeie eienskappe beraam deur van standaard sagteware vir veelvuldige-eienskap genetiese ontledings gebruik te maak. Aansienlike variasie, hoë en meestal gunstige korrelasies, sowel as matige tot hoë oorerflikhede, is tussen en vir die onderskeie ligaamsgewigte van groeiende volstruise gevind. Oorerflikheidsberamings van 0.14, 0.22, 0.33, 0.43 en 0.43 is vir 1-maand, 4-maande, 7-maande, 10-maande en 13-maande-oue volstruise in ‘n vyf-eienskap dieremodel ontleding gekry. Alle karkaskomponentgewigte, met die uitsondering van die gewig van die lewer, het betekenisvolle genetiese variasie getoon. Oorerflikheidsberamings het tussen 0.21 (vir onderhuidse vetgewig) en 0.45 (vir nekgewig) gevarieer in veelvuldige-eienskapontledings. Die enigste moontlike ongunstige korrelasie was tussen liggaamsgewig en onderhuidse vetgewig, siende dat vet as ‘n afvalproduk gereken word in die huidige stelsel. Die oorerflikhede van die gewigte van indiwiduele spiere het van 0.14 tot 0.43 gevarieer, terwyl die genetiese korrelsies tussen hierdie gewigte en voorslaggewig deurgaans positief was, met waardes wat van 0.59 tot 0.82 gewissel het. Tydens die ontleding van vleisgehalte eienskappe was dit duidelik dat ligtheid (L*) en uiteindelike pH (pHu) genetiese variasie getoon het, met oorerflikheidsberamings van onderskeidelik 0.37 en 0.42. L* en pHu was negatief gekorreleerd op die genetiese vlak (-0.65 ± 0.19). Aangesien pH ‘n aanduiding is van verskeie vleisgehalteparameters, kan dit moontlik as ‘n indirekte seleksie-kriterium vir verbeterde vleisgehalte gesien word. Alle kwantitatiewe en kwalitatiewe veleienskappe het genetiese variasie getoon, met die uitsondering van velgradering en kroonlengte. Knoppie-eienskappe van die veerfollikels op die vel was ooreenstemmend matig tot hoog oorerflik. ‘n Negatiewe, maar gunstige, genetiese korrelasie is tussen liggaamsgewig en haarfollikelpunt beraam, siende dat haarfollikels ‘n defek is waarteen daar geselekteer moet word. Hierdie studie dui op voldoende genetiese variasie vir die meeste slageienskappe om voldoende genetiese vordering te verseker indien dit verlang sou word. Somminge van hierdie eienskappe wat tans van ekonomiese belang is, is vervolgens in ‘n voorlopige seleksie-indeks gekombineer. Dit was duidelik dat liggaamsgewig en velgrootte die meeste tot monetêre vordering bygedra het (onderskeidelik ongeveer 54 en 38%). Dit is vervolgens aangetoon dat monetêre vordering maklik haalbaar behoort te wees op alle vlakke van produksieprestasie en data-aantekening.

Thesis (PhD(Agric) (Agriculture))--University of Stellenbosch, 2009. / Traditionally, agricultural land was regarded mainly as a production factor. Accordingly, in their application of the market sales comparison approach to agricultural land, valuers relied on a set of attributes related to agricultural production as the primary determinants of an agricultural property’s highest and best use (HBU) and market value. These characteristics were measurable and related to the property’s income-generating capacity. The emergence of a multi-functional rural land market with alternative uses of agricultural land, such as for lifestyle purposes, has transformed this concept. Lifestyle inspired buyers often focus on a wider range of attributes not necessarily related to income, but associated more with satisfaction derived from the property. This creates a measurement problem for agricultural land valuers, as the characteristics valued by lifestyle buyers are more intangible and subjective, which leave valuers without a base from which to value such properties. The presence of lifestyle inspired buyers makes agricultural land valuations more demanding as it implies different interpretations of the same farm and complicates the choice of a single HBU. The continued use of familiar conventional farming attributes by valuers when valuing farms where lifestyle motivations are present, and the omission of less measurable characteristics, implies that the market sales comparison method cannot be executed accurately. The objectives of the study were twofold: to reveal the dominance of value attributes applicable to farming as HBU when valuing farms bought primarily for lifestyle purposes and to identify the characteristics of land important to lifestyle inspired farm buyers.

Thesis (PhD(Agric) (Animal Sciences))--University of Stellenbosch, 2005. / As most researchers have foreseen, and many breeders have hoped, the in vivo and in vitro production of livestock embryos and the birth of subsequent offspring never really replaced artificial insemination during the past 30 years. This was, to a large extent, due to very variable and unreliable numbers of embryos produced using these two methods. The present study was therefore undertaken to investigate certain aspects of assisted reproductive techniques (ART) to try and solve some of these difficulties. Problems addressed were the management of follicular development on the ovary by controlling the dominant follicle, and investigating alternative and more cost-effective culture media and conditions for embryo culture. A method to control the development of the dominant follicle in a cohort of follicles as well as the waves of follicular development in the ovaries of sheep, goats and cows with an estrogenic product was investigated. Estradiol cypionate (ECP) was used for this purpose, injected intramuscularly after the insertion of the progesterone or progestagen implant. ECP has a negative feedback effect on the secretion of pituitary FSH, and therefore follicular development. The animals of the three different species were randomly divided into two groups each, the ECP-group receiving the estradiol cypionate injection, and the control group receiving a saline injection. Five days after the ECP injection a program of follicular multi-stimulation with FSH hormone was initiated. The females of the different species were bred by either natural service (goats) or inseminated by laparoscopy (sheep) or trans-cervically (cows) to fertilize the ovulated ova. Embryos and unfertilized ova were collected surgically at the 8 to 16- cell stage 3 to 4 d after breeding in the sheep and goats, and trans-cervically in the cows. Significantly more CL formed, and a total number of ova and embryos, as well as transferable embryos, were collected from the ECP-group of sheep ewes and goat does compared to the control group that received no ECP (p<0.01). There was, however, no difference in the average number of unfertilized ova that were collected in the two sheep or goat groups. In the cows the number of CL counted, the total number of embryos and ova and of transferable embryos collected, were significantly greater (p<0.05) in the group that were injected with ECP compared to the group that received no ECP. The control group also had a significantly larger number of unfertilized ova than the ECP-group (p<0.05). It could therefore be concluded that more reliable numbers of embryos can be produced in vivo if the development of the dominant follicle as well as the subordinate follicles is controlled with estradiol cypionate. Since more than half a century ago, attempts have been made to culture cells and embryos outside the body (in vitro or ex vivo). This was done with different culture media and in various "incubators". Chapter 2 deals with two different culture media used: a standard TCM-199 culture medium and first trimester amniotic fluid (BAF) collected sterilely from pregnant cows after slaughter. Two different culture conditions were also investigated, the standard laboratory CO2 incubator versus culturing bovine embryos in the vagina of a goat doe. Two experiments were done: Firstly the permeability of different receptacles to CO2 gas was analyzed for possible culture in the vagina. Four-well plates and straws were used to incubate TCM-199 and BAF for a period of 120 h in the presence or absence of 5% CO2 gas. The pH values were measured every 24 h and recorded. In the second experiment pre-compacted morula stage bovine embryos were incubated in the above culture media in sealed 0.25 mL straws in a standard laboratory incubator and in the vagina of a goat doe. Evaluation was done on (1) stage of development and (2) number of blastomeres after 96 h of culture. In experiment one it was shown that the CO2 gas diffused out of the 4-well plate as well as the straws in the absence of CO2 gas, while in the presence of CO2, the pH of both media stabilized between 7.3 and 7.5. This meant that the semen straws were permeable to CO2 gas and could therefore be used as receptacles for culturing early stage bovine embryos. In the second experiment no statistical differences (p>0.05) were found in the number of Grade 1 pre-compacted bovine embryos that developed to the blastocyst stage, or the hatched blastocyst stage, neither for the culture medium used, or the method of culturing in the two incubators. Neither was there any difference (p>0.05) in the number of blastomeres that developed at the blastocyst stage between the two types of incubators used. Embryos tended to develop more blastomeres when cultured in BAF than when cultured in TCM-199 in both the standard laboratory incubator and when using the vagina of a goat doe as an incubator (p<0.05). After the collection of in vivo produced livestock embryos, they are evaluated under high magnification (minimum of 80X) with the aid of an inverted or stereo microscope. The Grade 1 embryos will give the best conception results when transferred to synchronized recipient female animals, while the Grade 3 embryos will give the worst results. The aim of the next experiment was to culture all three quality grades of in vivo produced pre-compacted morula-stage embryos of sheep, goats and cows in two different culture media and then compare the development of the embryos by evaluating the number of embryos reaching the hatched blastocyst stage. The results have shown that there were no significant differences between the development of the Grade 1 and the Grade 2 embryos from any of the three species when either cultured in TCM- 199 or heat inactivated early pregnancy-stage (<60 d) bovine amniotic fluid (BAF) were used as culture media. Significantly more in vivo produced Grade 3 pre-compacted morula-stage sheep, goat and cow embryos, however, developed to the hatched blastocyst stage when cultured in BAF with 10% FBS and antibiotics, compared to culture in TCM-199 with 10% FBS and antibiotics (p<0.05). The effect of co-culture on the survival of caprine embryos post transfer to a synchronized recipient female goat was also assessed. A total of 120 Kashmir embryos at the blastocyst stage were divided into three groups after thawing and reconstitution in four steps in glycerol and sucrose medium. The first group of embryos (G1, n=40) was individually transferred semi laparoscopically in D-PBS with 10% FBS and antibiotics to the ipsilateral horn of the CL over a period of 3 d. The second group of caprine blastocysts (G2, n=40) was similarly transferred in TCM-199 with FBS and antibiotics. The third group of frozen-thawed caprine blastocyst-stage embryos (G3, n=40) were first co-cultured for ~24 h in TCM-199 with serum and antibiotics in groups of up to five embryos inside a ~50 mm length of a semen straw in a cylindrical sponge in the anterior part of the vagina of a goat doe in her luteal phase. After the culture period these embryos were transferred in a similar way in TCM-199 without the co-culture as in G1 and G2. Ultrasound scanning showed that significantly more of the blastocyst embryos that were cocultured in the vagina (G3) before transfer developed to a pregnancy compared with the embryos transferred in D-PBS (G1). The co-culture Group 3 blastocyst-stage caprine embryos produced significantly more offspring than the non-cultured embryos transferred in both D-PBS (G1) and TCM-199 (G2) (p<0.05). The maturation of bovine oocytes to allow the oocyte to resume meiosis, is the first step in in vitro fertilization to produce IVMFC embryos. The composition of the maturation medium plays an important role in the success achieved with maturation. An investigation was therefore launched to evaluate the maturation ability of first trimester bovine amniotic fluid (BAF) to mature prophase I oocytes collected from abattoir ovaries to metaphase II oocytes, compared to a standard maturation medium such as TCM-199. In the first experiment three groups of ~100 oocytes each were matured in TCM-199 with estrus cow serum (ECS). The first group of oocytes was matured in a 50 μL micro-drop in an incubator, while the other two groups were matured in semen straws, one group in an incubator and the other group in the vagina of a goat doe in di-estrus. Six further groups of ~100 oocytes each, with BAF as maturation medium, three groups with ECS and three without ECS, were matured in the same receptacles and under the same conditions as with the TCM-199. No significant differences in number of oocytes reaching the metaphase II stage could be found for any of the nine treatment groups. In the ...

Thesis (PhD (Animal Sciences))--Stellenbosch University, 2011. / ENGLISH ABSTRACT: The Dorper sheep breeders developed their own linear type scoring system based on a 5-point scale which assesses Conformation, Size, Type, Fat distribution and Colour. For many decades Dorper sheep breeders have been so consistent with adherence to these breed standards without paying much attention to performance testing of their stud animals. However, there is a paucity of information pertaining to the genetic relationships between visually assessed traits and objectively measured growth, reproduction and fitness traits in the breed. Slow genetic gains in Dorper production traits are assumed to be caused by over-accentuation of type traits but those assumptions needed to be scientifically validated. It was therefore vital to derive these relationships as they could have a negative impact on genetic progress in the event that some antagonisms existed. Against this background, the major objectives of this study were to estimate genetic parameters and trends for production, reproduction, fitness and subjective traits using data extracted from National Small Stock Improvement Scheme (NSIS). Furthermore, the study correlated performance data with subjectively assessed traits to derive genetic relationships between them to establish the effect of selecting Dorper sheep on breed standards has on objective traits of economic importance. Genetic parameters and relationships were estimated for subjectively assessed and objectively measured traits using linear and threshold methods. Linear methods were applied via the implementation of Residual Maximum Likelihood (REML) procedures and Bayesian methods were implemented through Gibbs sampling. It was established through the implementation of single-trait and multi-trait analyses that live weight and growth traits were moderately to highly heritable. Maternal effects were also significant for such traits. Subjectively assessed traits were demonstrated to be lowly to moderately heritable using both linear and threshold methods. There were positive genetic and environmental correlations between live weight, growth and subjectively assessed traits with the exception of Colour. There was favourable selection response to live weight and growth traits in a Dorper flock, with the exception of average daily gain during the post weaning phase where there was a slight negative trend. Subjectively assessed traits with the exception of Size responded favourably to selection. It was concluded that breeders should consider removing Colour from their breeding objectives, and focus more on selecting animals based on BLUP breeding values of objectively measured traits. The across flock genetic evaluation of all Dorper records demonstrated through the implementation of both linear and threshold methods that reproduction and fitness traits were lowly to moderately heritable and exhibited favourable genetic correlations amongst themselves. It was further established that ewe rearing ability, ewe stayability and ewe productive life are lowly heritable and have some favourable correlations with component traits of reproduction. There was little genetic change in reproduction and fitness traits, but traits generally deteriorated where significant trends were found. It was concluded that breeders should select their animals on objectively measured production and reproduction traits and not put as much emphasis on breeding standards. / AFRIKAANSE OPSOMMING: Die Dorper skaaptelers het hul eie liniêre puntestelsel ontwikkel wat op ‘n 5-punt skaal bouvorm, grootte, tipe, vetverspreiding en kleur beoordeel. Dorper skaaptelers se fokus was vir baie dekades om hierdie rasstandaarde na te kom, sonder om aandag te gee aan die prestasietoetsing van hul stoetdiere. Rasverbetering in die Dorperskaapras is gebaseer op subjektiewe beoordeling van eienskappe soos dit in die skouring bepaal word. Daar is egter ‘n gebrek aan inligting aangaande genetiese verwantskappe tussen visueel beoordeelde eienskappe en objektiewe eienskappe soos groei, reproduksie en fiksheid. Dit word aangeneem dat stadige genetiese vordering in produksie-eienskappe van Dorpers deur ‘n oorbeklemtoning van tipe eienskappe veroorsaak word, maar hierdie aannames moet wetenskaplik bewys word. Daarom is dit uiters belangrik om die verwantskappe tussen subjektiewe en objektiewe eienskappe te bepaal, aangesien hulle ‘n moontlike negatiewe effek op genetiese vordering mag uitoefen as daar wel antagonismes bestaan. Teen hierdie agtergrond is die hoofdoelwitte van hierdie studie om prestasiedata vanuit die Nasionale Kleinveeverbeteringskema (NSIS) te onttrek en die beraming van genetiese parameters en tendense vir produksie, reproduksie, fiksheid en subjektiewe eienskappe. Verder het hierdie studie prestasiedata met subjektiewe beoordeelde eienskappe gekorreleer om genetiese verwantskappe tussen subjektiewe en objektiewe eienskappe te bepaal. Genetiese parameters en -verhoudings was beraam vir subjektief beoordeelde en objektiewe gemete eienskappe met die gebruik van lineêre- en drumpelwaardemetodes. Lineêre metodes is toegepas d.m.v die implementering van Residuele Maksimum Waarskynlikheid (REML) prosedures en die Bayesiaanse metodes deur Gibbs steekproefneming. Dit is bevestig dat dat liggaamsgewig en groei-eienskappe matig tot hoog oorerflik is. Maternale-effekte het ook ‘n beduidende invloed op hierdie eienskappe gehad. Subjektiewe eienskappe is laag tot matig oorerflik, volgens beide lineêre en drempelwaarde metodes. Daar was positiewe genetiese- en omgewingskorrelasies tussen liggaamsgewig, groei en subjektiewe eienskappe, met die uitsondering van kleur. Daar was ‘n gunstige seleksie respons vir liggaamsgewig en groei-eienskappe met die uitsondering van gemiddelde daaglikse toename gedurende die na-speense fase wat ‘n afname in die gemiddelde voorspelde teelwaardes getoon het. Subjektiewe eienskappe, met die uitsondering van grootte, het in die studietydperk geneties verbeter. Die gevolgtrekking is dat telers dit moet oorweeg om kleur (subjektiewe eienskap) van hul teeldoelwitte te verwyder en om diere op BLUP teelwaardes van objektiewe eienskappe moet selekteer. Die genetiese evaluasie van die nasionale kudde het getoon dat reproduksie- en fiksheidseienskappe laag tot matig oorerflik is en gunstige korrelasies onderlings toon. Dit is verder bevestig dat grootmaakvermoë, terughouvermoë en produktiewe leeftyd laag oorerflik is, en sekere gunstige korrelasies met die komponente van reproduksie toon. Daar was geen genetiese verandering in reproduksie en fiksheid eienskappe in die nasionale kudde nie, moontlik omdat geen seleksie toegepas is nie, a.g.v ‘n oorbeklemtoning van rasstandaarde. Die gevolgtrekking is dat telers diere moet selekteer gebaseer op produksie en reproduksie eienskappe, en minder klem lê op rasstandaarde.

Thesis (PhD (Animal Sciences))--Stellenbosch University, 2011. / ENGLISH ABSTRACT: The current study was undertaken to determine the effectiveness of the current South African chicken conservation programmes in conserving the genetic diversity of village chicken populations. Village chicken farmer’s production constraints such as feed availability, chicken mortality, prevalence of diseases and chicken sales were influenced by gender, age, wealth status, production system, chicken flock size, type of chicken breed owned, accessibility of veterinary services, availability of supplements, vaccines and shelter. Considerable phenotypic heterogeneity in qualitative traits of indigenous chicken populations and their distributions in different regions of South Africa revealed the absence of selection on a preferred phenotype, showing that the population is not standardized. Genetic diversity studies using both microsatellites and mtDNA markers demonstrated that the conservation flocks of South African chickens displayed considerable genetic variability that is different from that of the assumed founder populations (field chicken populations). The indigenous chicken mtDNA further revealed multiple maternal lineages in South African chickens, where conservation flocks and field chicken populations shared these major haplotypes A, D and E which are presumed to be of Chinese, South East Asia and Indian subcontinent origin, respectively. The overall findings of the study increased awareness of the importance of genetic management and utilization of indigenous chicken genetic resources of South Africa. As a result, the study provides a base-line dataset to complement the decision-making process on designing proper conservation strategies for South African indigenous chicken genetic resources. / AFRIKAANSE OPSOMMING: Die huidige studie is onderneem om die doeltreffendheid van die Suid-Afrikaanse hoenderbewarings programme in die bewaring van genetiese diversiteit in dorphoender bevolkings. Dorp hoenderboere se produksie beperkinge soos voerbeskikbaarheid, hoender mortaliteit, die voorkoms van siektes en hoenderverkope word beïnvloed deur geslag, ouderdom, rykdom status, produksie sisteem, hoender kudde grootte, tipe hoenderras, toegang tot veeartsenydienste, beskikbaarheid van supplemente, inentstowwe en skuiling. Merkbare fenotipiese variasie in kwalitatiewe eienskappe van die inheemse hoenderbevolking en hul verspreiding in verskillende areas van Suid-Afrika, is aanduidend dat daar nie seleksie plaasvind vir ‘n voorkeur fenotipe nie, wat dus toon dat die bevolking nie gestandardiseer is nie. Genetiese diversiteit studies met behulp van beide mikrosatelliete en mtDNA merkers het getoon dat die bewaringskuddes van Suid- Afrikaanse hoenders vertoon merkbare genetiese variasie wat verskil van die veronderstelde stigter bevolkings (veldhoender populasies). Die inheemse hoenders mtDNA het verder onthul dat verskeie moederlike afstammelinge in die Suid Afrikaanse hoenders, major haplotipes A, D, E wat afkomstig is vanaf die Chinese, Suid-Oos Asië en die Indiese subkontitent onderskeidelik; gedeel word saam met die bewaringskuddes en die veldhoender populasie. Die algemene bevindige van die studie verhoog die bewustheid van die belangrikheid van genetiese bestuur en benutting van inheemse hoender genetiese hulpbronne van Suid-Afrika. As gevolg hiervan, verskaf die studie ‘n basis-lyn datastel vir die besluitnemingproses oor die ontwerp van ‘n ordentlike bewaring strategieë vir die Suid-Afrikaanse inheemse hoender genetiese hulpbronne.