Aquafeed Ingredients Research Articles

Effects of the microalga Scenedesmus almeriensis as fishmeal alternative in diets for gilthead sea bream, Sparus aurata, juveniles

The rising costs of fishmeal worldwide promote great research effort aimed to find alternative and renewable ingredients for aquafeeds. In the last years considerable attention has been paid to the use of algae as a potential ingredient for fish feeds. The objective of this work was to evaluate the effects of the microalgae Scenedesmus almeriensis incorporated to diets intended to feed sea bream (Sparus aurata) juveniles in a 45-day trial. Growth, body composition, and intestinal functionality of fish were studied. Microalgae meal was tested in triplicate at different inclusion levels (0%, 12%, 20%, 25% and 39%). At the end of the trial, individual body weight was recorded for evaluation of growth and nutrient utilization, and biological samples were obtained for proximate analysis, determination of digestive enzyme activities, intestinal histology, and microvilli morphological evaluation. Results indicated that S. almeriensis did not cause negative effects on fish growth or nutrient utilization efficiency. Growth rate and protein utilization in fish fed on a diet with 20% Scenedesmus meal tended to be higher, although not significantly different from those fed on control diet. None of the treatments caused adverse effects on body composition. Fish fed 12% S. almeriensis showed higher trypsin than animals fed on control diet. Leucine-aminopeptidase and alkaline phosphatase activities showed a quadratic response with increasing levels of Scenedesmus biomass. Ultrastructural study revealed that the dietary inclusion of algal biomass, especially at 20% level, significantly increased the absorptive capacity of intestinal mucosa in both the anterior and posterior intestinal regions. This study confirmed the usefulness of S. almeriensis to partially replace fishmeal in practical diets for gilthead sea bream juveniles.

Beef tallow as an alternative to fish oil in diets for gilthead sea bream (Sparus aurata) juveniles: Effects on fish performance, tissue fatty acid composition, health and flesh nutritional value

Gilthead sea bream juveniles of 135 g average body weight were fed for 120 days a fish oil‐based commercial diet (CTRL) or one of two experimental isonitrogenous and isolipidic low fat (LF) fish meal‐based diets differing only by the lipid source, in order to evaluate the efficacy of beef tallow (BT) as an ingredient in aquafeeds. Both experimental feeds were formulated with 60 g/kg of BT; the LFBTFO diet also contained 35 g/kg of fish oil (FO) whereas a blend of BT and vegetable oils (VO) completely replaced FO in the LFBTVO diet. No differences in growth and feed efficiency were found between fish fed the LFBTFO diet and the CTRL group whereas fish fed the diet devoid of FO (LFBTVO) presented the poorest growth indicators and the lowest feed and protein efficiencies. The use of LF feeds contributed to maintain the hepatosomatic index and the proportion of triacylglycerols (TAG) in muscle and brain in spite of the dietary replacement of FO. Flesh from fish fed the LFBTFO diet supplied the same absolute amount of EPA + DHA than that of fish fed the CTRL diet, whereas a reduction of approximately 45% was registered when fish were deprived of FO.Practical applications: High proportions of BT can effectively be used as a valuable alternative to partially substitute FO in diets for gilthead sea bream juveniles without significantly affecting fish performance and health while promoting a limited impact on its health benefits for human consumption. The decline in the inclusion of marine ingredients in aquafeeds could actively contribute to the sustainability and profitability of the marine aquaculture industry.

Salmon testes meal as a functional feed additive in fish meal and plant protein-based diets for rainbow trout (Oncorhynchus mykissWalbaum) and Nile tilapia (Oreochromis niloticusL.) fry

Fishery processing by-products are a large resource from which to produce fishmeal and other products for a variety of uses. In this study, testes meal (TM) produced from pink salmon processing by-product was evaluated as a functional ingredient in aquafeeds. Nile tilapia and rainbow trout fry were fed five isonitrogenous and isoenergetic experimental diets for 4 and 9 weeks respectively. Two diets were fishmeal-based (FM) and three were plant protein-based (PP). Salmon TM was added to the FM and PP diets at 7% to replace 20% of fishmeal protein (FMTM and PPTM respectively). An additional control diet was prepared in which fishmeal was added to the PP diet to supply an equivalent amount of protein as supplied by TM (PPFM). Inclusion of TM in both the FM- and PP-based diets resulted in higher final body weights, although differences were only significant between rainbow trout fed FM or FMTM diets. Similar differences were calculated for other indices of fish performance, e.g. specific growth rate, feed conversion ratio, protein efficiency ratio and protein retention efficiency. Feed intake was significantly higher for fish fed FMTM compared with FM in rainbow trout. For tilapia, final weights were numerically higher, but not significantly different for fish fed diets containing TM compared with non-TM diets (FM vs. FMTM; PP vs. PPTM). Performance of trout or tilapia fed the PPFM diet did not increase compared with the PP diet. The results indicate that TM addition to both FM and PP diets increased feed intake and also increased metabolic efficiency, demonstrating that TM can be a functional ingredient in aquafeeds.

Aquafeed imprint on bogue (Boops boops) populations and the value of fatty acids as indicators of aquaculture-ecosystem interaction: Are we using them properly?

Escapes of farmed fish into the ecosystem have recently received a marked interest from scientists for their competition with wild populations or the risk of genetic contamination. Fatty acid profiles have been proposed as bio-indicators due to the inclusion of terrestrial oils in aquafeed ingredients. This study evaluated 1) the effect of wasted food on the fatty acid content of a farm-associated fish and 2) the suitability of fatty acid profiles as a bioindicator of aquaculture-ecosystem interactions, using the bogue (Boops boops) as a model. This species is an opportunistic fish usually associated with–or even found in–sea farms, and with a high natural occurrence along the Mediterranean and Atlantic coasts. The results showed that fish farms had a direct effect on the condition index, muscle and whole lipid content of bogue inside or around the sea cage, and this effect disappeared completely at 3km from the cages. Despite the fact that aquafeeds also affected the bogue fatty acid profiles by increasing linoleic and oleic acids and reducing DHA, these profiles were very similar to those of bogue sampled close to a sewage outfall, denoting that these fatty acids are not exclusively influenced by aquaculture and therefore should not be considered as good biomarkers for escapees. However, bogues influenced by aquaculture were higher in linolenic acid than those found further than 3km from the farm or close to the sewage, suggesting this fatty acid as a better indicator of aquaculture influence.

In vitro digestion of protein sources by crude enzyme extracts of the spiny lobster Panulirus argus (Latreille, 1804) hepatopancreas with different trypsin isoenzyme patterns

The development of cost-effective and nutritionally adequate formulated diets is a key step in the sustainable expansion of spiny lobster aquaculture. Despite proteins are the major and most expensive component of diets, few studies are available on protein digestibility in spiny lobsters and such assessments have never been performed by in vitro methods. Two techniques were used for studying in vitro protein digestion of some common aquafeed ingredients by the spiny lobster Panulirus argus: i) the digestion cell in which the digestion products are removed by dialysis, and ii) electrophoresis which allows the visualization of the different protein fractions in the tested meals. Since three main trypsin isozyme patterns or phenotypes have been recently described in P. argus, the potential differences in protein digestion between individuals with different trypsin isozyme patterns were assessed. Results herein presented demonstrate for the first time in a crustacean species that the different trypsin phenotypes differ in protein digestion efficiency. Also, the digestion cell method was applied for the first time to a crustacea, proving to be sensitive to small changes in digestion efficiency. This method could be used in further in vitro studies for examining other aspects of spiny lobsters digestive process.

Utilization of plant proteins in fish diets: effects of global demand and supplies of fishmeal

Aquafeed ingredients are global commodities used in livestock, poultry and companion animal feeds. Cost and availability are ditated less by demand from the aquafeed sector than by demand from other animal feed sectors and global production of grains and oilseeds. The exceptions are fishmeal and fish oil; use patterns have shifted over the past two decades resulting in nearly exclusive use of these products in aquafeeds. Supplies of fishmeal and oil are finite, making it necessary for the aquafeed sector to seek alternative ingredients from plant sources whose global production is sufficient to supply the needs of aquafeeds for the foreseeable future. Significant progress has been made over the past decade in reducing levels of fishmeal in commercial feeds for farmed fish. Despite these advances, the quantity of fishmeal used by the aquafeed sector has increased as aquaculture production has expanded. Thus, further reduction in percentages of fishmeal in aquafeeds will be necessary. For some species of farmed fish, continued reduction in fishmeal and fish oil levels is likely; complete replacement of fishmeal has been achieved in research studies. However, complete replacement of fishmeal in feeds for marine species is more difficult and will require further research efforts to attain.

Effects of dietary squid viscera meal on growth and cadmium accumulation in tissues of large yellow croaker, Pseudosciaena crocea R.

Cadmium (Cd) is a toxic environmental pollutant with a long biological half-life and can produce both hepatic and renal injuries in mammals and fish. Squid viscera meal (SVM), an effective attractant for aquatic animals, is widely used as an ingredient in aquafeeds. However, SVM is rich in Cd and its complexes. A study was conducted to evaluate the effects of dietary SVM on the growth and Cd deposition in the tissues of large yellow croaker, Pseudosciaena crocea R. Three practical diets were formulated to contain a 0, 50 and 100 g · kg−1 SVM diet, correspondingly containing a 0.21, 7.26 and 12.08 mg Cd · kg−1 diet. Each diet was randomly assigned to triplicate groups of 100 juveniles of large yellow croaker (mean initial weight, 9.75 ± 0.35 g) in floating sea cages (1.0 m × 1.0 m × 1.5 m). Fish were fed twice daily (05:00 and 17:00) to satiation for 8 weeks. The results showed that there were no significant differences in fish survival among the three dietary treatments, but significant higher specific growth rates (SGR) were observed in the fish fed diets with 50 or 100 g · kg−1 SVM diet compared to the control group (P < 0.05). The cadmium concentrations in fish tissues (muscle, liver, kidney and gill) were significantly influenced by the dietary SVM. The cadmium concentrations in all tissues significantly increased with increasing dietary Cd levels (P < 0.05). In all the dietary treatments, the highest Cd level was always observed in the kidney, followed by the liver and the gill. Fish fed diets with 50 and 100 g · kg−1 SVM had significantly higher Cd accumulations in the kidney (2.65, 4.44 mg · kg−1), liver (0.58, 0.93 mg · kg−1) and gill (0.35, 0.53 mg · kg−1) compared with the control group (0.42, 0.26 and 0.12 mg · kg−1, respectively). The Cd level in fish muscle, however, was undetectable in all treatments. Therefore, based on these results, accumulation of Cd in edible tissue (muscle) of farmed large yellow croaker is not a food safety issue. However, long-term feeding of diets with SVM may result in accumulation of Cd in the kidney, liver and gills of fish.

Effect of extrusion cooking on anti-nutritional factor tannin in linseed (Linum usitatissimum) meal

Primary objective Various oilseeds and their by-products usually constitute a major source of dietary protein as aquafeeds for warmwater herbivorous/omnivorous fish species. The oilseed meals available in India are fairly rich in protein and most of them are traditionally used as valuable feed for farm animals. However, among the factors that limit incorporation of these ingredients in aquafeeds are amino-acid imbalance and presence of anti-nutritional factors. Enhancement of the nutritive value of these ingredients and reduction (or removal) of anti-nutritional factors can be attempted by processing so as to increase the bio-availability of these nutrients. It has been found that various anti-nutritional factors can be destroyed by the process of extrusion cooking. Extrusion is a process whereby raw feed material is exposed to controlled conditions of high temperature, pressure and moisture. In the present experiment, extrusion cooking is used to reduce the anti-nutritional factor tannin in linseed (Linum usitatissimum) meal.Research design A single-screw cooking extruder, designed and manufactured at the Indian Institute of Technology, Kharagpur, was used for the study. Experiments were carried out following a rotatable central composite design to determine the optimum values of the process variables for which maximum reduction of tannin (Y) occurs. The process variables selected for the study were: barrel temperature (X1) (60–100°C), extruder speed (X2) (60–100 rpm) and oilseed moisture content (X3) (30–50%). Following the design, a second-order response model was fitted.Main outcomes and results The optimized values of the process variables were found to be X1=82.5°C, X2=90 rpm and X3=41.22%, and the value of the predicted response (i.e. reduction of tannin Y) was found to be 61.25%.

Effects of dietary squid viscera meal on growth and cadmium accumulation in tissues of Japanese seabass, Lateolabrax japonicus (Cuvier 1828)

Cadmium (Cd) is a toxic environmental pollutant with a long biological half-life and can produce both hepatic and renal injuries in mammals and fish. Squid viscera meal (SVM), an effective attractant for aquatic animals, is widely used as an ingredient in aquafeeds. However, SVM is rich in Cd and its complexes. A study was conducted to evaluate the effects of dietary SVM on the growth and Cd deposition in tissues of Japanese seabass, Lateolabrax japonicus. Three practical diets were formulated to contain 0, 50 and 100 g SVM kg−1 diet, respectively, containing 0.21, 7.26 and 12.08 mg Cd kg−1 diet. Each diet was randomly assigned to triplicate groups of 80 Japanese seabass (mean initial weight, 10.89±0.21 g) in floating sea cages (1.5 × 1.5 × 2.0 m). Fish were fed twice daily (06:30 and 16:30 hours) to satiation for 8 weeks. The results showed that there were no significant differences in fish survival among three dietary treatments, but significant higher specific growth rates (SGR) were observed in the fish fed diets with 50 or 100 g SVM kg−1 diet than that from the control group (P<0.05). The Cd concentrations in the kidney, liver and gill were found in a decreasing order at each treatment, and positively correlated with dietary Cd levels. Fish fed diets with 50 and 100 g SVM kg−1 diet had significantly higher Cd accumulations in the kidney (3.25, 5.85 mg kg−1), liver (0.76, 1.26 mg kg−1) and gill (0.42, 0.58 mg kg−1) compared with the control group (0.82, 0.34 and 0.32 mg kg−1 respectively) (P<0.05). The Cd concentration in fish muscle; however, was undetectable in any treatment. Therefore, based on these results, accumulation of Cd in edible tissue (muscle) of farmed Japanese seabass is not a food safety issue. However, long-term feeding of diets with SVM may result in accumulation of Cd in the kidneys, liver and gills of fish.

Present Scenario and Future Prospects of Phytase in Aquafeed - Review -

Aquaculture pollution is a major concern among the entrepreneurs, farmers and researchers. Excess discharge of phosphorus and nitrogen into the water bodies is the principal pollutant responsible for this. Plant-based feed ingredients due to its high phytic acid content enhances both nitrogen and phosphorus discharge thereby increasing the pollution level. Dietary phytase treatment is probably the best answer to address this problem. This review explains the nature and properties of phytate, its interactions with other nutrients and the application of phytase in aquafeed to reduce the pollution. This review also covers the different biotechnological aspects for lowering the phytic acid level in the common aquafeed ingredients, as an alternate approach to controlling the pollution level. Some of future research needs have also been highlighted to attract the attention of more researchers to this area.

Co-drying fish silage for use in aquafeeds

Drying experiments were conducted in a poly-tunnel on three co-mixtures of fish silage and wheat bran. Initial moisture contents of the mixtures ranged from 516 to 638 g/kg and an experiment was designed to measure drying times of aquafeed ingredients in a dry, tropical environment. Moisture levels of the co-dried mixtures were reduced to less than 100 g/kg within a drying period of 2 or 3 days. Temperature, solar radiation and relative humidity values during the experiment ranged from 30 to 48 °C, 110 to 650 W/m 2 and 40 to 92%, respectively. These results show that solar drying of fish silage products can be conducted effectively in standard poly-tunnels. This potential method for large-scale drying could greatly enhance the use of fish silage as an aquafeed ingredient, if applied in tropical regions.

Nutritional value of fisheries by-catch and by-product meals in the diet of red drum ( Sciaenops ocellatus)

Discarding of by-catch and generation of by-products from capture fisheries has long been recognized as wasteful, but greater effort is needed to make use of these resources in aquaculture as its growth throughout the world requires increased production of feeds to support the cultured organisms. Protein resources, primarily fish meal, will probably be a constraint to further development of the aquaculture industry. Fisheries by-catch or by-product meals theoretically have good potential to reduce dependence on fish meal, although research in this subject is limited. A digestibility study with sub-adult red drum and a feeding trial were conducted with juveniles to evaluate the use of various by-product ingredients in aquafeeds. A shrimp by-catch meal (SBM) from shrimp trawling in the Gulf of Mexico, a shrimp processing waste meal (SWM) from aquacultured Litopenaeus vannamei, two underutilized fish meals [Pacific whiting meal without soluble (PW) and Pacific whiting meal with soluble (PWS)], and a fish-processing waste [red salmon head meal (RSHM)] from Alaska were included in the diets. The digestibility study employed chromic oxide as a marker and stripping for fecal collection. No differences ( P>0.05) in organic matter, crude protein, energy and total phosphorus digestibility were observed among fish fed Special Select™ menhaden fish meal, SBM, PW or PWS, while digestibility of these nutrients and energy from RSHM was significantly lower. During the 6-week feeding trial, no significant differences were observed among fish fed diets in which 25% of the protein from menhaden fish meal was replaced with RSHM or 50% was replaced by SBM in 40% crude protein diets. Fish fed diets in which 50% or 100% of protein from menhaden fish meal was replaced with PWS, PW and SWM showed significantly ( P<0.05) reduced growth and feed efficiency, although there was no significant difference in survival of fish fed the different diets. More research is needed to optimize the use of these ingredients and to eliminate limiting factors by improving processing techniques, amino acid availability and palatability.

Effects of dietary lipid sources on flavour volatile compounds of brown trout (Salmo trutta L.) fillet

Summary The high cost and unpredictable availability of fish meal and fish oil (FO) forced feed mill companies to look for alternative ingredients for aquafeeds. In this study, the effects of alternative dietary lipid sources [FO as control, canola oil (CO), oleine oil (OO), poultry fat (PF) and pork lard (PL)] in trout feed on flavour volatile compounds occurring in brown trout (Salmo trutta L.) fillet were evaluated after 70 days of feeding (rearing temperature 14.6� C). Total amounts of volatile compounds identified were higher for fillets of fish fed diets containing only FO as lipid sources. Total amount of alcohols and aldehydes of the fillets were linearly directly related to the percentage content of polyunsaturated fatty acids (PUFA) n-3 of brown trout flesh. The use of alternative dietary lipid sources, modifying the fillet fatty acids composition, affect the total amount of volatile compounds and, changing the relative amount of each volatile compound, affect the flavour of the fish flesh.

Assessment of the effect of plant inhibitors on digestive proteases of nile tilapia using in vitro assays

This study was conducted to evaluate the effect that feeding on differently treated soybean meals may have on digestive protease activity of the Nile tilapia (Oreochromis niloticus). Untreated full fat soybean (USB), heated fullfat soybean (HSB), soaked fullfat soybean (SSB) and commercial defatted soybean meal (DSB) totally replaced fish meal (FM) in test diets (30% crude protein) fed to fish juveniles (mixed sexes) for 30 days. After this period, total activity of digestive proteases was determined in each group and the ability of such proteases to hydrolyse the different protein sources and formulated feeds was tested in vitro. Significant differences were observed between treatments, with lower values obtained for fish fed on USB, suggesting a modification in the composition of secreted proteases. In addition, an inhibitory effect produced by wheat bran included in the test diets on protease activity of fish was also shown. The usefulness of using in vitro assays for a preliminary assessment of the nutritive value of aquafeed ingredients is discussed.