Thesis (MscAgric (Animal Sciences))--University of Stellenbosch, 2006. / Six non-lactating, ruminally cannulated Holstein cows were used in a three part study to determine the effect of biotin supplementation to dairy cows on forage fermentation characteristics. Cows were randomly assigned to two groups in a 2 x 3 change-over experiment. All cows received oat hay ad libitum and one of two concentrate feeds, fed twice daily at 2 kg per feeding as a top dressing. The concentrates were identical in composition, except for a premix that was included to provide either 0 or 40 mg supplemental biotin/cow per day when the concentrate was fed at a rate of 4 kg/cow. Cows received the respective treatments for 28 days before being changed over to the other treatment. All cows therefore received both treatments. The first 21 days in each period were used for adaptation, while the last 7 days of the period were used for an in sacco trial, as well as for the collection of rumen liquor for two in vitro studies. The in vitro studies were a gas production trial and an in vitro digestibility trial. Forages differing in neutral detergent fibre (NDF) content were used as substrates in the study. Lucerne hay (440 g NDF/kg DM), oat hay (680 g NDF/kg DM), and wheat straw (798 g NDF/kg DM) were chosen to represent high, medium and low quality forages. In the gas production study, samples (0.5 g) of the three forages were incubated at 39ºC in buffered rumen liquor (obtained from cows in the different treatments) in glass vials. Pressure readings were taken after 12, 18, 24, 30 and 48 hours incubation using a digital pressure gauge fitted with a 21 gauge needle. Pressure readings were converted to gas volumes with the aid of a predetermined regression equation. In the in vitro digestibility trial, forage samples (0.25 g) were weighed into Ankom F57 filter bags and incubated at 39ºC in an Ankom Daisy II incubator in buffered rumen liquor. Three bags of each substrate were removed from the incubation jars after 18, 24 and 30 h incubation. Bag residues were analyzed for dry matter, organic matter and NDF. In the in sacco degradability trial, forage samples (5 g) were weighed into 100 x 200 mm Ankom Forage Bags and inserted into the rumina of the respective cow simultaneously. One bag per substrate was removed from each cow at after 4, 8, 18, 24, 30 and 48 h incubation, while two bags per substrate were removed after 72 and 96 h to ensure enough residue for subsequent chemical analysis. Samples of rumen liquor were taken at each of the mentioned incubation times for VFA analysis, while rumen pH was also measured at these times. All the data collected were subjected to a one-way ANOVA, least square means were determined and significance was declared at P<0.05. Biotin supplementation increased the rate of gas production (0-12 h) of all three substrates, as well as cumulative gas production at 48 h. No treatment effects were observed in the in vitro digestion study. Biotin supplementation increased the rate of in sacco NDF disappearance and calculated effective NDF degradability in oat hay and wheat straw, but not in lucerne hay. The rumen pH curve appeared higher for the biotin treatment than for the control and the value at the 72 h sampling time was significantly higher for the biotin treatment than for the control treatment (6.13 vs 5.94). Rumen pH tended to be higher (P<0.10) at 18 h (6.44 vs 6.23), 48 h (6.13 vs 6.00) and 96 h (6.14 vs 6.04). There was also a tendency (P<0.10) for the mean pH over the total 96 h period to be higher for the biotin treatment than for the control (6.09 vs 5.97), while the maximum and minimum pH values did not differ between treatments. Molar proportions of volatile fatty acids did not differ between treatments and the acetic acid proportion was relatively high (acetic:propionic = 74:15), which was probably because the cows were not on a very high concentrate diet. It was concluded that biotin supplementation to dairy cows may improve fermentation rates and NDF digestibility of certain forages.

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) -- University of Stellenbosch, 2002. / ENGLISH ABSTRACT: Experiment 1: Two studies were conducted to research the effect of divergent selection for multiple rearing ability on carcass weight, mutton production, meat quality and carcass characteristics of similar-aged Merino sheep. Data of 114 19-month-old Merino sheep, 40 ewes and 74 rams were used in this study. The study was done in two parts over 2 years. Only rams (52) were slaughtered over a two-week period in study A. Twenty-two rams and 40 ewes were slaughtered over a three-week period in study B. The sheep were descended from two selection lines that have been divergently selected for maternal multiple rearing ability since 1986. In brief, ewe and ram progeny of ewes rearing more than one lamb per joining (i.e. that reared twins at least once) were preferred as replacements in the high (H) line. Descendants of ewes that reared fewer than one lamb per joining (i.e. that were barren or lost all lambs born at least once) were preferred as replacements in the low (L) line. In study A the mean (±SE) slaughter weight of H line rams . were 12% heavier (P<O.OI) than that of L line contemporaries. A corresponding difference (P<O.OI) of 13% was found for carcass weight Adjustment for the higher live weight by analysis of covariance ofH line rams resulted in most of the line differences being eliminated (P>0.05). The difference between the weight of the loin retail cut remained significant (P<O.OI) in favour of the H line (1.64±0.04 vs. 1.37±0.08 kg, respectively). Skin weight (3.93±0.15 vs. 3.34±0.07 kg respectively; P<O.OI) and skin thickness (2.28±0.1l vs. 1.97±0.06 mm respectively; P<0.05) were greater in L line rams than in H line contemporaries. Rams in the L line also had heavier (P<0.05) trotters than the H line (l.05±0.03 vs. 0.96±0.02 kg respectively). In study B there were no interaction between line and sex and the data were pooled to present the main affects of sex and line. In study B the mean (±SE) slaughter weight of H line animals was 7% heavier (P=0.05) than that of L line contemporaries (44.02±0. 7 vs. 41.2±1.2 kg, respectively). A corresponding difference (P<0.05) of 11% was found for carcass weight between the two lines (pooled sexes) (l6.1±0.3 vs. 14.4±0.5 kg, respectively). There was no difference in the tenderness of the meat between the two selection lines but L line animals tended (P<0.16) to have more tender meat than H line contemporaries. Adjustment for the higher live weight of H line animals by analysis of covariance resulted in most of the line differences being eliminated (P>0.05). Hindquarter weight still remained significantly (P<O.OI) in favour of the H line after correction for live weight. Meat of L line animals was healthier based on their PUF A/SF A ratio. Experiment 2: This experiment was conducted to quantify the effect (noted in the first experiment) of selection for and against multiple rearing ability in Merino sheep on m. longissimus dorsi postmortem pH profiles. Data of 20 Merino sheep (10 rams and 10 ewes) were used. The sheep were slaughtered at a commercial abattoir. After slaughter pH was measured at 45 min, 2, 4, 8, 10, 12, 16, 20, 24, 33 and 48 h post slaughter, respectively. The pH was measured on the right side of each carcass in the m. longissimus dorsi between the 1st and the 6th lumbar vertebrae. The m. longissimus dorsi between the 1st and the 6th lumbar vertebrae of the left side was used for meat quality analysis. The initial pH of H line animals tended to be higher than that of L line contemporaries. At 48 h post-slaughter the pH of L line was higher (P<0.05) compared to that of H line animals. The meat of H line animals was tougher (99.79±3.58 vs. 88.32±3.38, P<0.05) than that of L line contemporaries, but there were no differences in the other meat quality characteristics. A higher initial pH (found in the first experiment, with a similar tendency in the second experiment) could indicate a lower susceptibility to stress in the H line. Experiment 3: An experiment was done to compare the meat-production potential between Merino and South African Mutton Merino (SAMM) ewes with increasing age. Slaughter data of . 653 Merino and SAMM ewes were used. Animals were slaughtered between 220 and 2719 days of age, which encompassed a range of slaughter weights from 27 to 100 kg. The ewes were differentiated according to age, 219 ewes being younger than 600 days and 416 being older than 600 days at slaughter. Young SAMM ewes had 10% heavier carcass weights than young Merino ewes and the difference was 47% between mature ewes. Mean maximum carcass weights of 33.44 and 22.65 kg were derived for the SAMM and Merino, at respective age of 2100 and 1900 days. SAMM ewes had a 47% thicker fat depth. Although Merinos were earlier maturing than the SAMM ewes, the latter breed had more subcutaneous fat at the mature stage. Experiment 4: The fourth experiment examined the effect of breed and sex on the carcass composition, yield of retail cuts, fat depth and chemical composition of meat from 35 South African Mutton Merino (SAMM) (17 rams and 18 ewes) and 61 Dormer (21 rams and 40 ewes) sheep. As there was no breed x sex interaction, the data were pooled to present the main effects of breed and sex. There were no differences in slaughter and carcass weight between Dormer and SAMM sheep. Dormers' had more fat (kidney, back fat depth) than SAMM sheep. The eye-muscle area of the Dormers' was 13% larger than that of the SAMM sheep. Rams were heavier (64.86±0.85 vs. 44.55±0.74 kg) than the ewes at slaughter. All the traits that were recorded, were heavier or higher in rams (P<0.05). After adjustment for higher live weight of the rams, the proportion of neck retail cut from the rams was higher than that from ewes and the proportion of hindquarter weight from the ewes was higher (P<0.05) than that from rams. After adjustment for the higher live weight of the rams, the moisture (75.35±0.37 and 73.35±0.37%) and lipid (2.68±0.33 and 3.80±0.33%) contents differed significantly (P<0.05) between the rams and ewes, respectively. With the significantly higher SFA value of the SAMM sheep and higher MUF A value of the Dormer sheep, meat from Dormer sheep could be regarded as healthier from a human prospective than that from SAMM sheep. Experiment 5: A study was done to test an ultrasound scanner (used on pigs) for the prediction of subcutaneous backfat and m. longissimus dorsi depth on Merino (52 rams), SA Mutton Merino (17 rams and 18 ewes) and Dormer (21 rams and 40 ewes) sheep. The sheep were scanned with an ultrasound scanner to predict the backfat and eye-muscle depth on the live animal. All animals were slaughtered to measure the true values of the fat depth and eye-muscle depth (25 and 45mm from the midline at the 13th rib). Overall regression equations over breeds (SAMM and Dormer, pooled breeds), and lines (H and L line Merinos, pooled lines) were obtained. Compared to previous research, the correlations between scanned values and true values were comparatively low (r = 0.07 - 0.25). Evidence from the literature suggested higher correlations of r = 0.53 - 0.56. Higher correlations could be achieved in older and fatter animals. The fact that the operator had no experience of scanning sheep could also have contributed to the low correlations. / AFRIKAANSE OPSOMMING: Eksperiment 1: Twee studies is gedoen om te kyk na die invloed van seleksie vir meerling grootmaakvermoe by Merino's op karkas-, vleiseienskappe en vleiskwaliteit is. Data van 114 19 maand oue Merino skaap, 40 ooie en 74 ramme is in die studie gebruik. Die studie is gedoen in twee dele oar 'n tydperk van twee jaar. Slegs ramme (52) is geslag oor 'n tydperk van twee weke in studie A. Twee en twintig ramme en 40 ooie is in studie B geslag oor 'n pericde van drie weke. Merino-ooie en -ramme afkomstig van 'n hoe (Il-lyn) en lae (L-lyn) lyn geselekteer vir rneerling grootmaakverrnoe is gebruik in 'n studie wat oor twee jaar uitgevoer is. Die twee lyne is intensief geselekteer vir en teen meerling grootmaakverrnoe vanaf 1986. Ram- en ooi-nageslag wat afkomstig is van ooie wat een of meer keer tweelinge in haar lewe per lam kans groot gemaak het is gebruik vir die H-lyn, terwyl ram en ooi nageslag afkomstig van ooie wat een of minder as een lam per lamkans groot gemaak het is gebruik vir die L-Iyn. In studie A is 52 rarnme (42 H-Iyn en 10 Llyn) geslag en slag- en karkaseienskappe is bestudeer. In ondersoek B is 22 ramme (16 l-l-lyn en 6 L-lyn) en 40 coie (34 H-Iyn en 7 L-Iyn) gebruik. Slag-, karkas- en vleiseienskappe is bestudeer. In ondersoek A is gevind dat die slagmassa van die Il-Iyn ramme 12% hcer en die karkasmassa 13% hcer is as die van die L-lyn ramme. Na kovariansie ontleding van die swaarder slagmassa van die H-Iyn diere, was die pote (1.05±0.03 vs. 0.96±0.02 kg; P<0.05) en velie swazrder (3.93±0.15 vs. 3.34±0.07 kg; P<O.Ol) en die velle dikker (2.28±0.11 vs. 1.97±0.06 mm; P<0.05) by L-Iyn diere as by H-lyn diere. Die groothandel lende snit van die H-Iyn diere was swaarder (1.64±0.04 vs. 1.37±0.08 kg; P<0.05) as die van L-Iyn diere. By studie B was daar geen interaksie tussen lyn en geslag nie, dus is die data verpoel om die betekenisvolheid van die hoofeffekte van lyn en geslag weer te gee. 'n Sewe persent hoer slagmassa is by H-Iyn diere waargeneem (44.02±0.7 vs. 41.20± 1.2 kg; P<0.05). 'n Ooreenstemmende verskil van (P<0.05) 11% is gevind in karkas massa tussen die twee lyne (16.1±0.3 vs. 14.4±0.5 kg). Daar was geen veskil in taaiheid van die vleis nie, maar diere van die H lyn se vleis het geneig (P<0.06) om taaier te wees. Na die kovariansie ontleding met massa as kovariant was die boude (P<O.OI) van die H-lyn diere en die lende (P<O.OI) groothandel snit van die ooie swaarder, verder was die verskille dieselfde as in ondersoek A Die vetsuurresultate toon dat net by die verhouding tussen die poli-onversadigde en vesadigde vetsure (PUF A/SF A) 'n verskil tussen die Iyne was. Die vetsuur resultate dui daarop dat die Llyn diere gesonder vleis vir menslike voeding het as die van die H Iyn diere. Eksperiment 2: In 'n tweede eksperiment is gekyk wat die invloed van seleksie vir meerling grootmaakvermoe by Merino skape op post mortem m. longissimus dorsi pH profiele is. Daar is gebruik gemaak van 20 Merino skape (10 ooie en 10 ramme), 10 H lyn en 10 Llyn diere. Die skape is geslag by 'n kornrnersiele abattoir. Die pH metings is geneem, 45 min, 2, 4, 6, 8, 10. 12, 16, 20, 24, 33 en 48 uur na slag. Die pH is geneem in die m. longissimus dorsi van die regter sy tussen die 1ste en 6de lumblale werwels. Die linker kant is gebruik vir vleiskwaliteits toetse Die pH lesing van H lyn diere wat 45 min na slagting geneem is het hoer geneig as in Llyn, terwyl pH lesings van die Llyn diere 48 h na slagting hoer was. Die vleis van die H lyn diere was taaier (99.79±3.58 vs. 88.32±3.38; P<0.05) as die van die Llyn diere, maar daar was geen verskille in die ander vleiskwaliteits toetse nie. Die hoe begin pH kan daarop dui dat die H lyn skape minder spanning voor slag ervaar he! Eksperiment 3: Die invloed van ouderdom op vleis produksie potensiaal, slag en karkasmassa en vetdikte by Suid Afrikaanse Vleis Merino (SAVM) en Merino ooie is ondersoek. Data van 635 Merino en SAVM ooie is gebruik. Die ooie was tussen 220 en 2719 dae oud met slagting en slagmassas wat gewissel het tussen 27 en 100 kg. Die ooie is opgedeel ten opsigte van ouderdorn. Die jong groep was ooie wat jonger as 600 dae oud was en die die res was bestempel as die ou groep. Die karkas massa van die jong SAVM ooie was 10% hcer as die van die Merino ooie en by die ou groep was die verskil 47% Ouer SAVM ooie het 52% dikker vet as die Merino ooie gehad. Merino ooie het 'n maksimum karkas massa van 22.65 kg op 'n ouderdom van 1900 dae gehad terwyl SAVM ooie 'n maksimum karkas massa van 33.44 kg op 'n ouderdom van 2100 dae gehad he! Al is die Merino 'n vroer ryp skaap as die SAVM, het die SAVM meer vet as volwasse dier. Eksperiment 4: In die experiment is gekyk na die effek van ras en geslag op slagmassa, karkasmassa, vleiseienskappe asook chemiese en vetsuur samestelling van die vleis van SAVM en Dormer skape. Slagdata van 61 Dormers' (21 ramme en 40 ooie) en 35 SAVM's (17 ramme en 18 ooie) is gebruik, Daar was geen interaksie tussen ras en geslag nie en dus is die data verpoel om die invloed van die hoof effekte (ras en geslag) te toets. Geen verskille is in die slagmassa tussen die Dormers en SAVM gevind nie. Die vet (onderhuids en niervet) van die Dormers was meer en die oogspier oppervlakte was 13% groter as die van SAVM skape. Ramme was swaarder (64.86±0.85 vs. 44.55±0.74 kg) as die ooie met slag. Na kovariansie ontleding van swaarder slagmassa van die ramme was die groothandel nek snit van die ramme swaarder (P<0.05) as die van die ooie en die boude van die ooie swaarder (P<O.Ol) in vergelyking met die van die ramme. Die voginhoud van vleis vanaf ramme was hoer (77.35±0.37 vs 75.35±0.37) as die van die coie. Ooie het 'n hcer persentasie vet in die vleis van die 11113de ribsnit gehad (2.68±0.33 vs. 3.80±0.33 %) Volgens die vetsuur analises het SAVM diere 'n hoer persentasie versadigde vetsure en die Dormers 'n groter persentasie mono-onversadigde vetsure gehad. Dit kan 'n aanduiding wees dat vleis vanaf Dormer skape gesonder is vir menslike gebruik. Eksperiment 5: Hierdie studie is gedoen om 'n ultraklank apparaat (gebruik by varke) te toets vir voorspelling van onderhuidse vet en oogspierdiepte by skape. Daar is gebruik gemaak van 52 Merino ramme (42 van die H-lyn en 10 van die Llyn), 61 Dormer skape (21 ramme en 40 ooie) en 35 SAVM skape (17 ramme en 18 ooie). Die vetdikte en oogspierdiepte op die lewende diere is bepaal met 'n ultraklank apparaat, waarna die diere geslag is en die werklike waardes direk op die koue karkas gemeet is. Regressie vergelykings is opgestel om korrelasies tussen ultraklank waardes en werklike waardes te kry. In hierdie proef was die korrelasies tussen geskatte en werklike waardes swak (r = 0.07-0.25). Beter korrelasies is egter weI deur ander navorsers gekry (r = 0.53- 0.56) Beter korrelasies kan in ouer en vetter diere verkry word. Die feit dat die operateur nie baie ondervinding met die skandering van skape gehad het nie kon bydrae tot die swak korrelasies.

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%.