Published in Scientific Papers. Series D. Animal Science, Vol. LXII, Issue 2
Written by Mirela CREȚU, Lorena DEDIU, Angelica DOCAN, Victor CRISTEA Raluca Cristina ANDREI (GURIENCU)
In this study we investigate the effect of different feeding levels (FL1-2.5%BW day-1, FL2- 3%BW day-1, FL3-3.5% BW day-1, FL4-4 %BW day-1, FL5-4.5 %BW day-1 and, ad libitum-FL6) on the growth performance, morphologic indexes and body composition of rainbow trout (Oncorhynchus mykiss) reared in a recirculating aquaculture system. 360 juvenile rainbow trout (34.17±0.11 g, mean±SD) were randomly distributed to 12 rearing units for 44 days. At the end of the trial period, the ANOVA test showed that growth performance was significantly affected by feeding levels (p<0.05). Final mean body weight, weight gain, and specific growth rate(SGR) increased with increasing feeding level. Feed conversio rate (FCR) was below 0.7 for all groups, except FL6 were FCR registered a value of 0.83 (g/g). The protein efficiency ratio was significantly affected by the feeding level (p<0.05) and the best value was obtained for FL1 group (2.59±0.05 g/g). Significant changes (p<0.05) in ash, protein, lipids, and water content were observed at the end of the experimental period. Protein and lipids contents of rainbow trout meat increased with increasing feeding level, while moisture content and ash significantly decreased. Also, this increasing trend was observed in terms of the hepatosomatic index, but without significant differences between groups (p>0.05). The viscerosomatic index of fish the FL1, FL2, and FL3 was significantly lower than those from FL4, FL5, and FL6. Based on the obtained results, it is recommended, from an economic point of view, a feeding level of 2.5 % BW day-1 as optimum for rainbow trout, reared in a recirculating aquaculture system, from 30g to 130 g.
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