The Influence of Feeding Level on Growth Performances of European Catfish (Silurus glanis L., 1758) Juveniles under Recirculating Water Conditions

The study was carried out with one summer-old Silurus glanis juveniles, having the mean size 23.04±2.05 cm and weight 73.84±19.12 g, reared in recirculating water condition, in order to assess the impact of feeding level on growth performances and body size variation of fish. Two feeding levels were tested (R1=1.5% BW/day and R2=2.5% BW/day), in duplicate, during 6 weeks, and the biomass gain (BG), feed conversion ratio (FCR), specific growth rate (SGR), protein efficiency ratio (PER), morphometric relationship between length-weight (LWR) and coefficient of variation (CV) were assessed. Data revealed that the overall mean weight of the biomass was doubled during the trial, from 14.92 kg to 31.17 kg, and the body growth significantly increases with the increment of the feeding rate (13.48 kg in R1 and 17.70 kg in R2), underlying the good potential of the species, at this life stage, for fast-growing under intense conditions. The calculated SGR in R1 was 1.43%/day and in R2, significantly higher, as 2.05 %/day, for the almost similar values of FCR (0.74 g/g) and PER (2.50 g/g) recorded between the treatments

Effect of starvation and re-feeding with different dietary protein level on some hematological parameters of juvenile rainbow trout (Oncorhynchus Mykiss, Walbaum, 1792)

The aim of this experiment was to analyze the effect of applying of cyclical short periods of starvation (2 days and 4 days) on the hematological profile of rainbow trout. This experiment lasted for 46 days and was carried out in the facility of the University “Dunărea de Jos” from Galaţi. Six treatments with duplicate were assigned, as follows: two control groups, feed daily, ad libitum, with commercial pellets containing 41% crude protein (D41) and 50% crude protein (D50); two groups starved for 2 days (D2) and then fed with commercial pellets with 41% crude protein (D2/41), respectively 50% crude protein (D2/50) and two groups starved for 4 days (D4) and then fed with commercial pellets with 41% crude protein (D4/41), respectively 50% crude protein (D4/50). Starvation and re-feeding with different dietary protein level had no significant (p˃0.05) effect on some hematological parameters including hematocrit, mean corpuscular volume, mean corpuscular hemoglobin, while hemoglobin, Red blood cell counts and mean corpuscular hemoglobin concentration, registered significant differences (p˂0.05). Significantly higher (p˂0.05) concentration of hemoglobin was observed in the case of fish fed with higher protein content, while the increasing of the starvation period led to a significant decrease of the hemoglobin concentration. Furthermore, starvation and subsequent feeding led to a significant decrease of the erythrocyte number with the increasing of the starvation period