Feeding is crucial in aquaculture, accounting for 60% of production costs. Reducing overfeeding and increasing efficiency is important for profitability and water quality in intensive aquaculture as general. Investigating feeding frequency preferences could improve growth performance and survival rate of pikeperch. This study aims to determine the optimal feeding frequency for sustainable and efficient aquaculture practices in pikeperch juvenile.
Material and methods
Juvenile pikeperch [n=750 ; total length (TL) = 239.5 ± 16.7 mm and body weight (BW) = 106.6 ± 24.8 g] were divided into five groups (with three replications each) and subjected to different feeding regimes over a 24-hour period: 12 feeds at 2-hour intervals, 6 feeds at 4-hour intervals, 4 feeds at 6-hour intervals, 3 feeds at 8-hour intervals, and 2 feeds at 12-hour intervals. Fish in all groups were fed with an Imetronic ® self-feeding system (Pessac, France) that allowed for easy adjustment of feeding frequencies, actual batched feed, and controlled daily feeding rate (DFR). The DFR was set at 1% of the total biomass of fish per tank. After 28 days, each tank was weighed and the current daily feed intake for each group was recorded. Production parameters [TL, somatic length (SL), Fulton’s condition coefficient (FC), specific growth rate (SGR), feed conversion ratio (FCR), specific heterogeneity rate (SHR), survival rate (SR) , ] and f in condition among tested groups w ere assessed at the beginning and end of the experiment . The pectoral, ventral, dorsal, caudal, and anal fins, and the level of fin damage rate were determined according to Policar et al. (2016). Blood samples were collected from 6 anesthetized fish per group at the beginning and end of the feeding trial for biochemical analysis, including plasma levels of total protein (TP), albumin (ALB), globulin (GLB), amylase (AMYL), lipase (LIPA), total cholesterol (TCHOL), glucose (GLU), ammonia (NH3), and triglyceride (TAG).
Following the 112-day feeding trial, there were no significant differences in fish biometric parameters (TL, SL, BW) among all tested groups. The group with an 8-hour feeding frequency had the highest values of FC (0.95) and SGR (0.95%.day-1), while the group with a 4-hour feeding frequency had the lowest values (FC = 0.84, SGR = 0.82%.day-1). No differences were observed in FCR (0.92–1.19), SHR (322.13–342.13‰.day-1 ), and SR (98.69–100%) among all groups (Fig. 1). There was no cannibalism rate, ensuring high survival rates. Fin erosion was minimal in all groups, with juveniles with a 12-hour feeding frequency showing the most visible erosion effects. In contrast, the dorsal second and caudal fins in juveniles with an 8-hour feeding frequency were less affected (only 12%). No significant differences were found in selected biochemical parameters in all groups based on pikeperch blood plasma analysis after the 112-day feeding trial. Feeding interval 8-hour was evaluated as optimal for intensive juvenile pikeperch rearing, resulting with excellent and acceptable SGR (0.95%.d-1) and FCR (0.95kg.kg-1), high SR (100%) and minimal fin erosion, and well-maintained biochemical parameters in blood plasma.
Higher feeding frequency led to smaller feed consumption, as observed in previous studies on other fish species (Gilannejad et al., 2021). However, some studies showed that juvenile carnivorous species grew better when fed to satiation (Booth et al., 2008; Enes et al., 2015). Fish size, species, and husbandry conditions may influence the optimal feeding frequency, as our study on pikeperch suggested. Nevertheless, all groups rapidly adapted to different feeding frequencies, indicating their flexible feeding behavior.
The study was supported by the Ministry of Agriculture of the Czech Republic (project NAZV QK22020144) and by the Ministry of Education, Youth and Sports of the Czech Republic (project GAJU 028/2022/Z) .
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