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Effect of the daily meal time on the growth of rainbow trout fed different ration levels
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Edité par CCSD ; Springer Verlag -
International audience. This study examined the effect of ration level and time of delivery of a single daily meal on the growth performance of rainbow trout held under constant water temperature and a natural photoperiod. Two similar trials were conducted, the first from March to July, 1992, using ration levels of 0.5, 1.5 and 2.5% BW d–1 and the second from August 1992 to January 1993, using ration levels of 1.5, 2.0 and 2.5% BW d–1. In five of the six treatment groups (three ration levels × two seasons), when the daily meal was presented in the post-dawn period the growth rate was lower than in trout fed at either mid-light or pre-dusk. No time-of-feeding effect was found when trout were fed excess rations. Specific growth rate (SGR) was not affected by feeding time, but was correlated with ration level; furthermore, there was a significant increase in SGR during the first section of the first trial and a significant decrease in the SGR throughout the duration of the second trial. Ration level was significantly correlated with condition factor, carcass visceral adipose tissue content and skeletal muscle lipid content, but there was no effect of the timing of the daily meal on these variables.
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