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No description available.

Marine omega-3s, EPA and DHA, have been strongly evidenced to decrease the risk of cardiovascular disease, the leading cause of death in the United States. One of the richest sources of EPA and DHA in the U.S. diet is farmed Atlantic salmon, which has shown a steady consumption growth in the past decade. The U.S. shows the most production potential for salmon produced with an emerging production method, recirculating aquaculture systems (RAS), which directly addresses the environmental challenges associated with the traditional farming method, open-net pens. Because of the higher costs associated with RAS, the salmon it produces requires a price premium, and little is known about whether U.S. consumers are willing to pay such a premium. We conduct a hypothetical choice experiment across all major regional markets of the U.S. (n = 2857) to estimate consumers' willingness-to-pay for RAS and other attributes valued by producers and consumers. Our results show that U.S. consumers are willing to pay a premium for RAS, but only after prioritizing freshness (fewer days since harvest) and U.S. production, all of which were significant to the p < .001 level. Higher omega-3 content also justified a significant premium, but byproduct recycling and stocking density did not have any real influence on purchases. We express these willingness-to-pay (WTP) estimates as percentages of a reference product priced with model estimates. These adjusted retail premiums should be paired with RAS salmon production costs to understand the economic viability of RAS and illuminate the path to EPA and DHA nutrient security in the U.S. / Master of Science / Two micronutrients found in cold-water fish, EPA and DHA, have been strongly evidenced to decrease the risk of cardiovascular disease, the leading cause of death in the United States. One of the richest sources of EPA and DHA in the U.S. diet is farmed Atlantic salmon, which has shown a steady consumption growth in the past decade. The U.S. shows the most production potential for salmon produced with an emerging production method, recirculating aquaculture systems (RAS), which directly addresses the environmental challenges associated with the traditional farming method, open-net pens. Because of the higher costs associated with RAS, the salmon it produces requires a price premium, and little is known about whether U.S. consumers are willing to pay such a premium. We conducted an experiment with U.S. consumers (n = 2857) to estimate willingness-to-pay for RAS and other attributes valued by producers and consumers. Our results show that U.S. consumers are willing to pay a premium for RAS, but only after prioritizing freshness (fewer days since harvest) and U.S. production. Higher omega-3 content also justified a significant premium, but byproduct recycling and stocking density did not have any real influence on purchase

Yes / There remains an unmet need for safe and cost-effective adjunctive treatment of advanced colorectal cancer (CRC). The omega-3 polyunsaturated fatty acid eicosapentaenoic acid (EPA) is safe, well-tolerated and has anti-inflammatory as well as antineoplastic properties. A phase 2 randomised trial of preoperative EPA free fatty acid 2 g daily in patients undergoing surgery for CRC liver metastasis showed no difference in the primary endpoint (histological tumour proliferation index) compared with placebo. However, the trial demonstrated possible benefit for the prespecified exploratory endpoint of postoperative disease-free survival. Therefore, we tested the hypothesis that EPA treatment, started before liver resection surgery (and continued postoperatively), improves CRC outcomes in patients with CRC liver metastasis. Methods and analysis: The EPA for Metastasis Trial 2 trial is a randomised, double-blind, placebo-controlled, phase 3 trial of 4 g EPA ethyl ester (icosapent ethyl (IPE; Vascepa)) daily in patients undergoing liver resection surgery for CRC liver metastasis with curative intent. Trial treatment continues for a minimum of 2 years and maximum of 4 years, with 6monthly assessments, including quality of life outcomes, as well as annual clinical record review after the trial intervention. The primary endpoint is CRC progression-free survival. Key secondary endpoints are overall survival, as well as the safety and tolerability of IPE. A minimum 388 participants are estimated to provide 247 CRC progression events during minimum 2-year follow-up, allowing detection of an HR of 0.7 in favour of IPE, with a power of 80% at the 5% (two sided) level of significance, assuming drop-out of 15%. Ethics and dissemination: Ethical and health research authority approval was obtained in January 2018. All data will be collected by 2025. Full trial results will be published in 2026. Secondary analyses of health economic data, biomarker studies and other translational work will be published subsequently. Trial registration number NCT03428477. / The EMT2 trial is funded by Yorkshire Cancer Research (L387) and is sponsored by the University of Leeds. The EMT2 biospecimen collection is funded by the National Institutes of Health (1R01CA243454-01A1) and is sponsored by the University of Leeds ( governance-ethics@ leeds. ac. uk). Both studies have been adopted to the NIHR Clinical Research Network (CRN) Portfolio (CPMS ID 34700 and 47372, respectively) and have benefited from CRN research staff support.

La investigación que presentamos a continuación se ubica en el ámbito que se conoce como "Antropología de la Religión". Se trata del estudio de un grupo religioso de origen peruano, al que se le conoce como "La Hermandad del Cordero de Dios" o "La Divina Revelación Alfa y Omega". Este es pues nuestro Objeto de Estudio.

Background Iron deficiency (ID) is the world‟s most prevalent micronutrient deficiency and predominantly affects developing countries, also South Africa. In areas with low fish consumption and high n-6 PUFA vegetable oil intake, there is a risk for having inadequate n-3 PUFA status. Both iron and n-3 PUFA play important roles in the immune response, and supplementation is a strategy to alleviate deficiencies. However, little is known about potential interactive effects between concurrent iron and n-3 PUFA supplementation on the immune system. This is also important in the context that iron supplementation may be unsafe and may increase morbidity and mortality. Aim The overall aim of this thesis was to assess the effects of iron and docosahexaenoic (DHA)/eicosapentaenoic acid (EPA) supplementation, alone and in combination, on the immune system of ID children. More specifically, these effects were investigated on the occurrence and duration of illness and school-absenteeism due to illness, peripheral blood mononuclear cell (PBMC), red blood cell (RBC) and plasma total phospholipid fatty acid composition, iron status, fatty acid-derived immune modulators and targeted PBMC gene expression. Furthermore, association of PBMC, RBC and plasma total phospholipid fatty acid composition with allergic disease, were also examined. Design In a 2-by-2 factorial, randomised, double-blind, placebo-controlled trial, South African children (n = 321, aged 6–11 y) were randomly assigned to receive oral supplements of either 1) iron (50 mg as ferrous sulphate) plus placebo; 2) DHA/EPA (420/80 mg) plus placebo; 3) iron plus DHA/EPA (420/80 mg); or 4) placebo plus placebo for 8.5 mo, four times per week. Absenteeism and illness symptoms were recorded and biochemical parameters for compliance as well as parameters fundamental to immune function were assessed at baseline and endpoint. Furthermore, in a cross-sectional design, associations of allergic disease with baseline fatty acid composition of PBMC, RBC and plasma were examined. Results The combination of iron and DHA/EPA significantly attenuated respiratory illness caused by iron supplementation. DHA/EPA supplementation alone improved respiratory symptoms at school, but increased headache-related absenteeism. DHA/EPA and iron supplementation individually tended to increase and decrease anti-inflammatory DHA and EPA-derived mediators, respectively. Furthermore the anti-inflammatory DHA-derived immune mediator, 17HDHA was higher in the DHA/EPA plus placebo and iron plus DHA/EPA groups than in the iron plus placebo group. Also, the pro-inflammatory arachidonic acid (AA)-derived modulators (5- and 15-hydroxyeicosapentaenoic acid) were significantly lower in the iron plus DHA/EPA group compared to the placebo plus placebo groups. In the study population, 27.2% of the children had allergic disease and AA in PBMC phospholipids was significantly lower in the allergic children than in the non-allergic children. In RBC phospholipids dihomo-gamma-linolenic acid (DGLA) and the ratio of DGLA: linoleic acid (LA) correlated negatively and the n-6:n-3 PUFA ratio positively with total immunoglobulin E (tIgE). Furthermore, trans-C18:1n-9, tended to be higher in the allergic group. Conclusion DHA/EPA prevented respiratory illness caused by iron supplementation and although DHA/EPA on its own reduced respiratory morbidity when the children were present at school, surprisingly it increased the likelihood of being absent with headache and fever. The biochemical findings compliment the clinical results and support previous observations about DHA/EPA supplementation to reduce inflammation, but add to the current knowledge base that a relatively high oral dose of non-haem iron modulates circulating lipid-derived immune modulators and related gene expression. Furthermore, when supplementing with iron and DHA/EPA combined, in this ID population with low fish intake, the anti-inflammatory effect of DHA/EPA is maintained concurrently with attenuation of respiratory morbidity. This finding support the notion that excess iron (probably as non-transferrin bound iron) becomes available for pathogens and is probably why we found that iron increased respiratory infectious morbidity. The improved clinical outcome with combined supplementation seems to be related to increased lipid-mediator synthesis gene expression and the availability of DHA/EPA, leading to a more pro-resolving profile and enhanced immune competence. Overall these results give better insight into immune function and infectious morbidity in relation to n-3 PUFA and iron status and treatment, as well as the possible association of fatty acid status with allergic disease in young South-African school children. / PhD (Nutrition), North-West University, Potchefstroom Campus, 2015

Background Iron deficiency (ID) is the world‟s most prevalent micronutrient deficiency and predominantly affects developing countries, also South Africa. In areas with low fish consumption and high n-6 PUFA vegetable oil intake, there is a risk for having inadequate n-3 PUFA status. Both iron and n-3 PUFA play important roles in the immune response, and supplementation is a strategy to alleviate deficiencies. However, little is known about potential interactive effects between concurrent iron and n-3 PUFA supplementation on the immune system. This is also important in the context that iron supplementation may be unsafe and may increase morbidity and mortality. Aim The overall aim of this thesis was to assess the effects of iron and docosahexaenoic (DHA)/eicosapentaenoic acid (EPA) supplementation, alone and in combination, on the immune system of ID children. More specifically, these effects were investigated on the occurrence and duration of illness and school-absenteeism due to illness, peripheral blood mononuclear cell (PBMC), red blood cell (RBC) and plasma total phospholipid fatty acid composition, iron status, fatty acid-derived immune modulators and targeted PBMC gene expression. Furthermore, association of PBMC, RBC and plasma total phospholipid fatty acid composition with allergic disease, were also examined. Design In a 2-by-2 factorial, randomised, double-blind, placebo-controlled trial, South African children (n = 321, aged 6–11 y) were randomly assigned to receive oral supplements of either 1) iron (50 mg as ferrous sulphate) plus placebo; 2) DHA/EPA (420/80 mg) plus placebo; 3) iron plus DHA/EPA (420/80 mg); or 4) placebo plus placebo for 8.5 mo, four times per week. Absenteeism and illness symptoms were recorded and biochemical parameters for compliance as well as parameters fundamental to immune function were assessed at baseline and endpoint. Furthermore, in a cross-sectional design, associations of allergic disease with baseline fatty acid composition of PBMC, RBC and plasma were examined. Results The combination of iron and DHA/EPA significantly attenuated respiratory illness caused by iron supplementation. DHA/EPA supplementation alone improved respiratory symptoms at school, but increased headache-related absenteeism. DHA/EPA and iron supplementation individually tended to increase and decrease anti-inflammatory DHA and EPA-derived mediators, respectively. Furthermore the anti-inflammatory DHA-derived immune mediator, 17HDHA was higher in the DHA/EPA plus placebo and iron plus DHA/EPA groups than in the iron plus placebo group. Also, the pro-inflammatory arachidonic acid (AA)-derived modulators (5- and 15-hydroxyeicosapentaenoic acid) were significantly lower in the iron plus DHA/EPA group compared to the placebo plus placebo groups. In the study population, 27.2% of the children had allergic disease and AA in PBMC phospholipids was significantly lower in the allergic children than in the non-allergic children. In RBC phospholipids dihomo-gamma-linolenic acid (DGLA) and the ratio of DGLA: linoleic acid (LA) correlated negatively and the n-6:n-3 PUFA ratio positively with total immunoglobulin E (tIgE). Furthermore, trans-C18:1n-9, tended to be higher in the allergic group. Conclusion DHA/EPA prevented respiratory illness caused by iron supplementation and although DHA/EPA on its own reduced respiratory morbidity when the children were present at school, surprisingly it increased the likelihood of being absent with headache and fever. The biochemical findings compliment the clinical results and support previous observations about DHA/EPA supplementation to reduce inflammation, but add to the current knowledge base that a relatively high oral dose of non-haem iron modulates circulating lipid-derived immune modulators and related gene expression. Furthermore, when supplementing with iron and DHA/EPA combined, in this ID population with low fish intake, the anti-inflammatory effect of DHA/EPA is maintained concurrently with attenuation of respiratory morbidity. This finding support the notion that excess iron (probably as non-transferrin bound iron) becomes available for pathogens and is probably why we found that iron increased respiratory infectious morbidity. The improved clinical outcome with combined supplementation seems to be related to increased lipid-mediator synthesis gene expression and the availability of DHA/EPA, leading to a more pro-resolving profile and enhanced immune competence. Overall these results give better insight into immune function and infectious morbidity in relation to n-3 PUFA and iron status and treatment, as well as the possible association of fatty acid status with allergic disease in young South-African school children. / PhD (Nutrition), North-West University, Potchefstroom Campus, 2015

Résumé : L’hypertension artérielle pulmonaire (HTAP) est une maladie rare dans laquelle les artères pulmonaires subissent un important remodelage et un recrutement de cellules proinflammatoires dans la paroi. Généralement les patients atteints sont diagnostiqués tardivement. Or, à son stade avancé, l’HTAP est irréversible. Aucun traitement actuel ne permet de soigner définitivement les patients. Nous émettons l’hypothèse que l’inflammation pourrait être à l’origine de plusieurs dysfonctions cellulaires et que sa résolution pourrait probablement prévenir l’HTAP. Deux modèles d’HTAP expérimentale ont été utilisés. Le premier met en jeu des artères pulmonaires humaines (APH) cultivées in vitro et rendues hyperréactives et sur lesquelles les effets des Résolvines D1 et E1 ainsi que leurs précurseurs respectifs ont été évalués. Le deuxième est un modèle in vivo bien connu de rats hypertendus à la monocrotaline (MCT) sur lesquels le rôle curatif du MAG-DHA (un monoacylglycéride de l’acide docosahexaénoïque) a été étudié quand l’HTAP est déjà installée. Les résultats démontrent que 24 h de prétraitement in vitro avec le TNFalpha, l’IL-6 ou l’ET-1 augmente la réactivité pharmaco-mécanique et la sensibilité au Ca2+ des APH stimulées avec 80 mM de KCl, 1 µM de 5-hydroxytryptamine (5-HT), 30 nM U-46619 et 1 µM de PDBu. En revanche, 300 nM de RvD1 ou de RvE1 ainsi que 1µM de MAG-DHA ou de MAG-EPA (monoacylglycéride de l’acide éicosapentaénoïque) renversent les effets induits par les traitements proinflammatoires et vasoconstricteurs. De plus, in vivo, il a été démontré que 7 jours de traitement avec le MAG-DHA peuvent permettre de résoudre le statut inflammatoire dans un modèle d’hypertension pulmonaire induite par la MCT chez le rat. Dans les deux modèles, l’expression de biomarqueurs inflammatoires (TNFalpha, COX-2, STAT3) et les niveaux de phosphorylation des activateurs nucléaires du remodelage tels que c-Fos, c-Jun, NFkB et MMP9 étaient augmentées par les traitements proinflammatoires. Cependant, les expériences d’immuno-buvardage montrent que la RvD1, la RvE1 et leurs précurseurs normalisaient les niveaux de détections de ces marqueurs de l’inflammation. En conclusion, l’ensemble des données montrent que les Résolvines D1 et E1 ainsi que leurs précurseurs sont des candidats efficaces pour résoudre l’inflammation induite pour prévenir l’hyperréactivité pharmacologique des artères pulmonaires. / Abstract : Pulmonary hypertension (PH) is rare disease characterized by an important remodelling and proinflammatory cells recruitement into the pulmonary artery wall. Because of the late diagnostic, the patient care is often performed when PH is at its irreversible and most severe stage. Unfortunatly, none of the actual treatments are able to cure the patients for the long term. We hypothesize that inflammation could be a major event at the origin of all the other cellular dysfunctions that characterise PH. Resolvins; metabolites from Oméga-3 could resolve inflammation and potentially prevent or reverse PH. In the present study, two models of PH have been used. The first one is an in vitro model involving cultured human pulmonary arteries (HPA) in which inflammatory or hyperreactive conditions have been induced to evaluate the effects of Resolvin D1 and E1 and their precursors. The second model is a well-known in vivo model of monocrotalineinduced PH in rats, treated with MAG-DHA (monoacylglyceride form of docosahexaenoic acid) to evaluate the curative ability of this compound to resolve the disease at its severe stage. Results show that 24-h pre-treatment with TNFα, IL-6 or ET-1 increased the reactivity and Ca2+ sensitivity of HPA as revealed by agonist challenges with: 80 mM KCl, 1 μM 5- hydroxytryptamine (5-HT), 30 nM U-46619 and 1 μM PDBu. However, 300 nM RvD1 or RvE1, as well as 1 μM MAG-DHA or MAG-EPA (monoacylglyceride form of eicosapentaenoic acid) strongly reversed the over responsiveness induced by proinflammatory and hyperreactive treatments.Moreover, a 7-day treatment with MAG-DHA is able to resolve the inflammatory status in a rat model of monocrotaline-induced pulmonary hypertension. In both models, the inflammatory status enhanced the expression of inflammatory biomarkers (TNF-α, COX-2, STAT-3) as well as the detection of MMP9 and phosphorylated nuclear factors such as P-c-Fos, P-c-Jun and P-NF-κB involved in the activation of wall remodeling. Hence, RvD1, RvE1 and their precursors normalized the expression of these inflammatory biomarkers. In conclusion, Resolvin D1 and E1 and their respective precursors MAG-DHA and MAGEPA could inhibit inflammation status to prevent and potentially cure pulmonary hypertension.

Thesis (MScAgric) -- University of Stellenbosch, 2000. / ENGLISH ABSTRACT: Lipids remain one of the most important nutrients required by broilers. The growing awareness that some Western societies have too high a dietary ratio of n-6/n-3 polyunsaturated fatty acids is of direct relevance to broiler nutrition and lipid metabolism. Meaningful quantities of n-3 polyunsaturates have been incorporated into major poultry tissues, so that the production of broiler meat with high n-3 polyunsaturates becomes advantageous for the broiler industry as they are perceived as having a 'healthier' lipid profile. Unfortunately, such broiler meat is rather susceptible to oxidative deterioration, and oxidation often determines shelf life of poultry meat products. The addition of a-tocopherol (vitamin E) to broiler diets is an effective means of improving the oxidative stability of broiler meat. Elevated a-tocopherol levels in broiler feeds increase tissue concentrations thereof resulting in improved stability of membranal structures which may be expected to increase the oxidative stability of broiler meat and meat products. Three investigations were done at Mariendahl Poultry Research Station in Stellenbosch. The broilers were kept in 1 x 0.4 x 0.5 m cages in a broiler rearing house. All the trials started with day-old chicks, except experiment 1 where 3-week old broilers were used. At the end of trials 2 and 3 the 6-week old broilers were slaughtered and the carcasses prepared for chemical analysis. Experiment 1: Metabolisabie energy of Canola acid oil and Famarol acid oil for broiler chickens. In trials with 21-day-old male broilers the true metabolisabie energy value, corrected for nitrogen retention (TMEn) was determined by the balance method for Canala acid oil (CAO) and Famarol acid oil (FAO). The trials were duplicated, each time using different samples of the two oils from the same source (experiment 1 and 2). Each of the two oils were blended in two ratios with a basal diet to form the test diets, viz. 100% Basal; 96% Basal: 4% Oil; 92% Basal: 8% Oil. In experiment 3, 50 % bran was added to the maize to form the basal diet. The balance trials lasted for 3 days after an adaptation period of 4 days. The TMEn values determined by regression for the broilers of CAO did not differ significantly (P>0.05) between experiments 1 and 2. However, the value for experiment 3 was significantly (P<0.05) higher than those for experiments 1 and 2. The TMEn values of FAO also did not differ significantly (P>0.05) between experiments 1 and 2, although the value for experiment 3 was significantly higher than that of experiment 1. The addition of 50 % bran to the basal diet in experiment 3 could have stimulated the digestive breakdown process and hence increase the secretion of digestive enzymes. This could lead to an increase in the utilisation of the test lipid and therefore an increase in the TMEn value. The TMEn values of CAO differed significantly (P<0.05) from those of FAO for all three the experiments (exp. 1:30.6 ± 0.399 MJ/kg for CAO vs. 25.9 ± 0.441 MJ/kg for FAO; expo 2: 31.0 ± 0.633 MJ/kg for CAO vs. 26.1 ± 0.668 MJ/kg for FAO: expo 3: 32.1 ± 0.867 MJ/kg for CAO vs. 27.1 MJ/kg for FAO).Experiment 2: of broilers. The dietary effects of various combinations of Canala acid oil (CAO, a high level of C18:3n-3 and MUFA) and Famarol Effects of various dietary n-6/n-3 fatty acid ratios on the perfonnance and body composition acid oil (FAO, a high level of 18:2n-6 and SFA) on tissue fatty acid composition were studied in broiler carcasses and abdominal fat pads. From day-old to six weeks, chicks were fed one of six diets containing 100% FAO, 80% FAO-20% CAO, 60% FAO-40% CAO, 40% FAO-60% CAO, 20% FAO-80% CAO, 100% CAO. There were no statistical differences (P>0.05) in average daily gain (1.71 ± 0.059 g) or feed conversion ratios (1.97 ± 0.051) among dietary groups. No statistical differences (P>0.05) were found in the chemical proximate composition of the carcasses for the moisture (66.20 ± 0.112 %), protein (17.63 ± 0.484 %), lipid (15.92 ± 1.507 %) and ash (0.95 ± 0.115 %) content among dietary groups. No statistical differences (P>0.05) were found in the chemical proximate composition of the abdominal fat pads for the moisture (28.77 ± 0.112 %), protein (3.03 ± 0.484 %), lipid (63.32 ± 9.789 %) and ash (0.45 ± 0.135 %) content among dietary groups. With the increase in dietary CAO levels, the percentages of C18:2n-6 and C20:4n-6 in the carcasses decreased respectively with 1.78 % from 20.88 % and 0.35 % from 1.05 %, whilst C18:3n-3 and longer chain n-3 fatty acids such as C20:5n-3 and C22:6n-3 increased respectively with 2.25 % from 1 %, 0.1 % from 0.1 % and 0.67 % from 0.2 %. The same tendency was seen in the abdominal fat pads where C18:2n-6 and C20:4n-6 decreased respectively with 1.55 % from 20.75 % and 0.98 % from 1.2 % with an increase in dietary CAO, whilst C18:3n-3, C20:5n-3 and C22:6n-3 increased respectively with 2.13 % from 1.15 %, 0.45 % from 0.03 % and 0.95 % from 0.05 %. The n-3/n-6 ratio in the carcasses and abdominal fat pads increased respectively with 0.16 % from 0.06 % and 0.19 % from 0.06 % with an increase in dietary CAO. These results clearly indicate that dietary CAO enriched with a-linolenic acid lower saturated fatty acids respectively in broiler carcasses and abdominal fat pads with 4.88 % from 31.6 % and 10.63% from 31.1 %, whilst increasing monounsaturated fatty acids with 3.87 % from 44.95 % and 7.25 % from 46.7 % respectively and polyunsaturated fatty acids with 1.02 % from 23.45 % and 2.38 % from 23.2 % respectively. Experiment 3: Effect of dietary vitamin E on the performance of broilers and oxidative stability, colour, microbiological stability, fatty acid composition and pH of broiler meat during refrigerated and frozen storage. Experiment 1 was carried out with 220 one-day-old broiler chicks to evaluate the effect of eleven concentrations of vitamin E (0, 20, 40, 60, 80, 100, 120, 140, 160, 180 and 200 mg a-tocopheryl acetate 1 kg diet) on their production performance and the oxidative stability of their frozen broiler carcasses. The diets with vitamin E levels 0 to 100 mg were fed from day-old to 42 days of age while the diets with vitamin E levels 120 to 200 mg were fed from 21 to 42 days of age. The oxidative stability, evaluated by thiobarbituric acid reactive substances (TBARS) values, was determined after 30, 90, 120 and 150 days of storage at -20°C. There were no statistical differences (P>0.05) in average daily gain (1.85 ± 0.111 g) or feed conversion ratios (2.29 ± 0.397) among dietary groups. TBARS values increased significantly (P<0.05) with increasing time of storage (basal diet: day 30 = 1.71 ± 0.51; day 150 = 4.89 ± 0.51), but decreased significantly (P<0.05) with increasing vitamin E levels (day 150: basal = 4.89 ± 0.51; 100 mg / kg = 1.09 ± 0.27). Experiment 2 was carried out with day-old broiler chicks to evaluate the effect of five concentrations of vitamin E (0, 40, 80, 120 and 160 mg atocopheryl acetate / diet) on their performance and the oxidative stability of their refrigerated carcasses. The experimental diets were fed from day-old to 42 days of age. The oxidative stability, evaluated by TBARS values, colour deterioration and microbiological stability were determined after 0, 4, 8, 10 and 12 days of storage at 4°C. Fatty acid analysis was done on the samples of days 0 and 12. There were no statistical differences (P>0.05) in average daily gain (1.88 ± 0.117 g) or feed conversion ratios (2.37 ± 0.467) among dietary groups. TBARS values increased significantly (P<0.05) with increasing time of storage, but decreased significantly (P<0.05) with increasing vitamin E levels. There were no statistical differences (P>0.05) in colour measurements for L* (44.97 ± 0.662), a* (5.23 ± 0.315) or b* (12.76 ± 0.321) values between treatments. Microbiological counts increased significantly (P<0.05) over time with vitamin E concentration showing no effect. There were no statistical differences (P>0.05) for any of the fatty acid groups measured (SFA: Day 0 = 26.1 ± 1.13%, Day 12 = 26.1 ± 1.17%; MUFA: Day 0 = 41.4 ± 1.46%, Day 12 = 40.2 ± 2.28%; PUFA: Day 0 = 32.4 ± 1.95%, Day 12 = 33.8 ± 2.52%) among dietary groups. Similarly, none of the fatty acids showed statistical significant (P>0.05) concentration changes over time. There were no statistical differences (P>0.05) in pH (6.01 ± 0.206) among dietary groups. / AFRIKAANSE OPSOMMING: Lipiede is steeds een van die mees belangrike voedingstowwe wat deur braakuikens benodig word. Die groeiende bewuswording dat sekere Westerse gemeenskappe 'n te hoë verhouding van n-6/n-3 poli-onversadigde vetsure in hul dieet het, is direk relevant vir braaikuikenvoeding en lipiedmetabolisme. Betekenisvolle hoeveelhede n-3 polionversadigde vetsure is geïnkorporeer in die belangrikste hoendersnitte, met die gevolg dat die produksie van braaikuikenvleis met hoë n-3 poli-onversadigde vetsure voordelig is vir die braaikuikenindustrie en geag word 'n meer "gesonde" beeld te hê. Ongelukkig is sodanige braaikuikenvleis redelik vatbaar vir oksidatiewe bederf, en oksidasie bepaal dikwels die rakleeftyd van hoendervleisprodukte. Die byvoeging van a-tokoferol (vitamine E) by braaikuikendiëte is 'n effektiewe manier om die oksidatiewe stabiliteit van braaikuikenvleis te verbeter. Verhoogde a-tokoferol vlakke in braakuikenvoere verhoog die weefselkonsentrasie wat verhoogde stabiliteit van die membraanstrukture en derhalwe moontlike verhoogde oksidatiewe stabiliteit van braakuikenvleis en -produkte tot gevolg het. Drie ondersoeke is onderneem by Mariendahl Pluimvee Navorsingstasie te Stellenbosch. Die braakuikens is aangehou in 1 x 0.4 x 0.5m hokke in braaikuikenhuise. In al die proewe is dagoud kuikens gebruik, behalwe eksperiment 1 waar drieweek oue kuikens gebruik is. Aan die einde van proewe 2 en 3 is die ses-week oue braaikuikens geslag en die karkasse voorberei vir analise. Eksperiment 1: braaikuikens. Die ware metaboliseerbare energie waarde van Canola voergraadolie (CAO) en Famarol voergraadolie (FAO), Metaboliseerbare energie van Canola voergraadolie en Famarol voergraadolie vir gekorregeer vir stikstof retensie (WMEn), is by wyse van proewe op 21 dae oue braaikuikenhaantjies bepaal deur van die balansrnetode gebruik te maak. Die proewe is tweemaal herhaal vir verhoogde akkuraatheid, met die gebruik van verskillende monsters van die twee olies vanaf dieselfde bron. Die olies is in twee verhoudings met 'n basale diëet gemeng om die proef dieet te vorm, nl. 100% Basaal; 96% Basaal: 4% Olie en 92% Basaal: 8% Olie. Die balans proewe het 3 dae geduur na afloop van 'n aanpassingsperiode van 4 dae. Die WMEn waardes van CAO, bepaal deur middel van regressie analise, het nie betekenisvol verskil (P>0.05) tussen eksperimente 1 en 2 nie. Die waarde van eksperiment 3 was betekenisvol hoër (P<0.05) as die van die eerste twee eksperimente. Die WMEn waardes van FAO het ook nie betekenisvol verskil (P>0.05) tussen eksperimente 1 en 2 nie, maar die waarde vir eksperiment 3 was betekenisvol hoër as dié van eksperiment 1. Die WMEn waardes van COA het betekenisvol verskil (P< 0.05) van dié van FAO vir al die eksperimente (exp. 1: 30.6 ± 0.399 MJ/kg vir CAO vs. 25.9 ± 0.441 MJ/kg vir FAO; expo 2: 31.0 ± 0.633 MJ/kg vir CAO vs. 26.1 ± 0.668 MJ/kg vir FAO: expo 3: 32.1 ± 0.867 MJ/kg vir CAO vs. 27.1 MJ/kg vir FAO). Eksperiment 2: Die invloed van verskeie rantsoen n-6/n3 vetsuurverhoudings op die produksie en liggaamsamestelling van braaikuikens. Die rantsoeneffek van verskeie kombinasies Canola voergraadolie (CAO, 'n hoë vlak van C18:3n-3 en monoonversadigde vetsure) en Famarol voergraadolie (FAO, 'n hoë vlak van 18:2n-6 en versadigde vetsure) op die weefselvetsuursamestelling is bestudeer in braaikuikenkarkasse en abdominale vetneerlegging. Die kuikens is van dagoud to op ses-weke ouderdom een van ses diëte gevoer met die volgende samestellings: 100% FAO, 80% FAO-20% CAO, 60% FAO - 40%CAO, 40% FAO - 60% CAO, 20% FAO - 80% CAO, 100% CAO. Daar was geen statistiese verskil tussen die rantsoengroepe (P>0.05) in die gemiddelde daaglikse toename (1.71 ± 0.059 g) of die voeromsetverhoudings (1.97 ± 0.051) nie. Geen statistiese verskil (P>0.05) is gevind in die chemiese samestelling van die karkasse vir vog (66.20 ± 0.112 %), proteïn (17.63 ± 0.484 %), lipied (15.92 ± 1.507 %) en as (0.95 ± 0.115 %) inhoud tussen die rantsoen groepe nie. Geen statistiese verskille (P>0.05) is gevind in die chemiese samestelling van die abdominale vetneerlegging vir vog (28.77 ± 0.112 %), proteien (3.03 ± 0.484 %), lipied (63.32 ± 9.789 %) en as (0.45 ± 0.135 %) inhoud onder die rantsoengroepe nie. Met die verhoging in die rantsoen CAO vlakke het die persentasie van C18:2n-6 en C20:4n-6 in die karkasse verminder met 1.78 % en 0.35 % respektiewelik, terwyl C18:3n-3 en langer ketting n-3 vetsure soos C20:5n-3 en C22:6n-3 respektiewelik met 2.25 %, 0.1 % en 0.67 % verhoog het. Dieselfde tendens is opgemerk in die abdominale vetneerlegging waar C18:2n-6 en C20:4n-6 afgeneem het met 1.55 % en 0.98 % respektiewelik met die verhoging van rantsoen CAO, terwyl C18:3n-3, C20:5n-3 en C22:6n-3 verhoog het met 2.13 %, 0.45 % en 0.95 % respektiewelik. Die n- 3/n-6 verhouding in die karkasse en abdominale vetneerlegging het verhoog met 0.16 % en 0.19 % respektiewelik met die verhoging van die rantsoen CAO. Die resultate toon onomwonde aan dat rantsoen CAO verryk met c-Iinoletensuur, verlaag versadigde vetsure in braaikuikenkarkasse en -adbdominale vetneerleggings met 4.88 % en 10.63% respektiewelik, terwyl die mono-onversadigde vetsure met 3.87 % en 7.25 % respektiewelik verhoog word en polionversadigde vetsure met 1.02 % en 2.38 % respektiewelik verhoog word. Eksperiment 3: Die invloed van vitamine E op die produksie van braaikuikens en die oksidatiewe stabiliteit, kleur, mikrobiologiese stabilitiet, vetsuursamestelling en pH van braaikuikenvleis gedurende verkoelde en bevrore berging. Eksperiment 1 is uitgevoer met 220 dagoud braaikuikens ten einde die effek van elf konsentrasies van vitamine E (0, 20, 40, 60, 80, 100, 120, 140, 160, 180 en 200 mg a-tokoferyl acetaat / kg voer) op hul produksieprestasie en die oksidatiewe stabiliteit van hul gevriesde braakuikenkarkasse te evalueer. Die diëte met vitamine E vlakke 0 tot 100 mg is vanaf dagoud tot 42-dae-ouderdom gevoer, terwyl die diëte met vitamine E vlakke van 120 tot 200mg gevoer is vanaf 21 tot 42- dae-ouderdom. Die oksidatiewe stabiliteit, soos geëvalueer deur tiobarbituriese suur reaktiewe stowwe (TBARS) waardes, is bepaal na 30, 90, 120 en 150 dae van berging teen -20°C. Daar was geen statistiese verskille (P>0.05) in die gemiddelde daaglikse toename (1.85 ± 0.111 g) of voeromsetverhoudings (2.29 ± 0.397) tussen die rantsoengroepe nie. TBARS waardes het betekenisvol toegeneem (P<0.05) met die verhoging in bergingsperiode, maar het betekenisvol afgeneem (P<0.05) met verhoogde vitamine E vlakke. Eksperiment 2 is uitgevoer met dagoud braaikuikens ten einde die effek van vyf konsentrasies van vitamine E (0, 40, 80, 120 and 160 mg a-tokoferyl acetaat / kg voer) op hul prestasie en die oksidatiewe stabiliteit van hul verkoelde karkasse te evalueer. Die eksperimentele diëte is gevoer vanaf dagoud tot 42- dae-ouderdom. Die oksidatiewe stabiliteit, geëvalueer deur middel van TBARS waardes, kleur afname en mikrobiologiese stabiliteit is bepaal na 0, 4, 8, 10 en 12 dae van berging teen 4°C. Vetsuuranalises is gedoen op die monsters van dae 0 en 12. Daar was geen statistiese verskille (P>0.05) in die gemiddelde daaglikse toename (1.88 ± 0.117 g) of voeromsetverhoudings (2.37 ± 0.467) tussen die rantsoengroepe nie. TBARS waardes het betekenisvol verhoog (P<0.05) met die verlengde bergingsperiode, maar het betekenisvol afgeneem (P<0.05) met verhoogde viatmine E vlakke. Daar was geen statistiese verskille (P>0.05) in kleur metings vir L* (44.97 ± 0.662), a* (5.23 ± 0.315) of b* (12.76 ± 0.321) waardes tussen behandelings nie. Mikrobiologiese tellings het betekenisvol verhoog (P<0.05) oor tyd met die vitamine E konsentrasie wat geen effek getoon het nie. Daar was geen statisties betekenisvolle verskille (P>0.05) vir enige van die vetsuurgroepe tussen die behandelings nie. Soortgelyks het geen van die vetsure statisties betekenisvolle (P>0.05) konsentrasieveranderings oor tyd aangetoon nie. Daar was geen statistiese verskil (P>0.05) in die pH (6.01 ± 0.206) tussen die rantsoengroepe nie.

Thesis (MBA)--Stellenbosch University, 2006. / ENGLISH ABSTRACT: The Omega function is a relatively newly developed performance measure, falling within the class of downside risk measures. This measure does not make any assumptions regarding the return distributions evaluated, but incorporates the actual return distribution in its calculation. The sensitivity of this measure to simulated changes within the class of stable distributions was tested, within the range of parameters that was evident in the South African investment environment. The Omega and Sharpe ratios that were calculated for these distributions were ranked and compared. Even though the rankings were similar, discrepancies did occur. On investigation it was found that these discrepancies were caused by the inability of the Sharpe measure to differentiate between increased volatility caused by higher probability weighted gains (or positive skewness) and losses, as the Sharpe ratio penalises funds for volatility. The simulated tests were extended to various distributions, which have different risk profiles and distribution shapes, and ranked. A higher incidence of ranking differences occurred due to the inability of the Sharpe ratio to differentiate between gains and losses, correctly account for the risk of positively skewed distributions and lastly due to negative Sharpe ratios, caused by the average realised returns being exceeded by the threshold (target) rate, resulting in incorrect rankings. Comparison of rankings based on the Sharpe and Omega measures was performed on the class of general equity unit trusts over a five-year period, which resulted in statistically similar rankings. In extending the evaluation over shorter periods, the ran kings were still statistically similar, even though some differences were noteworthy. As the returns became more variable, the Omega measure captured this variation and risk whilst the Sharpe ratio was unable to, as its formulation is limited to two statistics, thus losing all this additional information. Normally performance evaluation is not initiated with a detailed analysis of the return distributions in order to determine which performance measure is more appropriate. The Omega measure incorporates the distribution into the calculation, which is not the case with the Sharpe measure. Therefore, even if the distributions are normal, the Omega measure gives exacty the same result as the Sharpe measure. However, where return distributions diverge from normality, we can be certain that the Omega measure will correctly incorporate the divergence, whilst it has been shown that in certain instances the Sharpe measure does not. The Omega measure adds another dimension to risk-adjusted performance evaluation and should be incorporated in the evaluation process. / AFRIKAANSE OPSOMMING: Die Omega-funksie, wat as 'n afwaartse risikomaatstaf geklassifiseer word, is 'n relatiewe nuut-ontwikkelde prestasiemaatstaf. Hierdie maatstaf maak nie enige aannames ten opsigte van die opbrengsverdelings wat ge-evalueer word nie, maar inkorporeer die werklike opbrengsverdeling in die berekening. Die sensitiwiteit van hierdie maatstaf tot gesimuleerde veranderinge in die klas van stabiele verdelings is getoets, binne die parameters van toepassing in die Suid Afrikaanse beleggingsomgewing. Die Omega- en Sharpe-maatstawe is bereken, georden en vergelyk. Alhoewel die rangordes meestal dieselfde was, het verskille in sommige gevalle voorgekom. Hierdie verskille is veroorsaak deur die onvermoe van die Sharpe-maatstaf om te onderskei tussen verhoogde volatiliteit veroorsaak deur 'n hoer waarskynlikheidsgeweegde wins, of positiewe skeefheid en verliese. Die Sharpe-maatstaf penaliseer alle volatiliteit. Die gesimuleerde toetse is uitgebrei na alternatiewe verdelings wat verskillende risikoprofiele het en is weereens georden. Weereens was die rangordes meestal dieselfde. Die verskille wat plaasgevind het, is veroorsaak deur die onvermoe van die Sharpe-maatstaf om tussen winste en verliese te onderskei, positiewe skeefheid korrek te verdiskonteer en laastens om negatiewe Sharpe-verhoudings in die korrekte rangorde te plaas. 'n Vergelyking van die rangordes van die Sharpe- en Omega-maatstawe is gedoen op die algemene effektetrusts oor 'n tydperk van vyf jaar. Die rangordes in geheel was statisties dieselfde. Hierdie toetse is vervolgens uitgebrei om korter tydperke in te sluit, wat weereens in geheel statisties dieselfde korrelasie getoon het, maar 'n paar individuele portefeuljes se rangordes het heelwat verskil. Soos die opbrengste gevarieer het, kon die Omega-maatstaf hierdie variasies en risiko verdiskonteer terwyl die Sharpe-maatstaf nie in staat was om hierdie risiko te verdiskonteer nie, aangesien sy formulering beperk is tot twee statistieke wat 'n verlies van inligting tot gevolg het. Normaalweg word prestasie-beoordeling nie begin met 'n gedetailleerde analise van die opbrengsverdelings om te bepaal watter prestasie-maatstaf meer toepaslik is nie. Die Omega-maatstaf inkorporeer die verdeling in die berekening, wat nie die geval is met die Sharpe-maatstaf nie. AI is die opbrengsverdelings normaal, gee die Omega-maatstaf dieselfde resultate as die Sharpe-maatstaf. Waar die verdelings egter afwyk van normaal, weet ons dat die Omega-maatstaf die afwykings korrek verdiskonteer, terwyl dit bewys is dat die Sharpe-maatstaf in sekere omstandighede nie die afwykings korrek verdiskonteer nie. Die Omega-maatstaf voeg 'n verdere dimensie by risiko-aangepaste prestasiemeting en behoort dus ingesluit te word in die evauleringsproses.