Abstract
The effects of 8 nutritional variables (Ca/P, Eicosapentaenoic acid (20:5n-3) + Docosahexaenoic acid (22:6n − 3) (EPA + DHA), Arachidonic acid (20:4n − 6) (ARA), Se, vitamins E, C, D and A) were investigated to identify their respective importance and interactions in pikeperch larval development. In this respect, two modalities (low and high levels) of each variable were tested through a fractional factorial experimental design allowing a reduction from 256 (28) to 16 (28 – 4) experimental units. Survival was significantly higher in larvae fed a high Ca/P diet while larval growth was significantly lower in larvae fed the same diet variant, associated with a higher incidence of kyphosis and pectoral anomalies in these larvae. Lordosis and scoliosis seemed to be mostly affected by dietary long chain polyunsaturated fatty acids (LC-PUFAs). A significant interaction was shown between n-3 LC-PUFA and vitamin C on jaw anomalies, while myocyte-specific enhancer factor 2C (mef2c) gene expression correlated positively with dietary vitamin C increment. Results also demonstrated an effect of the different nutrients and their interactions on the activity levels of digestive enzymatic activities. The results of the present study highlight the importance of the interactions between Ca/P, LC-PUFAs and vitamins C and E, suggesting their essential roles as key nutritional factors influencing pikeperch larval development.
Highlights
Pikeperch (Sander lucioperca) has been identified as a candidate for diversification with a great potential in European aquaculture industry[1,2,3,4,5]
High global scores of interest (>3) were obtained for diets 5, 7, 11. All these www.nature.com/scientificreports experimental treatments contained the lowest dietary Ca/P ratio (0.6); in addition, these treatments (3, 7, 11) with the exception of diet 5 are characterized by the highest n-3 LC-PUFA content (EPA + docosahexaenoic acid (DHA) = 3.5%)
The lowest weight and specific growth rate (SGR) were recorded in larvae fed diet 10 which combined the highest dietary Ca/P ratio and the lowest EPA + DHA, followed by treatments 8, 12, and 6 which were characterized by the highest dietary Ca/P ratio (Table 1)
Summary
Pikeperch (Sander lucioperca) has been identified as a candidate for diversification with a great potential in European aquaculture industry[1,2,3,4,5]. It has been shown that the structure and functional ability of the digestive tract are affected by the larval developmental stage as well as by the diet composition[10] In this respect, literature suggested a combined effect of weaning age/size and diets on skeletal anomalies and larval performance in pikeperch[10,11,12]. Tailored commercial starter feeds do not exist for this species, and feeds used in hatcheries are likely developed for marine species, such as Gemma Micro (Skretting, Norway) and Otohime (Reed Mariculture, California) During this critical life stage, adequate feeds are needed to fulfil the nutritional requirements of fish larvae. As Ca and P exist in a constant ratio in fish bone[53], this suggests needs to be maintained in fish feeds[54]
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