In a 6-week feeding trial with juvenile red drum, Sciaenops ocellatus (mean initial weight of 2.3±0.1g), a control diet was formulated to contain 40% crude protein, with equal contributions from ...fishmeal (FM) and soy protein concentrate (SPC) as the protein sources, and 10% crude fat, using fish oil (FO) as the main lipid source. Then, in five experimental diets, 10, 20, 30, 40 and 50% of FM, SPC, and FO in the control diet was replaced by combinations of meals from the freshwater autotroph Arthrospira sp. and the heterotroph thraustochytrid Schizochytrium limacinum. In a sixth diet, FO was completely replaced by S. limacinum meal. Growth, feed utilization, and the majority of the body condition indices evaluated in fish fed the microalgae meals were not significantly (P>0.05) different from that of fish receiving the control diet. While slight changes were observed in the proximate composition of whole fish after receiving the test diets, increased proportions of 22:6n−3 and 16:0, alongside decreases of 18:1n−9, 18:1n−5, and 18:2n−6 were observed in whole body, muscle tissue and liver of fish, which mirrored the diet composition. Overall, results of the present study indicate that up to 50% of dietary FM, SPC, and FO can be replaced by Arthrospira sp. and S. limacinum meals without compromising fish performance. In addition, S. limacinum meal can be used as the chief source of lipid for this species. In terms of absolute inclusion levels of the microalgae meals, the diet with the highest level of FM-FO replacement (50%) contained 28.87% Arthrospira sp. and 6.72% S. limacinum meals (35.59% altogether). While this is already a considerable level of incorporation of algal meals in diets for a carnivorous fish, there seems to be scope for further FM-FO replacement in the diet of red drum.
•Up to 50% of fishmeal and fish oil of a control diet can be replaced by algal meals in the diet of Sciaenops ocellatus.•Schizochytrium limacinum meal can be used as the chief source of dietary lipid for this species.•These results advance the use of sustainable alternative protein and lipid feedstuffs for marine carnivorous fish diets.•Also, they help minimize environmental impacts of the use of fishmeal and fish oil, the global supply of which is dwindling, although demand and price are increasing.•There seems to be scope for further fishmeal and fish oil replacement in the diet of S. ocellatus.
Fishes belonging to the family Pomacentridae (clownfishes and damselfishes) dominate the marine ornamental fish trade. However, only 1.0–4.2% of marine ornamental species traded in the US are ...reproduced in captivity, while the vast majority are wild-caught, an environmentally damaging practice. Reproduction in captivity undoubtedly is an adequate strategy for moving in the direction of sustainability. Among ornamental marine fish species, the most spectacular advances in captive breeding have been made for clownfishes. Twenty-five species of clownfishes have been captive-bred for commercial purposes. Furthermore, numerous clownfish varieties or color morphs have been developed through selective breeding and hybridization between species has been achieved. Of at least thirty-nine damselfish species that have been reproduced in captivity, only nine are currently commercially available. This is related to the small size of eggs and to the underdeveloped state of altricial damselfish larvae. In addition, long larval periods (up to 50 dph) and low survival rates (typically less than 10%) create barriers to the success in commercial aquaculture of damselfishes. Improvements in the low survival of damselfish larvae can be expected as zootechnical aspects for larviculture are perfected (especially improved nutrition).
The present study evaluated the replacement of fishmeal (FM) by blends of alternative protein sources in diets for juvenile (8.0 ± 0.5 g) Totoaba macdonaldi. Using a FM-based control diet containing ...53% crude protein and 13% crude fat, a 3 × 3 factorial experiment was conducted replacing FM, at levels of 33, 66 and 100% by weight, with three blends of the test ingredients, as follows: 1) Arthrospira meal blend: 70% Arthrospira sp. meal, 15% blood meal, 15% soy protein concentrate (SPC); 2) blood meal blend: 70% blood meal, 15% Arthrospira sp. meal, 15% SPC; and 3) SPC blend: 70% SPC, 15% blood meal, 15% Arthrospira sp. meal. At the end of the 6-week feeding trial, significant effects of the alternative protein blends were detected, in which fish fed the Arthrospira meal and SPC blends had significantly (P < .05) better performance than fish fed the blood meal blend across all growth parameters (percent weight gain and thermal growth coefficient) and feed utilization indices (feed efficiency and protein efficiency ratio). Also, fish fed the former two blends deposited more crude protein and fat in whole body and muscle tissues, concurring with the growth response observed. However, the effects of protein blend on body condition indices (hepatosomatic index, condition factor, and muscle ratio) and on the concentrations of trypsin and chymotrypsin in anterior intestine and pyloric caeca, did not depict clear trends. A correspondence between levels of dietary amino acids (AA) in blends and accumulated AA in muscle, was not observed. However, significant effects of the level of FM replacement were also detected, in which the responses in growth, feed utilization, most body condition indices, and proximate composition of fish whole body, deteriorated as the level of FM replaced increased. All things considered, results indicate that the Arthrospira meal and SPC blends, but not the blood meal blend, can be used to replace at least 33% FM in the diet for totoaba, without adversely affecting growth and survival. The possible reasons for the decreased performance of fish fed the blood meal blend, or when fed any of the blends at levels higher than 33%, are discussed.
•Alternatives for fishmeal (FM) were evaluated in diets for Totoaba macdonaldi.•Arthrospira meal, blood meal, and soy protein concentrate (SPC) were tested.•Partial replacement was achieved using Arthrospira meal and SPC.•Up to 33% FM was replaced without adversely affecting fish growth and survival.
The objective of this study was to evaluate the use of soybean oil (SO) and two microalgal meals derived from Schizochytrium limacinum (SL1 and SL2) to replace fish oil (FO) in diets for Totoaba ...macdonaldi juveniles. Nine isoproteic (54% crude protein, CP) and isolipidic (14% crude fat, CF) diets were formulated based on a 3 × 3 factorial design, using the three lipid sources and three replacement levels, 33%, 66% and 100%. A control diet containing FO as the main lipid source served as a reference. Diets were fed for 6 weeks and were randomly assigned to six replicate tanks of a recirculating aquaculture system, with 25 fish stocked per tank. Initial mean fish weight was 8.08 g; at the end of the trial, statistical differences for growth responses such as weight gain (WG; P = 0.0069) and thermal growth coefficient (TGC; P = 0.0027) were detected. WG (SL1 = 50.75 g, SL2 = 51.43 g) and TGC (0.148) of fish fed the S. limacinum meals were significantly higher than in those fed SO (WG = 41.13 g; TGC = 0.129). Conversely, the hepatosomatic index (HSI; P = 0.0009) of fish fed SO was significantly higher (1.38%) compared to those fed the microalgae meals (SL1 = 1.13%, SL2 = 1.22%). Also, proximate composition of liver was significantly influenced by the lipid source and CF was significantly higher (P = 0.0067) in fish fed SO (47.68%) than in fish fed SL1 (37.44%) or SL2 (39.86%). The fatty acid (FA) profile of muscle and liver reflected the dietary FA composition; SO prompted increased concentrations of 18:2n-6 and total n-6 FA in fish fillet; whereas, the S. limacinum meals increased 22:6n-3, total n-3 FA and the n-3/n-6 ratios, which is highly desirable in food destined for human consumption. In addition, the concentration of pancreatic lipase 1 (70.2 kDa) in anterior intestine and pyloric caeca of fish significantly decreased (P = 0.0019) from 2.93 to 1.85 mg g−1 as the level of FO replaced increased. These findings indicate that up to 100% of FO can be replaced by S. limacinum meals improving the growth of T. macdonaldi and preserving the nutritional value and the health benefits of the fillet for human consumption; whereas, SO decreased growth and the concentration of 22:6n-3, 20:5n-3, total n-3, and n-3/n-6 ratios, while increasing the HSI and the risk of hepatic dysfunction and steatosis.
•Complete replacement of dietary fish oil by Schizochytrium limacinum meals was achieved for Totoaba macdonaldi.•Compared to soybean oil, S. limacinum meals successfully improved growth performance of T. macdonaldi.•Accumulation of DHA in fish fed S. limacinum preserved their nutritional value and health benefits for human consumption.
A 7-week study was conducted to evaluate the replacement of fishmeal (FM) by hydrolyzed soy protein (HSP) or black soldier fly larvae meal (BSFM) in diets for Totoaba macdonaldi juveniles ...(2.5 ± 0.1 g). A control diet containing FM as the main protein source was formulated with crude protein and crude fat contents of 52% and 14%, respectively. Then, in a series of isoproteic and isocaloric diets, HSP was incorporated at levels of 15 and 25%, or partially defatted BSFM at levels of 25 and 40%, in place of FM by weight. Fish fed the control diet and the diet containing HSP at 15% FM replacement had similar performance across all growth parameters, feed utilization, and body indices. In contrast, fish fed HSP at 25% FM replacement had significantly inferior final weight (46.59 g) and FCR (1.19). Fish fed BSFM at both levels of inclusion (25 and 40%) resulted in significantly reduced growth (final weight of 48.11 and 42.8 g, respectively) and also worse FCR (1.06 and 1.30, respectively), as compared to fish fed the control diet (final weight and FCR of 59.72 g and 0.94, respectively). Minimal changes in whole body proximate composition of fish and no changes in proximate and amino acid composition of muscle tissue were observed in response to dietary HSP or BSFM. Compared to fish fed the control diet, the fold change in trypsin gene expression increased significantly in fish fed 25% HSP, but not in fish fed 15% HSP. A similar numerical trend was observed for chymotrypsin gene expression, although differences were not statistically significant (P = 0.0768). No significant differences were observed for the gene expression of both enzymes in response to dietary BSFM; regulation of both proteases appears to take place at a transcriptional level. In summary, at least 15% of dietary fishmeal can be replaced by HSP without altering growth, survival, or any feed utilization and body indices of T. macdonaldi juveniles. Conversely, fish fed diets replacing 25% FM by HSP or by 20 and 40% BSFM displayed significantly inferior growth.
•Fishmeal was replaced by hydrolyzed soy protein or black soldier fly larvae meal in diets for Totoaba macdonaldi.•Up to 15% of fishmeal can be replaced by hydrolyzed soy protein without altering fish performance.•Replacing 25% fishmeal by hydrolyzed soy protein resulted in inferior growth.•Growth was also negatively affected when fed 25 and 40% black soldier fly larvae meal.•Expression of trypsin or chymotrypsin genes increased with increased FM replacement, but did not match the growth response.
Juveniles of wild Pacific blue shrimp Litopenaeus stylirostris (mean initial weight ± standard deviation = 1.5 ± 0.1 g) were acclimated from a natural seawater salinity of 35‰ to salinities of 0, ...2.5, 5.0, 7.5, 10, 15, and 25‰. After reaching the desired salinities, L. stylirostris were cultured for 32 d and growth, feed conversion ratio, and survival, as well as hemolymph and culture water osmolality, were determined. The L. stylirostris exposed to 0‰ died before or shortly after reaching the salinity end point. Final mean body weight of L. stylirostris held at 2.5‰ (3.1 ± 0.8 g) was significantly reduced compared with all other treatments. In contrast, those held at salinities from 5‰ to 35‰ had similar performance, with mean body final weight ranging from 3.8 to 4.5 g, showing that L. stylirostris can be cultured across this range of salinities without adversely affecting growth, survival, or feed conversion ratio. Litopenaeus stylirostris is a euryhaline organism, able to maintain its hemolymph osmolality relatively constant despite changes in salinity. The isosmotic salinity of L. stylirostris, estimated from the point of intersection between the regression lines of water salinity versus water osmolality and water salinity versus hemolymph osmolality, was 26.7‰. Litopenaeus stylirostris is an efficient osmoregulator with potential for low‐salinity culture.
A 6-week growth trial was conducted to assess the replacement of fishmeal (FM), soy protein concentrate (SPC) and fish oil (FO) by Arthrospira sp. and Schizochytrium limacinum meals in diets for ...hybrid striped bass (Morone chrysops × M. saxatilis) juveniles of 10.6 ± 0.2 g initial individual weight (±standard deviation). A control diet was formulated with equivalent contributions of FM and SPC to provide 40% crude protein. Menhaden FO was the main lipid source, providing 10% crude fat. Five experimental diets replaced 10, 20, 30, 40 and 50% of FM, SPC, and FO from the control diet by combining two algal meals derived from the freshwater autotroph Arthrospira sp. and the marine heterotroph S. limacinum. Each diet was randomly assigned to three replicate aquaria, and twelve group-weighed fish were stocked per aquarium. Fish were group-weighed weekly to adjust the feeding ration, which started at 6% and gradually decreased to 3%, confirmed by visual feeding cues to avoid overfeeding. At the end of the trial, no statistical differences for responses such as condition factor (P = 0.6778), hepatosomatic index (P = 0.4542), intraperitoneal fat ratio (P = 0.0997), or feed efficiency (P = 0.2210) were detected. However, statistically significant differences were observed for percent weight gain (WG; P = 0.0323) and thermal growth coefficient (TGC; P = 0.0164). Weight gain (209.5%) and TGC (0.088) of fish fed the control diet was significantly lower than in fish fed the 30 and 50% replacement diets (WG: 232.8–235.3%), but no differences were detected among fish fed any other replacement level (WG: 217.1–227.9%). Whole-body proximate composition showed no statistical differences among fish for crude protein, moisture, or ash, except for crude fat content (P < 0.0001); the highest percentage of fat (9.3%) was observed in fish fed the 30% replacement level. The dietary fatty acid profile influenced the fatty acid profile of fish, eliciting an increment in the content of specific fatty acids, such as 16:0, 18:2n-6 and 22:6n-3. Although higher docosahexaenoic acid (DHA) content was observed in whole-body of hybrid striped bass fed the experimental diets, this fatty acid did not contribute to a higher body lipid content. The findings indicate that the combination of Arthrospira sp. and S. limacinum meals can replace a significant proportion of fish-derived feedstuffs in hybrid striped bass feeds, promoting suitable growth performances with up to 50% replacement under these conditions, and promoting the accumulation of DHA in fish tissues, which would ultimately benefit consumers.
•Arthrospira sp. and S. limacinum meals favored the replacement of fish derived feedstuffs in hybrid striped bass diets.•Microalgae meals improved growth performance of hybrid striped bass with up to 50% replacement of fishmeal and fish oil.•Docosahexaenoic acid accumulation in fish due to the dietary inclusion of S. limacinum would ultimately benefit consumers.
By-products from finfish processing from fisheries and aquaculture are often discarded. However, the enzymatic content of viscera has potential biotechnological and industrial applications. Such is ...the case for the sciaenids Cynoscion othonopterus, Cynoscion xanthulus, and Cynoscion parvipinnis, which are food and game fishes from the Gulf of California and whose viscera are commonly discarded after fish dressing. In this study, optimum temperature and pH for activity, as well as molecular weights of pepsin from the stomach of C. othonopterus, C. xanthulus, and C. parvipinnis were evaluated for the first time. Pepsin molecular weights were 30, 32.1, and 32.3 kDa, respectively. The highest activity of pepsin against hemoglobin was recorded between 40 and 45?C for C. othonopterus and C. xanthulus and at 40?C for C. parvipinnis. The optimum pH was 2.0 for the three sciaenids. Biochemical characteristics were comparable to pepsins from other marine and freshwater fish species, so they could likely be used in some processes using this enzyme, like collagen extraction, fish silage production, or fish processing, among others.
The research assessed the inclusion of MRD-Pro?, a bacterial-derived single-cell protein (SCP), in the diets of Nile tilapia (Oreochromis niloticus) fry with an initial weight of 0.12 grams. Using a ...diet composed of 45% crude protein and 14% crude fat, with an initial fishmeal content of 8.0% (designated as Diet 0.00% SCP, the control), SCP replaced 50% and 100% of the fishmeal on a protein basis, incorporated at levels of 4.25% and 8.50%, respectively. In addition, two more diets were prepared with higher levels of SCP, 14.50% and 21.00%. All diets were isoproteic and isolipidic. Weight gains of fish fed with the control diet (27.26 g) and the 4.25% SCP diet (21.61 g) were statistically comparable among themselves but were significantly greater than those of fish fed the 8.50% SCP (10.45 g), 14.50% SCP (11.54 g), or 21.00% SCP (7.28 g) diets, a trend observed across all growth and feed utilization indices. Increasing dietary SCP significantly reduced the crude fat and dry matter content in fish muscle tissue, while minimal changes in the amino acid profile of fish muscle tissue were observed. The bacterial-based SCP MRD-Pro? is a nutritious feed additive that can be effectively incorporated, within limits, into the diet of tilapia fry.
Sciaenops ocellatus
has a long history in aquaculture and many difficulties associated with its commercial culture have been addressed and successfully resolved; nevertheless, further research in ...lipid nutrition could address more comprehensive questions on the way these nutrients are utilized. The purpose of this study was to evaluate
S. ocellatus
growth and lipase gene expression in response to increasing dietary lipid supplementation. Four experimental diets were formulated to provide 3, 10, 16, or 23% lipid using menhaden fish oil. Twenty juveniles (mean initial weight 2.3 ± 0.1 g) were stocked per aquaria in a recirculating system; each diet was assigned to three aquaria and fed to fish for 6 weeks. At the end of the study, fish fed 3% of dietary lipid were significantly (
P
< 0.0001) smaller and showed significantly lower feed efficiency, condition factor, hepatosomatic index, and intraperitoneal fat than fish fed the other diets, but no differences were observed among fish fed 10, 16, or 23% lipid. A straight broken-line regression model for thermal growth coefficient provided an estimated value of 9.4% of dietary lipid as the optimal inclusion level. The bile salt-dependent lipase (BSDL) of red drum was 80.3 kDa. Relative gene expression of BSDL was significantly higher (
P
= 0.0007) in fish fed 10% lipid, with no differences among the other dietary treatments. Results provided could help monitor the metabolic status of farmed fish and contribute to optimize diet formulations based on maximum gene expression of BSDL for supplementation of dietary lipid.
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