Effect of light conditions during the incubation period on eggs of rainbow trout brooders fed with different levels of dietary ascorbic acid

Articles in Press

Document Type : Research Paper

Authors

Department of Fisheries, Hamoun International Wetland Research Institute, University of Zabol, Zabol, Iran

10.22059/jfisheries.2022.337019.1309

Abstract

The aim of this study was to investigate the effect of light conditions on incubation of rainbow trout eggs fed with different levels of ascorbic acid. For this purpose, 54 trout brooders (812 ± 1.5 g) were introduced into the tanks with dimensions of 1.5 × 1.5 × 1 m and a volume of 910 liters (6 fish per each tank). Fish brooders were fed three diets containing 0, 100 and 1000 mg/kg of L-ascorbyl-2-polyphosphate for 16 weeks. At the end of the experimental period, the oocytes of 4 fish from each replicate were taken. The eggs were incubated under absolute darkness and constant light. The results showed that the effect of ascorbic acid on work fecundity was significant (p<0.001) and that there was an interaction between ascorbic acid and light and its effect on the percentage of eyed eggs (p<0.001). Regarding the degree-day up to the eyed stage, the results showed no interaction among treatments (p = 0.777). Moreover, in relation to the degree-day up to the stage of alevin, the results showed no interaction among treatments (p = 0.145). The results of this study showed that feeding with a diet containing 1000 mg/kg ascorbic acid compare to control and 100 mg/kg ascorbic acid diets leads to improved reproductive indices. Also, in the diet of 1000 mg/kg ascorbic acid and darkness, the percentage of eyed eggs compared to the other two treatments and constant light conditions increased significantly (p<0.05). The results of this study indicate the necessity to feed trout breeders with high levels of ascorbic acid to achieve higher reproductive efficiency.

Keywords

Journal of Fisheries

Articles in Press, Accepted Manuscript
Available Online from 03 January 2023

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