Influence of dietary lipid sources on growth,reproductive performance and fatty acid compositions of muscle and egg in three‐spot gourami (Trichopodus trichopterus) (Pallas, 1770)

Five isonitrogenous (420 g kg^?1 crude protein) and isoenergetic (16.3 kJ g^?1) practical diets were formulated to contain fish oil (FO), Kilka fish oil (KFO), linseed (LO), canola (CO) and soybean (SBO) oils fed to juveniles of three‐spot gourami (Trichopodus trichopterus) (initial weight 1 ± 0.03 g) three times per day to apparent satiation for 14 weeks. Results showed the mean final weight of brooders was not significantly affected by dietary oil sources. Specific growth rate for fish fed in SBO and CO diets was statistically higher than for fish fed diet LO. Fish fed diets CO and KFO showed in significantly higher GSI value compared with other diets. Absolute fecundity was greatest in fish fed diets KFO and CO, which significantly differ with other treatments. Except for KFO diet, high fertilization percentages (87.3–93.45%) were observed in other treatments. Fatty acid composition of muscle and egg was found to be positively correlated with their respective dietary lipid sources. High levels of EPA, DHA and n‐3 HUFA in brooders fed diet FO negatively affect egg quality parameters. Therefore, the results demonstrated that vegetable oil‐based diets (CO, SBO and LO, respectively) can positively affect on growth performance of juveniles compared with fish oil‐based diets. Furthermore, CO and LO diets, respectively, showed positive effects on reproductive performance in T. trichopterus compared with fish oil diets during experimental period under controlled conditions.     

Schizochytrium as a replacement for fish oil in a fishmeal free diet for jade perch,Scortum barcoo (McCulloch & Waite)

A 10‐week trial was conducted to determine the response of juvenile jade perch Scortum barcoo on the replacement of dietary fish oil (FO) in a fishmeal free diet. Three iso‐nitrogenous, isocaloric and isolipidic diets were formulated, each containing a different primary fat source: FO, linseed oil (LO), and a mixture of Schizochytrium and LO. The substitution of FO with the mixture of Schizochytrium and LO did not cause a difference in growth. However, there was an 8% reduction in weight gain in fish fed dietary LO, indicating that juvenile jade perch do require a minimal concentration of dietary n‐3 highly unsaturated fatty acids (HUFA). Fish fed the Schizochytrium diet stored more efficient n‐3 HUFA and in particular DHA in their flesh, and retained a higher fillet recovery compared to fish fed FO. In addition, we demonstrated that jade perch are able to produce both n‐3 HUFA and n‐6 HUFA when dietary PUFA are present. Fish fed the LO diet for 10 weeks contained the lowest amount of n‐3 HUFA in fillets among dietary treatment groups. However, feeding these fish the Schizochytrium diet for an additional 4 weeks increased the n‐3 HUFA content towards the same concentration of n‐3 HUFA found in the flesh of fish fed FO, without affecting the sensory properties of the fillets. In contrary, feeding the Schizochytrium diet for a continuous period of 14 weeks lowered overall sensory property scores.     

The effect of non‐marine HUFA supplementation with fish oil removal on growth and survival of the Pacific white shrimp,Litopenaeus vannamei

The use of non‐marine arachidonic acid (ArA) and docosahexaenoic acid (DHA) as highly unsaturated fatty acid (HUFA) enrichments was evaluated as complete replacements for marine fish oil in practical diets formulated with solvent‐extracted soybean meal (SESM). Litopenaeus vannamei juveniles (0.59 g) were reared over 84 days in an outdoor tank system with no water discharge. Fishmeal was replaced with SESM, while fish oil was replaced with HUFA‐rich algal cells, alternative oil and/or fermentation products. Spray‐dried Schizochytrium algal cells (Schizomeal‐Hi DHA) served as the DHA enrichment source. Oil extracted from Mortierella sp. was used as the ArA enrichment (AquaGrow^® ArA). DHA and ArA sources (Advanced BioNutrition Corp., Columbia, MD, USA) were non‐marine products obtained from a commercial supplier. Five diets were formulated with ArA inclusion levels of 0, 0.65, 1.3, 2.6 and 5.2 g kg^?1. In addition, one diet was formulated to be DHA deficient and another was formulated with menhaden fish oil (control). Different inclusion levels of non‐marine ArA had no effect on survival or growth. Shrimp fed the non‐marine HUFA‐supplemented diets had lower average weight compared to shrimp offered the diet containing fish oil. No differences were detected in average weights of shrimp offered the ArA‐deficient and ArA‐supplemented diets.     

Replacement of fish oil with vegetable oils in diets for jundiá (Rhamdia quelen Quoy and Gaimard 1824): effects on performance and whole body fatty acid composition

The jundiá (Rhamdia quelen) is a siluriform with great potential for aquaculture in South America. Fish oil is a raw material in diets for fish. However, the fisheries that provide fish oil have reached their limit of sustainability. Thus, the use of alternative sources for this ingredient is primordial. The aim of this study was to evaluate the performance and body composition of the jundiá fed with different sources of the vegetable oils. Jundiá (1.0±0.2 g) were fed for 31 days with five isonitrogenous (37%) and isoenergetic (19 kJ g^?1) diets, in which the following oils were added: 50 g kg^?1 corn oil (CO), 50 g kg^?1 fish oil (FO), 50 g kg^?1 linseed oil (LO), 33.4 g kg^?1 fish oil and 16.7 g kg^?1 linseed oil (1/3LO), 16.7 g kg^?1 fish oil and 33.4 g kg^?1 linseed oil (2/3LO). The performance did not show differences between treatments. The final fatty acid profile and n‐3/n‐6 ratio of the fish were highly influenced by the diet. Fish‐fed diets with linseed and/or fish oil showed superior n‐3/n‐6 ratios to the minimal recommended by the World Health Organization; whereas fish fed diets with corn oil showed an inferior value. Albeit in the present study the commercial size of fish was not attained, these results show a clear tendency. The desaturation/elongation capacity was evidenced, in this species, for the first time. Linseed oil can be utilized as a substitute for fish oil in diets of jundiá without affecting their performance and for producing good‐quality fish. However, more studies are necessary to confirm these results for commercial size.     

Effects of different dietary lipid sources in the diet for Pangasius nasutus (Bleeker, 1863) juveniles on growth performance,feed efficiency,body indices and muscle and liver fatty acid compositions

Four isonitrogenous (300 g kg^?1 crude protein), isoenergetic (21 kJ g^?1) experimental diets were formulated to contain fish oil (FO), soybean oil (SBO), crude palm oil (CPO) and linseed oil (LO), respectively, as the lipid sources, added at 120 g kg^?1 of crude lipid each. The diets were fed by hand to triplicate groups of Pangasius nasutus (Bleeker, 1863) juveniles (mean weight 10.66 ± 0.04 g), to apparent satiation twice daily for 12 weeks. Fish survival rate was 100% among all the treatments. Growth performance (DGR) was similar among fish fed the SBO, CPO and LO diets, but was significantly (P < 0.05) higher in the CPO compared to fish fed the control (FO) diet. Fish fed SBO and CPO diets also recorded significantly (P < 0.05) higher intraperitoneal fat compared to fish fed the control, whereas fish fed the LO diet did not significantly differ from the other treatments. Muscle and liver fatty acid profile of fish from all the treatments generally mirrored the composition of the diets fed and the major fatty acids recorded were 18:3n‐3 and 18:2n‐6 in the tissues of fish fed the LO and SBO treatments, respectively. Results of this study suggests that P. nasutus fed diets containing vegetable oils (especially CPO and SBO) produce better growth performance, without compromising fish survival and feed efficiency compared with those fed a diet containing only FO.     

Influences of dietary fatty acid profile on growth, body composition and blood chemistry in juvenile fat cod (Hexagrammos otakii Jordan et Starks)

This study was conducted to investigate the influence of dietary lipid source and n‐3 highly unsaturated fatty acids (n‐3 HUFA) level on growth, body composition and blood chemistry of juvenile fat cod. Triplicate groups of fish (13.2 ± 0.54 g) were fed the diets containing different n‐3 HUFA levels (0–30 g kg^?1) adjusted by either lauric acid or different proportions of corn oil, linseed oil and squid liver oil at 100 g kg^?1 of total lipid level. Survival was not affected by dietary fatty acids composition. Weight gain, feed efficiency and protein efficiency ratio (PER) of fish fed the diets containing squid liver oil were significantly (P < 0.05) higher than those fed the diets containing lauric acid, corn oil or linseed oil as the sole lipid source. Weight gain, feed efficiency and PER of fish increased with increasing dietary n‐3 HUFA level up to 12–16 g kg^?1, but the values decreased in fish fed the diet containing 30 g kg^?1 n‐3 HUFA. The result of second‐order polynomial regression showed that the maximum weight gain and feed efficiency could be attained at 17 g kg^?1 n‐3 HUFA. Plasma protein, glucose and cholesterol contents were not affected by dietary fatty acids composition. However, plasma triglyceride content in fish fed the diet containing lauric acid as the sole lipid source was significantly (P < 0.05) lower than that of fish fed the other diets. Lipid content of fish fed the diets containing each of lauric acid or corn oil was lower than that of fish fed the diets containing linseed oil or squid liver oil only. Fatty acid composition of polar and neutral lipid fractions in the whole body of fat cod fed the diets containing various levels of n‐3 HUFA were reflected by dietary fatty acids compositions. The contents of n‐3 HUFA in polar and neutral lipids of fish increased with an increase in dietary n‐3 HUFA level. These results indicate that dietary n‐3 HUFA are essential and the diet containing 12–17 g kg^?1 n‐3 HUFA is optimal for growth and efficient feed utilization of juvenile fat cod, however, excessive n‐3 HUFA supplement may impair the growth of fish.     

Effects of total replacement of fish oil by pork lard or rapeseed oil and recovery by a fish oil finishing diet on growth,health and fish quality of gibel carp (Carassius auratus gibelio)

An 84‐day growth trial was designed to investigate effects of dietary replacements fish oil with pork lard (PL) or rapeseed oil (RO) on growth and quality of gibel carp (Carassius auratus gibelio var. CAS III) (initial body weight: 158.2 ± 0.2 g), and responses of the fish refed fish oil (FO) diet. Three isonitrogenous (crude protein: 30%) and isolipid (crude lipid: 10%) diets were formulated containing 7.73% FO, PL or RO. Five experimental treatments including FO group (FO), PL group (PL), RO group (RO), group fed PL for 42 days and refed FO for 42 days (PL+rFO), RO and refed FO group (RO+rFO) was tested. At the end of first 42 days, the fish fed PL and RO had higher mortality than that of the control (P > 0.05). At the end of whole experiment, fish fed PL and RO showed higher plasma cortisol than FO fish (P < 0.05). RO+rFO fish showed higher lysozyme activity than RO fish (P < 0.05). Fish growth and feed utilization, composition of whole body and muscle, free amino acids, texture, off‐flavour substances or sensory attributes were not affected by dietary treatments (P > 0.05). PL and RO diet decreased muscle EPA, DHA and n‐3/n‐6 ratio (P < 0.05), while FO‐refeeding had recovery effect. It can be concluded that the replacement of FO by PL and RO does not affect the growth, feed utilization or fish tasting quality in gibel carp. Fish muscle fatty acids modified by dietary PL and RO can be recovered by refeeding with FO diet.     

The effect of total replacement of fish oil with DHA‐Gold® and plant oils on growth and fillet quality of rainbow trout (Oncorhynchus mykiss) fed a plant‐based diet

This study investigated the effect of the replacement of fish oil (FO) with DHA‐Gold (DHA‐G)‐supplemented plant oils (PO) in rainbow trout fed plant‐protein‐based diets. Five diets (450 mg g^?1 digestible protein and 150 mg g^?1 crude lipid) were fed to rainbow trout (initial weight 37 ± 0.5 g) for 12 weeks in a 15 °C recirculating water system. The lipid inclusion types and levels were FO, PO and PO with DHA‐G supplemented at 30 mg g^?1, 60 mg g^?1 or 90 mg g^?1 of the diet replacement for corn oil. Fish fed 90 mg g^?1 DHA‐G were significantly larger and consumed more feed than fish‐fed PO or FO (218 g and 2.6% bwd^?1 versus 181 g and 2.4% and 190 g and 2.3%, respectively). Feed conversion ratio was significantly increased in fish fed 90 mg g^?1 DHA‐G (0.99) as compared to fish‐fed FO (0.90) and 30 mg g^?1 DHA‐G (0.91). Panellists found trout fillets from fish fed the 90 mg g^?1 DHA‐G diet to have significantly fishier aroma and flavour than fish fed the FO diet. Fatty acid analysis demonstrated that 60 mg g^?1 or 90 mg g^?1 DHA‐G supplementation increased PO fed fish fillet DHA to fatty acid levels equivalent or higher than those fish fed a FO diet.     

Effects of different dietary lipid sources in the diet for Pangasius hypophthalmus (Sauvage, 1878) juvenile on growth performance,nutrient utilization,body indices and muscle and liver fatty acid composition

Four isonitrogenous (300 g kg^?1 crude protein), isoenergetic (21 kJ g^?1) experimental diets were formulated to contain fish oil (FO), soybean oil (SBO), crude palm oil (CPO) and linseed oil (LO), respectively, as lipid sources each at inclusion level of 120 g kg^?1 and fed to triplicate groups of 15 juvenile iridescent shark, Pangasius hypophthalmus (Sauvage, 1878) (mean weight 10.00 ± 0.70 g) to apparent satiation twice daily for 12 weeks. The results showed that survival of fish was consistently over 95% for all treatments whereas growth performance in the SBO and CPO treatments was similar and significantly (P < 0.05) higher than for fish fed the LO diet. However, fish fed all vegetable oil‐based diets performed better than those fed the FO diet. Muscle and liver fatty acid composition for all treatments generally reflected the composition in the diet and the ratio of n‐3/n‐6 was found to play an important role in P. hypophthalmus, suggesting that excessive amounts of n‐3 fatty acids reduce the overall growth performance. Results of this study thus suggests that P. hypophthalmus fed diets containing vegetable oils (especially CPO and SBO) produce better growth than those fed FO diet without showing any signs of nutrient deficiency.