ARTICLE 70 FEED & ADDITIVE MAGAZINE February 2024 making fish uncomfortable, increasing physical activity and reducing growth. Crowding, low oxygen, type of feeder, light, stress and waste accumulation are some of them. RESEARCH INSIGHTS In accordance with a comparative study of automatic feeding and self-feeding done in juvenile Atlantic Salmon fed diets of different energy levels by Michaelis et.al., the fish groups tended to become more homogeneous in size with the passage of time in groups fed using self-feeders than in those feds using automatic feeders. Dietary energy content influenced growth and digestible energy intake of salmon fed by means of automatic feeders, but this was not seen in self-fed salmon. These results indicate that regulation of feed intake is influenced by the feeding strategy, probably because pellets are only available on demand for fish fed with self-feeders, whereas in groups fed by means of automatic feeders, pellets are freely available in excess. As per Rasmussen and Ostenfeld (2000) and Johansen et al. (2001) feed-unrestricted salmonids grew more rapidly because they were building up greater quantities of body fat than the feed-restricted fish. It was observed that in non-schooling fish as feed availability decreases, competition usually increases, thus dominant individuals may monopolize and acquire large proportions of the feed supply (Jobling and Koskela 1996; Saether and Jobling 1999). The relationship between DE intake and energy gain was found to be linear in D. labrax and was independent of feed intake and body weight. The requirement for digestible energy for maintenance was calculated to be 43.6 kJ BW (kg)−0.79 day−1 and for digestible protein as 0.66 g BW (kg)−0.69 day−1. The partial efficiency of utilization for growth was 0.68 and 0.52 for digestible energy and digestible protein, respectively. These values obtained through the study were in turn used in the optimization of practical feeding for D. labrax culture. In Haddock, it was reported that when food energy is restricted, they tend to achieve a balance between somatic growth and reproduction. When female haddock received low rations (< 5 kcal day-1) a lower proportion spawned, and the dry weights of the eggs were lower compared with females on high rations (> 13 kcal day -1). In Blackspot Seabream, the fish condition factor (K), often used for monitoring husbandry and nutritional conditions, were significantly higher in fish fed the highest feeding level. During a study on Portunus trituberculatus, krill oil was supplemented and it significantly promoted the growth and moulting, increased activities of ETC complexes, the membrane potential, NAD+ level, NAD+/NADH ratio and the copy number of mitochondrial DNA, up-regulated the expression levels of genes related to lipolysis, ETC and energy metabolism. Furthermore, dietary krill oil also specifically improved the free radical scavenging, reduced the level of lipid peroxides and the degree of DNA oxidative damage, mitigated the damage to mitochon-
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