O presente estudo teve como objetivo avaliar o efeito da utilização de níveis crescentes do prebiótico mananoligossacarídeo (MOS) em juvenis de tilápia do Nilo sob os parâmetros de desempenho e morfologia intestinal. O estudo foi conduzindo no lago da Usina Hidrelétrica de Salto Caxias, no rio Jacutinga, localizada no município de Boa Vista da Aparecida, no estado do Paraná, na área experimental da Universidade Estadual do Oeste do Paraná (Unioeste). Foram utilizados 20 juvenis de tilápia-do-Nilo com peso inicial 12,62 g, em cada gaiola, totalizando 16 gaiolas de 0,25 m3 cada. As gaiolas foram distribuídas em tanques rede de 4 m3 (quatro gaiolas por tanque-rede) compondo um delineamento inteiramente casualizado, com quatro tratamentos, 0,0; 0,2; 0,4 e 0,8% de inclusão de MOS na dieta e quatro repetições. A alimentação foi realizada quatro vezes ao dia, até a aparente saciedade, durante 60 dias. Ao final de 30 e 60 dias de cultivo foram realizadas biometrias para cálculo dos índices de desempenho e coleta de material para análise histológica do intestino. Os parâmetros de qualidade da água se mantiveram dentro dos valores de referência para a espécie. O consumo de ração aos dias de experimento foi maior (P<0,05) nos peixes suplementados com 0,4% quando comparados ao grupo controle. Aos 30 dias de experimento, peixes alimentados com 0,4% de MOS na dieta apresentaram maior (P<0,05) altura das vilosidades intestinais e, aos 60 dias, peixes alimentados com a dieta controle apresentaram maior (P<0,05) altura das vilosidades intestinais. No entanto os parâmetros de desempenho não foram significativamente afetados pela adição de MOS a dieta. No presente trabalho, uso estratégico de prebióticos durante o ciclo de produção abre perspectivas promissoras na modulação das características morfológicas do intestino, apesar de não ter influenciado no crescimento de juvenis de tilápia-do Nilo. / The present study has as an objective to analyze the effect of using crescent levels of prebiotic mananoligosaccharides (MOS) in Nile tilapia juveniles, according to the parameters of performance and intestinal morphology. The study was done at Salto Caxias hydroelectric plant lake, Jacutinga river, located in Boa Vista da Aparecida city, state of Paraná, experimental area of UNIOESTE – Universidade Estadual do Oeste do Paraná. An amount of 20 Nile tilapia juveniles were used, with 12,62 g initial weight, in each cage, being 16 0,25-cubic-meter cages. The cages were distributed in 4-cubic-meter tanks (four cages in each tank) generating a randomized lineation, with four species of treatments, 0,0; 0,2; 0,4 and 0,8% of MOS inclusion in diet and four repetitions. The feeding process happened four times a day, until apparent satiety, for 60 days. After 30 and 60 days, biometry was done to calculate performance levels and to analyze intestinal histology. The parameters of water quality were kept within reference values for the species. The consumption of ration during the experiment days was higher (P<0,050) for fish supplemented with 0,4% when compared to the control group. After 30 days of the onset, fish fed with 0,4% of MOS in their diet presented higher (P<0,05) intestinal villi and, after 60 days, fish fed with control diet presented higher (P<0,05) intestinal villi. However, the parameters of performance were not significantly affected by the addition of MOS to the diet. In the present study, strategic use of prebiotics during the production cycle brings up promising perspectives to modulate morphological features of the intestine, although it did not influence the growth of Nile tilapia juveniles.

Made available in DSpace on 2014-07-29T15:07:37Z (GMT). No. of bitstreams: 1 Dissertacao Pedro Fellipe Vieira Gomides.pdf: 164428 bytes, checksum: 8d8786470a4ce06f25123d51b9512f84 (MD5) Previous issue date: 2011-08-01 / In order to determine the stocking density for hybrid amazon pintado (Pseudoplatystoma tigrinum female x Leiarius marmoratus male) were distributed in 12 ponds, 570 juveniles with initial average weight of 82 g. The ground ponds of 50 m2 has minimum and maximum depth of 0.9 and 1.3 m. Different stocking densities were studied 0.5; 0.8; 1.1 e 1.4 fish/m2 during 270 days. The completely randomized design with four treatments and three replicates, each pond was an experimental unit, and the number of fish per pond varied according to treatments. The variables studied were: water quality, productive performance, biometric indices, glucose and economic evaluation. For statistical analysis, data were subjected to analysis of variance with the statistical program SAS ® (2000), in case of statistical difference was used the Tukey test (5%). Was performed polynomial regression for the different densities. The greatest total weight and weight gain was obtained for the lower density. There was a negative linear regression for body weight, weight gain and feed intake with increasing density. Water quality and physiological characteristics of the amazon pintado were not affected by stocking density. It can be concluded, based on performance and economic profitability , the best stocking density for hybrid Amazon pintado that was 0.8 fish/m2. / Com o objetivo de determinar a densidade de estocagem para o híbrido pintado amazônico (Pseudoplatystoma tigrinum fêmea x Leiarius marmoratus macho) foram distribuídos em 12 viveiros, 570 juvenis com peso médio inicial de 82 g. Os viveiros escavados possuíam 50 m2 de lâmina d água e profundidade mínima e máxima de 0,9 e 1,3 m. Foram estudadas diferentes densidades de estocagem; 0,5; 0,8; 1,1 e 1,4 peixes/ m2 durante 270 dias de engorda. O delineamento foi inteiramente casualisado com quatro tratamentos e três repetições, sendo o viveiro como unidade experimental e o número de peixes por viveiro variou de acordo com os tratamentos. As variáveis estudadas foram de qualidade da água, desempenho produtivo, índices biométricos, perfil glicêmico e avaliação econômica. Para análise estatística, os dados foram submetidos à análise de variância com o auxílio do programa estatístico SAS ® (2000), e, em caso de diferença estatística foi aplicado o teste Tukey (5%). Para os diferentes níveis de densidade foi realizada regressão polinomial. No período total o maior peso vivo e ganho de peso foi obtido para a menor densidade. Houve regressão linear negativa para peso vivo, ganho de peso e consumo de ração com o aumento da densidade. A qualidade da água e as características fisiológicas do pintado amazônico não foram influenciadas pela densidade de estocagem. Pode-se concluir baseado na rentabilidade econômica e no desempenho do híbrido pintado amazônica que a melhor densidade de estocagem foi de 0,8 peixes/m2.

Orientadores: Felix Guillermo Reyes Reyes, Marili Villa Nova Rodrigues / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-19T20:15:42Z (GMT). No. of bitstreams: 1 Branco_LucianadaConceicaoCastello_M.pdf: 696133 bytes, checksum: 0c1ae932e7cdd4cd2fea5388f7a0bb5a (MD5) Previous issue date: 2012 / Resumo: Os antimicrobianos são aplicados mundialmente na tilapicultura para o tratamento de bacterioses, principais doenças que acometem esta espécie. Entre os antibióticos, a enrofloxacina (ENR), pertencente à família das quinolonas, é utilizada internacionalmente e tem demonstrado ser eficaz no tratamento de infecções bacterianas. No Brasil, seu uso na criação de peixes ainda não foi aprovado, mas o Ministério da Agricultura, Pecuária e Abastecimento (MAPA) incluiu, em 2010, este fármaco no Plano Nacional de Controle de Resíduos e Contaminantes em Peixes (PNCRC). A ENR é biotransformada pelos animais à ciprofloxacina (CIP), composto este que apresenta atividade antimicrobiana e é utilizado na medicina humana. O processamento de alimentos tem mostrado ser um fator positivo para a segurança dos alimentos, devido à possível degradação de resíduos de antimicrobianos que poderiam causar o desenvolvimento de resistência em micro-organismos ou induzir efeitos adversos na saúde de seres humanos. Assim, é de grande importância, do ponto de vista da saúde pública e de conhecimento científico, conhecer o comportamento de resíduos de medicamentos veterinários nos alimentos quando submetidos ao processamento. O fishbúrguer, preparado com carne de tilápia, têm demonstrado elevada aceitação pelos consumidores. Isto reflete o novo estilo da vida em que os requisitos para a compra de um alimento incluem os benefícios nutricionais e também a conveniência de preparação. Para avaliar a diminuição dos níveis de resíduo de ENR e CIP presentes em filé de tilápia, durante processo de produção e fritura dos mesmos, torna-se necessário o desenvolvimento e validação de metodologia analítica que apresentem precisão, exatidão e sensibilidade para determinar este composto e seu metabólito. Portanto, os objetivos deste trabalho foram em filé de tilápia, bem como em um produto derivado, fishbúrguer, para avaliar a estabilidade dessas substâncias durante o processo de produção e fritura. Para este fim, um método simples, rápido e de baixo custo, utilizando LC-MS, foi desenvolvido e validado para a determinação simultânea de ENF e CIP. O preparo de amostra foi baseado na precipitação de proteínas com ácido tricloroacético, extração com acetonitrila e limpeza do extrato com hexano. A separação cromatográfica foi realizada em uma coluna C18. Para ambos os compostos, as curvas de calibração na matriz demonstraram linearidade superior a 0,99. O método foi seletivo, exato (91-100% de recuperação) e preciso (coeficientes de variação abaixo de 5%). Limites de detecção e quantificação foram, respectivamente, 3,5 e 10,4 µg/kg para ambos os compostos. Os valores calculados CCa e CCß foram, respectivamente, 107 e 114 µg/kg para ENR e 105 e 110 µg/kg para CIP (LMR estabelecido pela Comissão da UE é de 100 µg/kg para a soma de ENR e CIP). O método foi empregado para a determinação de resíduos de ENR e CIP em amostras de filés de tilápia obtidos a partir de peixes expostos a ENR (dose única de 40 mg/kg de peso corpóreo - administrado via ração). Os animais foram sacrificados após 4, 8 e 12 h de exposição. Resíduos acima do LMR foram encontrados mesmo após 12 h de administração do fármaco. A fim de avaliar a influência do processo de produção e fritura sobre os níveis residuais de ENR e CIP, fishbúrgueres foram preparados com filé de tilápias expostas a ENR. O método analítico para determinação da ENR e CIP no filé de tilápia foi adaptado e validado para a análise de fishbúrgueres antes e após fritura. Os métodos adaptados foram validados e mostraram-se linear, com coeficiente de correlação maior que 0,99, precisos (coeficiente de variação abaixo de 6%) e exatos (recuperação média de 90 a 106%). Foram analisadas amostras de fishbúrgueres (antes e após fritura) utilizando os métodos validados. Não foi verificada redução significativa dos níveis residuais da soma de ENR e CIP durante o preparo dos fishbúrgueres. No entanto, redução (p<0,05) de, aproximadamente, 10% foi verificada como consequência da fritura. Porém, essa redução pode ser considerada baixa em termos de segurança dos consumidores / Abstract: Antimicrobials are used worldwide for the treatment of tilapicultura bacteriosis, main diseases that affect this species. Among the antibiotics, enrofloxacin (ENR), belonging to the quinolone family, is used internationally and has been shown to be effective in treating bacterial infections in fish. In Brazil, its use in fish farm is not yet approved, but the Ministry of Agriculture, Livestock and Supply (MAPA) included, in 2010, this drug in the National Plan for Control of Residues and Contaminants in Fish (PNCRC). ENR is biotransformed in the body of animals being converted to ciprofloxacin (CIP), an active compound used in human medicine. Food processing has shown to be a positive factor for the food safety, due to the possible degradation of antimicrobial agents that could potentially cause development of resistance in microorganisms or induce adverse health effects in humans. Thus, it is of great importance, from the standpoint of public health and scientific knowledge, to know the behavior of veterinary drugs in foods when subjected to processing for consumption. The fishburger, prepared with meat from tilapia, have shown high acceptance by the consumers. This follows the new style of life in which the requirements for the purchase of a food include the nutritional benefits and the convenience of preparation. To evaluate the degradation of ENR present in meat processed as tilapia fishburger, it becomes necessary to develop and validate analytical methods that present precision, accuracy and sensitivity to determine this compound and CIP as well. Therefore, the objectives of this study were to develop and validate analytical method for the determination of ENR and CIP in tilapia fillet, as well as in a product derived from tilapia meat (fishburger) and to evaluate the stability of these substances during the frying of fishburgers prepared from tilapias exposed to ENR. For this purpose, a simple, fast and low cost LC-MS method for the simultaneous determination of ENR and CIP residues in tilapia fillet and fishburgers was developed and validated. Sample preparation was done by protein precipitation with trichloroacetic acid, acetonitrile extraction and extract clean up with hexane. The chromatographic separation was performed on a C18 column. For both compounds, matrix matched calibration curves showed linearity higher than 0.99. The method was selective, accurate (91-100% recovery) and precise (coefficients of variation below 5%). Limits of detection and quantification were, respectively, 3.5 and 10.4 µg/kg for both compounds. The calculated CCa and CCß values were, respectively, 107 and 114 µg/kg for ENR and 105 and 110 µg/kg for CIP (MRL established by the EU Commission is 100 µg/kg for the sum of ENR and CIP). The method was employed for the determination of ENR and CIP residues in samples of tilapia fillets obtained from fishes exposed to ENR (single dose of 40 mg/kg b.w incorporated in the feed). The animals were killed after 4, 8 and 12 h of exposure. Sum of residues of ENR and CIP above the MRL were found, even after 12 h of ENR administration. In order to evaluate the influence of cooking (frying) on the residual levels of ENR and CIP, fishburgers were formulated with fillet of tilapias exposed to ENR. The analytical method for the determination of ENR and CIP in tilapia fillet was adapted and validated for the analysis of the fishburgers before and after frying. Adapted and validated methods showed linearity with a correlation coefficient greater than 0.99, selectivity, precision (coefficient of variation below 6%) and accuracy (average recovery of 90 to 106%). Samples of fishburgers (before and after frying) were analyzed using the validated methods. A small reduction (approximately 10%) in the residual levels of ENR and CIP as a consequence of frying was verified, indicating that both compounds are stable to cooking conditions / Mestrado / Ciência de Alimentos / Mestre em Ciência de Alimentos

Thesis (M. Sc. (Aquaculture)) -- University of Limpopo, 2021 / Tilapia production in South Africa is failing to reach sustainable commercial levels of development, despite the efforts by the government to improve aquaculture production. Limpopo Province has been practicing fish farming since the 1980s, with tilapia being the most widely farmed fish. Currently, tilapia production in Capricorn and Vhembe districts in Limpopo Province remains low. In this study, factors affecting tilapia production in aqua dams, earthen ponds, concrete ponds, and RAS systems in Capricorn and Vhembe districts were explored. Eight different production systems were used to collect field data, four in each district. Water quality parameters in aqua dams, earthen ponds, concrete ponds, and RAS system were determined. The abundance of phytoplankton was determined in three different production systems. And lastly, a questionnaire was used to determine factors critical for successful tilapia production from the farmer’s perspective in Capricorn and Vhembe districts. The levels of ammonium and ammonia were below detection limits in all the production systems in Capricorn and Vhembe districts. The results showed that water temperature, alkalinity (as bicarbonate and carbonate), potassium, total phosphate frequently did not meet the requirement for the culture of tilapia in all the production systems in Capricorn and Vhembe district throughout the study. The concrete ponds, aqua dams, and RAS systems in both districts were mostly affected by these parameters. The phytoplankton abundance varied according to the type of production system and water quality parameters of the production systems. The concrete pond in Olifanshoek, Vhembe district had the highest total phytoplankton composition. An aqua dam in Bungeni had the highest total phytoplankton composition compared to other aqua dams in Capricorn district. The earthen ponds in Vondo in Vhembe district had the lowest tilapia yield and total phytoplankton composition compared to all the production systems in Capricorn and Vhembe districts. Phytoplankton species abundance was not correlated to primary production and tilapia yield, and there was no correlation between primary production and tilapia yield. Tilapia farmers in Capricorn and Vhembe district both ranked “value chain accessibility”, “appropriate technology approach”, “market factors”, “level of operational integration”, and “access to multiple market destination” as the most important socio-economic factors affecting tilapia production in both districts. Tilapia vii production in Capricorn and Vhembe districts is not profitable because of low tilapia yields due to low stocking densities and because of low-priced imported tilapia from China and low-priced wild-caught tilapia sold by local fishermen in villages. The study concluded that tilapia production in Capricorn and Vhembe districts is not successful because farmers struggle to maintain optimum water quality and the water temperature was suitable for tilapia farming only for a short period of time. And lastly, tilapia production is failing to succeed in Capricorn and Vhembe district because it is not profitable. / Department of Agriculture, Land Reform and Rural Development and the Aquaculture Research Unit

The production of brook trout (<i>Salvelinus fontinalis</i>) in four headwater streams was studied with respect to natural variation in production and turnover ratios, contribution by age group and time of year, and correlations of physical and chemical variables with production. Lick Run and Ewings Run are spring fed streams with relatively high conductivity (105-135 µmhos). Guys Run and the South Fork of Potts Creek (SFPC) have moderate (25-63 µmhos} and low (17 µmhos) water conductivity, respectively. Two 200 m sections, each divided into four 50 m replicates, were studied in each stream. Annual production of brook trout averaged 45.4, 13.9, 17.2 and 14.0 kg ha^-1yr^-1 for Ewings Run, Lick Run, Guys Run, and SFPC, respectively. Production estimates were more variable within streams than among streams. Turnover ratios were consistent among streams and averaged 3.0 (s.d.=1.0} for age 0 trout, 1.3 (s.d.=0.4) for age 1 trout, and 1.6 {s.d.=0.4) for all ages combined. Age 1 trout contributed an average of 39% to annual production estimates. Age 0, 2, and 3 fish averaged 30%, 24%, and 7% of annual production estimates. Over 90% of the annual production of brook trout occurred between December and July. The December to May and May to July periods had equal levels of production of adult trout. The May to July period had the highest production of age 0 trout. The July to October period had the lowest production for all ages and the greatest incidence of negative production. No meaningful correlations of production with percent pool, percent bedrock, conductivity, discharge, or surface area were found. It was concluded that variables relating to habitat quality, such as instream cover, may have a more detectable effect on production than broad environmental variables. / M. S.

Commercial capture-based aquaculture of the Atlantic bluefin tuna (ABT), Thunnus thynnus (L.), has been prominent in the Mediterranean for over a decade. Owing to several limitations encountered in working with the species, including its high commercial value, there has been little research carried out relating to this species. The objective of this study was to examine several health parameters of captive ABT. These included an examination of coronary artery lesions, haematology, plasma biochemistry, assessment of immune function and changes in fatty acid (FA) flesh content through the on-growing period. Arteriosclerosis in fish is a pathologic condition of uncertain etiology and involves the main coronary artery in teleosts. Apart from reports of their widespread occurrence in salmonids, they have been described from a restricted number of wild ABT specimens but have not received further attention. This investigation analysed the effect of size and period of net-pen rearing on the prevalence and severity of arteriosclerotic lesions in ABT. Coronary arteries from wild and captive fish were investigated and prevalence was 100 %, but increasing structural degradation was observed with increasing fish size, suggesting that lesions progress throughout the life of the fish. Due to the limited availability of wild specimens, the effect of captivity on arteriosclerosis in ABT could not be adequately quantified, although observations suggest that the farming process has no major effect on arteriosclerotic lesions in ABT. Studies on the haematology, plasma biochemistry and immunology of ABT are limited. Haematological and plasma biochemical indices are useful in animal health assessment but use of these requires the establishment of species-specific ranges. Blood was collected from captive ABT specimens of varying weight (61-361 kg) and the major haematological (n = 45), plasma biochemical (n = 30) and immunological parameters (n = 45) were quantified. Size-based differences were found in haematological indices between experimental sub-groups including increased erythrocyte number and haemoglobin level in smaller ABT. No differences were found in immunological parameters except for total IgM levels, which were higher in the smaller individuals. Preliminary investigations indicated that disease prevalence in captive ABT is very low. Epidermal mucus is an important interface between fish and their environment and comprises immunological components which act as a first barrier against pathogen entry or colonisation. Mucus was collected from captive ABT and analysed for innate immune components. The presence of IgM was detected in the mucus of ABT by an enzyme-linked immunosorbent assay and several different enzymes were detected with an API-ZYM kit assay. Zymography experiments confirmed the presence of protease-like enzymes in the mucus, while enzyme assays quantified alkaline phosphatase, protease, esterase and cathepsin B activities. Lysozyme levels were high. The mucus agglutinated sheep erythrocytes but did not demonstrate complement or bacteriolytic activity. There is restricted information on the fatty acid composition of farmed ABT or how this is influenced when the fish are held under commercial aquaculture conditions. This study investigated the FA composition of farmed ABT, its variation by dorsal muscle region and the correlation between dietary FA composition with that of the fish. Analysis of flesh samples retrieved from farmed ABT did not reveal significant differences in the FA composition of experimental sub-groups irrespective of size, time held in captivity or diet. These results indicate that FA metabolism in ABT is substrate-selective. Gene expression measurements from several organs of ABT showed that expression of Δfad5 and elovl5, genes involved in FA metabolism, were highest in the brain followed by the liver but no expression of these genes was detected in the spleen. The findings of this research address aspects of health evaluation and nutritional status in farmed ABT and are discussed in terms of farming practice. Conclusions from some of these studies suggest that the practice of holding wild-captured stock in cages for periods of up to 18 months does not result in significant impact on ABT.

Thesis (PhD) -- tellenbosch University, 2014. / ENGLISH ABSTRACT: This study is part of the continuing global research effort dedicated to finding alternative aquafeed ingredients, which not only replace fish meal and fish oil as sources of essential nutrients in aquafeeds, but also provide specialist functional properties when included in feeds. Due to constraints in supply of fish meal and fish oil originating from wild capture fisheries, the continually growing aquafeed industry requires new sources of raw materials for the production of high quality feeds. The aim of the study was to investigate the specialist functional properties of feed ingredients (with emphasis on immune-stimulation potential) derived from fish processing waste after enzymatic hydrolysis by endogenous proteolytic enzymes (autolysis). Further aims were to (i) quantify effects of these feed ingredients on production performance of two species relevant to the South African aquaculture industry, namely Mozambique tilapia Oreochromis mossambicus and South African abalone Haliotis midae, (ii) compare performance to commercially available enzymatically produced feed ingredients, and (iii) separate the functional effects of these fish processing waste derived feed ingredients from the acid used to preserve them against bacterial spoilage during the autolysis process. Oil recovered after autolysis of rainbow trout viscera proved to be an attractive feed ingredient due to favourable effects on the non-specific cellular immune function of both Mozambique tilapia and South African abalone. However, in South African abalone, increased immune function due to inclusion of fish oil was accompanied by a significant decrease in production performance. The inclusion of hydrolysed proteins, obtained by autolysis of fish waste, in aquaculture feeds also improved non-specific immunity and survival of Mozambique tilapia significantly – independently of the preserving acid – although the same was not observed for South African abalone. Production performance was dependent on dietary hydrolysed protein inclusion levels in both species; excessive inclusion resulted in decreased production performance. The performance of dietary hydrolysed protein from autolysis and those from commercial production processes were significantly different, possibly as a result of different raw material origins and production processes. It is further shown that formic acid can contribute to improved water stability in abalone feeds, a novel mode of action not previously described. The study concludes that the simple autolysis process for processing of fish waste can provide aquafeed ingredients with immune stimulatory potential, which can contribute to improved production performance in the Mozambique tilapia and the South African abalone. The result can contribute to improved sustainability of the aquafeed industry, through substitution of fish meal and fish oil derived from capture fisheries with processed fish waste components. / AFRIKAANSE OPSOMMING: Hierdie studie vorm deel van die voortdurende en wêreldwye soeke na nuwe akwakultuur voerbestanddele wat nie net vismeel en –olie kan vervang as bron van noodsaaklike voedingstowwe nie, maar wat ook gespesialiseerde funksionele eienskappe openbaar wanneer dit in akwavoere ingesluit word. As gevolg van beperkings in die voorsiening van vismeel en –olie afkomstig vanaf wilde visserye, word die voortdurend groeiende akwavoer bedryf genoodsaak om nuwe grondstowwe te benut vir die vervaardiging van hoë kwaliteit voere. Die doelwit van die studie was om moontlike gespesialiseerde funksionele eienskappe (met spesifieke klem op potensiële immuun-stimulasie) van voerbestanddele te ondersoek wat herwin is vanaf reënboogforel proseseringsafval, na ensiematiese hidrolise d.m.v. endogene ensieme teenwoordig in die afval (outolise). Verdere doelwitte was om (i) effekte op produksie prestasie van hierdie bestanddele te kwantifiseer in twee akwakultuur spesies relevant tot die Suid- Afrikaanse bedryf (naamlik die Mosambiekse kurper Oreochromis mossambicus en die Suid- Afrikaanse perlemoen Haliotis midae), (ii) om produksie prestasie te vergelyk met kommersieel beskikbare voerbestanddele voorberei d.m.v. ensiemtegnologie, en (iii) om die moontlike effekte van die voerbestanddele te skei van die van die sure gebruik om die bestanddele te preserveer tydens die outolitiese proses. Daar is bevind dat olie herwin na outolise van reënboogforel ingewande ‘n goeie voerbestanddeel is wat gunstige effekte op die nie-spesifieke, sellulêre immuniteit van beide Mosambiekse kurper en Suid-Afrikaanse perlemoen gehad het. In die Suid-Afrikaanse perlemoen het verbeterde immuunfunksie gepaard gegaan met ‘n verswakking in produksie prestasie. Die gehidroliseerde proteïen komponent van ge-outoliseerde prosesseringsafval het ook beduidende verbetering in nie spesifieke immuniteit en oorlewing van Mosambiekse kurper tot gevolg gehad - onafhanklik van die preserverende suur - maar dieselfde is nie in die Suid-Afrikaanse perlemoen waargeneem nie. Produksie prestasie was afhanklik van die insluitingsvlakke van gehidroliseerde proteïen in beide spesies en dit is bevind dat oormatige insluiting produksie nadelig beïnvloed. Prestasie van proteïen afkomstig van outolise en die van ‘n kommersiële produksieproses het beduidend verskil, moontlik as gevolg van verskillende grondstowwe en prosesseringstegnieke. Daar is verder vir die eerste keer getoon dat mieresuur ‘n beduidende verbetering in waterstabiliteit in sekere perlemoenvoere teweeg kan bring. Die studie kom tot die slotsom dat die eenvoudige outolise proses funksionele akwavoerbestanddele kan produseer wat kan bydra tot ‘n verbetering in produksie prestasie in die Mosambiekse kurper en Suid-Afrikaanse perlemoen. Die resultaat kan bydra tot verbeterde volhoubaarheid van die akwavoer bedryf, deur vismeel en –olie afkomstig van wilde visserye, te vervang.

Intensive and semi-intensive aquaculture systems are dependent on nutrient input either in the form of supplemental or complete feeds. Most complete diets still include high fish meal (FM) levels (≥10%). However, as the industry attempts to reduce its reliance on FM, feeds must now be formulated with much lower levels especially for omnivorous species such as tilapia. By 2015, mean FM inclusion in tilapia diets was projected to fall below 3% and be further reduced to 1% by 2020. In the global context of competition for crops, finding suitable plant-based replacers for FM and meeting the increasing demand for seafood, lower-cost and under-utilised plant feedstuffs are now receiving greater attention. The study was divided into three distinct components – field survey, growth experiments, and life cycle assessment. Field surveys were used to contextualise the growth experiments and assess commercialisation opportunities for multi-enzyme inclusion in tilapia feeds. Two sets of digestibility and growth experiments were designed to evaluate the feasibility of using high inclusions of plant-based ingredients sourced from locally available feedstuffs in Thailand to substitute FM at low inclusion levels (0 – 5%). The research evaluated the hypothesis regarding the potential of exogenous enzymes (protease, xylanase and phytase) to minimize anti-nutritional effects on nutrient digestibility of proteins, polysaccharides and phosphorus in tilapia. The research also assessed the secondary effects of enzyme supplementation on economic efficiency and life cycle environmental impacts. Tilapia is the second most cultured finfish globally and Thailand is the sixth largest producer. Based on the findings of the field survey, feeding practices of Thai tilapia farmers were confirmed to be diverse. Feed inputs included, but were not limited to, agro-industrial by-products (e.g. rice bran, corn bran etc.) and commercial diets. Commercial diets contained 15 – 30% crude protein and lower protein livestock diets (i.e. pig ration) were often used for supplemental feeding or “fattening”. The experimental low FM diets were therefore formulated as grow-out or “fattening” diets for semi-intensive green-water systems, a prominent feature (>60%) of Thai tilapia farming. In Phase 1, the digestibility experiment assessed the digestibility and growth in tilapia fed 0%, 3% and 5% FM diets with and without xylanase (0.385 g kg-1) and phytase (0.075 g kg-1). Performance decreased significantly with declining FM levels. No differences in feed intake, feed conversion ratio (FCR), specific growth rate (SGR) and weight gain were observed between the enzyme and control diets. Nevertheless, tilapia fed the enzyme supplemented 3% FM and control 5% FM performed similarly (P < 0.05). No enzyme-related effects were noticed for protein digestibility but phosphorus (P) digestibility improved by 9%, except at 0% FM level (P > 0.05). The enzymes had no apparent influence on nitrogen (N) retention contrary to previous studies, however, higher retention for P was observed. Villus length decreased with declining FM levels yet no improvements were seen in tilapia fed enzyme diets. In a simultaneous grow-out experiment, the six experimental diets were compared to an industry 10% FM standard. Conversion ratio was the lowest (1.66) in adult tilapia fed 10% FM diet however the enzyme supplemented 0% FM fed fish had a comparatively low FCR of 1.67. There were no significant enzyme-related effects on weight gain¸ SGR and protein efficiency. Proximal villi results were inconsistent. The cost of feed decreased with declining FM levels but increased with enzyme inclusion. Nevertheless, the economic returns per kg of whole fish produced were better using enzyme supplemented diets compared to the controls. Though the size of the effects on growth and nutrient utilisation were modest, the findings suggested that xylanase and phytase had some level of synergistic action on the targeted anti-nutrients. However, further research was required. In Phase 2, two control diets (2% FM, negative control (NC) and 10% FM, positive control (PC)) were compared with three enzyme supplemented 2% FM diets (NO-PRO, 0.385 g kg-1 xylanase and 0.075 g kg-1 phytase only; LO-PRO, xylanase + phytase + 0.2 g kg-1 protease and HI-PRO, xylanase + phytase + 0.4 g kg-1 PRO). Growth performances improved with enzyme supplementation compared to the NC (P < 0.05). Of the enzyme supplemented diets, the LO-PRO diet showed the highest improvements in weight gain (26%) and feed intake (19%), the latter comparing statistically to the 10% FM PC diet. The HI-PRO diet had the best FCR (1.88), again comparable to the PC (1.73). The NO-PRO diet had the highest protein, P, lipid and energy digestibility, suggesting no additive effect of protease on these coefficients. In terms of gut histomorphology, the LO-PRO and PC diets had the highest measurements and were statistically similar which may have explained similarities in feed intake. Compared to the NC, the HI-PRO diet produced the highest level of change in net profit due to gains in feeding efficiency however, the LO-PRO showed better improvements in terms of growth. Based on these findings, the ternary combination of protease with xylanase and phytase (LOPRO) has potential in limiting FM use for tilapia grow-out feeds, however, the economic efficiencies were still below that of a 10% FM diet. Future considerations for research should target the indigestible dietary components in order to optimise enzyme dosages and maximise the benefits of each enzymes. In conclusion, a comparative life cycle assessment (LCA) was used to evaluate the environmental impacts of low FM diets and commercial feeds associated with tilapia production in Thailand. The study showed that the low FM enzyme supplemented diets had lower impact potentials and were environmental superior to the average (10% FM) commercial standard. LCA modules are recommended for least-cost formulation programmes as an option going forward. Additionally, LCA can be used as a predictive tool to guide farmers, especially small-scale producers, on the potential impacts of feed input choices and feeding practices. This will ensure higher product quality but also demonstrate environmental responsibility on the part of aquafeed and fish producers to final seafood consumers.

Interest in the subject of fish welfare is continuing to grow, with increasing public awareness and new legislation in the UK. Water quality has long been recognised as being of prime importance for welfare: water provides the fish with oxygen and removes and dilutes potentially toxic waste metabolites. This thesis investigates the interactions between water quality and the welfare of farmed rainbow trout (Oncorhynchus mykiss Walbaum). A literature review was undertaken to identify current recommended water quality limits for the health and welfare of farmed rainbow trout. Contradictions in the literature regarding suggested ‘safe’ water quality limits were also identified, as were deficiencies in some of the methods used to arrive at conclusions for recommended limits. The literature relating to the effects of poor water quality on welfare were also reviewed. The review ends with a discussion about water quality monitoring in the context of on-farm welfare assessment and how the information might be used in such a scheme. A telephone survey of UK rainbow trout farmers was undertaken to ascertain the level of water quality monitoring currently conducted. Participants in this study accounted for over 80% of 2005 UK rainbow trout production. It was established that 54% of farmers monitored dissolved oxygen to some extent and 69% monitored temperature, the most commonly measured water quality parameters and among the most important for health, welfare and growth. Subsequent visits were made to a sample of the participants in the telephone survey to obtain more detailed information of the farming operations, such as frequency of water quality monitoring, retention of production data and slaughter methods. Monitoring water quality will be an integral part of any on-farm welfare assessment scheme, and while measuring some water quality parameters requires specialist equipment, farmers should be able to monitor the essential parameters, dissolved oxygen and temperature. Any on-farm welfare assessment scheme for rainbow trout should incorparate fish-based measures in addition to resource-based parameters in order to provide as complete an overview of trout welfare as possible. An epidemiological study was undertaken to investigate the current status of welfare on UK rainbow trout farms and to identify risk factors for welfare. Forty-four trout farms from throughout the British Isles were visited between July 2005 and April 2007, sampling a total of 3700 fish from 189 different systems. Farms were visited twice, once in winter and once in summer, to account for any seasonal differences in fish physiology and environmental conditions. Data were collected on a range of fish parameters, together with background information on the batch from which the fish originated. Particular emphasis was placed on water quality due to the potential effects this can have on welfare. The water in each system sampled was monitored for 24 hours, with measurements of dissolved oxygen, temperature, pH, specific conductivity and ammonia taken every 15 minutes. A welfare score was developed for each fish using a multifactorial method, combining data on the condition of the fins, the condition of the gills, the stress hormone cortisol, the splenosomatic index and the mortality levels for the population of fish in the system. Using this welfare score and the individual components of the score as response variables, multi-level models were developed using the water quality, system and husbandry data collected. The primary risk factor that was associated with deteriorating welfare was disease. The purpose for which the fish was being farmed was also important, as fish farmed for the table market had on average worse welfare than those farmed for restocking fisheries. Seasonal effects, linked to higher water temperatures in summer, were associated with poorer welfare scores. Aside from seasonal effects, there is not much evidence that poor water quality is a major problem for the welfare of farmed rainbow trout in the UK. While deteriorating water quality certainly has the potential to affect the welfare of farmed rainbow trout, water quality measurements were within recommended ranges for the majority of farms visited. The results of this epidemiological study suggest that factors other than water quality may have a greater impact on trout welfare, such as exposure to diseases and production differences between farming for the table and restocking markets.

This thesis examines pond aquaculture as a development strategy in the Philippines, with particular reference to its impact on the local environment and the livelihoods of local people. / A theoretical framework is provided by recent literature in development studies and human geography, which attempts to move away from an essentialist and ethnocentric development praxis, and towards a locally-based, participatory process of empowerment. From the perspective of such 'alternative' development ideas, orthodox strategies involving modernization, formalization of economic activities, and resource mobilization, can be reassessed. / The promotion of pond aquaculture--and the widespread mangrove deforestation associated with it--is shown to be a strategy endorsed and supported by national and international development agencies. What is often overlooked, however, is the local ecological and economic importance of mangrove ecosystems. This study examines the effects of mangrove removal and fishpond development on the entitlements of people in three coastal communities in the Philippines. Aquacultural development is shown to have detrimental effects on the integrity of the coastal ecosystem and the livelihoods of certain groups of local residents; a rich common property resource is converted into a privately-owned system of cultivation. While benefits accrue to those with access to the capital necessary for the construction of fishponds, the costs of development are borne largely by mangrove gatherers and artisanal fisherfolk, whose share of a diminishing resource base is steadily declining. For these marginal groups, aquaculture is shown to provide few compensating economic benefits. / The study supports, through concrete local evidence, the criticisms made of orthodox approaches to development, and the need to construct attitudes and strategies which are more attuned to local sustainability and equity.