Progress
November 2014
Objectives of the study: To increase the knowledge of nutrients essential for first feeding pikeperch. The study investigates the effects of increasing inclusion of phospholipids and the additional effect of single HUFAs (EPA and DHA) on pike perch larval performance (growth, stress sensitivity) and larval development (i.e. organ development, tissue/liver morphology, digestive tract. Further effects on digestive enzymatic activity, liver proteomics, candidate gene expression and skeleton morphogenesis will be examined.
6 different diets with increasing content of PL and DHA are tested. Larvae are fed Artemia from dph 3-17 and from dph 12 gradually weaned to the 6 dry feed codes and consequently distributed into 18 tanks (triplicate setup). The experiment is terminated 35 dph and larvae sampled for analyses.
Objectives of the study: To increase the knowledge of nutrients essential for first feeding pikeperch. The study investigates the effects of increasing inclusion of phospholipids and the additional effect of single HUFAs (EPA and DHA) on pike perch larval performance (growth, stress sensitivity) and larval development (i.e. organ development, tissue/liver morphology, digestive tract. Further effects on digestive enzymatic activity, liver proteomics, candidate gene expression and skeleton morphogenesis will be examined.
6 different diets with increasing content of PL and DHA are tested. Larvae are fed Artemia from dph 3-17 and from dph 12 gradually weaned to the 6 dry feed codes and consequently distributed into 18 tanks (triplicate setup). The experiment is terminated 35 dph and larvae sampled for analyses.
Figure 1: 18 tanks of 50 L with feed dispensers of Artemia. 21 ˚C
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Figure 2: 18 tanks of 50 L with feed dispensers of Artemia. 21 ˚C
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Figure 3: Larvae counting for distribution into 18 tanks at dph 12
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Figure 4: Larvae counting for distribution into 18 tanks at dph 12
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Participating organizations (WP leader in bold): P2. FCPCT, P15.ULL, P16. FUNDP, P21. DTU and P29. ASIALOR
Task 10.1 Effect of selected dietary nutrients on pikeperch larval development and performance.
Initially a multifactorial approach will be used to investigate the impact of nutritional quality on growth rate, stress as well as on deformity occurrence and immunology aspects of developing pikeperch larvae, in order to increase juvenile yield.
A possible explanation is likely to be related to the dietary ratios of Ca/P. At present formulated feeds developed for marine fish larvae are used for weaning pike perch, with Ca/P ratios much higher than those observed in common freshwater fish diets. The multifactorial approach will be conducted in DTU facilities, based on a frSub-taskal and factorial experimental design and fish will be fed diets differing by their levels of CA/P, vitamin A, D and C, and level of phospholipids with two modalities per conditions (high and low levels). Developing pikeperch larvae / fry will be used for the experiments and fed either enriched live feed or formulated dry feeds. A confirmatory study will be performed to establish adequate levels of those selected nutrients in order to develop specific enrichment products and formulated diets, to increase pike perch survival during weaning and increase early juvenile welfare. On year 4, the developed products and protocols will be tested under commercial farm conditions.
The influence of the selected nutrients will involve stress tests, organ development, morphology of digestive tract, liver, digestive enzymatic activity in stomach, pancreas and intestines, proteomics and in situ hybridization techniques, analyses of candidate genes expression, as well as lipid and fatty acid analyses. Specifically, skeleton morphogenesis will be studied by a radiographic method and specific staining of bone and cartilage in combination with complementary approaches such as real time quantitative PCR in order to quantify expression of some relevant genes involved in the skeletal system.
Task 10.2 Effects of pikeperch early fatty acid nutrition on long-term stress sensitivity.
In this task, the long term influence of early enrichment (i.e., fish marine phospholipids, DHA concentrations and n-6/n-3 ratios) will be examined on both larvae (where possible) and juvenile fish on pikeperch physiology and welfare indicators The various dietary nutritional treatments (i.e., high and low dietary levels of DHA and phospholipids as well as different ratios of n-6/n-3 by inclusion of vegetable oils) will be linked to tolerance of sub-lethal physiological stresses of larvae / post larvae) and compromised behaviors Using an approach where oxygen consumption is measured in larvae/post larvae following a stressful event, also known as post stress oxygen consumption, this provides valuable insight on the metabolic cost of recovering from different stressors, and the duration recovery based on dietary treatment. Neural development is investigated using visual and mechano-sensory acuity during avoidance responses as proxies, and verified from ultra structural examination by light and electron microscopy. Studies of pathways of fish tissue lipid / fatty acid catabolism / resynthesis, fatty acid composition and influence on eicosanoid activity in relation to early feeding and dietary lipid composition will be performed. To further investigate on lipid metabolism on stress related tolerance, salinity will be used as an environmental cue. The tissue capability to synthesize LC-PUFAs in larval/juveniles will be studied. Skeleton morphogenesis and mineralization will also be studied. Larvae/juvenile will be incubated with 14C fatty acid LC-PUFA precursors after rearing under different salinities.
The findings may display novel and valuable information concerning fundamental aspects of lipid metabolism of pikeperch.
Task 10.1 Effect of selected dietary nutrients on pikeperch larval development and performance.
Initially a multifactorial approach will be used to investigate the impact of nutritional quality on growth rate, stress as well as on deformity occurrence and immunology aspects of developing pikeperch larvae, in order to increase juvenile yield.
A possible explanation is likely to be related to the dietary ratios of Ca/P. At present formulated feeds developed for marine fish larvae are used for weaning pike perch, with Ca/P ratios much higher than those observed in common freshwater fish diets. The multifactorial approach will be conducted in DTU facilities, based on a frSub-taskal and factorial experimental design and fish will be fed diets differing by their levels of CA/P, vitamin A, D and C, and level of phospholipids with two modalities per conditions (high and low levels). Developing pikeperch larvae / fry will be used for the experiments and fed either enriched live feed or formulated dry feeds. A confirmatory study will be performed to establish adequate levels of those selected nutrients in order to develop specific enrichment products and formulated diets, to increase pike perch survival during weaning and increase early juvenile welfare. On year 4, the developed products and protocols will be tested under commercial farm conditions.
The influence of the selected nutrients will involve stress tests, organ development, morphology of digestive tract, liver, digestive enzymatic activity in stomach, pancreas and intestines, proteomics and in situ hybridization techniques, analyses of candidate genes expression, as well as lipid and fatty acid analyses. Specifically, skeleton morphogenesis will be studied by a radiographic method and specific staining of bone and cartilage in combination with complementary approaches such as real time quantitative PCR in order to quantify expression of some relevant genes involved in the skeletal system.
Task 10.2 Effects of pikeperch early fatty acid nutrition on long-term stress sensitivity.
In this task, the long term influence of early enrichment (i.e., fish marine phospholipids, DHA concentrations and n-6/n-3 ratios) will be examined on both larvae (where possible) and juvenile fish on pikeperch physiology and welfare indicators The various dietary nutritional treatments (i.e., high and low dietary levels of DHA and phospholipids as well as different ratios of n-6/n-3 by inclusion of vegetable oils) will be linked to tolerance of sub-lethal physiological stresses of larvae / post larvae) and compromised behaviors Using an approach where oxygen consumption is measured in larvae/post larvae following a stressful event, also known as post stress oxygen consumption, this provides valuable insight on the metabolic cost of recovering from different stressors, and the duration recovery based on dietary treatment. Neural development is investigated using visual and mechano-sensory acuity during avoidance responses as proxies, and verified from ultra structural examination by light and electron microscopy. Studies of pathways of fish tissue lipid / fatty acid catabolism / resynthesis, fatty acid composition and influence on eicosanoid activity in relation to early feeding and dietary lipid composition will be performed. To further investigate on lipid metabolism on stress related tolerance, salinity will be used as an environmental cue. The tissue capability to synthesize LC-PUFAs in larval/juveniles will be studied. Skeleton morphogenesis and mineralization will also be studied. Larvae/juvenile will be incubated with 14C fatty acid LC-PUFA precursors after rearing under different salinities.
The findings may display novel and valuable information concerning fundamental aspects of lipid metabolism of pikeperch.
