A dietary level of Aroclor 1254 (100 ppm) was fed to rainbow trout (Salmo gairdneri) for 15 weeks to determine the effects on hepatic microsomal enzyme induction. Fish were also fed combined polychlorinated biphenyl (PCB) (100 ppm) and cyclopropene fatty acids (CPFA) (50 ppm) to determine the effects on mixed function oxidase (MFO) induction. Dietary PCBs markedly induced the microsomal activities of 7-ethoxyresorufin O-deethylase, 7-ethoxy-coumarin O-deethylase, and benzo(a)-pyrene monooxygenase. Ethoxyresorufin O-deethylase activity continued to increase to a level 77-fold higher than control at week 15. Ethoxycoumarin O-deethylase and benzo(a)-pyrene monooxygenase activities increased to 7.1-fold and 48-fold over control at week 9 and then slightly decreased to 6.8-fold and 45-fold over control at week 15, respectively. Cytochrome P450 values remained approximately 2-fold above controls from week 5 through week 15. At weeks 1 and 3, cytochrome P450 levels were not significantly different from control. Ethoxyresorufin O-deethylase, ethoxycoumarin O-deethylase, and benzo(a)pyrene monooxygenase activities in the combined PCB and CPFA-fed trout were significantly higher than in controls and CPFA-fed fish, and significantly lower than in PCB-fed fish. There was no significant difference in cytochrome P450 levels after week 5. This is the first time dietary PCBs have been shown to induce the MFC system in PCB-fed rainbow trout. / Graduation date: 1980

The effects of different dietary lipids on the growth, nutrition and tissue lipid profiles of rainbow trout raised to market size on a commercially available ration were examined. Rainbow trout of 80 g mean initial weight were fed pellets prepared according to Oregon Moist Pellet specifications for 20 weeks. Salmon oil (0MP-1), soybean oil (OMP-2), linseed oil (OMP-3), chicken fat (OMP-4), pork lard (OMP-5) and beef tallow (OMP-6) were used for the 6% lipid component of the diets. No differences in feed conversion or growth rate were observed across diet groups. Trout nutrition was monitored by three blood parameters -- red blood cell (RBC) fragility (hemolysis), packed cell volume (PCV) (hematocrit), and percent hemoglobin. The OMP-1 diet appeared to have caused oxidative stress in trout as measured by hemolysis, while hematocrit and percent hemoglobin values were uniform across diet groups. Tissue levels of total n-3 fatty acids were highest in the OMP-3 group and decreased in the order OMP-1 > OMP-2 = OMP-4 = OMP-5 = OMP-6. However, unaltered linolenic acid (18:3 n-3) comprised almost 50% of the n-3 fatty acid content of OMP-3 trout tissue lipid. The level of total 20:5 n-3 plus 22:6 n-3 (18%), was 33% higher in tissue from OMP-1 trout than tissue from all other diet groups which held fairly constant at 12% across OMP groups 3-6. The lowest tissue level of total 20:5 n-3 plus 22:6 n-3 was found in the OMP-2 trout, 10%. Trout raised on the OMP-1 diet also retained higher tissue stores of 20 and 22 carbon monoenes than trout fed OMP diets 2-6, but less than dietary levels. In contrast, trout fed OMP diets 2-6 retained higher tissue levels of these same fatty acids than dietary levels. The diet ratio of polyunsaturated fatty acids (PUFA)/22:1 appeared to influence whether 22:1 was conserved or oxidized. The most favorable balance of trout tissue monoenes, n-6 fatty acids and total 20:5 n-3 plus 22:6 n-6 for human health was found in trout fed the OMP-6 diet. / Graduation date: 1988

Juvenile rainbow trout (Salmo gairdneri Richardson) from the Lardeau River in southeastern British Columbia were studied in both their natural environment and stream tanks. In the river, highest densities of recently emerged trout occurred in areas with overhanging cover, shallow depth and minimal current. Older, underyearling trout were generally found in regions with smaller bottom particle size than yearlings; both age classes avoided fast current areas. Young trout migrated from the Lardeau River to Kootenay Lake during spring and summer. Except during these seasons trout were larger and more abundant in the upper versus the lower river; this was probably a result of better rearing habitat and higher biological productivity in the upper river. Trout fed almost exclusively on drifting organisms. Lake origin drift was an important food to riverine trout during summer; kokanee (Oncorhynchus nerka) eggs and fry were significant during fall and spring respectively. In stream tanks, where it was possible to manipulate prey populations, live prey were consumed significantly more than the same species when dead, suggesting that prey body movement was an important prey characteristic. In both the field and stream tanks, trout consumed prey within a discrete size range with larger fry generally consuming bigger prey than smaller fry. Further work is suggested which would improve our understanding of the feeding ecology of stream rearing trout. / Science, Faculty of / Zoology, Department of / Graduate

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.

This research reports on the determination of the effects of fish size and feed pellet size on the settling characteristics of Rainbow trout (Salmo gairdneri) culture, tank cleaning wastes. Flocculant particle settling curves (Type II) were developed from settling column analysis of cleaning wastes from 11-311 gram Rainbow trout fed a moist pellet diet (Oregon Moist Pellet ®). Four feed pellet sizes were investigated: 3/32, 1/8, 5/32 and 3/16 inch. Overall non-filterable residue removal curves and individual particle settling velocity distribution curves, derived from the Type II settling curve of each fish size and feed pellet size group, were compared. Slopes and y-intercepts of the linearized overall non-filterable residue removal curves and individual particle settling velocity distribution curves were compared using the Equality of Slope Test (S:SLTEST). Results of the test for a common regression equation indicated there were no significant differences in the proportional distribution of particle sizes within the cleaning wastes. Variations observed in the initial rates of removal within the overall non-filterable residue removal curves were considered insignificant Settling trials were pooled in order to obtain single curves, characterizing the overall solids removal rate and the individual particle settling velocity distribution of the waste solids. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate