Thesis (MScAgric)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: AN ASSESSMENT OF PERFORMANCE EVALUATION PROCEDURES OF DORPER RAMS UNDER EXTENSIVE MANAGEMENT CONDITIONS. During 1988 to 2000, Dorper rams (n=2565) maintained on the Kalahari Experimental Farm during performance test periods of approximately 180 days, were subjected to evaluation according to specific body measurements and breed standards. The respective body measurements included live weight, shoulder height, body length, body width, scrotal circumference and average daily weight gain (ADG). The measurements were recorded at the beginning and end of each evaluation period. The rams were evaluated visually by breed inspectors and classified according to breed standards. Live weight recorded at the beginning of evaluation periods, was moderate to high, and positively correlated with most of the body measurements recorded in the study. The exception was ADG, which was negatively correlated (-0.25) with live weight. Live weight recorded at the end of evaluation periods was moderately and positively correlated with scrotal circumference (0.57), and highly correlated with body width (0.76). Average daily weight gain was high and positively correlated with live weight (0.63) recorded at the end of the evaluation periods. Large variations within test periods, that could be attributed to age differences and variation between the respective groups of rams, necessitated correction of the data for the effect of year/season. The rams were divided into above- and below average groups according to their weight at the beginning of the test period. Analysis of the growth patterns of rams during the study period, using the adjusted end data, indicated that 75% of the rams remained in their respective groups. This finding supports the above-mentioned positive correlation of 0.58 that was reported for live weight at the beginning and end of evaluation periods. Body measurements recorded at the beginning of the evaluation periods were in most cases moderately to high and positively correlated (P<0.0001) with measurements recorded at the end of the evaluation periods. The exception was ADG, which was low and negatively correlated with the respective body measurements that were recorded at the beginning of evaluation periods. After each body measurement was quantified by the sum of squares, it became evident that year/season had the greatest influence on the body measurements recorded at the end of an evaluation period. Year/season influenced live weight, body width, shoulder height, scrotal circumference and ADG, with the largest effect on live weight and the least influence on ADG (R2 = 31.62). After correction for year/season, the contribution of the respective measurements to live weight recorded at the end of evaluation periods were still in the same order. After a step-wise procedure for adjusted live weight at the end of evaluation periods was performed, it was found that body width contributed the most to live weight. Average daily gain made the third largest contribution, i.e. with respect to body width (largest) and body length (second largest), to corrected live weight recorded at the end of evaluation periods. The high correlations reported between the respective body measurements necessitated the analysis of the data for multi-colinearity to determine whether the partial contribution of the respective body measurements would differ from the initial values. The partial contribution of the respective body measurements, however, was not affected by the analysis. Regression analysis indicated that the respective body measurements and weights recorded at the beginning of evaluation periods decreased significantly (P<0.0001) over the entire period (1988-2000). The largest annual decreases were reported for ADG (- 2.5%) and body width (-1.1%), respectively. The decreases in ADG and body width are indications that Dorper sheep decreased in size during the period of this study. The value of visual appraisal methods therefore need to be seriously considered to determine whether this is a valuable management tool to assess the production performance of Dorper rams under extensive conditions. The influence of corrected body measurements and ADG, i.e. after selection by breed inspectors and according to breed standards, was plotted on scatter plots. The plots indicated that the breed inspectors selected larger and heavier rams throughout. It is however, still the case in the Dorper industry that rams that perform below average are sometimes classified and used as stud breeding material. Body width and shoulder height were the body measurements that received the highest and lowest approval as visual selection criteria, respectively. A possible reason for this is that the tendency of a smaller Dorper sheep can be attributed to the decreasing shoulder height, as the latter is an indication of body frame size. Visual appraisal should therefore be used in conjunction with scientific methods. Optimum size for the Dorper should be established. / AFRIKAANSE OPSOMMING: ‘N BEOORDELING VAN PRESTASIE-EVALUERINGSPROSEDURES VAN DORPERRAMME ONDER EKSTENSIEWE BESTUURSTOESTANDE Dorperramme (n=2565) is vanaf 1988 tot 2000 te Kalahari Proefplaas in prestasietoetstydperke van ongeveer 180 dae onder ekstensiewe toestande volgens sekere liggaamsparameters en rasstandaarde geëvalueer. Die onderskeie liggaamsmates het lewende gewig, skouerhoogte, liggaamsbreedte, liggaamslengte, skrotumomtrek en gemiddelde daaglikse toename (GDT) ingesluit. Die parameters is aan die begin en einde van elke toetsperiode gemeet. Die ramme is visueel deur rasinspekteurs geëvalueer en volgens rasstandaarde geklassifiseer. Die lewende gewig van die ramme wat aan die begin van die toetsperiodes aangeteken is, was matig tot hoog en positief met meeste van die liggaamsparameters gekorreleerd. Die uitsondering was GDT, waar ʼn negatiewe korrelasie (-0.25) gevind is. Die lewende gewig van die ramme aan die einde van die toetsperiodes was matig en positief met beide skrotumomtrek (0.57) en die hoogste met liggaamsbreedte (0.76) gekorreleerd. Gemiddelde daaglikse toename was hoog en positief (0.63) met lewende gewig aan die einde van die toetsperiode gekorreleerd. Groot variasie binne toetsperiodes, wat aan ouderdomsverskille en variasie tussen toetsgroepe toegeskryf kan word, het genoodsaak dat die data vir die effek van jaar/seisoen gekorrigeer word. Ramme is volgens begingewig in bo- en ondergemiddelde groepe gerangskik. Groeipatrone van die ramme is met gekorrigeerde einddata ondersoek en gevind dat 75% van ramme gedurende die toetsperiode in hul onderskeie groepe gebly het. Hierdie bevinding verleen steun aan die positiewe korrelasie van 0.58 wat vir lewende gewig aan die begin en einde van toetsperiodes hierbo gevind is. Die liggaamsmates wat aan die begin en einde van die toetsperiodes gemeet is, was in die meeste gevalle matig tot hoog en positief (P < 0.0001) met mekaar gekorreleerd. Die uitsondering was GDT, wat laag en negatief met liggaamsmates, wat aan die begin van toetsperiodes aangeteken is, gekorreleerd was. Die seisoenseffek het die grootste bydrae tot lewende gewig aan die einde van die toetsperiodes gemaak, d.i. nadat elke meting deur die somme van kwadrate gekwantifiseer is. Dit is gevolg deur liggaamsbreedte, -lengte, skouerhoogte, skrotumomtrek en GDT (R² = 31.62%). Nadat daar vir jaarseisoen gekorrigeer is, was die bydrae van die onderskeie parameters tot lewende gewig aan die einde van toetsperiodes nog in dieselfde volgorde. Nadat ʼn stapsgewyse prosedure vir gekorrigeerde lewende gewig aan die einde van toetsperiodes gedoen is, is gevind dat liggaamsbreedte die grootste bydrae tot lewende gewig aan die einde van toetsperiodes gemaak het. Gemiddelde daaglikse toename het die derde grootste bydrae, d.i. na liggaamsbreedte en –lengte tot gekorrigeerde lewende gewig aan die einde van toetsperiodes gemaak. Vanweë die hoë korrelasies wat tussen die onderskeie liggaamsmates gevind was, is daar ook vir multi-kollineariteit getoets om vas te stel of die parsiële bydraes van die onderskeie liggaamsmetings verander. Dit het egter onveranderd gebly. Regressie-analises het getoon dat liggaamsmates geneem aan die begin en einde van die toetsperiodes betekenisvol (P<0.0001) oor die hele tydperk (1988 – 2000) afgeneem het. Die grootste jaarlikse afnames was vir GDT (-2,5%) en liggaamsbreedte (-1,1%) bereken. Die negatiewe waardes wat verkry is, toon dat die Dorper oor tyd kleiner word. Die toepaslikheid van die visuele seleksiemetodes moet dus ernstig bevraagteken word. Die invloed van gekorrigeerde liggaamsmates en GDT op seleksie volgens rasstandaarde wat deur die rasinspekteurs gedoen is, is toe op puntediagramme aangetoon. Dit het getoon dat die rasinspekteurs deurentyd groter en swaarder ramme vir stoetseleksie selekteer. Daar is egter steeds ramme wat ondergemiddeld presteer en wat aan die Dorperbedryf as stoetramme beskikbaar gestel word. Liggaamsbreedte was die liggaamsmate wat die hoogste voorkeur van rasinspekteurs gekry het. Die liggaamsmate wat die minste deur die rasinspekteurs in ag geneem is, was dié van skouerhoogte. ʼn Moontlike verklaring vir laasgenoemde is dat die tendens van die kleinerwordende Dorper hieraan gekoppel kan word, omdat skouerhoogte 'n aanduiding van raamgrootte is. Visuele beoordeling behoort in samewerking met wetenskaplike metodes gebruik te word om sodoende ʼn optimum grootte vir die Dorper daar te stel.

Thesis (MScAgric)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: Two in vitro experiments were conducted to evaluate the effect of exogenous fibrolytic enzyme application on dry matter (DM) and neutral detergent fibre (NDF) degradation and gas production (GP) of mature forages and forage-concentrate mixtures. The forages used in the first experiment were lucerne hay (LH), oat hay (OH) and wheat straw (WS). The same forages were used in the second experiment, but they were mixed with a concentrate feed to make three mixtures consisting of 80% (HC), 50% (MC) or 20% (LC) concentrate. The extracellular enzyme fraction (supernatant) of a fungal strain, ABO 374, was used as feed additive. The supernatant was used in a fresh (SU-ABO374) or lyophilized (CSIR-ABO374) form, the latter being reconstituted with water immediately before application. The liquid supernatants were applied to the incubation medium and not directly to the substrate, at a rate equivalent to 7.5 ml/kg feed DM. In the control treatments of both experiments, water was used instead of the liquid supernatants. For the DM and NDF degradability trials in both experiments, 500 mg forage samples were weighed into 50 x 50 mm dacron bags which were incubated anaerobically at 39ºC in 1.4L of a rumen liquid inoculated buffered medium in 2L fermentation jars. Bags from all treatments were removed after 2, 4, 8, 12, 24, 48, 72 and 96 h of incubation. For the gas production determinations, 500 mg of the respective substrate samples were weighed into 120 ml glass vials which were incubated for 96 h in 40 ml inoculated medium to which 0.5 ml of the respective enzyme solutions were added. Gas pressure was recorded manually with a digital pressure gauge after 2, 4, 8, 12, 24, 48, 72 and 96 h and pressure was converted to volume with a predetermined regression. The 96 h substrate residues were washed, dried, weighed and analyzed for NDF and OM. In both experiments the substrates differed in terms of DM and NDF degradability and gas production rates, but the enzyme treatments had no effect. The lack of response to enzyme application was ascribed to a number of factors, including the fact that enzyme application was into the incubation medium and not directly onto the substrates and also that no significant pre-incubation interaction time was allowed. The same preparations gave positive results in previous trials where they were applied directly onto the substrates and where a pre-incubation interaction time of 16 hours was allowed. (Key words: Exogenous enzymes, forages, concentrate based diets, DM and NDF degradation, gas production ) / AFRIKAANSE OPSOMMING: Die invloed van eksogene fibrolitiese ensieme op in vitro fermentasiekinetika van ruvoer- en gemengde voersubstrate. Twee in vitro-experimente is uitgevoer om die invloed van eksogene fibrolitiese ensieme op droëmateriaal (DM) en neutraal-onoplosbare vesel (NDF) degradering en gasproduksie (GP) van volwasse ruvoersubstrate en ruvoer-kragvoermengsels te bepaal. Ruvoere in die eerste eksperiment was lusernhooi (LH), hawerhooi (HH) en koringstrooi (KS). Dieselfde ruvoere is in die tweede eksperiment gebruik, maar hulle is met ‘n kragvoer gemeng om drie mengsels te maak, bestaande uit 80% (HK), 50% (MK) of 20% (LK) kragvoer. Die ekstrasellulêre ensiemfraksie (supernatant) van ‘n fungiale stam, ABO 374, is as ‘n voertoedieningsmiddel gebruik. Die supernatant is is in ‘n vars (SU-ABO374) of gevriesdroogde (WNNR-ABO374) vorm gebruik, waar laasgenoemde onmiddellik voor toediening gerekonstitueer is. Die vloeistof-supernatante is nie direk op die substrate gevoeg nie, maar tot die inkubasiemedium gevoeg, teen ‘n hoeveelheid ekwivalent aan 7.5 ml/kg voer DM. In die kontrolebehandeling van beide eksperimente, is water in plaas van die vloeistofsupernatante gebruik. Vir die DM- en NDF-degraderingsproewe in beide eksperimente, is 500 mg van die onderskeie ruvoere in 50 x 50 mm dacronsakkies geweeg wat anaerobies by 39ºC geïnkubeer is in 1.4L van ‘n rumenvloeistof-geïnokkuleerde medium in 2L fermentasieflesse. Vir alle behandelings is sakkies na 2, 4, 8, 12, 24, 48, 72 en 96 h inkubasie verwyder. Vir gasproduksiebepalings is 500 mg van die onderskeie substraatmonsters in 120 ml glasbotteltjies geweeg en vir 96 h in 40 ml geïnokkuleerde medium geïnkubeer waarin 0.5 ml van die onderskeie ensiemoplossings gevoeg is. Gasdruk is na 2, 4, 8, 12, 24, 48, 72 en 96 h bepaal met behulp van ‘n digitale drukmeter en druk is met behulp van ‘n voorafbepaalde regressie na volume omgeskakel. Die 96 h substraatresidue is gewas, gedroog, geweeg en ontleed vir NDF en OM. In beide eksperimente het die substrate verskil ten opsigte van DM- en NDF-degradeerbaarheid en gasproduksietempo’s, maar die ensiembehandelings het geen invloed gehad nie. Die gebrek aan respons is aan verskeie faktore toegeskryf, insluitend die feit dat ensiemtoediening in die inkubasiemedium toegedien is en nie direk op die substrate nie, asook die feit dat daar nie ‘n noemenswaardige pre-inkubasie interaksietyd toegalaat is nie. Dieselfde ensiempreparate het positiewe resultate gelewer in vorige proewe waar dit direk op die substraat toegedien is en waar ‘n pre-inkubasie interaksietyd van 16 ure toegelaat is. (Sleutelwoorde: Eksogene ensieme, ruvoere, kragvoerdiëte, DM- en NDF-degradering, gasproduksie)

Thesis (MPhil)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: trout was conducted at the Jonkershoek trout research station of the Division of Aquaculture, University of Stellenbosch. Treatments consisted of ten experimental diets containing increasing levels of Spirulina (0%, 0.05%, 0.1%, 0.15%, 0.3%, 0.6%, 1.25%, 2.5%, 5% and 10%). The data was analyzed through means of a one-way ANOVA and Tukey’s pair wise comparison test for significant differences between treatments for the various parameters of flesh pigmentation and growth. The results indicates that the inclusion of Spirulina in the diets of rainbow trout will cause a undesirable yellowing of fillets, particularly at levels of inclusion at 5 percent and above, which may limit its use in diets for rainbow trout. There was an inconsistent increase in b* (yellowblue) and Chroma values with increasing levels of Spirulina inclusion, which may indicate the deposition of carotenoids (yellow-orange colour range) instead of the desired deposition of xanthophylls (pink-red colour range) in the flesh of the rainbow trout. This increase in b* (yellow-blue) values was significantly higher (P<0.05) at inclusion levels above 5 percent. Spirulina had no significant effect on weight gain of rainbow trout at any level of inclusion. No significant differences (P>0.05) were observed in any of the other production performance parameters (growth rate, feed intake, feed conversion ratio, viscerosomatic index, hepatosomatic index, and liver lipid content) that were evaluated. Low mortality rates were observed with no significant differences between treatments. A trend of decreased feed intake with increased levels of Spirulina inclusion became significant at the 2.5 percent level of inclusion, caused by deterioration in the palatability of the feed. A significantly higher dress-out percentage was observed at levels of Spirulina inclusion above 5 percent. A trend of decreased liver lipid content with increased Spirulina inclusion was observed, though not significant at any level of Spirulina inclusion. This observation justifies further investigation because of its potential to improved carbohydrate metabolism in carnivorous fish Results confirm that up to 10% Spirulina can effectively replaced soybean meal in the control diets for rainbow trout while simultaneously improving carcass dress-out at high inclusion levels. / AFRIKAANSE OPSOMMING: rantsoen van reënboog forel te evalueer. Die eksperiment is opgestel by die Akwakultuur Divisie, van die Universiteit van Stellenbosch, se navorsingstelsel in Jonkershoek, buite Stellenbosch. Reënboog forel (Oncorhynchus mykiss) vingerlinge van gemiddeld 20 gram is gebruik en ingedeel in 20 ronde tenks volgens kommersieële digthede (250 per tenk). Die rantsoene is gemeng met verskeie vlakke van Spirulina insluiting (0%, 0.05%, 0.1%, 0.15%, 0.3%, 0.6%, 1.25%, 2.5%, 5% en 10%). Twee herhalings van elke rantsoen is gevolg vir ‘n periode van 3 maande. Die vis is ad lib (volgens behoefte) gevoer, drie maal per dag. Daar was ‘n neiging tot ‘n verhoging in b* (geel-blou) en Chroma waardes met verhoogde insluitingsvlakke van Spirulina. Hierdie is wel ‘n aanduiding van die deponeering van karoteen, maar val in die geel-oranje kleur reeks en is nie die verlangde pienk-rooi (xantofil) kleur in die spier weefsel van die vis nie. Die verhoging in b* (geel-blou) waardes was statisties betekenisvol (P<0.05) bo die 5% insluitings vlak. In vergelyking met die kontrole (0%) rantsoen, was daar geen betekenisvolle massa toename na afloop van die proef tussen die verskeie behandelings nie. Behalwe vir ‘n verskil in voer inname, was daar geen statisties betekenisvolle verskil (P>0.05) waarneembaar tussen die verskillende behandelings ten opsigte van die verskeie produksie prestasie parameters nie. Daar was wel ‘n afnemende neiging in voer inname met verhoogde vlakke van Spirulina wat betekenisvol geraak het bo 2.5% insluitingsvlak. Smaaklikheid kan die moontlike rede hiervoor wees. Baie lae mortaliteite is ervaar by al die insluitings vlakke. Daar was ook ‘n neiging in hoër uitslag persentasie by verhoogde insluitingsvlakke van Spirulina wat betekenisvol geraak het bo 5 % insluiting. ‘n Afnemende vlak van lewer lipied inhoud is waargeneem maar was nie betekenisvol by enige van die insluitingsvlakke nie. Resultate van die proef dui daarop dat 10% Spirulina insluiting effektief kan dien as ‘n gedeeltelike plaasvervanger vir soyaboon meel in forel rantsoene. Die hoër uitslag persentasies hou belofte in. Die onverlangde vergeeling van die filette mag die gebruik van Spirulina beperk by reënboog forel rantsoene veral bo 5 % insluitings vlakke. Die verlaging in lewer lipied vlakke by ‘n verhoging van Spirulina insluiting regverdig vêrdere navorsing oor die potensiaal van Spirulina om die metabolisme van koolhidrate te verbeter by karnivoor visspesies.

Thesis (MScAgric (Animal Sciences)--University of Stellenbosch, 2007. / The objective of this investigation was to determine the effect of supplemented conjugated linoleic acid (CLA) on milk production and milk composition of lactating dairy cows in production systems commonly used in South Africa. In the first of three trials, samples of 24 bulk tanks were collected to get an impression of the CLA status of milk in the Western Cape Province, South Africa. Six samples were each collected from Jersey and Holstein herds in total mixed ration (TMR)-based systems. Another six samples were each collected from Jersey and Holstein herds on pasture-based systems. An additional three samples were also collected from co-op silos. One of these came from a mixed herd on TMR, one from a Jersey herd on TMR and the third sample from a mixed herd on pasture. The CLA levels of the milk were within the range reported in literature, albeit on the low side. The mean CLA level in milk fat of cows from pasture and TMR-based systems were 10.5 and 5.45 mg/g of fatty acids, respectively. This is in agreement with trends reported in the literature with cows on pasture having higher levels of CLA in their milk than cows on TMR’s. In this study, breed had no effect on the CLA level in milk fat.

Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 1985. / The domestication of ostriches and commercial ostrich breeding has a long and interesting history. Orstriches were successfully domesticated in Algeria during 1857 and also successfully bred in Italy during 1859. In South Africa the domestication of wild ostriches started in the Cape Colony with 80 tame birds during 1865. This number increased to 32 247 birds within ten years (De Mosenthal, 1877). Ostrich farming reached a peak during 1913 with 757 000 birds (De Jager, 1985, personal communication). Currently (1985) there are approximately 120 000 domesticated ostriches in South Africa. The commercial production of ostrich meat started in 1958 and the first abattoir was built in 1964. At the present moment 85 000 birds are slaughtered anually. Although the income from the carcass of a 14 month old ostrich comprise only 15% of the total income of a 14 month old bird (With the hide comprising 65% and, the first harvest feathers 20%), the subjects of carcass characteristics and meat quality has long been neglected. Very little is known about the anatomy of the skeleton and muscles of the ostrich, the post mortem reactions of these muscles and the effects of different slaughtering, chilling and deboning practices. The necessity of the above mentioned have proved very usefull in the beef, sheep, pork and poultry industries. With this present study we described the essential skeletal and muscular anatomy and included well known practices to the meat industry, such as electrical stimulation of the carcasses, post mortem pH monotoring of certain muscles, different deboning practices and vacuum packed ageing of selected cuts of ostrich meat. The obtained results are in agreement with general meat science, with expected inter-species variation, e.g. where the final pH-values of pork is relatively low at approximately 5,5; that of beef is higher at 5,7 and ostrich meat even higher at 6,0. Certain other fields of essential research are pointed out in this study, such as the growth and development of the ostrich, as well as certain basic biochemical research on the meat of the ostrich.

Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: The two main determinants of post-slaughter processing outcomes are rates of pH and temperature decline. Muscle pH and temperature interact continuously during rigor development to affect both the muscle contracture and proteolytic enzyme activity. The pH, however, can be manipulated independently of temperature by electrical inputs applied to the carcass. Electrical inputs that should be considered range from electrical stunning to the various forms of electrical immobilisation (EI) and stimulation (ES) that occur during and after the dressing procedures. EI is used to suppress convulsions that occur after electrical stunning to ensure operator safety to maintain high throughputs speeds while ES is used to induce rapid tenderisation, although having other biochemical and biophysical effects on meat. The objective of the study was to supply information on the effect of different EI and ES treatments, frequencies and pulse widths on the meat quality of beef. There are very little data on the effect of EI when it is combined with ES on meat quality. This study used two different EI frequencies (high – 800 Hz; HFI and low – 15 Hz; LFI) combined with either high (1040 V; HVS) or medium (300 V; MVS) voltage ES to study the effect of these treatments on meat quality. In the following experiment the EI waveform and ES was standardised using HFI with MVS with the frequency being changed to either 5, 15 or 50 Hz. Then the pulse width of the waveform was changed to 0.1, 0.5, 1 and 10 ms to optimise the ES system. Meat quality measurements were made from the Longisimmus dorsi (LD) and Semimembranosus (SM) after 1, 5 and 9 days of chilled storage at 0 C. The LD (shear force = 94.3±2.2; cooking loss = 26.85±0.29; retail drip = 0.996±0.037; storage drip = 2.78±0.155; WBC (water binding capacity) = 45.4±0.36) had significantly lower shear force and higher water binding capacity than the SM (shear force = 103.7±2.5; cooking loss = 34.63±0.25; retail drip = 2.12±0.103; storage drip = 3.63±0.245; WBC = 59.3±0.57). Day of assessment (Day 1 = 122.7±2.9; Day 5 = 87.7±2.2; Day 9 = 81.0±2.4) had a significant effect on tenderness of the LD as shear force declined with an increase of day of assessment. The LFI HVS (storage drip = 3.30±0.223; shear force = 102.9±4.5) produced significantly greater drip during storage and shear force values when compared to the HFI followed by either HVS (storage drip = 2.45±0.261; shear force = 85.2±4.0) or MVS (storage drip = 2.60±0.178; shear force = 94.2±4.2) in the LD, probably attributable to different rates of pH decline post mortem. LFI HVS (a* = 20.79±0.31; chroma = 22.92) and LFI MVS (a* = 20.24±0.27; chroma = 22.23±0.30) had a redder and more vivid bloomed colour than HFI HVS (a* = 19.71±0.33; chroma = 21.49±0.37) and HFI MVS (a* = 20.00±0.27; chroma = 21.98±0.31), while LFI HVS (a* = 15.27±0.40) and HFI MVS (a* = 14.64±0.29) had a redder colour compared to HFI HVS (13.85±0.35) at day 9 for the LD. The oxygen consumption rate (MTT assay) correlated inversely linear (r = -0.63 and -0.73) with the a* values 24 hrs post mortem allowing for 3 hrs of bloom. Stimulation with 15 Hz (0.47±0.040) and 5 Hz (0.41±0.045) had a higher pH decline (ΔpH) during stimulation than 50 Hz (0.29±0.027). Shear force measurements and cooking loss percentage were obtained from the LD after 24 hrs of chilled storage at 0 C. There were no difference between the stimulation treatments for shear force (15 Hz = 121.3±3.3; 5 Hz = 123.8±7.6; 50 Hz =114.8±7.94), while cooking loss was higher in 15 Hz (28.8±0.47) than 50 Hz (25.9±0.71) which correlated (r = 0.43; p = 0.01) with ΔpH. There were no differences between 10 ms (0.46±0.020), 1 ms (0.43±0.020) and 0.5 ms (0.44±0.019) pulse widths on the ΔpH while 0.1 ms (0.33±0.020) had a lower decline. Stimulation with a 1 ms (94.6±5.6) pulse width had the lowest shear force that varied from 10 (111.3±3.8) and 0.1 ms (111.3±5.8). While cooking loss (0.1 = 25.3±0.48; 0.5 = 26.9±0.67; 1 = 25.9±0.63; 10 = 25.5±0.66) and water-holding capacity (0.1 = 36.1±1.60; 0.5 = 37.3±1.42; 1 = 37.5±1.15; 10 = 36.9±1.45) was not affected in the LD after 24 hrs of chilled storage at 0 C. Colour measurements on the SM indicated that a 0.1(a* = 19.38±0.50; chroma = 22.70±0.51), 0.5 (a* = 20.89±0.49; chroma = 24.34±0.56) and 10 ms (a* = 19.69±0.46; chroma = 22.98±0.58) pulse width had a deeper red and a more vivid colour than 1 ms (a* = 16.66±0.37; chroma = 19.99±0.32) at day nine of retail display. In conclusion, HFI improves meat quality when combined with either HVS or MVS and that MVS either improves (colour stability) or has no adverse effects on meat quality (tenderness and WBC) in relation to HVS when combined HFI. In addition, it shows that there are alternative electrical parameters to voltage that can be used to change the pH decline and by changing frequency and pulse width, subtle changes can be made to an ES system. Since every abattoir is different due to layout, chiller space and cooling regime these electrical parameters can be modulated to optimise an electrical stimulation system without expensive modification to the whole system. / AFRIKAANSE OPSOMMING: Die tempo van pH en temperatuur daling is die twee hoof bepalings van na-slag prosseserings uitkomste. Spier pH en temperatuur het ’n gedurige interaksie tydens rigor ontwikkeling en beïvloed die spier sametrekking en proteolitiese ensiem aktiwiteit. Die spier pH kan onafhanklik van temperatuur gemanipuleer word, deur elektriese golfvorms deur die karkas te stuur. Die elektriese golfvorms wat in ag geneem moet word varieer van elektriese impulse tydens bedwelming tot die verskeie golfvorms van elektriese immobilisasie (EI) en stimulasie (ES) wat gebruik kan word gedurende en na die slagproses. EI word gebruik om konvulsies te beheer wat onstaan na elektriese bedwelming om werker veiligheid en hoë deurvloei tempos te verseker, terwyl ES die verouderings proses versnel, alhoewel dit ander biochemiese en biofisiese uitwerkings het op vleis. Die studie het verneem om inligting te verskaf oor die effek van verskillende EI en ES kombinasies, frekwensie en puls wydtes op die kwaliteit van beesvleis. Daar is baie min inligting van EI in kombinasie met ES se effek op vleis kwaliteit. Die studie het gebruik gemaak van twee verskillende (EI) frekwensies (hoog – 800 Hz; HFI and laag – 15 Hz; LFI) wat gekombineer is met of hoë (1040 V; HVS) of medium (300 V; MVS) spanning ES se effek op vleis kwaliteit. In die volgende eksperiment was die EI golfvorm en die ES gestandardiseer en HFI met MVS was gebruik met die frekwensie wat verander is tussen 5, 15 en 50 Hz. Daarna was die pulse wydte van die golfvorm verander tussen 0.1, 0.5, 1en 10 ms om die ES sisteem te optimiseer. Vleis kwaliteit van die Longisimmus dorsi (LD) en Semimembranosus (SM) spiere was bepaal na 1, 5 en 9 dae van verkoelde storing teen 0°C. Die LD (skeurkrag = 94.3±2.2; kookverlies = 26.85±0.29; kleinhandel drup verlies = 0.996±0.037; storing drip verlies = 2.78±0.155; WBV (water bindings vermoë) = 45.4±0.36) het ‘n betekenisvolle laer skeurkrag waardes en hoër water bindings vermoë gehad in vergelyking met die SM (skeurkrag = 103.7±2.5; kookverlies = 34.63±0.25; kleinhandel drupverlies = 2.12±0.103; bergings drupverlies = 3.63±0.245; WBV = 59.3±0.57). Die dag van assesering (Dag 1 = 122.7±2.9; Dag 5 = 87.7±2.2; Dag 9 = 81.0±2.4) het ’n betekenisvolle effek gehad op die skeur krag waardes en het afgeneem met ’n toename in die dag van assesering. LFI HVS (storing drupverlies = 3.30±0.223; skeurkrag = 102.9±4.5) het betekenisvolle hoër vog verliese gehad tydens verkoelde storing en skeur krag wanneer dit vergelyk word met HFI gevolg deur of HVS (storing drupverlies = 2.45±0.261; skeurkrag = 85.2±4.0) of MVS (storing drupverlies = 2.60±0.178; skeurkrag = 94.2±4.2). LFI HVS (a* = 20.79±0.31; chroma = 22.92) en LFI MVS (a* = 20.24±0.27; chroma = 22.23±0.30) het ‘n helder en dieper rooi kleur gehad in vergelyking met HFI HVS (a* = 19.71±0.33; chroma = 21.49±0.37) en HFI MVS (a* = 20.00±0.27; chroma = 21.98±0.31), terwyl LFI HVS (a* = 15.27±0.40) en HFI MVS (a* = 14.64±0.29) ’n rooier en helderer kleur as HFI HVS (13.85±0.35) gehad het in die LD. Die suurstof verbruik tempo (MTT analise) korreleer omgekeerd (r = -0.63 en -0.73) met die a* waardes 24 hr post mortem na 3 hr van blootstelling van lug. Stimulasie met 15 (0.47±0.040) en 5 Hz (0.41±0.045) het ’n hoër pH daling (ΔpH) tydens stimulasie as 50 Hz (0.29±0.027). Skeurkrag waardes en kookverliese is verkry vanaf die LD na 1 dag van verkoelde storing teen 0 C. Daar was geen verskil tussen stimulasie frekwensie se effek of skeurkrag (15 Hz = 121.3±3.3; 5 Hz = 123.8±7.6; 50 Hz =114.8±7.94) nie, terwyl die kookverliese hoër was in die 15 Hz (28.8±0.47) as 50 Hz (25.9±0.71) behandeling wat gekorreleer (r = 0.43; p = 0.01) het met ΔpH. Daar was geen verskill tussen 10 (0.46±0.020), 1 (0.43±0.020) en 0.5 ms (0.44±0.019) puls wydtes se effek op ΔpH nie, terwyl 0.1 (0.33±0.020) ms ‘n kleiner afname tot gevolg gehad het. Stimulasie met ‘n 1 ms (94.6±5.6) puls wydte het die laagste skeurkrag gehad wat verskil het van die 10 (111.3±3.8) and 0.1 ms (111.3±5.8) puls wydtes, terwyl kookverliese (0.1 = 25.3±0.48; 0.5 = 26.9±0.67; 1 = 25.9±0.63; 10 = 25.5±0.66) en waterbindingsvermoë (0.1 = 36.1±1.60; 0.5 = 37.3±1.42; 1 = 37.5±1.15; 10 = 36.9±1.45) nie beïvloed was nie. Kleur metings van die SM het getoon dat ‘n 0.1 (a* = 19.38±0.50; chroma = 22.70±0.51), 0.5 (a* = 20.89±0.49; chroma = 24.34±0.56) en 10 ms (a* = 19.69±0.46; chroma = 22.98±0.58 puls wydtes die helder en dieper rooi kleur gehad het as 1 ms (a* = 16.66±0.37; chroma = 19.99±0.32) teen dag 9 van kleinhandel vertoning. Ter opsomming, lei HFI tot beter vleis kwaliteit wanneer dit gekombineer word met of HVS of MVS. Verder lei MVS tot of ’n verbetering (kleur stabiliteit) of geen nadelige effek op vleis kwaliteit (sagtheid en WBV) in vergelyking met HVS wanneer dit gekombineer word met HFI. Die studie bewys ook dat daar ander elektriese parameters bestaan as spanning, wat verander kan word om die pH daling te beïvloed. Deur die frekwensie en pulswydte te verander, kan klein veranderinge aangebring word aan ’n ES sisteem. Elke abattoir is verskillend as gevolg van uitleg, koelkamer spasie en verkoelings tempo en hierdie elektriese parameters kan verander word om ’n ES sisteem te optimiseer sonder enige duur veranderinge aan die hele sisteem.

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

Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2011. / Includes bibliography. / ENGLISH ABSTRACT: Two studies were done to determine the distribution rate and efficiency of dietary melamine (MEL) to poultry meat and eggs. The possibility of MEL distribution into meat and eggs after feeding cyromazine (CYR) was also investigated. Five separate diets were formulated for broiler and layer chickens containing graded levels of MEL. In the broiler trial (Experiment 1), a number of 480 day-old Cobb 500 broiler chickens were divided into five treatment groups. Diets contained 0 (CON), 50 (MEL50), 100 (MEL100), 500 (MEL500) mg/kg MEL or 4 mg/kg CYR (CYR4). The duration of the trial was 36 days and breast muscle, kidney and liver samples were harvested on Days 11, 13, 15, 18, 22, 29 and 36 after the start of the feeding and analyzed for MEL. For the duration of the trial, all experimental diets were presented ad libitum and feed intake, weight gain, mortality rate, feed conversion ratio (FCR), protein efficiency rate of birds and the European production efficiency rate were determined. In the layer trial (Experiment 2), 120 Hyline Silver hens (24 weeks of age) were randomly divided into five treatment groups. The treatment diets were the same as for Experiment 1. The duration of the trial was 20 days and layers received the treatment diets for the first 10 days after which the control diet was provided for another 10 days. Feed intake, mortality rate, egg production and egg weights were recorded daily, while live weight was recorded at the beginning and end of the trial. Dietary MEL levels of up to 500 mg/kg did not have any detrimental effect on production parameters for broilers. In the layer trial, feed intake and egg weights were negatively affected by the MEL500 treatment. Dietary MEL was absorbed by broilers and layers and rapidly distributed to the kidneys, livers, muscles and eggs. As the dietary MEL concentration increased from 50 and 100 mg/kg to 500 mg/kg, an increase (P < 0.01) was observed in muscle tissue and egg MEL residue concentrations. Melamine concentration for broilers peaked at 22 days of age and decreased until day of slaughter. The kidneys contained the highest MEL residue levels, compared to other organ tissues, such as muscle and liver. In layer hens, a MEL distribution plateau in eggs was reached between Days 1 and 4 and decreased from Day 7 to 10. The distribution of MEL in eggs was higher to albumin than to the yolk. Upon withdrawal, MEL concentration in these tissues declined to undetectable levels within seven days. No MEL could be detected in meat or eggs when birds received the CYR4 treatment. The distribution efficiency (DEf) of MEL to meat and eggs did not appear to be dose dependant. For meat, the DEf varied between 1.2 and 2.7% and for eggs it varied between 0.7 and 0.8%. / AFRIKAANSE OPSOMMING: Twee studies is uitgevoer om die verspreidings tempo en effektiwiteit van melamien (MEL) na hoender vleis en -eiers te bepaal. Die moontlikheid van MEL verspreiding na vleis en eiers deur die voeding van cyromazien (CYR) is ook ondersoek. Vyf aparte diëte is geformuleer vir braaikuikens en lê-henne wat verskillende MEL insluitings vlakke bevat het. Vir die braaikuiken proef (Eksperiment 1), is 480 dag oud Cobb 500 braaikuikens ingedeel in vyf behandelings groepe. Diëte het 0 (CON), 50 (MEL50), 100 (MEL100), 500 (MEL500) mg/kg MEL en 4 mg/kg CYR (CYR4) bevat. Die tydsduur van hierdie proef was 36 dae en bors-, spier-, nier- en lewer monsters is ingesamel op Dae 11, 13, 15, 18, 22, 29 en 36 wat geëvalueer is vir MEL. Tydens die verloop van die proef is alle eksperimentele diëte ad libitum gevoer en voerinname, massa toename, mortaliteit, voeromsettings verhouding, proteïen effektiwiteits tempo asook die Europese produksie effektiwiteits tempo is bepaal. Vir die lê-hen proef (Eksperiment 2), is 120 Hyline Silver henne (24 weke oud) ewekansig verdeel in vyf behandelings groepe. Die behandelings diëte het dieselfde MEL en CYR konsentrasies bevat as Eksperiment 1. Die tydsduur van hierdie proef was altesaam 20 dae waarvan henne behandelings diëte vir die eerste 10 dae ontvang het, waarna henne vir die daarop volgende 10 dae ‘n kontrole dieët wat 0 mg/kg MEL bevat gevoer is. Voerinname, mortaliteit, eier produksie en eier gewig is daagliks opgeteken, terwyl lewende massa aan die begin en einde van die proef gemeet is. Melamien dieët vlakke tot 500 mg/kg het geen negatiewe effek op braaikuiken produksie parameters gehad nie. Vir lê-henne, is slegs voerinname en eier gewig negatief beïnvloed vir MEL500. Melamien is na inname geabsorbeer deur braaikuikens en lê-henne en het vinnig versprei na die niere, lewer, spiere en eiers. Soos die MEL vlakke van die behandelings diëte toegeneem het van 50 en 100 mg/kg na 500 mg/kg, het ‘n beduidende (P < 0.01) toename in spierweefsel en eier MEL residu konsentrasies voorgekom. Melamien konsentrasies vir braaikuikens het gepiek op 22 dae en geleidelik afgeneem tot op dag 36. In lê-henne het ‘n MEL verspreidings platu in eiers plaasgevind tussen Dag 1 en 4 en geleidelik afgeneem tydens Dag 7 en 10. Die niere het die hoogste MEL residu vlakke bevat in vergelyking met die lewer- en spierweefsels. Die verspreiding van MEL in eiers was hoër na die albumien as na die dooier. Tydens onttrekking het die MEL konsentrasie vlakke in hierdie weefsels in so ‘n mate afgeneem dat dit onbespeurbaar was binne sewe dae. Geen MEL kon in vleis- en eiermonsters gemeet word vir CYR4 nie. Die verspreidings doeltreffendheid (DEf) van MEL na vleis en eiers was nie dosis afhanklik nie. Vir vleis het die DEf gevarieër tussen 1.2 en 2.7% en vir eiers tussen 0.7 en 0.8%.

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 ...

Dissertation (PhD(Agric))--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: This study is a search for a quantifiable measure which estimates the genetic merit of female animals’ breeding efficiency. For practical reasons, such a measure must be both simple and inexpensive to record, irrespective of the herd management strategy. A literature investigation was undertaken to summarize breeding objectives for reproduction efficiency and to review different ways of expressing genetic reproduction efficiency. Traits to assess these in terms of the breeding objective, merits and requirements in terms of data collection are discussed. During the lifetime of a cow events occur which influence her fertility. A distinction is made between component traits and aggregate traits: a component trait points to one event, while aggregate traits are composites of more than one event. Although all the traits discussed seem relevant for breeding value estimation, the practical application depends on the herd management system in use. Age at first calving and days to calving are component traits that are easily and inexpensively measurable. Heritability estimates for the age at first calving were moderate. The heritability estimated for days to calving was 0.09. Calving rate comes close to the overall breeding objective. The estimated heritability of calving rate is low (0.04), resulting in slow genetic improvement. Calving success was defined and investigated even though some constraints exist. A sire model proved that genetic variation exists for calving success on the underlying scale. The corresponding heritability estimate was 0.27. Three categorical traits were defined. For stayability a sire variance of 0.41 was estimated with a heritabitity on the underlying scale of 0.27. The sire variances and heritabilities estimated for retention and calf tempo were high. Of the three traits, calf tempo is the one that reflects the true fertility of the bull’s female progeny. Calf tempo was redefined as net breeding merit, a trait describing the retention of male animals and the reproductive performance of their female offspring. The obtained sire variances show that the trait is heritable and can be improved by selection. Net breeding merit gives an indication of the ‘success’ of sires in a given population. A heritability estimate of 0.20 was estimated on a data set comprising offspring of bulls older than nine years, but when offspring of all sires were included, heritability estimates of 0.08 and 0.11 for the Afrikaner and Bonsmara, respectively, were found. Adjusting for young females was investigated by using the best linear unbiased estimate (BLUE) deviations to derive adjustment factors for herd level in order to predict performance for net breeding merit. Variation in the BLUE deviations occurred between all age class groups for the Afrikaner, whereas for the Bonsmara the variation between the BLUE deviations for the 3 year olds seems greater than the variation in the other age groups. It is suggested that the standardized curve for herd performance level derived from the BLUE deviations be used to adjust the phenotypic values of younger animals. This way the comparison between older and younger animals should be more valid. In conclusion, reproductive traits are heritable and genetic improvement can be achieved through selection. Any economical viable beef enterprise should include at least one trait in their selection criteria that will improve the reproductive efficiency. / AFRIKAANSE OPSOMMING: Hierdie studie is ‘n ondersoek na ‘n kwantifiseerbare maatstaf wat die genetiese meriete van vroulike diere se teeldoeltreffendheid beraam. Om praktiese redes moet so ‘n beraming sowel eenvoudig as goedkoop wees om te bepaal, onafhanklik van die kudde bestuurstrategie. ‘n Literatuurstudie is onderneem om die teeldoeleindes vir reproduktiewe doeltreffendheid op te som, sowel as om die verskillende wyses van genetiese reproduksiedoeltreffendheid beskrywing onder oë te neem. Verskeie eienskappe om hierdie beskrywings in terme van teeldoeleindes, meriete en dataversamelings-vereistes te raam, word bespreek. Gedurende ‘n koei se leeftyd kom gebeurtenisse voor wat haar vrugbaarheid beïnvloed. Daar word onderskei tussen komponenteienskappe en aggregaateienskappe: ‘n komponenteienskap verwys na een gebeurtenis, terwyl aggregaateienskappe na samestellings van meer as een gebeurtenis verwys. Hoewel al die eienskappe wat bespreek word relevant voorkom, sal die praktiese toepassing afhang van die kuddebestuurstelsel in gebruik. Ouderdom by eerste kalwing en dae tot kalwing is komponenteienskappe wat maklik en goedkoop bepaal kan word. Oorerflikheidsramings vir die ouderdom van eerste kalwing was matig. Die oorerflikheidsraming vir dae tot kalwing was 0.09. Kalffrekwensie is baie na aan die oorkoepelende teeldoelwit. Die geraamde oorerflikheid vir kalffrekwensie is laag (0.04), wat stadige genetiese verbetering tot gevolg het. Kalfsukses is gedefinieer en ondersoek, hoewel enkele beperkings bestaan het. ‘n Vaar-model het aangetoon dat genetiese variasie ten opsigte van kalfsukses op die onderliggende skaal bestaan. Die ooreenkomstige oorerflikheidsraming was 0.27. Drie kategoriese eienskappe is gedefinieer. Vir blyvermoë in die kudde is ‘n vaar-variansie van 0.41 geraam, met ‘n oorerflikheid van 0.27 op die onderliggende skaal. Die vaar-variansies en oorerflikhede wat vir retensie en kalftempo bereken is, was hoog. Van die drie eienskappe is kalftempo die een wat die ware vrugbaarheid van die bul se vroulike nageslag reflekteer. Kalftempo is herdefinieer as netto teelmeriete, ‘n eienskap wat die retensie van manlike diere en die reproduktiewe prestasie van hulle vroulike nasate beskryf. Die verkreë vaar-variasies wys dat die eienskap oorerflik is en verbeter kan word met seleksie. Netto teelmeriete gee ‘n aanduiding van die “sukses” van ‘n vaar in ‘n gegewe populasie. ‘n Oorerflikheidsraming van 0.30 is verkry op ‘n datastel bestaande uit die nageslag van bulle ouer as nege jaar, maar as die nageslag van alle vaars ingesluit is, was die oorerflikheidsraming onderskeidelik 0.08 en 0.11 vir die Afrikaner en Bonsmara. Aanpassing vir jong vroulike diere is ondersoek deur gebruik te maak van die beste lineêre onpartydige beramings (BLUE) om korreksiefaktore vir die kuddevlak te verkry, ten einde die prestasie ten opsigte van netto teelmeriete te voorspel. Variasies in die BLUE afwykings het voorgekom tussen alle ouderdomsgroepe vir die Afrikaner, terwyl vir die Bonsmara die variasie tussen BLUE afwykings vir die 3-jaar oud diere groter was as vir die ander ouderdomsgroepe. Dit word voorgestel dat die gestandardiseerde kurwe vir kuddeprestasievlak wat afgelei word van BLUE afwykings gebruik word om die fenotipiesewaardes van jonger diere aan te pas. Op hierdie wyse behoort die vergelyking tussen ouer en jonger diere meer geldig te wees. Ten slotte, reproduktiewe eienskappe is oorerfbaar en genetiese vordering is moontlik deur seleksie. Enige ekonomies lewensvatbare vleisbees-onderneming behoort ten minste een eienskap wat die reproduktiewe doeltreffendhied sal verbeter, in te sluit in seleksie kriteria.