UBC Theses and Dissertations
Lipid composition and fatty acid profiles of eggs from wild and cultured chinook salmon (oncorhynchus tshawytscha) broodstock Ashton, Heather
In Experiment 1, eggs of Big Qualicum (BQ) and Robertson Creek (RC) wild and cultured Chinook salmon (Oncorhynchus tschawytcha) were analyzed for lipid composition and fatty acid profiles. Each of the cultured broodstocks had been fed two formulated diets designated as COMM and WV33. Significantly higher concentrations of saturated and n3 fatty acids and lower concentrations of n6 and n9 fatty acids were found in both the total and polar lipids of the eggs from the wild fish than in those from either group of cultured fish. Highly unsaturated fatty acids (HUFAs), primarily 20:5n3 and 22:6n3, were the major contributors to the n3 series in both the wild and cultured eggs. The n3:n6 ratios of both the total and polar lipids were up to 5.3 times greater in the wild than in the cultured eggs. The monounsaturate concentration was significantly greater in the cultured eggs than in the wild eggs. The fatty acid composition of the eggs generally reflected the fatty acid profiles of the diets fed to the broodstock. Condition factors for the wild fish were significantly lower than for either group of cultured fish, reflecting the significantly greater body length of the wild fish than the cultured fish. There were no significant differences in body weights. Survival to eyeing among the cultured eggs was lower than that reported by the respective federal government hatcheries for the wild eggs. The quality of eggs was poor in both stocks fed the WV33 diet, with high incidences of abnormal and retained eggs and low fertility, particularly in the RC fish. Survival to eyeing was poorest in the RC-WV33 eggs. Some factor other than lipid and fatty acid composition (possibily Vitamin C) appeared to be responsible, as the fatty acid profiles in the WV33 eggs were generally closer to those of the wild fish than to those of the COMM fish. There was no explanation for the inferior performance of the RC-WV33 fish compared to the BQ-WV33 fish. In experiment 2, feed was withdrawn from a group of Chinook broodstock for 7 days beyond the usual 7 day starvation period prior to transport to freshwater for final maturation. There were no differences in lipid composition and few differences in fatty acid profiles. Fecundity and survival to eyeing were not compromised by this treatment. Experiment 3 was carried out to determine whether a formulated diet (COMM) augmented with krill (designated as the BROOD diet) for six weeks prior to the pre-transport starvation period would affect lipid composition, fatty acid profiles and incubation success. The control diet was the COMM formulation. The BROOD eggs were significantly lower in total lipid concentration due to the presence of significantly less neutral lipid than in the COMM eggs. Small significant differences in individual fatty acids were found between the two groups. While some of these differences reflected the dietary fatty acids (eg. 22:1n11), others appeared to be due to retention (ie. n3 fatty acids) or to elongation and desaturation of fatty acids (eg. 18:1n9). No differences in incubation success were found between the groups.
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