Replacement of dietary fish oil with vegetable oils improves the growth and flesh quality of large yellow croaker (Larmichthys crocea)

The present study investigated the effects of total replacement of dietary fish oil by different vegetable oils on growth performance, nutritional quality and fatty acid profiles of rainbow trout (Oncorhynchus mykiss) at optimum and high temperature conditions. Five iso-nitrogenous and iso-lipidic diets including 100% fish oil and vegetable oils were prepared for rainbow trout fingerlings with an average weight of 11.27±0.01 g. After the fish were fed experimental diets for 9 weeks at the optimum temperature (17.74±0.01°C), all groups were fed an FO diet containing only fish oil for 4-weeks at the upper optimum temperature conditions (19.28±0.11°C). In both feeding trials, experimental fish were hand-fed ad libitium twice a day. Results showed that growth performance and feeding efficiency were significantly better (p<0.05) in groups fed by VO-based diets compared to groups fed by FO based diet at optimum temperature. Survival was 100% in CANO, SFO, CO PNO groups and 94.12±3.39% in FO (control) group at the end of the 9 weeks. Growth, feed consumption and survival of fish fed the upper-optimum temperature were significantly differed (p<0.05). In particular, while the survival rate of the groups fed with vegetable oil-based diets at optimum temperature and then fed only fish oil remained 100%, this rate decreased to 54.17±1.39% in the control group. Eicosapentaenoic acid (EPA, 20:5n-3), docosahexaenoic acid (DHA, 22:6n-3) and n-3 PUFA of fish fed by VO based diets were low. When all groups were fed only FO diet for 4 weeks at upper-optimum temperatures, EPA, DHA and n-3 PUFA ratios increased. In addition, after the upper-optimum temperature trial, increases in the nutritional quality indices of fish meat were also detected.

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Hepatic gene expression profiles in juvenile rainbow trout (Oncorhynchus mykiss) fed fishmeal or fish oil-free diets

British Journal Of Nutrition ◽

10.1017/s0007114508981411 ◽

2008 ◽

Vol 100 (5) ◽

pp. 953-967 ◽

Cited By ~ 55

Author(s):

Stéphane Panserat ◽

Cathy Kolditz ◽

Nadège Richard ◽

Elisabeth Plagnes-Juan ◽

Francois Piumi ◽

...

Keyword(s):

Gene Expression ◽

Fatty Acid ◽

Fish Oil ◽

Vegetable Oils ◽

Protein Metabolism ◽

Plant Proteins ◽

Fish Oil Replacement ◽

Fishmeal Replacement ◽

Dietary Fish ◽

By Products

Reducing the reliance on fishery by-products as amino acid and fatty acid sources in feeds for farmed fish is a major objective today. We evaluated the effect of dietary fish oil or dietary fishmeal replacement by vegetable oils and plant proteins respectively through analysis of hepatic transcriptomes in rainbow trout (Oncorhynchus mykiss). Fish were fed right from first feeding with diets based on plant by-products before being killed. We analysed the hepatic gene profile using trout cDNA microarrays (9K). Our data showed that seventy-one and seventy-five genes were affected after fish oil and fishmeal replacement respectively. The major part of modified gene expression coding for proteins of the metabolic pathways was as follows: (i) a lower level of expression for genes of energy metabolism found in fish after fishmeal and fish oil replacement; (ii) a lower level of gene expression for fatty acid metabolism (biosynthesis) in fish fed with vegetable oils; (iii) a differential expression of actors of detoxification metabolism in trout fed with vegetable oils; (iv) a lower level of expression of genes involved in protein metabolism in fish fed with plant proteins. Overall, our data suggest that dietary fish oil replacement is linked to a decreased capacity of fatty acid biosynthesis (fatty acid synthase) and variation of detoxification metabolism (cytochrome P450s) whereas dietary fishmeal replacement may depress protein metabolism in the liver as reflected by glutamine synthetase.

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