Two experiments were conducted to study the effect of protein source and level in the diet of juvenile chinook salmon (Oncorhynchus tshawytscha) reared in fresh water tanks. The protein sources compared were a freeze-dried pollock muscle and euphausid mix (9:1)(FPE), three whole herring meals processed differently from the same lot of raw herring and a casein-gelatin mix supplemented with arginine and DL-methionine (CS). The protein sources were tested at three levels of dietary protein in isocaloric diets fed to satiation to duplicate groups of fish for a 42-day period. Protein was replaced by dextrin and glucose on an estimated metabolizable energy basis. The various methods employed to evaluate protein quality yielded different values relative to FPE. In terms of growth rate and assays based on body protein gain, FPE was found to be the best protein source.
Low temperature (75°C) drying of herring meal caused a slight reduction in protein quality compared to freeze-drying . High temperature (150°C) dried herring meal was found to be an extremely poor quality protein source. Although high estimates of protein quality were obtained for CS, lower food intake depressed growth in fish fed CS diets. The determination of the endogenous loss of nitrogen from fish enabled the partitioning of protein intake into the amounts used for growth, maintenance and exogenous excretion for each protein source. In Experiment 2, two series of isocaloric diets were tested containing 17 to 47% protein, in increments of 10%, provided by FPE at two levels of dietary energy. The equation y = -0.50699 + 0.25398x - 8.37872x² ,(where y = specific growth rate, and x = protein energy:total energy (PE:TE)) was derived to quantify the dietary protein requirement for juvenile chinook salmon over a 105-day period. Maximum growth was achieved at a PE:TE ratio of 0.55. However, for practical purposes the PE:TE ratio required was found to lie in the range between 0.35 and 0.55. The range permits the fish culturist to consider economic efficiency in diet formulation. / Land and Food Systems, Faculty of / Graduate
| Identifer | oai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/25827 |
| Date | January 1985 |
| Creators | McCallum, Ian |
| Publisher | University of British Columbia |
| Source Sets | University of British Columbia |
| Language | English |
| Detected Language | English |
| Type | Text, Thesis/Dissertation |
| Rights | For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
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