Molting Frequency Research Articles

Assessing the chronic toxicity of climbazole to Daphnia magna: Physiological, biochemical, molecular, and reproductive perspectives

The widespread use of climbazole (CBZ) has led to its increased presence in aquatic environments, potentially threatening freshwater ecosystems. However, evidence regarding the harmful effects of CBZ on aquatic organisms remains limited. In this study, Daphnia magna was exposed to CBZ at concentrations of 0, 0.2, 20, and 200 μg/L for 21 days to evaluate its chronic toxicity through assessment of life-history traits, physiological parameters, biochemical analyses, and gene expression. The results indicated that CBZ exposure delayed the days to the first brood, reduced the frequency of molting per adult, decreased the offspring number at first brood, diminished the body length, and decreased both the total number of broods per female and the total number of offspring per female. Additionally, CBZ inhibited the swimming speed, filtration rate, and ingestion rate. Moreover, CBZ altered the levels of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH), while increasing malondialdehyde (MDA) levels. Gene expression analysis revealed varied responses in mRNA levels related to metabolic detoxification (cyp360a8, gst, and p-gp), digestive enzymes (α-amylase, α-esterase, and trypsin), energy (ak), oxygen transport (dhb), and reproduction (nvd, cyp314, ecr, vtg, and jhe) following CBZ exposure. These results indicate that the presence of CBZ in aquatic environments can induce toxicity by altering energy acquisition, supply, and metabolism; impairing metabolic detoxification pathways; eliciting oxidative stress; and causing reproductive toxicity in D. magna.

Comparative analysis of cholesterol and its alternative squalene: The impact on growth and lipid metabolism in coin-sized Eriocheir sinensis

Cholesterol is crucial for the growth and development of crabs, but its high cost limits its widespread use in feed. Squalene, a key precursor in cholesterol synthesis, has the potential to replace cholesterol, but its effectiveness in promoting crab growth and cholesterol levels remains unclear. This study investigated the cholesterol and squalene requirements of coin-sized Eriocheir sinensis, the impact of cholesterol and squalene on growth and lipid metabolism, and the relative bioavailability of squalene. A total of 420 coin-sized crabs were divided into seven experimental groups and fed different diets for eight weeks. The diets included three cholesterol levels at 0 % (Control), 0.2 %, and 0.4 %, and four squalene levels at 0.05 %, 0.1 %, 0.2 %, and 0.4 %. Here, we reported that both 0.2 % and 0.4 % cholesterol significantly increased final body weight (FBW), weight gain rate (WGR), and specific growth rate (SGR) of coin-sized crabs, and 0.2 % cholesterol showed the best growth-promoting effect. Similarly, increasing dietary squalene levels significantly enhanced FBW, WGR, and SGR, with 0.4 % squalene providing the best growth-promoting effect. Additionally, 0.4 % squalene significantly decreased hepatopancreas index (HSI), but did not affect molting frequency (MF). Interestingly, although squalene and cholesterol exerted opposite effects on biochemical indices such as cholesterol and triglyceride levels in the hemolymph, both promoted cholesterol deposition in the hepatopancreas. Relative bioavailability of squalene compared to cholesterol on growth and cholesterol deposition was 82.61 % and 81.73 %, respectively, which might be closely related to lipid metabolism-related genes. In conclusion, the study revealed that similar to cholesterol, squalene was important for crab growth and cholesterol deposition, and squalene could serve as a potential substitute to reduce the reliance on cholesterol in crab feed.

The impact of using predigested feed on growth and molting frequency in blue swimming crab (Portunus pelagicus) enlargement

Abstract Blue swimming crab is one of the leading fishery export commodities which occupies the 3rd largest position after tuna and shrimp. Crab maintenance so far uses rasbora fish feed which has several drawbacks, including inappropriate nutrition, depending on the season, and is difficult to handle. Therefore, simple artificial feed is needed to support crab growth. The purpose of this study was to determine the effect of artificial feeding supplemented with pancreatic extract on crab growth. The research design used in this study was completely randomized design (CRD) with different concentrations of pancreatic extract (0%, 3%, 6%, 9%). Parameters observed included water quality (temperature, dissolved oxygen, pH, salinity, and ammonia), feed proximate, crab biology. The results of this study indicate that the water quality in this study supports the life of blue swimming crabs. The feed proximate results show that the proximate value is in accordance with the crab’s needs. The results of swimming crab biology showed that the highest growth of crab was owned by the artificial feed + 9% pancreas and the lowest was in the trash fish treatment. Based on the results it can be seen that the best treatment to support the life of the blue swimming crab is artificial feed + 9% pancreas. Predigestion feed with the help of pancreatic extract concentrations can increase crab growth compared to ordinary feed or rasbora fish feed.

Exploring the effects of dietary cholesterol on growth, immunity, and lipid metabolism of juvenile Chinese mitten crabs (Eriocheir sinensis)

This study aims to investigate the nutritional needs and physiological functions of dietary cholesterol in juvenile Chinese mitten crabs (Eriocheir sinensis). In the 8-week feeding experiment, we evaluated the effects of various cholesterol levels (0 control, 0.6, 1.3, 2.6, 5.9, 12.0 g/kg diet) on growth, immune capacity, lipid metabolism, molting, and cholesterol and bile acid metabolism. Crabs (1.06 ± 0.04 g) were divided into six groups with four replicates of 40 crabs per tank. The highest weight gain was found in crabs fed 5.9 g/kg cholesterol (P < 0.05), while the highest molting frequency was observed in the 0.6 g/kg group (P < 0.05). Cholesterol significantly changed fatty acid composition in the hepatopancreas, and 5.9 g/kg cholesterol increased immune enzyme activities (acid phosphatase, alkaline phosphatase, and polyphenol oxidase) (P < 0.05). A 5.9 g/kg cholesterol significantly upregulated lipogenesis- and catabolism-related genes, while higher levels of cholesterol (12.0 g/kg) downregulated lipogenesis-related genes significantly (P < 0.05). Low cholesterol levels upregulated chitinase expression, while ecdysone receptor and molt-inhibiting hormone expressions were upregulated with cholesterol levels (P < 0.05). Cholesterol also upregulated the gene in bile acid metabolism. The total bile acids, the proportion of primary bile acids, and the content of primary bile acids increased significantly compared to the control. Based on quadratic regression model analysis, the optimal dietary cholesterol level for juvenile E. sinensis is 5.74–5.77 g/kg. The study suggests that cholesterol promotes growth and immunity in juvenile E. sinensis by regulating molting frequency, improving lipid and HUFA utilization, and increasing bile acids.

PEMANFAATAN CACING TANAH (Lumbricus rubellus) PADA PENDEDERAN LOBSTER AIR TAWAR (Cherax quadricarinatus) DENGAN SISTEM RESIRKULASI

Recirculation systems are intensive cultivation methods that offer an attractive alternative to extensive systems for lobster farming. This study aims to evaluate the utilization of earthworms (Lumbricus rubellus) in the juvenile rearing of freshwater lobsters (Cherax quadricarinatus) using a recirculation system. The research was conducted at the Wet Laboratory of the Seed and Fish Feed Production Technology Study Program, Politeknik Indonesia Venezuela, from October to November 2022. The experimental design used was a Completely Randomized Design (CRD) non-factorial, consisting of 4 treatments and 4 replications: A (control), B (10% of biomass), C (15% of biomass), and D (20% of biomass). The results showed that treatment D (20% of biomass) produced the highest absolute weight growth, with an average of 12.0 g, while treatment A (control) had the lowest weight with an average of 1.2 g. The highest absolute length growth was also observed in treatment D, with an average of 4.5 cm, while treatment A had the lowest length growth at 0.7 cm. The highest feed conversion ratio (FCR) was achieved by treatment B (10% of biomass) with an average of 2.57, whereas the lowest FCR was observed in treatment D with an average of 1.63. The highest molting frequency over 30 days was recorded in treatment D, while the lowest molting frequencies were found in treatments A and B. ANOVA test results indicated that the earthworm treatments significantly affected absolute weight growth, absolute length growth, feed conversion ratio (FCR), and molting frequency of the lobsters over 30 days. However, there was no significant effect on the survival rate (SR) of the lobsters.

Functional Study of the Role of the Methyl Farnesoate Epoxidase Gene in the Ovarian Development of Macrobrachium nipponense.

Methyl farnesoate epoxidase (MFE) is a gene encoding an enzyme related to the last step of juvenile hormone biosynthesis. Mn-MFE cDNA has a total length of 1695 bp and an open reading frame (ORF) length of 1482 bp, encoding 493 amino acids. Sequence analysis showed that its amino acid sequence has a PPGP hinge, an FGCG structural domain, and other structural domains specific to the P450 family of enzymes. Mn-MFE was most highly expressed in the hepatopancreas, followed by the ovary and gill, weakly expressed in heart and muscle tissue, and barely expressed in the eyestalk and cranial ganglion. Mn-MFE expression remained stable during the larval period, during which it mainly played a critical role in gonadal differentiation. Expression in the ovary was positively correlated and expression in the hepatopancreas was negatively correlated with ovarian development. In situ hybridization (ISH) showed that the signal was expressed in the oocyte, nucleus, cell membrane and follicular cells, and the intensity of expression was strongest at stage O-IV. The knockdown of Mn-MFE resulted in a significantly lower gonadosomatic index and percentage of ovaries past stage O-III compared to the control group. However, no differences were found in the cumulative frequency of molting between the experimental and control groups. Moreover, the analysis of ovarian tissue sections at the end of the experiment showed differences between groups in development speed but not in subcellular structure. These results demonstrate that Mn-MFE promotes the ovarian development of Macrobrachium nipponense adults but has no effect on molting.

Effect of Adding Calcium Dolomite (CaMg(CO3)) and Tohor (CaO) in Cultivation Media to Increase Moulting of Litopenaeus vannamei

Vaname shrimp (Litopenaeus vannamei) is a fishery commodity that is the largest contributor to exports compared to other commodities. The success of shrimp survival and growth cannot be separated from the molting process, which requires calcium. The calcium that absorbed from the cultivation media can play a greater role in the process of exoskeleton formation. Dolomite lime (CaMg(CO3)) and tohor (CaO) can be sources of calcium that can be added to cultivation media. The research method used in this study was a completely randomized design (CRD) consisting of 5 different treatments (A: without additional lime, B: 0.8 gr dolomite, C: 0.8 gr tohor, D: 0.3 gr dolomite + 0.5 gr of tohor, E: 0.5 gr of dolomite + 0.3 gr of tohor) with 3 repetitions. The results showed that the addition of lime at different doses provided a molting frequency ranging from 2.07 – 3.23 times during the 60 days rearing period, where treatment E was the optimum treatment. The absolute weight growth obtained ranged from 2.52 gr – 5.03 gr, with an absolute length of 5.25 cm – 9.11 cm. The highest survival rate during maintenance in treatment E reached 72%. The water quality conditions measured during the activity were alkalinity 135 – 146 ppm, Ca hardness 132.74 – 172.39 ppm, temperature 29.9 – 30.3°C, DO 6.3 – 6.5 mg/l, pH 7 .9 – 8.3 and salinity 32 -34 ppt.

Microplastics impair the reproductive behavior and life history traits of the amphipod Parhyale hawaiensis

We investigated the distribution and effects of waterborne microplastic (MP) (polyethylene microspheres, 53–63 um) on the emergent model for ecotoxicology, the amphipod Parhyale hawaiensis, during 30 days of exposure. The following life-history traits were measured: (1) survival, (2) specific growth rate (SGR), (3) reproductive performance (precopulatory pairing behavior, fecundity, and time to release neonates), (4) molting frequency, (5) F1 newborn offspring survival and (6) MP bioaccumulation. No significant mortality or molt was seen in any of the treatments. MP caused a reduction in SGR, being more pronounced in females. The time for precopulatory pairing was 3-fold longer in amphipods exposed to MP. Fecundity decreased by 50 %, and the time to release juveniles was 6.7 days longer for amphipods exposed to MP. Finally, neonate survival decreased by 80 % after ten days of release. MP disrupts the reproductive mechanisms and triggers adverse effects on life history traits in P. hawaiensis.

NPC Intracellular Cholesterol Transporter 1 Regulates Ovarian Maturation and Molting in Female Macrobrachium nipponense.

NPC intracellular cholesterol transporter 1 (NPC1) plays an important role in sterol metabolism and transport processes and has been studied in many vertebrates and some insects, but rarely in crustaceans. In this study, we characterized NPC1 from Macrobrachium nipponense (Mn-NPC1) and evaluated its functions. Its total cDNA length was 4283 bp, encoding for 1344 amino acids. It contained three conserved domains typical of the NPC family (NPC1_N, SSD, and PTC). In contrast to its role in insects, Mn-NPC1 was mainly expressed in the adult female hepatopancreas, with moderate expression in the ovary and heart. No expression was found in the embryo (stages CS-ZS) and only weak expression in the larval stages from hatching to the post-larval stage (L1-PL15). Mn-NPC1 expression was positively correlated with ovarian maturation. In situ hybridization showed that it was mainly located in the cytoplasmic membrane and nucleus of oocytes. A 25-day RNA interference experiment was employed to illustrate the Mn-NPC1 function in ovary maturation. Experimental knockdown of Mn-NPC1 using dsRNA resulted in a marked reduction in the gonadosomatic index and ecdysone content of M. nipponense females. The experimental group showed a significant delay in ovarian maturation and a reduction in the frequency of molting. These results expand our understanding of NPC1 in crustaceans and of the regulatory mechanism of ovarian maturation in M. nipponense.

Effects of high doses of zearalenone on some antioxidant enzymes and locomotion of Tenebrio molitor larvae (Coleoptera: Tenebrionidae).

The mealworm Tenebrio molitor L. (Coleoptera: Tenebrionidae) feeds on wheat bran and is considered both a pest and an edible insect. Its larvae contain proteins and essential amino acids, fats, and minerals, making them suitable for animal and human consumption. Zearalenone (ZEA) is the mycotoxin most commonly associated with Fusarium spp. It is found in cereals and cereal products, so their consumption is a major risk for mycotoxin contamination. One of the most important effects of ZEA is the induction of oxidative stress, which leads to physiological and behavioral changes. This study deals with the effects of high doses of ZEA (10 and 20mg/kg) on survival, molting, growth, weight gain, activity of antioxidant enzymes superoxide dismutase (SOD) and glutathione S-transferase (GST), and locomotion of mealworm larvae. Both doses of ZEA were found to (i) have no effect on survival, (ii) increase molting frequency, SOD, and GST activity, and (iii) decrease body weight and locomotion, with more pronounced changes at 20mg/kg. These results indicated the susceptibility of T. molitor larvae to high doses of ZEA in feed.

Comparative Transcriptome Analysis Reveals the Light Spectra Affect the Growth and Molting of Scylla paramamosain by Changing the Chitin Metabolism.

Light is an essential ecological factor that has been demonstrated to affect aquatic animals' behavior, growth performance, and energy metabolism. Our previous study found that the full-spectrum light and cyan light could promote growth performance and molting frequency of Scylla paramamosain while it was suppressed by violet light. Hence, the purpose of this study is to investigate the underlying molecular mechanism that influences light spectral composition on the growth performance and molting of S. paramamosain. RNA-seq analysis and qPCR were employed to assess the differentially expressed genes (DEGs) of eyestalks from S. paramamosain reared under full-spectrum light (FL), violet light (VL), and cyan light (CL) conditions after 8weeks trial. The results showed that there are 5024 DEGs in FL vs. VL, 3398 DEGs in FL vs. CL, and 3559 DEGs in VL vs. CL observed. GO analysis showed that the DEGs enriched in the molecular function category involved in chitin binding, structural molecular activity, and structural constituent of cuticle. In addition, the DEGs in FL vs. VL were mainly enriched in the ribosome, amino sugar and nucleotide sugar metabolism, lysosome, apoptosis, and antigen processing and presentation pathways by KEGG pathway analysis. Similarly, ribosome, lysosome, and antigen processing and presentation pathways were major terms that enriched in FL vs. CL group. However, only the ribosome pathway was significantly enriched in up-regulated DEGs in VL vs. CL group. Furthermore, five genes were randomly selected from DEGs for qPCR analysis to validate the RNA-seq data, and the result showed that there was high consistency between the RNA-seq and qPCR. Taken together, violet light exposure may affect the growth performance of S. paramamosain by reducing the ability of immunity and protein biosynthesis, and chitin metabolism.

The Photoperiod Significantly Influences the Growth Rate, Digestive Efficiency, Immune Response, and Antioxidant Activities in the Juvenile Scalloped Spiny Lobster (Panulirus homarus)

This study aimed to elucidate the effects of different photoperiods (0 L:24 D, 6 L:18 D, 12 L:12 D, 18 L:6 D, 24 L:0 D, “Light (L) and Dark (D)”) on the growth performance and physiological responses of the juvenile scalloped spiny lobster (Panulirus homarus). Over a period of 56 days, parameters such as growth rate, digestive enzyme, immune enzyme, and antioxidant enzyme were meticulously evaluated in 90 lobsters subjected to these varying light conditions. The present study found no significant differences in survival rate (SR), molting frequency (MF), and meat yield production (MYP) among the various photoperiod treatments (p &gt; 0.05). Notably, the highest weight gain rate (WGR) and specific growth rate (SGR) were observed under a 12 L:12 D photoperiod. In the continuous dark phase (0 L:24 D), pepsin (PEP) activity remained high in gastric tissues, while trypsin (TRYP) and chymotrypsin (CHT) activities reached the highest in hepatopancreas tissues. The α-amylase (AMS) activity in the hepatopancreas was most elevated under 18 L:6 D, and the optimal lipase (LPS) activity was recorded under 12 L:12 D. The activity of acid phosphatase (ACP) in the hepatopancreas was highest in the absence of light (0 L:24 D), whereas the activities of alkaline phosphatase (AKP) and lysozyme (LZM) were most effective under the 12 L:12 D photoperiod. The total antioxidant capacity (T-AOC), along with catalase (CAT) and superoxide dismutase (SOD) activities of the hepatopancreas reached the highest at 12 L:12 D. The highest activity of glutathione peroxidase (GSH-Px) was seen under 18 L:6 D. The concentration of malondialdehyde (MDA), a marker of oxidative stress, was found to be highest under 12 L:12 D. Consequently, this specific photoperiod is essential for achieving optimal growth and maintaining appropriate physiological balance in the scalloped spiny lobster during aquaculture. These findings provide a foundational guideline for establishing the lighting environment in the farming of the juvenile scalloped spiny lobster.

Efficiency of Algal oil as a Feed Ingredient for the Development of Maturation Diet for the Spent Penaeus monodon (Fabricius) Spawners

This study designed to understand the effect of Algal oil as feed ingredients to attain reproductive success in the spent spawners of P. monodon. Five diets prepared were D1, D2, and D3 with 2.5%, 5% and 7.5% algal oil respectively, reference diet with fish oil and negative control diet without fish oil. The results showed that the maturation diet increased the moulting frequency and shortened the time of full maturation of the ovary. In D2 fed spawners, the duration of spawnings was minimized and the fecundity was also increased and the Gonado Somatic Index was also high. Compared with control diet, the abortive spawning and gaped ovary formed was also less in algal oil based diet (D2). D2 fed spawners also enhanced the percentage of the formed eggs, fertilized eggs and their hatching and also showed maximum prophenoloxidase activity. Though the reference diet had influenced in all reproductive parameters, the success was inferior to the experimental algal diet. The algal oil (5%) based diet was found to be very efficient in the reproductive success of spent spawners and therefore this diet can be used for the recycling of spent spawners.

Growth performance and survival rate of spiny lobster Panulirus homarus (Linnaeus, 1758) with formulated feeding enriched by spinach extract

Abstract. Lubis AS, Efrizal, Syaifullah, Rusnam, Nurmiati, Puari AT. 2023. Growth performance and survival rate of spiny lobster Panulirus homarus (Linnaeus, 1758) with formulated feeding enriched by spinach extract. Biodiversitas 24: 6010-6016. In the context of spiny lobster Panulirus homarus (Linnaeus, 1758) aquaculture and marine conservation, assessing factors that influence growth and survival is critical. Spinach extract can be added as a feed additive to enhance the growth and survival rate of lobsters. This study aimed to analyze the effect of formulated feed enriched with spinach extract on spiny lobsters' growth and survival performance. A completely randomized design with five treatments and five replications: formulated feed with spinach extract 0 mg (Feed A1), 0.4 mg (Feed A2), 0.5 mg (Feed A3), 0.6 mg (Feed A4), and 0.7 mg (Feed A5) were used. The result showed that the formulated feed enriched with spinach extract had a significant effect on absolute weight, specific growth rate, length, and width of the carapace in growth performance (P&lt;0.05) but had no significant on the survival rate and the molting frequency (P&gt;0.05). The best result was treatment A3, adding 0.5 g of spinach extract to lobster feed with absolute weight 39.67±6.20 g, length of carapace 0.46±0.06 cm, width of carapace 0.28±0.05 cm, specific growth rate 0.38±0.06% day-1, molting frequency 1.00±0.00 times lobster-1, and survival rate 100±0.00%. The Spinach extract of 0.5 mg was the best for the survival and growth of the lobster (Duncan's test). The chemical of the feed showed that the tested feed met the nutritional needs of lobsters with a protein content of 39.74-42.60%. However, the number of amino acids in the best test feeds was still low quantity compared to several other studies, so the growth of lobsters was still slow. Based on research results, enriched 0.5 g of spinach extract to formulated feed is the best result for increasing the growth and survival rate of lobsters.

Optimal dietary lysine improves the growth performance, molting frequency, lipid metabolism, immunity and antioxidant of postlarval mud crab Scylla paramamosain

A 56-day feeding trial was designed to investigate the effect of different dietary lysine (Lys) levels on the growth, molting, lipid metabolism, antioxidant, and immunity of postlarva Scylla paramosain. Six diets with 1.20%, 1.46%, 1.84%, 2.06%, 2.35%, and 2.67% Lys levels (dry matter) were formulated and experimented on the postlarva Scylla paramamosain. The results showed that Scylla paramamosain fed with the 2.06% lysine obtained the highest growth performance and the highest molting frequency. Appropriate dietary Lys levels (1.73–2.03%) can improve the antioxidant capacity of Scylla paramamosain. Although unaffected by dietary Lys, the whole-body lipid content of the 1.20% Lys group was numerically higher than those of the 1.46–2.67% Lys groups. The variation in whole-body crude protein content showed a similar trend with those in the content of EAA and NEAAs, with the highest whole-body crude protein content appearing in the 2.06% Lys group. The crabs obtained the highest expression of igf, fas, EcR and fabp genes in the 2.06% Lys group. When dietary Lys levels were > 1.20%, the transcription level of immune related-genes increased. As suggested by the results of the second order polynomial regression analysis of weight gain, the Lys requirement of postlarva Scylla paramamosain is 2.03% (4.51% of dietary protein).

Comparison of the gut microbiota and untargeted gut tissue metabolome of Chinese mitten crabs (Eriocheir sinensis) with different shell colors.

The Chinese mitten crab (Eriocheir sinensis) is a highly valued freshwater crustacean in China. While the natural shell color of E. sinensis is greenish brown (GH), we found a variety with a brownish-orange shell color (RH). Although RH is more expensive, it exhibits a lower molting frequency and growth rate compared with GH, which significantly reduces its yield and hinders large-scale farming. The growth and development of animals are closely related to their gut microbiota and gut tissue metabolic profiles. In this study, we compared the gut microbiome communities and metabolic profiles of juvenile RH and GH crabs using 16S rRNA gene sequencing and liquid chromatography-mass spectrometry (LC-MS), respectively. Our findings indicated that the intestinal microbial composition and metabolic characteristics of E. sinensis differed significantly between RH and GH. At the operational taxonomic unit (OTU) level, the α-diversity of the gut microbiota did not differ significantly between RH and GH, while the β-diversity of the RH gut microbiota was higher than that of the GH gut microbiota. At the species level, the richness of unclassified_c_Alphaproteobacteria was significantly higher in the GH group, while the RH group had a significantly higher richness of three low-abundance species, Flavobacteria bacterium BAL38, Paraburkholderia ferrariae, and uncultured_bacterium_g__Legionella. In the current study, 598 gut tissue metabolites were identified, and 159 metabolites were significantly different between GH and RH. The metabolite profile of RH was characteristic of a low level of most amino acids and lipid metabolites and a high level of several pigments compared with that of GH. These metabolites were enriched in 102 KEGG pathways. Four pathways, including (1) Central carbon metabolism in cancer, (2) protein digestion and absorption, (3) alanine, aspartate and glutamate metabolism, and (4) aminoacyl-tRNA biosynthesis, were significantly enriched. The correlation analysis between metabolites and microbiotas indicated that most key differential metabolites were positively correlated with the abundance of Shewanella_sp_MR-7. This research provided a greater understanding of the physiological conditions of E. sinensis varieties with different shell colors by comparing the gut microbiota and gut tissue metabolome.

Effects of eggshell and seashell powder as natural dietary calcium supplements on growth, molting frequency, and carapace calcium composition of juvenile red claw crayfish, Cherax quadricarinatus.

The growth performance of red claw crayfish, Cherax quadricarinatus, fed diets with different sources and concentrations of natural calcium was evaluated. Formulated diets containing 30% protein and 8% lipid were prepared using supplementation of 0 (control), 3%, 6%, 9% eggshell, and 6% seashell. C. quadricarinatus juveniles with an average total weight of 0.21 ± 0.01 g and length of 25.0 ± 0.10 mm were obtained from ten ovigerous females bred in captivity. An aquarium with a size of 0.72 m² was divided into eight compartments with an area of 0.09 m² per compartment and was individually stocked with juvenile crayfish. A total of eight juvenile crayfish were used per dietary treatment. There were five dietary treatments in total and each of these treatments were replicated three times. The addition of eggshell and seashell powder exerted positive effects on the growth performance, molting frequency, and survival of the crayfish. Crayfish fed with a 6% eggshell-supplemented diet exhibited the best overall growth performance. The calcium percentage of the carapace increased with the increase in calcium content of the diets. Meanwhile, the performance of diets comprising eggshells and seashells was not significantly different (P > 0.05). Considering the low cost and abundance of eggshells, the addition of 6% of this product to the diet is recommended for the best growth of juvenile C. quadricarinatus.

Effects of dietary trimetlylamine oxide on the growth performance, feed utilization and appetite regulation of Chinese mitten crab (Eriocheir sinensis)

A 60-day feeding trial was conducted to evaluate the effects of different TMAO (trimetlylamine oxide) supplement levels (0%, 0.12%, 0.24%, and 0.48%, named G1, G2, G3, and G4, respectively) on growth performance, feed utilization, intestinal enzyme activities and appetite regulation of Eriocheir sinensis. The results showed that diet supplemented with 0.24% trimetlylamine oxide (TMAO) significantly improved the weight gain rate (WGR), specific growth rate (SGR), feed intake (FI) and feed utilization (p < 0.05), while having no effect on the survival rate (SR) and molting frequency (MF) of crabs (p > 0.05). Moreover, moderate dietary TMAO levels significantly improved the intestinal enzyme activities (α-amylase, trypsin, lipase and γ-glutamyl transferase) of crabs. The RT-qPCR results showed that the expressions of the orexigenic neural signal-related factors neuropeptide Y (npy) and ghrelin were significantly up-regulated. The expressions of AKT/TOR/4E-BP signaling pathway related genes (protein kinase B (akt), target of rapamycin (tor) and 4E-binding protein (4e-bp)), anorexia-regulating peripheral hormones (leptin and cholecystokinin (cck)) and leptin receptor (lepr) were significantly down-regulated in the hepatopancreas, thoracic ganglia and cranial ganglia tissues. The anorexigenic neural signal-related factors cocaine and amphetamine regulated transcript (cart) and pro-opiomelanocortin (pomc) were significantly down-regulated in the hepatopancreas, thoracic ganglia and cranial ganglia tissues. Based on the quadratic regression analysis of WGR against dietary TMAO level, the optimum TMAO requirement of E. sinensis was suggested to be 0.27%. In conclusion, present results suggested that dietary supplementation with 0.27% TMAO can improve the growth performance, feed intake, intestinal enzyme activities and appetite regulation of E. sinensis.

Growth Performance, Molting Frequency and Carapace Coloration of Two Different Size Classes of Red Swamp Crayfish (Procambarus clarkii) Fed with Different Diets

In this study, the effects of three different commercial aquarium feeds were tested on the growth performance, molting frequency and carapace coloration of red swamp crayfish (Procambarus clarkii) in two different size classes (4 and 5 cm). For this purpose, six experimental groups were formed according to crayfish size (S1: Size 1 and S2: Size 2) and feed type (BF: bottom fish food, CF: cichlid food and CG: crustacean granules) as S1BF, S1CF, S1CG, S2BF, S2CF and S2CG, and the crayfish were fed with these diets for 12 weeks. The final mean weight (FMW) of the S1CG was higher than the S1BF (P&amp;lt;0.05). The final mean total length (FMTL) and final mean carapace length (FMCL) of S2BF were the lowest (P&amp;lt;0.05). No significant differences were recorded in the feed conversion ratios (FCR), specific growth rates (SGR) and survival rates (SR) of red swamp crayfish in two different size classes (P&amp;gt;0.05). The lowest cheliped injury and cannibalism rates were found in the crayfish fed with crustacean feed in both size classes. The mean molting frequencies (MMF) of the S1CG and S2CG were statistically higher than the S1CF and S2BF, respectively (P&amp;lt;0.05). S2CG has the highest final lightness (L*) value (P&amp;lt;0.05). The final redness (a*) and final yellowness (b*) values of the S1BF and S2BF groups were the lowest (P&amp;lt;0.05). The results showed the positive effects of crustacean feed on all the tested parameters in both size classes. Further studies are needed to investigate the efficient use of species-specific rations in the crayfish species.

The Effect of Adding Fermented Mulberry Leaves (Morus spp.) in Feed Formulation to Stimulate Molting of Mud Crab (Scylla serrata)

One of the factors in aquaculture activities that affect the production and growth process of mud crab is molting. Several techniques have been developed to accelerate the molting of mud crabs, namely ablation, mutilation, and supplementation. One form of supplementation is through the use of fermented mulberry leaves in mud crab feed. Therefore, this study aimed to analyze the effect of adding fermented mulberry leaves (Morus spp.) in feed to stimulate the molting of mud crabs (S. serrata). This research was carried out in traditional ponds in Bugis Village, Sape District, Bima Regency, for 60 days. The method used was an experimental method with a completely randomized design (CRD) consisting of five treatments and three replications, namely control treatment/trash fish (P1), 20% Mulberry Leaf Fermentation (P2), 25% (P3), 30% (P4), and 40% (P5). Research parameters comprise frequency and percentage of molting, absolute growth, specific growth rate, feed utilization efficiency, feed conversion ratio, survival rate, and water quality. The results showed that the combination test feed of fermented mulberry leaf (Morus spp.) in the mud crab (S. serrata) diet did not affect all the parameters measured. The provision of mangrove crab feed formulation with a concentration of 25% mulberry leaf fermentation (P3) and control treatment (P1) gave a faster initial molting, which was the first 10 days of the rearing period with the highest average frequency and percentage of molting of 37 and 41%, respectively.