Thesis (MScAgric (Agronomy)--University of Stellenbosch, 2007. / Soil salinity is a serious constrain to crop production in many countries. In the Western Cape canola production area, large variability in soil properties within the same field is a very common feature. Some of this variability may be ascribed to differences in salinity. These saline patches affected the germination and survival of cereal crops like wheat and may therefore also be a reason for the high variability and generally low canola yields obtained in this area. It will therefore be important to quantify the effect of such saline conditions on the germination and seedling establishment of canola in an effort to improve yields. In this study several experiments were conducted under controlled conditions in either Petri dishes in an incubator or pots in a temperature controlled glasshouse to determine the salinity response of canola. Results of the experiments done in Petri dishes, showed that the germination response of canola (Brassica napus L., cv. Tornado) to increasing levels of salinity is very similar to that of wheat (Triticum aestivum L., cv SST 88). Although canola germinated more rapidly than wheat at a temperature of 20 ºC, the final percentage germination for both crops decreased severely when NaCl induced salinity exceeded levels of an EC of 8 dS m-1, but less severe responses were obtained with NaCl/CaCl2 induced salinity. Under soil conditions an interaction between soil type and salinity level showed that the responses in sandy soil to an increase in salinity from 0 to 8 iv dS m-1 were less severe than in loamy soil and especially when salinity stress was induced by NaCl. Although cultivar Spektrum showed more tolerance to saline conditions during the germination and seedling stages in pot experiments when compared to other cultivars tested, these results will have to be confirmed in field trails where grain yield and quality can be measured.

Thesis (MScAgric (Agronomy))--University of Stellenbosch, 2011. / Includes bibliography. / ENGLISH ABSTRACT: Little is known about the nutrient requirements of broccoli grown for seed production. During 2006 and 2007 broccoli were grown for seed production in sand bags in a net structure, using a drain to waste hydroponic system. The experimental design was a randomized complete block with seven treatments replicated in four blocks. In 2006 seven nutrient solution treatments were tested. The Standard solution based on Steiner’s universal solution was compared with different levels of N, S, K and Ca with regard to the effect on total biomass, nutrient concentration, nutrient assimilation, seed yield and quality. No significant differences in total biomass produced were found. Total dry mass increased by 225% from the mature head stage until harvest of seed. Nutrient concentration in plant samples were not influenced by treatments except where low levels of K and S in nutrient solutions led to significantly lower levels of K and S concentrations. The total assimilation of elements were calculated to determine the effect of the much longer growth period needed for seed production in comparison to normal head production on nutrient requirements. Major elements assimilated ha-1 was: N 173.0 kg, P 35.5 kg, K 348.4 kg, Ca 114.7 kg, Mg 30.5 kg, S 42.2 kg. The seven treatments used during 2007 included three of the treatments which were used in 2006 as well as treatments with foliar sprays containing Ammonium Nitrate and Calcium Metalosate. The standard solution treatment was also used in 2007 to compare results with 2006. Plant analysis done on plants from the standard solution (2006 & 2007) showed similar trends. As the plants developed towards maturity there was a relative increase in concentration in the top plant parts (pods, flowers and stems) for Ca, Mg and S. Contrary, N and P concentration declined. The minor elements, Fe, Mn and B also increased in concentration in the top plant parts at harvest indicating a strong relative flow of these elements to the top plant parts towards maturation. Concentration values of major elements in plant samples were generally different when the two years were compared. Element concentrations in the seed pods were in general higher than in the rest of the plant indicating the pods as a strong sink on the plants. During both years the two best nutrient solutions for yield were the same, namely the Standard solution and Standard - K which contain low levels of K. During 2006 no significant differences in seed quality were found. During 2007 no significant differences were found for seed quality measurements, except for size (of the cotyledons). The results indicate that no special adjustments need to be made to the Standard solution in order to produce good broccoli seed yield of good quality. As substantial differences in nutrient solution composition did not significantly affect the quality of broccoli seed produced. Seed yield was however significantly affected by nutrient solution composition. Key words: Brassica seed, broccoli seed, seed production, broccoli nutrition, hydroponic production, broccoli production, nutrient assimilation. / AFRIKAANSE OPSOMMING: Min inligting is bekend rakende die voedingsbehoeftes van brokkoli wat gekweek word vir saadproduksie. Gedurende 2006 en 2007 is brokkoli gekweek vir saadproduksie in sakke sand in ‘n net struktuur met ‘n oop hidroponiese besproeiingstelsel. Die proefontwerp was ‘n ewekanisige geheel blok met sewe behandelings wat ewekansig binne bloke toegeken is en herhaal is in vier blokke. Sewe voedingsmengsel behandelings is gedurende 2006 toegepas. Die Standaard mengsel is geskoei op Steiner se universele mengsel en dit is vergelyk met verskillende vlakke van N, S, K en Ca t.o.v. die invloed daarvan op biomassa produksie, voedingselement konsentrasie, voedingselement assimilasie, saad opbrengs en saad kwaliteit. Biomassa geproduseer het nie wesenlik verskil nie. Totale droë massa het met 225% toegeneem vanaf die volwasse kop tot die oes stadium. Die konsentrasie van voedings elemente in plant monsters is nie beïnvloed deur behandelings nie behalwe in gevalle waar lae konsentrasies van K en S in die voedingsmengsels gelei het tot lae konsentrasies van K en S in plantontledings. Die totale opname van voedingselemente is bereken om die effek van die veel langer groeiperiode wat benodig word vir saadproduksie in vergelyking met normale kop produksie te bepaal t.o.v. voedingselement behoefte. Makro element opname per hektaar was as volg: N 173.0 kg, P 35.5 kg, K 348.4 kg, Ca 114.7 kg, Mg 30.5 kg, S 42.2 kg. Die sewe behandelings van 2007 het drie behandelings van 2006 ingesluit asook behandelings van blaarbespuitings met Ammonium Nitraat en Kalsium Metalosaat. Die Standaard voedingsmengsel is weer gebruik ten einde die resultate van 2006 en 2007 te vergelyk. Voedingselement ontledings op plante van die Standaard mengsel (2006 & 2007) is vergelyk en het soortgelyke tendense aangedui. Soos wat plante ontwikkel het na volwassenheid was daar ‘n relatiewe toename in konsentrasie in die boonste plant dele (peule, blomme en stele) van Ca, Mg en S. In teenstelling hiermee het die konsentrasies van N en P afgeneem. Die mikro elemente Fe, Mn en B het ook in konsentrasie toegeneem in die boonste plant dele teen oes wat daarop dui dat daar ‘n sterk relatiewe vloei van hiedie elemente na die boonste plant dele plaasvind met volwasse wording. Die konsentrasie vlakke van makro elemente in plantontledings het in die algemeen wesenlik verskil tussen die twee jare. Die voedingselement konsentrasies was in die algemeen hoër in die saad peule as in die res van die plant wat daarop dui dat die peule as ‘n sterk sink op die plant funksioneer. In beide jare was die hoogste opbrengs afkomstig van die Standaard voedingsmengsel en die Standaard – K mengsel wat lae vlakke van K bevat het. Gedurende 2006 is geen wesenlike verskille in saadkwaliteitsnorme gevind nie. Soortgelyke resultate is gevind in 2007 behalwe vir grootte van die kiemblare. Die resultate dui daarop dat dit nie nodig is om die Standaard voedingsmengsel samestelling te verander ten einde goeie opbrengs saad van goeie gehalte te produseer nie. Wesenlike verskille in voedingsmengsels het geen invloed op die kwaliteit van brokkoli saad gehad nie. Saad opbrengs is egter wesenlik beïnvloed deur die samestelling van die voedingsmengsels. Sleutel woorde: brassica saad, brokkoli saad, saad produksie, brokkoli voeding, hidroponiese produksie, brokkoli produksie, voedingstof assimilasie.

Thesis (MScAgric)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: This study was done during 2010 and 2011 as a component study within a long-term crop rotation/soil tillage trial that was started in 2007 at the Langgewens Research Farm near Moorreesburg in the Western Cape Province of South Africa. The aim of this study was to determine the effect of crop rotation and soil tillage on the soil moisture content, mineral-N levels of the soil, leaf area index, chlorophyll content of the flag leaf, biomass production, grain yield and grain quality of spring wheat (Triticum aestivum L). The experimental layout was a randomised complete block design with a split-plot treatment design replicated four times. Wheat monoculture (WWWW), lupin-wheatcanola- wheat (LWCW) and wheat-medic (McWMcW) crop rotation systems were included in this study and allocated to main plots. This study was confined to wheat after medic/clover, wheat after canola and wheat monoculture. Each main plot was subdivided into four sub-plots allocated to four tillage treatments namely: Zero-till (ZT) – soil left undisturbed until planting with a star-wheel planter No-till (NT) – soil left undisturbed until planting and then planted with a no-till planter Minimum-till (MT) – soil scarified March/April and then planted with a no-till planter Conventional-till (CT) – soil scarified March/April, then ploughed and planted with a no-till planter. Soil samples were collected every two weeks from just before planting until before harvest, from which gravimetric soil moisture and total mineral-N (NO3--N and NH4+-N) were determined. Plant samples were collected every four weeks until anthesis, starting four weeks after emergence. From these leaf area index and dry-matter production were determined. Chlorophyll content and light interception were measured at anthesis. At the end of the growing season the total biomass, grain yield and grain quality was determined. Crop rotations which included medics (McWMcW) or canola/lupins (LWCW) led to higher mineral-N content of the soil at the start of the 2011 growing season when compared to wheat monoculture, but did not have an effect on soil moisture. Conservation tillage (minimum- and no-till) practices resulted in higher soil moisture whilst conventional-till resulted in the highest mineral-N content for 2010. There was however no differences in mineral-N content between tillage methods for 2011, whilst soil moisture content was affected in the same way as the previous year. Both crop rotation and tillage influenced crop development and biomass production. In general, increased soil disturbance together with wheat after medics and wheat after canola resulted in better development of the wheat crop with regards to dry matter production and leaf area index. The positive effect of medic and canola rotations was also evident on chlorophyll content and light interception. Grain yield was positively influenced by wheat after medics and wheat after canola, with both systems out-yielding wheat monoculture in 2010 and 2011. Minimum- and no-till resulted in the highest grain yield in both years. Crop rotation and tillage practice showed no clear trends with regards to grain quality. This illustrated the important effect of environmental conditions during grain-filling. Environmental factors such as rainfall and temperature had significant effects in both years of the study, but the importance and advantages of crop rotation, especially with a legume crop such as medics included, was evident even though this component study was done early in terms of the long-term study. The positive effect of implementing conservation tillage practices such as minimum- and no-till were also clearly shown in results obtained throughout this experiment. / AFRIKAANSE OPSOMMING: Die studie is gedurende 2010 en 2011 uitgevoer as ‘n deelstudie van ‘n langtermyn grondbewerking- en wisselbouproef op die Langgewens proefplaas naby Moorreesburg in die Wes-Kaap Provinsie van Suid-Afrika. Die doel van hierdie studie was om die effek van grondbewerking en wisselbou op grondvog, minerale stikstof in die grond, blaaroppervlakindeks, chlorofilinhoud van die blare, graanopbrengs en -kwaliteit van lente koring (Triticum aestivum L) te kwantifiseer. Die eksperiment is uitgelê as ‘n volledig lukrake blokontwerp met ‘n verdeelde perseel ontwerp met vier herhalings. Wisselboustelsels wat aan hoofpersele toegeken is sluit koring monokultuur (WWWW), lupien-koring-kanola-koring (LWCW) en medic-koring (McWMcW) in. Grondbewerking is toegeken aan subpersele. Die grondbewerkingsbehandelings het ingeslui: Zero-bewerking (ZT) – die grond is onversteurd gelaat en koring is met ‘n sterwielplanter geplant, Geen-bewerking (NT) – die grond is onversteur gelaat tot en met planttyd waar koring met ‘n geenbewerking (no-till) planter geplant is, Minimum-bewerking (MT) – die grond is in Maart/April met ‘n tandimplement bewerk en met ‘n geen-bewerking planter geplant, Konvensionele-bewerking (CT) – die grond is in Maart/April met ‘n tandimplement bewerk die grond is in Maar/April geploeg met ‘n skaarploeg en met ‘n geenbewerking planter geplant. Grondmonsters is elke twee weke versamel van net voor plant tot net voor oes. Vanaf die versamelde monsters is die grondwaterinhoud grawimetries bepaal en ook die totale minerale stikstofinhoud (NO3--N en NH4+-N). Plantmonsters is vierweekliks versamel beginnende vier weke na opkoms tot en met antese. Blaaroppervlakindeks en biomassaproduksie is bepaal. Die chlorofilinhoud en ligonderskepping is tydens antese bepaal. Aan die einde van die groeiseisoen is totale biomassa, graan opbrengs asook graankwaliteit bepaal. Wisselboustelsels, wat medics (McWMcW) of kanola/lupine (LWCW) ingesluit het, het ‘n hoër minerale stikstofinhoud aan die begin van die 2011 groeiseisoen getoon. Wisselbou het egter geen effek op grondvog gehad nie. Minimum- en geenbewerking het ‘n hoër grondvoginhoud tot gevolg gehad, terwyl die persele onder konvensionele bewerking ‘n hoër minerale stikstof inhoud gehad het in 2010. In 2011 was daar geen verskille in die minerale stikstofinhoud tussen verskillende die bewerkingsmetodes nie en grondvog gedurende 2011 is op dieselfde wyse as in 2010 beïnvloed. Beide wisselbou en bewerkingsmetode het ‘n invloed gehad op gewasontwikkeling en biomassaproduksie. Die algemene tendens was dat, soos grondversteuring toegeneem het in die koring na medics en koring na kanola, het beter gewasontwikkeling plaasgeving met betrekking tot droëmassaproduksie en blaaroppervlakindeks. Die positiewe effek van wisselbou is ook waargeneem in die chlorofilinhoud van die blare en die ligonderskeppingspotensiaal van die blaredak. Graanopbrengs is positief beïnvloed deur die wisselboustelsel, met beide koring na medics en koring na kanola wat hoër graanopbrengste as koring monokultuur vir beide jare gelewer het. Die hoogste graanobrengs is ook gekry onder die minimumen geen-bewerkingsbehandelings vir 2010 en 2011. Wisselbou en bewerkingsmetodes het geen duidelike invloed op koringkwaliteit gehad nie. Dit is ‘n weerspieëling van die belangrike invloed van omgewingsfaktore gedurende die korrelvulstadium van koring. Omgewingsfaktore soos reënval en temperatuur het betekenisvolle effekte in beide jare van die studie gehad, maar die belang van ‘n wisselbou wat ‘n stikstofbinder soos medics insluit, was reeds in hierdie vroeë stadiums van die langtermynproef opvallend. Die positiewe effek van minimum- en geen-bewerking was ook duidelik sigbaar gedurende die verloop van die studie. / The Western Cape Agricultural Trust for the opportunity and the finances to do this study

Thesis (MscAgric (Animal Sciences))--University of Stellenbosch, 2006. / The development of basic husbandry techniques and determining basic performance parameters are among the first steps towards culturing a new species. Silver kob, Argyrosomus inodorus, is a large Sciaenid and endemic to South Africa and Namibia and has been selected as a candidate aquaculture species. However, the proposed culture raises many questions, with two of them being the adaptability to captive conditions and product quality in the captive raised fish. To address these, trials were set up with eighty-three silver kob, divided into three ponds and fed three different diets. The effects of the diet on performance and quality were determined over a nine month trial period. The fish fed the pilchard diet adapted faster to the captive conditions than the fish fed the artificial diets. The growth of these fish were also markedly better than that of the fish fed the artificial diets, although after the adaptation period, the growth rate of the fish fed the artificial diets surpassed that of the fish fed the pilchards. Fifteen fish, five from each treatment were sacrificed and compared on a chemical and sensory level to wild-caught fish (control, n=6). Differences (p≤0.05) were noted in the total lipid content and fatty acid composition between the fish fed the different diets and the control. Sensory analysis revealed that the fish fed pilchards differed (p≤0.05) from the other groups by having an undesirable odour and flavour. The body partitioning and the proximate chemical composition of silver kob were determined. The length-weight relationship for silver kob raised in captivity was determined and a b-value of 3.32 was obtained, which indicates allometric growth with the fish becoming more rotund as their length increases. The results of these trials indicates that silver kob, A. inodorus adapts in captive conditions. The final product also compares favourably to wild-caught fish. The use of digital image analysis as a method of determining fish condition was also assessed with promising results for future application in research and production systems.

Thesis (MScAgric)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The objective of this study was to determine the effect of extrusion, as a method of heat treatment, on the dry matter (DM) and crude protein (CP) degradability parameters of various vegetable protein sources commonly used in the Western Cape Province, South Africa. The feedstuffs used were lupins (LUP), full fat soybeans (SB), full fat canola seeds (FCS), soybean meal (SBM), canola meal (CM) and sunflower meal (SFM). In the first trial, the degradability parameters were determined according to an in sacco degradability procedure. Four non-lactating Holstein cows, fitted with rumen cannulae, were used in the trial and all cows received the same basal lactation diet. The samples were incubated in dacron bags and bags were removed at intervals of 0, 2, 4, 8, 16, 24 and 48 hours. Dry matter and CP disappearance values were determined and fitted to a onecompartment model by means of an iterative least-square procedure in order to determine the DM and CP degradability parameters. Results indicated that extrusion significantly lowered the effective degradability of the DM-fraction (20.1% on average) of all the feedstuffs, except LUP, and the effective degradability of CP in all the raw materials (27% on average). The second trial was an in vitro degradability trial that ran parallel with the in sacco degradability trial and was done with the aid of a DaisyII Incubator (ANKOM Technology Corp., Fairport, NY). The same feedstuffs were tested in both trials. A composited sample of rumen liquor from two of the cows used in the in sacco trial was used for in vitro incubation of the samples. The data obtained in this trial were analyzed in a similar way to that of the in sacco trial. Due to a limited amount of residue left after incubation, CP disappearance could not be calculated at each time interval for SB and SBM in the in vitro trial. In this case, actual disappearance values after 8h were used to compare treatments. Extrusion significantly lowered the effective degradability (as determined in vitro) of DM in all the feedstuffs tested (16.8% on average), as well as the effective degradability of CP in LUP, FCS, CM and SFM (21.8% on average). A comparison of the actual disappearance values after 8 hours incubation indicated that extrusion also lowered the rate of CP disappearance for SB and SBM. The values obtained in the in vitro trial and those from the in sacco trial, for the same feedstuffs, were compared. It appeared as if the in vitro determined values were overestimations of the in sacco determined values. A regression analysis showed a high correlation between the actual in vitro CP disappearance values after 8h incubation and in sacco determined effective degradability values. The third part of this study was a set of chemical analysis to determine the effect of extrusion on certain nitrogen fractions of the feedstuffs tested in the above mentioned trials. Solubility in a mineral buffer solution was determined to estimate the potential rumen degradability of the protein. The buffer insoluble nitrogen (BIN) fraction of all the feedstuffs, except FCS, was significantly increased by extrusion. Extrusion lowered the acid detergent insoluble nitrogen (ADIN) content of all feedstuffs, except FCS, which could imply that the temperature reached during extrusion (115°C - 120°C) was not high enough to cause damage to the protein. The neutral detergent insoluble nitrogen (NDIN) fraction of extruded SB, SBM, CM and SFM was significantly higher than that of the raw feedstuffs. Extrusion left the NDIN-fraction of FCS and LUP unaltered. Comparison of the NDIN : ADIN ratio of extruded with that of the raw feedstuffs provided reason to believe that extrusion had a positive effect on all feedstuffs (except FCS). Extrusion appears to be a useful method to decrease rumen degradation of vegetable protein sources, without causing heat damage. Furthermore, this means that protein sources of which the use have been limited due to its high rumen degradable protein (RDP) content, could be included in diets at higher levels following extrusion. The protein sources mentioned are also good sources of energy and the combination of energy and rumen undegradable protein (RUP) in the diet of the high-producing dairy cow could only be beneficial. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die effek van ekstrusie op die droëmateriaal (DM) en ruproteïen (RP)-degradeerbaarheidsparameters van verskeie plantaardige proteïenbronne wat algemeen in die Wes-Kaap (RSA), gebruik word, te bepaal. Ekstrusie is ‘n metode van hitteprosessering wat algemeen gebruik word deur plaaslike en internasionale veevoervervaardigers. Die volgende grondstowwe is geëvalueer: lupiene, volvet sojabone, volvet canolasaad, sojaboon-oliekoekmeel, canola-oliekoekmeel en sonneblom-oliekoekmeel. In die eerste proef is die degradeerbaarheidsparameters met behulp van ‘n in sacco studie bepaal. Vier droë Holstein koeie met rumen kannulas is in die studie gebruik en al vier koeie het dieselfde basale dieet ontvang. Monsters is in dacronsakkies geïnkubeer en die sakkies is uit die rumen verwyder na onderskeidelik 0, 2, 4, 8, 16, 24 en 48 uur intervalle. Die waardes van DM- en RP- verdwyning is bereken en dan met ‘n iteratiewe kleinste kwadraat prosedure op ‘n een-kompartement model gepas om die in sacco DM- en RPdegradeerbaarheidsparameters te bepaal. Die resultate van die studie het getoon dat ekstrusie die effektiewe degradeerbaarheid van die DM-fraksie van al die grondstowwe, behalwe lupiene, betekenisvol verlaag het (met gemiddeld 20.1%), asook die effektiewe degradeerbaarheid van die RP-fraksie van al die grondstowwe (met gemiddeld 27%). Die tweede proef was ‘n in vitro-degradeerbaarheidsstudie wat met behulp van ‘n ANKOM DaisyII Inkubeerder uitgevoer is en wat parallel met die in sacco-studie gedoen is. Dieselfde grondstowwe is in beide proewe geëvalueer. ‘n Saamgestelde monster van die rumenvloeistof van twee van die koeie wat vir die in sacco-studie gebruik is, is gebruik vir die in vitro-inkubasie van die monsters. Data-verwerking is op ‘n soortgelyke wyse as dié van die in sacco-studie uitgevoer. As gevolg van ‘n beperkte hoeveelheid residu na afloop van die inkubasies, kon die RP-verdwyning vir volvet sojabone en sojaboon oliekoekmeel nie bereken word nie. In hierdie geval is waargenome verdwyningswaardes na 8h gebruik om behandelings te vergelyk. Hierdie studie het getoon dat ekstrusie die effektiewe degradeerbaarheid van DM (soos in vitro bepaal) in al die getoetste grondstowwe betekenisvol verlaag het (met gemiddeld 16.8%). Die effektiewe degradeerbaarheid van RP in lupiene, volvet canola saad, canola oliekoekmeel en sonneblom oliekoekmeel is ook betekenisvol verlaag (met gemiddeld 21.8%). ‘n Vergelyking van die oorspronklike verdwyningswaardes van volvet sojabone en sojaboon oliekoekmeel na ‘n inkubasieperiode van 8 ure het ook getoon dat ekstrusie die tempo van RP-verdwyning uit die rumen vertraag het. Die in sacco- en in vitro-bepaalde waardes vir elke grondstof is vergelyk en dit kom voor asof die in vitro-waardes oorskattings van die in sacco-waardes is. ‘n Regressie-analise het verder getoon dat daar ‘n hoë korrelasie was tussen die waargenome in vitro RPverdwyningswaardes na 8 ure inkubasie en die beraamde effektiewe degradeerbaarheid, soos in sacco bepaal. Die derde deel van die studie was ‘n stel chemiese analises wat uitgevoer is om die effek van ekstrusie op sekere stikstof (N)-fraksies van die grondstowwe, wat in bogenoemde proewe gebruik is, te bepaal. Die oplosbaarheid van N in ‘n mineraal-bufferoplossing kan gebruik word as aanduiding van die potensiële rumendegradeerbaarheid van die proteïen. Die bufferonoplosbare N-fraksie van al die grondstowwe (behalwe volvet canolasaad) is betekenisvol verlaag deur ekstrusie. Ekstrusie het ook die suur-onoplosbare N-fraksie (ADIN) van al die grondstowwe (behalwe volvet canolasaad) betekenisvol verlaag. Dit kan moontlik daarop dui dat die temperatuur wat tydens ekstrusie (115°C - 120°C) bereik is, nie hoog genoeg was om die proteïen in die grondstowwe te beskadig nie. Ekstrusie het die N-fraksie wat onoplosbaar was in ‘n neutrale oplossing (NDIN) betekenisvol verhoog in volvet sojabone, sojaboonoliekoekmeel, canola-oliekoekmeel en sonneblom-oliekoekmeel en dit onveranderd gelaat in lupiene en volvet canolasaad). Die verhouding van NDIN : ADIN van die geëkstrueerde grondstowwe is vergelyk met dié van die rou grondstowwe. Dit blyk dat ekstrusie wel ‘n positiewe effek op al die grondstowwe (behalwe volvet canolasaad) gehad het. Dit wil dus voorkom asof ekstrusie wel aangewend kan word om die rumendegradeerbaarheid van plantaardige proteïenbronne te verlaag sonder om die protein te beskadig. Dit kan daartoe lei dat proteïenbronne waarvan die gebruik voorheen beperk was as gevolg van die hoë rumen-degradeerbare proteïen-inhoud daarvan nou wel in rantsoene ingesluit kan word na die ekstrusie daarvan. Die proteïenbronne, soos genoem, is ook redelike bronne van energie en die kombinasie van energie en rumen nie-degradeerbare proteïen in die rantsoen van die hoog-produserende melkkoei kan slegs voordelig wees.

Thesis (MScAgric)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: Porcine somatotropin (pST) is a naturally occurring protein (hormone), secreted by the pituitary gland of young pigs and is one of the major growth regulating factors. High levels of pST is found in circulating blood of young animals, resulting in the partitioning of nutrients into lean tissue and bone growth. Supplying an exogenous source of pST should increase the deposition of lean muscle and bone and decrease the deposition of fat in the older (above 60 kg) pig. To ascertain whether pST would have a positive influence on production- and meat characteristics in the South African scenario for pigs slaughtered at a high bodymass, a trail was conducted. For group housed animals pST had no significant effect on the following parameters: feed intake, calculated cumulatively on a weekly basis, ADG, live weight, carcass weight, carcass length, ham length or chest depth, intramuscular fat area, muscle depth and colour measured with a Hennessey probe and waterbinding capacity. However, when the FCR of pigs in this investigation were calculated, there was a significant (p<0.05) influence by sex and pST detected. Boars converted their feed to live weight better than barrows and gilts from week ten onwards. Boars had an increased FCR when treated with pST. A significant increase was found in muscle area and a significant decrease in extra muscular (back fat) area of boars and barrows. A significant pST (p< 0.05) effect (3 mm reduction) was seen for backfat depth measured by the Hennessey probe and the intrascope. Porcine somatotropin significantly (p<0.05) increased the muscle area of the loin-cut for all animals. The area covered by subcutaneous fat of boars and barrows were significantly (P<0.05) reduced by pST treatment, with no effect detected for gilts (p>0.05). Porcine somatotropin treatment increased the muscle percentage and decreased the extramuscular fat percentage in such a way that the differences between sexes was reduced. Thus, more uniform fat-muscle distribution between carcasses was obtained by pST treatment. Control animals had a significantly higher pH24 than pST treated animals (P=0.049). Lower values were found for animals receiving pST for L* (p=0.016), a* (p=0.002) and b* (P=0.016). The effect on b* (yellow-blue range) in the M longissimus thoracis of pST treated animals showed slightly (but significantly) less yellow and more green compared to control animals (p=0.016). This combined with the lower L* values (brightness) indicates that pST treated animals had a significantly darker colour meat compared to the control animals. Individually housed animals showed no significant differences for the following characteristics: live weight, carcass weight, head, trotters, shoulder, middle back, middle belly, loin belly, thigh, fillet, carcass fat and kidney. Whereas pST caused a significantly lower percentage of the middle back of boars and barrows, but not in gilts, pST could only precipitate a lower percentage (11.18%) loin back of treated animals (p=0.026) v.s. control animals (12.05%). A trend (p>0.1) was detected for percentage bone in the middle back, with the pST treated (14.17% vs. 13.18%) animals having more bone than that of control animals. pST animals had a higher percentage (p=0.024) skin (5.04%) than the control animals (4.28%). This study shows that there is no negative effect of pST on meat quality characteristics and carcass composition, in fact there is less variation between carcasses obtained from different sexes treated with pST. The producer can bring heavier animals to the market with a reduced backfat percentage and a greater percentage meat with the help of pST. / AFRIKAANSE OPSOMMING: Vark somatotropien (pST) is ‘n natuurlike hormoon wat deur die pituitêre klier in die brein afgeskei word by klein varkies en is een van die belangrikste hormone betrokke by groei regulering. Hoë vlakke van pST kom voor in die bloed van jong varkies, dit veroorsaak dan die verspreiding van nutriente in die liggaam van die varkie sodat dit meer vleis en beengroei toon en minder vet deponeer. Namate die varkie volwasse word neem die bloedvlakke van pST af en begin die liggam meer vet deponeer ten koste van proteien groei, terselfde tyd begin die seksuele kenmerke ontwikkel. Die toediening van ‘n eksterne bron van pST behoort die groei van been en vleis te bevoordeel in ouer diere (bo 60 kg). Vir die doeleindes van die ondersoek wou ons bepaal of pST ‘n positewe effek het op groei en vleiskwaliteitseienskappe van varke wat in Suid Afrikaanse kondisies gebruik word en teen ’n hoër liggamsmassa as gewoonlik geslag word. Vir varke wat in groepe behuis was was daar geen effek op die volgende eienskappe nie: voer inname weekliks bepaa, gemiddelde daaglikse toename, liggaamsmassa, karkasgewig, karkas lengte, ham lengte, bors diepte, intrmuskulêre vet en spierdikte bepaal met ‘n Hennessey sonde asook waterbindigs vermoë. Bere het egter ’n beter voeromsettings faktor gehat as burge en soggies, maar as pST toegedien is het hulle voeromsettingsfaktor toegeneem. ’n Betekenisvolle (p<0.05) toename in spier area van alle diere, met ’n gesamentlike afname in onderhuidse vet area van bere en burge (nie soggies nie) is gevind. ’n Betekenisvolle afname (3 mm) in rugvetdikte is gevind by diere wat met pST behandel is. Hierdie effekte is so in die lewe gebring dat die verskil tussen die geslagte minder prominent is en karkasse meer uniform is. Betekenisvolle hoër pH24 waardes is gevind by kontrole diere as by pST behandelde diere (p=0.049). L* (p=0.016), a* (p=0.002) en b* (p=0.016) waardes was betekenisvol laer vir pST behandelde diere as vir kontrole diere. Die effek op b* waardes (geel-blou reeks) in die M. longissimus thoracis van behandelde diere was in so ‘n mate dat die vleis ietwat minder geel en meer groen was in vergelyking met die kontrole diere (p=0.016), saam met laer L* waardes (helderheid) is ‘n indikasie van ietwat donkerder vleis van behandelde diere. Individueel behuisde diere het geen betekenisvolle effek getoon vir die volgende parameters nie: liggamsgewig, karkasgewig, kop, voete, skouer, middel rug, middel maag, lende maag, dy, haas en niere. ‘n Betekenisvolle laer persentasie middel rug is gevind in bere en burge, maar nie vir soggies nie, maar in die lende rug is ‘n betekenisvolle effek gevind vir alle diere (11.8% vir pST en 12.05% vir kontroe , p=0.026). ‘n Neiging (p>0,1) is gesien vir die hoeveelheid been in die middle rug van diere behandel met pST (14.17% vs. 13.18%) Dier met pSt behandel het’n betekenisvol hoer persentasie vel as kontrole diere gehat (5.04% vs. 4.28%, p=0.024. Die resultate van die ondersoek bewys dat daar geen negatiewe effekte van pST op vleis- en karkaseienskappe is nie, daar is self minder variasie tussen karkasse van verskillende geslagte. Die boer kan swaarder diere bemark met minder rugvet en meer vleis met behulp van pST.

Thesis (MScAgric)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: Near infrared reflectance spectroscopy (NIRS) was evaluated as a tool to predict the chemical composition of ostrich meat, mutton and feedstuffs. Seventy-three calibrations were developed. NIRS analyses were conducted on an InfraAlyzer 500 spectrophotometer between 1100 and 2500 nm wavelengths. Near infrared reflectance calibrations were developed for (i) the proximate chemical composition of ostrich meat; (ii) the proximate chemical and mineral composition of mutton; (iii) the chemical composition and digestibility of lupins, full-fat canola and the determination of alkaloids in lupins; (iv) the chemical composition and digestibility of winter grains and maize; (v) the chemical composition and digestibility of cereal hay, cereal straw, wheat stubble and alfalfa-grass/hay mixtures. The chemical composition of different types of winter grain produced in the Western Cape area of South Africa, as well as the chemical composition and digestibility of winter grain hay and straw produced in a Mediterranean rainfall area were also determined. Near infrared reflectance spectrometry proved to be successful for the prediction of crude protein (CP) and fat in both animal species, as well as for ash and dry matter (DM) in freeze-dried mutton. Accurate calibrations were also developed for certain minerals (K, P, Na, Mg, Fe and Zn). Calibrations proved to be accurate for all the relevant chemical constituents in lupins, as well as the DM, CP and fat calibrations in full-fat canola. The alkaloid calibration showed potential although more samples should be included for a more accurate calibration. Winter grain calibrations were accurate for fat, acid detergent fibre (ADF), in vitro organic matter digestibility (IVOMD), lysine and methionine. All chemical composition calibrations of maize, except for ash, were accurate for future prediction. Chemical composition calibrations of wheat stubble and alfalfa-grass hay mixtures resulted in prediction with similar or slightly higher accuracy than calibrations reported in the literature. The calibrations developed for cereal hay and straw were not suitable for prediction purposes. Possible reasons were discussed to explain these inaccurate calibrations. Variation shown between different types of cereal grain (2-row barley, 6-row barley, oats, wheat and triticale) accentuated the need for the analysis of different batches of grain produced under different conditions for use in animal feed. The chemical composition and digestibility of winter grain straw and hay were also obtained. These values provide a database for calculation of inclusion levels of these feedstuffs in animal diets. These investigations showed the NIRS to be a successful and rapid tool for the prediction of the chemical composition of ostrich and lamb meat and locally produced feedstuffs. / AFRIKAANSE OPSOMMING: Naby infrarooi refleksie spektroskopie (NIRS) is geëvalueer as 'n metode om die chemiese samestelling van volstruis- en skaapvleis, asook voedingsgewasse te voorspel. Drie en sewentig kalibrasies is ontwikkel. NIRS ontledings is gedoen met ‘n InfraAlyzer 500 spektrofotometer tussen die golflengtes 1100 en 2500 nm. Naby infrarooi refleksie kalibrasies is ontwikkel vir (i) die basiese chemiese samestelling van volstruisvleis; (ii) die basiese chemiese en minerale samestelling van lamsvleis; (iii) die chemiese samestelling en verteerbaarheid van lupiene en volvet kanola en die bepaling van alkaloïede in lupiene; (iv) die chemiese samestelling en verteerbaarheid van wintergrane en mielies; (v) die chemiese samestelling en verteerbaarheid van graanhooie, graanstrooie, koringstoppels and lusern-gras/hooi mengsels. Die chemiese samestelling van verskillende tipes wintergrane wat in die Wes-Kaap omgewing van Suid-Afrika geproduseer word, sowel as die chemiese samestelling en verteerbaarheid van wintergraanhooi en –strooi wat geproduseer word in ‘n Mediterreënse reënval omgewing, is ook bepaal. Naby infrarooi refleksie spektrofotometrie was suksesvol in die voorspelling van ru-proteïen (RP) en vet in beide dierspesies, sowel as vir die bepaling van as en droë materiaal (DM) in gevriesdroogde lamsvleis. Akkurate kalibrasies is ook ontwikkel vir sekere minerale (K, P, Na, Mg, Fe en Zn). Kalibrasies ontwikkel vir die chemiese samestellings komponente in lupiene is reg deur die bank akkuraat, sowel as die DM, RP en vet kalibrasies vir volvet kanola. Die alkaloïed kalibrasie het goeie potensiaal getoon, alhoewel meer alkaloïedmonsters benodig word vir ‘n akkurate kalibrasie. Wintergraan kalibrasies was akkuraat vir vet, suurbestande vesels (SBV), in vitro organiese materiaal verteerbaarheid (IVOMV), lisien en metionien. Al die chemiese komponent kalibrasies vir mielies, behalwe die een vir as, was akkuraat vir toekomstige bepalings. Chemiese komponent kalibrasies vir koring stoppels en luserngras/ hooi mengsels het akkuraatheid getoon wat gelyk, of effe beter, is as kalibrasies wat in die literatuur opgeteken is. Kalibrasies ontwikkel vir graanhooie en graanstrooie was nie geskik vir voorspellingsdoeleindes nie. Moontlike redes vir die onakkurate kalibrasies is volledig bespreek. Variasie gevind tussen verskillende tipes wintergrane (2-ry gars, 6-ry gars, hawer, koring en korog) het die behoefte beklemtoon vir ontledings van grane geproduseer onder verskillende omgewingstoestande vir gebruik in dierevoeding. Die chemiese samestelling en verteerbaarheid van wintergraanstrooi en –hooi is ook bepaal. Hierdie waardes verskaf ‘n databasis vir berekening by insluiting van hierdie voergewasse in diererantsoene. Hierdie ondersoek het bewys dat NIRS ‘n suksesvolle en vinnige metode is vir die voorspelling van die chemiese samestelling van volstruis- en lamsvleis en plaaslik geproduseerde voergewasse.

Thesis (MPhil)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: CPM Dairy was developed to maintain amino acid balance. because the correct amino acid relationship has an influence on milk production and milk composition (Schwab e/ af. 1992, Rulquin e/ af. 1993). Rulquin e/ af. (1993) found that an increase in lysine and methionine concentration in the diet had no meaningful effect on milk production and milkfat production. However, milk protein production is described as a function of lysine and methionine concentration. In order to balance the amino acid relationships, the CNCPS model has been adopted, using the following guidelines: I. a dairy cow feed characteristic scheme, described by Van Soest e/ af. (1991) and Sniffen e/ aI. (1992), II. a model for rumen fermentation and bacterial growth in the dairy cow, described by Russel e/ af. (1992), Ill. feed val ues for dairy cow feeds, described by Sniffen e/ af. (1992). IV. a set of formulas describing the feeding needs of dairy cows under different circumstances, assembled by Fox e/ af. (1992). Bateman e/ af. (2001) studied the accuracy of formulation models according to crude protein (CP) and amino acid (AA)-flow to the duodenum in lactating dairy cow diets. CPM Dairy does not calculate direct flow of CP to the duodenum, but the following adjustment was made: the change-over of metabolizable protein (MP) to CP is done by increasing bacterial protein from 60% to 100% of bacterial-CP. Intestinal digestion of fraction B3-protein is increased from 80% to 100%, whereas fraction C-protein is increased from 0 to 100% to change feed-MP to feed-CP. CP from feed and microbes are summed to indicate total CP-flow to the duodenum. AA-flow, as calculated by CPM Dairy, is used without adjustments. A rise in MUN-Ievels are typical to spring and summer months. which can be ascribed to high soluble protein and low soluble carbohydrates in grasses and legumes. This gives rise to an excess N-uptake in the bloodstream. Grass silage, when fed as primary feeding source. has the same reaction. Blood-urea-nitrogen (BUN) is the amount of urea-N found in the blood of the cow. MUN is the fraction ofN in the milk in the form of urea. MUN is normally 85% the concentration of BUN. Studies show that an increase in BUN/MUN levels leads to a negative effect on the reproductive ability of the cow. An increase in BUN-levels leads to an increase in urea in the reproductive tract of the animal. Urea passes between the blood plasma and the reproductive tract. It is therefore obvious that a high BUN-concentration leads to high levels of urea in the reproductive tract. In order to eradicate this problem. the use of deodorise in the supplemental feed of the lactating dairy cow \vas recommended. Deodorise is a natural product manufactured by Alltech. The product is derived from the Yuccha Schidigera plant. Two glycocomponents (CI and C II) of this plant binds gasses such as N1-I3. (Alltech information sheet) During .June to August 2002 data were collected regarding the effect of deodorise on lactating dairy cows. No meaningful difference between the two groups in this experiment was found. / AFRIKAANSE OPSOMMING: CPM Dairy is ontwikkel am aminosuurbalans te handhaaC aangesien die korrekte aminosuurvcrhoudings 'n invloed op melkproduksie en mclksamcstelling het. (Schwab el al. 1992, Rulquin el al. 1993). Rulquin el al. (1993) hct gcvind dat 'n tacname in die konsentrasic van lisien en mctionien in dic rantsoen gccn nocmenswaardigc cffek op melkproduksie en meIkvctproduksie het nie. MelkproteYcnproduksie word cgtcr beskryf as 'n funksie van !isien- cn metionienkonscntrasie. Ten einde die aminosuurvcrhoudings te balanseer. is die CNCPS model aangcneem. wat die volgcndc riglyne gebruik : I. 'n Melkbees vocdingskarakteriseringskema, soos bcskryf deur Van Soest el 01. (1991) en Sniffen el 01. (1992). II. 'n Model van rumcnfermentasie en bakteriele groei in die melkbces, soos deur Russel e/al. (1992) beskryf. Ill. Voedingswaardes vir melkbeesvoedingstowwe, soos bcskryf deur Sniffen e/ 01. ( 1992). IV. 'n Stcl vergelykings wat die voedingsbehoeftcs van mclkbcestc onder vcrskillende omstandighede beskryf, saamgestel deur Fox e/ 01. (1992). Bateman e/ 01. (200 I) bestudeer die akkuraatheid van formulasiemodelle ten opsigte van RP- en aminosuur (AA)-vloei na die duodenum in lakterende melkkoeirantsacne. CPM Dairy bcreken nie dirckte vloei van RP na die elunderm nie. elus is dic volgenele aanpassing gcmaak : Die omskakeling van Metaboliseerbare proteYen (MP) na RP word gedoen deur bakteriele prote"len te verhoog vanaf 60% tot 100% van baktcriCle-RP. Dermkanaalvertering van ti'aksie B3 proteYen is verhoog vanaf 80% tot IOO(/j), terwyl fraksie C protc'len vanaf 0 tot 100% verhoog is ten einde voer-M P om te skakcl na voer- RP. RP vanafvoer en mikrobes word gesommeer en verskafvoorspellings vir totale RPvioei na dic duodenum. Die AA-vloei. so os deur CPM Dairy bereken word, is sonder wysigings gebruik. n Styging in MUN-vlakke word tipies in die lente- en somermaande ondervincL wat toegeskryl' kan word aan hoc oplosbare protc"ien en lae oplosbare koolhidrate in grasse en peulgewasse. Dit gee aanleiding tot 'n oonnaat N wat in die bloedstroom opgeneem word. Graskuilvoer, wanneer gevoer word as die primcre voedingsbron, het dieselfde uitwerking. Bloed-ureumstikstof (BUN) is die hoeveelheid ureum-N teenwoordiu: in die bloed van die koei. MUN is die fraksie N in melk in die vonn van ureum. MUN is gewoonlik 85% van die konsentrasie van BUN. Navorsing toon dat 'n toe name in BUN/MUN vlakke 'n nadelige uitwerking het op die reproduktiewe vermoc van die koei. 'n Toename in BUN-vlakke veroorsaak 'n toename in ureum in die dier se reproduksiekanaal. Ureum beweeg tussen die plasma en die reproduksiekanaal. Dit is dus duidelik dat 'n hoc BUN-konsentrasie sal lei tot hoc vlakke van ureum in die reprod uksiekanaal. Ten einde hierdie probleem uit te wis, is die gebruik van De-Odorase in die kragvoer van die lakterende koeie aanbeveel. De-Odorase is 'n natuurlike produk wat deur Alltech vervaardig word. Die produk is at1(omstig van die Yucca schidigera plant. Twee glikokomponente (CI en CII) van hierdie plant bind gasse so os Nl-h (Alltech inligtingstuk). Gedurende .Iunie tot Augustus 2002 is data ingesamel aangaande die uitwerking van De- Odorase op melkbeeste. Daar is geen betekenisvolle verskil tussen die twee groepe met hierdie ekspcriment waargeneem nle.

Thesis (MscAgric (Animal Sciences))--University of Stellenbosch, 2005. / The aim of this study was to develop a product using alternative red meat species, aquatic and terrestrial mammals, which would be acceptable to the consumer and suitable from a food safety aspect. Many of these alternative species are harvested seasonally. A product which is shelf stable needs to be developed to provide a supply of this meat all year round. The species used in this investigation were the Cape fur seal (Arctocephalus pusillus pusillus), the Grey seal (Halichoerus grypus) from the northern hemisphere, the Minke whale (Balaenoptera acutorostrata), horse, beef, mutton, blesbok (Damaliscus dorcas phillipsi) and springbok (Antidorcas marsupialis). Muscle (m. pectoralis) of Cape fur seal pups has a higher percentage fat (4.2g/100g) than the bulls (2.4g/100g), but similar levels of protein (23.2g/100g). Bull blubber samples have a higher percentage protein (26.6g/100g) than the pups (14.6g/100g), but a lower fat percentage (67.1g/100 g) compared with the pups (77.2g/100g). In the Cape fur seal bull meat, saturated fatty acids (SFA) contribute 33mg/100g, monounsaturated fatty acids (MUFA) 29mg/100 g and polyunsaturated fatty acids (PUFA) 38mg/100g of the total fatty acid content. In pups, the three fractions are 39, 30 and 31 mg/100g for SFA, MUFA and PUFA, respectively. Salami,prepared using exclusively seal meat, or seal meat with beef and pork, was produced in a pilot study, using two commercially available starter cultures. The pH values of all three batches started off at ca. 5.6, and dropped to 4.3. Water activity readings started off at 0.96 and dropped to 0.91 after 21 days. Salami produced from the meat of the Grey (Havert) seal and Minke whale, using three starter cultures, had recorded pH values (in both species), which started off between 5.68 and 5.92, and dropped to between 4.5 and 4.8 over the 21 days. Water activity showed an initial value of 0.96, which dropped to 0.90 after 21 days. The final force (N/cm2) that was needed to compress the salami samples was double that of the initial force required for the same species and starter culture combination. The raw seal meat contained 349.6 (mg/100 g sample) SFA, 271.6 (mg/100g sample) MUFA and 175.8 (mg/100g sample) PUFA, whilst the raw whale meat contained 312.3, 251.9 and 179.6 (mg/100g sample) SFA, MUFA and PUFA respectively. Fifteen batches of salami were made from horse, beef, mutton, blesbok and springbok, respectively, and starter cultures of Lactobacillus curvatus DF 38 (batch I), active bacteriocin producing Lactobacillus plantarum 423 (batch II) and then a mutant variation of Lactobacillus plantarum 423m, which did not produce the bacteriocin (batch III). Batch I had a higher final pH value (4.66), after 23 days, whereas the values for batches II and III were similar (4.42 and 4.46 respectively). On day 23 the water activity value was 0.90 for all starter cultures. Horse salami, in batch I, was the leanest in terms of fat content (34.34g/100g salami), with mutton salami having the highest fat content (37.52g/100g salami). Blesbok salami had the highest fat content in batch II (42.77g/100g meat), with beef the leanest (35.71g/100g meat). Salami made from horse and springbok proved to be the most desirable in terms of chemical composition, especially fatty acid profiles, with regard to P: S and n-6: n-3 ratios. Similar growth patterns in colony forming units (cfu) were recorded for L. plantarum 423, L. plantarum 423m and L. curvatus DF38 in MRS broth (Merck) at 30oC, although batch I reached asymptotic growth earlier. The percentage of L. plantarum 423 compared with the total population of microflora in mutton salami remained almost the same (80-95% variety) during the entire fermentation and maturation process. In horse salami, L. plantarum 423 was present at relatively low cell numbers (55-50% on day 1 and before smoking), but increased to 70% after smoking and stabilized to 70-80% for the remaining fermentation period. In beef salami, cell numbers in batch II decreased slightly during the first five days (from 95 to 70%), followed by an increase to 90%. In springbok salami, cell numbers in batch II remained fairly stable at 80-90%. In blesbok salami, batch II slowly decreased during the first three days, from 88% to 70%, then increased to 92% after 12 days and stabilized for the rest of the fermentation period. Similar results were recorded for batch I. Analytical sensory evaluation concluded that the salami prepared using starter culture I resulted in end products with lower sensory qualities. Salami prepared using blesbok and mutton also resulted in end products with lower sensory qualities and was perceived as significantly lower in salami flavour (P≤0.05) and higher in venison-like and mutton-like flavour respectively. The blesbok samples were rated significantly higher (P≤0.05) in sour meat aroma, sour meat flavour and venison-like flavour than the rest of the samples. The blesbok salami was rated significantly lowest for colour compared with the rest of the samples. The tastes of the springbok and horse salami were significantly (P≤0.05) more acceptable than those of the beef and blesbok salami.

Thesis (MScAgric)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The South African Ostrich industry was established more than 100 years ago. Despite appreciable fluctuations and modifications in demand, the industry perseveres, with meat and leather as the current primary driving force. Low and variable early chick survival is globally considered as a major constraint in the industry. In spite of obvious welfare and production implications, research findings concerning ostrich chick survival are scant. Four studies involving chick survival to 24 weeks post hatch were thus performed. South African Black ostrich (Struthio camelus var. domesticus) data obtained from a commercial pair-bred ostrich flock maintained at the Oudtshoorn Experimental Farm, South Africa comprising 10418 records were utilized to run a series of single- and multiple-trait binomial analyses using either linear models (ASREML) or threshold models (Monte Carlo Markov Chain methods, employing Gibbs sampling software) respectively. Suitable fixed and random effect models together with variance and (co)variance components were derived from these analyses. Ostrich chick survival to 24 weeks post hatch was low (28%) with a large environmental component. Preincubation storage time only affected 0 to 3 week survival, while incubator had a significant effect on cumulative survival traits to 24 weeks as well as on 13 to 24 week survival. Female chicks outperformed males at 0 to 12 weeks, 0 to 24 weeks, 4 to 12 weeks and 13 to 24 weeks with regard to survival. Hen age was significant for all traits except survival during the first week as well as for survival from 13 to 24 weeks post hatch. All analyses exhibited comparable low heritability estimates for all survival traits except for 0 to 1 week survival and 13 to 24 week survival (h2 = 0.12 and 0.10; m2 = 0.08 and 0.07 respectively) which demonstrated higher additive genetic and maternal components when threshold models, using Gibbs sampling algorithms, were employed. Neither moisture loss nor day of external pipping exhibited notable additive genetic correlations with any of the estimated survival traits. Day-old chick weight demonstrated a low correlation with early chick survival (rg = 0.24 ± 0.19) with heavier chicks tending to have a higher survival probability. The effects of rearing method on early chick survival and growth were also investigated. Comparisons between chicks reared and fostered by adult ostriches in a semiextensive environment and chicks imprinted onto humans under an intensive system and between regular human handling in an intensive rearing system and the standard farm protocol of an intensive rearing system were made. No difference in the early chick survival to 3 weeks post hatch of chicks reared by foster parents and those chicks imprinted onto humans was demonstrated. At later ages, those chicks reared by foster parents outperformed human imprinted chicks. Human imprinted chicks exposed to regular handling demonstrate an enhanced early survival when compared to chicks exposed to conventional rearing protocol in intensive systems. The study is seen to provide guidance for further research on this topic. / AFRIKAANSE OPSOMMING: Die Suid-Afrikaanse volstruisbedryf is meer as 100 jaar gelede gevestig. Die bedryf is volhoubaar, ten spyte van ‘n fluktuerende aanvraag na volstruisprodukte. Vleis en leer is tans die produkte wat die meeste tot die inkomste van boere bydra. Lae en wisselende kuikenoorlewing is ‘n belangrike knelpunt in die bedryf. Navorsingsuitsette rakende kuikenoorlewing is skaars, ten spyte van ooglopende welsyns- en produksie implikasies. Kuikenoorlewing tot en met 24 weke na uitbroei is dus in vier afsondelike studies ondersoek. Data van 10418 kuikens uit ‘n kommersiële broeipaargeteelde Suid-Afrikaanse Swart (Struthio camelus var. domesticus) kudde op die Oudtshoorn Navorsingsplaas, Suid-Afrika is gebruik om enkel- en meervoudige eienskappe met of liniêre modelle (ASREML) of drempelwaarde modelle (Monte Carlo Markov Ketting metodes, met Gibbs monstering sagteware) te pas. Die metodes is gebruik om toepaslike vaste- en toevalseffekte modelle saam met (ko)variansie komponente te bekom. Kuikenoorlewing tot 24 weke na uitbroei was laag (28%), met ‘n groot omgewingsbydraende komponent. Stoor van eiers voor pak het slegs kuikenoorlewing van 0 tot 3 weke beïnvloed, terwyl die broeikas wat gebruik is ‘n betekenisvolle invloed op kuikenoorlewing tot 24 weke ouderdom, sowel as op -oorlewing van 13 tot 24 weke gehad het. Wyfiekuikens het beter oorleef as mannetjie kuikens vir oorlewing gemeet van 0 tot 12 weke, 0 tot 24 weke, 4 tot 12 weke en van 13 tot 24 weke. Broeiwyfie ouderdom het ‘n betekenisvolle invloed op kuikenoorlewing in die eerste week na uitbroei en van 13 tot 24 weke na uitbroei, gehad. Kuikenoorlewing was relatief laag oorerflik, behalwe vir oorlewing van 0 tot 1 week en vir oorlewing van 13 tot 24 weke van ouderdom (h2 = 0.12 en 0.10; m2 = 0.08 en 0.07 onderskeidelik). Drempelwaarde modelle met Gibbs monstering algoritmes het hoër additiewe en maternale variansie verhoudings in vergelyking met liniêre modelle aangedui. Genetiese korrelasies van vogverlies en die dag van uitwendige pik met kuikenoorlewing was oor die algemeen onbeduidend. Dagoudkuikengewig is laag gekorreleerd met vroeë kuikenoorlewing (rg = 0.24 ± 0.19), met swaarder kuikens wat oor die algemeen beter oorleef. Die gevolge van verskillende grootmaak metodes op vroeë kuikenoorlewing en -groei is ook ondersoek. Vergelykings tussen kuikens grootgemaak deur volwasse volstruise as pleegouers in ‘n semi-intensiewe omgewing en kuikens grootgemaak deur mense onder ‘n intensiewe stelsel en tussen kuikens grootgemaak deur gewone menslike hantering in ‘n intensiewe grootmaak sisteem onder standard plaas protokol was bestudeer. Geen verskille was gevind in vroeë kuikenoorlewing tot 3 weke na uitbroei, van die kuikens grootgemaak deur volwasse volstruise en tussen die kuikens grootgemaak deur mense . By latere ouderdomme, het die kuikens wat grootgemaak was deur volwasse volstruise beter oorlewing getoon as die kuikens grootgemaak deur mense. Kuikens grootgemaak deur mense wat blootgestel was aan gereelde hantering het verhoogde vroeë oorlewing getoon in vergelyking met kuikens grootgemaak deur konvensionele grootmaak protokol in intensiewe stelsels. Die studie kan dus beskou word om leiding te verskaf vir verdere navorsing oor hierdie onderwerp.