Aquaculture Research最新文献

Live crustaceans, especially lobsters, crabs, and shrimp, fetch premium prices in many international seafood markets, especially in parts of Asia. To access these market opportunities, live crustaceans frequently need to be transported over long distances, which can involve prolonged air exposure resulting in elevated stress and increased morbidity and mortality. Interventions which deliver metabolic suppression to live crustaceans during their transport have the potential to improve outcomes from live shipping. In this study, the administration of adenosine (Ado) and L-theanine (L-th) were assessed for metabolic suppression in the New Zealand scampi, Metanephrops challengeri, a deep sea lobster which is highly prized as seafood, and with excellent prospects for supply into premium live seafood markets. The administration to scampi of Ado and L-th in isolation or as a mixture (Ado/L-th), caused a significant decrease in heart rate (HR) with a lasting effect for the 4 hr experimental period. However, this depression of HR did not translate into a systemic downregulation of metabolism, as measured by the key metabolites, i.e., glycogen utilization and the accumulation of lactate and ammonia. The lack of systematic metabolic downregulation would preclude the potential use of Ado and L-th for commercial application in live shipping of crustaceans.

The suppressor of cytokine signaling (SOCS) plays a negative role in the cytokine signaling pathway, preventing excessive signaling from interfering with the metabolic homeostasis of the body. By regulating the Janus kinase-signal transducer and activator of transcription pathway through negative feedback, SOCS have a significant impact on the regulation of both innate and adaptive immunity against pathogens, thus playing a crucial role in the immune response, growth, and development of the body. In this study, the cDNA sequences of SOCS1, 2, 3a, 3b, 4, 5b, 6, 7, 8, 9, and CISH genes of spotted seabass (Lateolabrax maculatus), an important marine economic fish in China, were cloned using RT-PCR, nested PCR, and RACE techniques. Multiple sequence alignment showed that the SOCS family members shared highly conserved functional structural domains, including the SRC homology 2 domain (SH2 domain) and the SOCS-box domain. The phylogenetic analysis showed that SOCS1, 2, 3a, 3b, 8, and CISH belonged to the type II subfamily of SOCS genes, while SOCS4, 5b, 6, 7, and SOCS9 belonged to the type I subfamily. Furthermore, gene organization and syntenic analysis confirmed the phylogenetic analysis and protein annotation of the SOCS gene family in spotted seabass. Constitutive expression of spotted seabass SOCS genes was observed in various tissues of healthy fish, with varying expression levels. Following the lipopolysaccharide and Edwardsiella tarda challenge, the expression profiles of spotted seabass SOCS genes were differently regulated in the gill, head kidney, intestine, and spleen. These findings provide a basis for future research on the functional properties of SOCS genes in spotted seabass.

Patagonian red octopus, Enteroctopus megalocyathus, an interesting species for Chilean aquaculture diversification, requires the improving of their experimental technology to obtain early juveniles. The first objective of the study was to enhance aspects of feeding and temperature management in broodstock, egg incubation, paralarvae rearing, and early juveniles’ growth. The results indicated that female weight decreases up to 46.0 ± 8.6% during the egg incubation. Test of 8, 14, and 18°C during egg incubation shows that at 18°C embryos do not survive. Paralarvae reared under four diet treatments: (1) unfed, (2) enriched Artemia (Nannochloropsis sp.), (3) copepod (Acartia spp.), and (4) juvenile crabs (Petrolisthes spp.) showed survival quadruplication when they fed copepods and crabs instead of Artemia. Juveniles reared at 11, 13, and 15°C improved feed conversion and protein efficiency ratios at 15°C. The second objective was to analyze batches of paralarvae and early juveniles of two different periods to obtain their performance indicators and to compare them between productive periods. The results of growth rates, the relative weight condition coefficient, and morphometric relationships are discussed in the context of paralarvae culture from 1 to 90 days after hatching (DAH) and early juveniles from 1 to 135 days postsettlement (DPS).

A 12-week feeding trial was conducted to investigate the nutrient utilization, growth performance, and hematological indices of Cyprinus carpio var. communis fingerlings fed diets based on aquatic macrophyte, Ceratophyllum demersum as a replacement of fish meal (FM). Six isonitrogenous and isocaloric diets containing graded levels of C. demersum 0%, 5%, 10%, 15%, 20%, and 25%, respectively, as replacer of FM were formulated. Total of 360 fingerlings with an initial weight of 3.65 ± 0.98 g were randomly stocked in 70 L plastic tanks water volume 60 L connected with a continuous flow-through system (1–1.5 L/min) for each treatment and were run in triplicate having 20 fish in each tank. At the end of the feeding trial, it was observed that the C. carpio var. communis fingerlings receiving 5% and 10% C. demersum in the diet showed improvements in live weight gain (LWG), specific growth rate (SGR), feed conversion ratio (FCR), and protein efficiency rate (PER). While further addition of C. demersum as a replacement of FM from 15% to 25% led to the progressive decline in the values of LWG, SGR, FCR, and PER. Hematological data also exhibited a linear declining trend beyond the 10% C. demersum replacement level. The fish fed with higher inclusions of C. demersum in each diet significantly (P < 0.05) affected whole body composition with the lowest protein and fat amounts recorded at higher replacement levels significantly (P < 0.05). The highest protein and fat contents were observed at 5% and 10% diets. Except serum glucose, cholesterol, alanine aminotransferase (ALT), and aspartate aminotransferase (AST), the other serum indices exhibited a decreasing trend with increasing inclusion of C. demersum in the diet. The results of the present study clearly demonstrated that the inclusion of 10% C. demersum did not affect the growth and other parameters of C. carpio var. communis fingerlings compared to the 50% FM diet. However, it is recommended that 10% FM can be substituted without compromising the growth and nutritional quality of fish.

A 50-day feeding experiment was performed to investigate the effects of dietary phospholipid (PL) addition on the survival, growth, serum, and hepatopancreas lipid indexes, calcium content, and neverland (Nvd) gene expression in button-sized juvenile Chinese mitten crab (Eriocheir sinensis). Five experimental diets were formulated with increasing addition of PL (0%, 1%, 2%, 3%, and 4%), which were named PL0, PL1, PL2, PL3, and PL4, respectively. Each diet was randomly assigned to four tanks of juvenile E. sinensis (initial weight: 5.00 ± 0.55 g), with eight crabs held in each tank. The results showed that PL addition significantly increased the survival rate (SR) but just slightly increased the weight gain rate (WGR) of juvenile E. sinensis. As the PL addition level increased, SR and WGR first increased and then decreased, with the highest values observed in the PL3 group. As the PL addition level increased, the activities of trypsin and cellulase significantly increased and then decreased, with the highest value observed in the PL2 group and PL3 group, respectively. As PL addition level increased from 1% to 2%, lipase activity increased sharply and then kept constant with a further increase of dietary PL. As PL addition level increased from 0% to 3%, the calcium content in the serum significantly increased from 7.96 to 12.43 mmol/L and then significantly decreased to 11.36 mmol/L with a further increase of PL addition. PL addition just slightly promoted the calcium content in the hepatopancreas compared with the control group. As PL addition level increased from 0% to 3%, the expression of Nvd in the hepatopancreas significantly increased by 1.47-fold and then decreased to basal level with a further increase of PL addition. In conclusion, 2%−3% addition of the optimal PL addition level was estimated to be 2%−3% for juvenile E. sinensis based on their survival, growth performance, and digestive enzyme activities. PL addition at a relatively higher level (3%) increased the calcium content and Nvd expression, the latter possibly facilitating cholesterol metabolism into vitamin D.