Abstract (EN):
Ammonia and urea nitrogen excretion and oxygen consumption of diploid and triploid rainbow trout were measured at several evenly spaced intervals from egg fertilization until 8 days after complete yolksac absorption at a constant temperature of 12°C. The same parameters were also measured in embryos transferred to temperatures of 5 and 10°C on each measurement day, to estimate the effect of temperature on the utilization of the endogenous energy reserves in embryos in the same stage of development and having identical energy reserves. Metabolic characteristics were not significantly different between diploid and triploid embryos at any experimental temperature. At the constant temperature of 12°C, oxygen consumption and ammonia nitrogen excretion slowly increased before hatching. Thereafter both increased considerably until yolksac absorption was completed. In the starving fry, after yolk absorption, oxygen consumption decreased, while ammonia excretion continued to increase until the end of the trial. Urea nitrogen excretion did not show much change before hatching. Thereafter it increased for a few days and then declined until complete yolksac absorption. In starving alevins, urea excretion rates continued to increase. While oxygen consumption and ammonia excretion rates were directly related to temperature, urea excretion was not affected by temperature. Temperature considerably affected utilization of the endogenous energy substrates: less protein energy was used to cover the energy needs of the embryos at higher temperatures. © 1990.
Language:
English
Type (Professor's evaluation):
Scientific
No. of pages:
10