Essential fatty acid metabolism and requirements of the lobster, Homarus americanus.
Date
1991
Authors
Harrison, Kim Elizabeth.
Journal Title
Journal ISSN
Volume Title
Publisher
Dalhousie University
Abstract
Description
In two long-term feeding trials, juvenile lobsters (Homarus americanus) were reared on semi-purified test diets supplemented with or deficient in selected (n $-$ 6) or (n $-$ 3) polyunsaturated fatty acids (PUFA) or the highly unsaturated fatty acid (HUFA), 22:6 (n $-$ 3). An attempt was made to establish which fatty acids are essential for lobsters and to determine symptoms or disorders associated with EFA deficiency to thereby suggest functions of those fatty acids in lobsters. In the first feeding experiment 800 sibling juvenile lobsters were reared at 20$\sp\circ$C and fed one of ten semi-purified test diets. Survival, growth, and whole body fatty acid composition were evaluated. In the second feeding trial, 100 sibling juveniles were reared at 10$\sp\circ$C or 20$\sp\circ$C and fed one of five semi-purified test diets. A multi-disciplinary approach was used to evaluate deficiency-related pathologies and to investigate the role of these nutrients in the lobster at the following levels of biological organization: (a) general: growth, molting, survivorship, (b) functional: metabolic rate, (c) structural: tissue and membrane histology, (d) compositional: tissue-specific fatty acid composition and (e) biochemical: fate of radio-labelled fatty acids.
Although juvenile lobsters could survive 10-12 weeks on diets deficient in both (n $-$ 3) and (n $-$ 6) PUFA, growth and molting rate were depressed, and rapid mortality occurred after this critical time. A diet high in saturated fatty acids enhanced these deficiency effects.
The oxygen consumption rate of lobsters fed the diet deficient in PUFA was significantly lower than that of lobsters fed diets with supplemental (n $-$ 3) or (n $-$ 6) PUFA. There was no affect of dietary fatty acids on ammonia excretion rates.
Lobsters fed the PUFA-deficient diet had a significantly lowered hepatosomatic index (HSI).
There were significant (and independent) effects of dietary fatty acids and temperature on lobster fatty acid composition.
In conclusion, (n $-$ 3) and/or (n $-$ 6) fatty acids are essential for juvenile lobsters and HUFAs (e.g. 22:6(n $-$ 3)) have a higher EFA value than 18-C PUFAs. EFA deficiency in the lobster is manifested at each level of biological organization; symptoms include changes in fatty acid composition, degenerative tissues (hepatopancreas), depressed metabolic rate and tissue catabolism, lethargy, poor growth and depressed molting rates, and mortality. (Abstract shortened by UMI.)
Thesis (Ph.D.)--Dalhousie University (Canada), 1991.
Although juvenile lobsters could survive 10-12 weeks on diets deficient in both (n $-$ 3) and (n $-$ 6) PUFA, growth and molting rate were depressed, and rapid mortality occurred after this critical time. A diet high in saturated fatty acids enhanced these deficiency effects.
The oxygen consumption rate of lobsters fed the diet deficient in PUFA was significantly lower than that of lobsters fed diets with supplemental (n $-$ 3) or (n $-$ 6) PUFA. There was no affect of dietary fatty acids on ammonia excretion rates.
Lobsters fed the PUFA-deficient diet had a significantly lowered hepatosomatic index (HSI).
There were significant (and independent) effects of dietary fatty acids and temperature on lobster fatty acid composition.
In conclusion, (n $-$ 3) and/or (n $-$ 6) fatty acids are essential for juvenile lobsters and HUFAs (e.g. 22:6(n $-$ 3)) have a higher EFA value than 18-C PUFAs. EFA deficiency in the lobster is manifested at each level of biological organization; symptoms include changes in fatty acid composition, degenerative tissues (hepatopancreas), depressed metabolic rate and tissue catabolism, lethargy, poor growth and depressed molting rates, and mortality. (Abstract shortened by UMI.)
Thesis (Ph.D.)--Dalhousie University (Canada), 1991.
Keywords
Biology, Animal Physiology., Biology, Zoology., Agriculture, Fisheries and Aquaculture.