Cherax quadricarinatus or redclaw is considered a good option for freshwater aquaculture and has been cultivated in several countries. However, nutritional studies are scarce. In present research, ...the effects of different protein‐energy (P/E) ratios in diets for male and female of pre‐adults were investigated. Its influence on growth performance, carcass amino acid and fatty acid profiles were determined. Six different dietary P/E ratios: 12, 13, 14, 15, 16, and 17 mg of crude protein (CP) kJ−1 g−1 of food for 70 days were tested on male and female pre‐adults (initial weight 10.8 ± 0.6 g). The experimental treatments were assigned in triplicate. The significantly highest (p < .05) and lower growth indices, feed utilization and survival were observed for male and female pre‐adults fed a diet with a P/E ratio of 16 mg/kJ and diet with a P/E ratio of 12 mg/kJ respectively. Amino acids and fatty acids contents of the carcass on males and females (p < .05) were significantly influenced by the diets with higher P/E ratios. The two‐slope broken line regression analysis and the quadratic model (second‐order polynomial) regression analysis of specific growth rate in redclaw pre‐adults male and female suggest that the diet containing P/E ratio of 16 mg/kJ is optimal. A diet with a dietary P:E ratio of 16 mg/kJ (240 and 80 g/kg of protein and lipid respectively) is recommended to stimulate growth performance and proper carcass amino acid and fatty acid profiles of both male and female pre‐adults.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Biofouling, the biological process leading to the accumulation of microorganisms, has been promoted for over a decade in aquaculture, particularly in biofloc technology, biofilm‐based systems and ...recently aquamimicry. However, the science behind biofouling is largely unknown in aquaculture. This document brings the science behind the biofouling process, reviews and analyses available information about the different phases of such a unique natural process. In aquatic or high humidity environments, substrata rapidly become colonized by microbes. After molecules form a thin film on any surface, bacterial adhesions occur and bacteria–bacteria, bacteria–eukaryotes and bacteria–substrate interactions take place; bacterial adhesion entails the production of adhesins and polysaccharides production. Coaggregation continues after irreversible adhesion, but the activated genes during the adhesion process associated with flagella and pili are suppressed in this stage. Throughout the process, bacteria communicate by excreting signalling or self‐inducing molecules, and other bacteria recognize these molecules that serve as a sort of checkpoint associated with their accumulation. Thereafter, the maturation phase is achieved and usually characterized by a colony equilibrium; some bacteria and other microorganisms achieve prominence in the colony, and many of the members have their functions and contributions to the microbial community. Finally, the detachment involves a complex but coordinated process involving several environmental signals, signal transduction pathways and effectors, promoting biofilm or biofloc split and dispersal to start the process again. In conclusion, biofouling is a complex, multifaceted process, but a deeper understanding of it and its consequent regulation would benefit microorganism‐based aquaculture.
The effects of different diets on spermatophore production and sperm quality were investigated in the river prawn Macrobrachium americanum. River prawns were cultured and fed with three diets for ...244 days: fresh food (50% squid meat, Dosidicus gigas and 50% sardine muscle, Sardinops sagax); commercial pellets (35 Purina®); and a 50:50 mixture of both diets. Spermatophore production was recorded every 24 days on average as the percentage of spermatophores produced per extraction per diet, weight and biochemical composition. Sperm quality was measured as the total number of sperm, the proportion of live/dead sperm and normal/abnormal sperm morphology. There were no significant differences in the mean biochemical composition of M. americanum spermatophores for any of the diets. Biochemical composition was 36.3% protein, 25.8% carbohydrate and 4.6% lipids for all data pooled. The weight of spermatophores and sperm counts was not significantly different among diets, nor were there any differences as a function of the male initial total length (p > .05). Male river prawn reproductive exhaustion was observed as a decline in spermatophore production, weight of the spermatophores and the number of sperm cells per spermatophore, with an increasing proportion of dead and abnormal sperm seen throughout the experiment. The recommended period of maintenance in captivity for male broodstock is less than 115 days. It is recommended to feed broodstock males of M. americanum with commercial pellets because no significant differences were detected with the diets tested; pellets are easier to use, ensuring the same spermatophore production and sperm quality that was obtained with fresh food.
This study aimed to evaluate the structural changes in the microbiota of
Penaeus monodon
during its ontogenetic development and evaluate functional shifts in metabolic pathways. To address these ...questions, shrimp were maintained under isolated conditions to avoid cross-contamination with other environmental bacteria and reared in twelve 50 L plastic tanks connected to a recirculation system. The replicates of pooled intestine specimens from 15 shrimp were analyzed at postlarvae, juvenile, and adult phases for nucleic acid extraction. We tested the V3 region of the 16S rRNA gene from the postlarvae, juvenile, and adult stages. Resulting amplicon sequence variants (ASVs) were used to evaluate both structural and functional shifts during tiger shrimp development. Although the richness and diversity of microbiota were only slightly affected, the phylum Proteobacteria (genus
Vibrio
) was significantly predominant in the earliest stages of life, while Actinobacteria (genus
Actinotalea
) significantly increased in adult shrimp. Moreover, functional predictions by PICRUSt suggested that microbiota is primarily involved in metabolic activities during each developmental stage. Overall, these results suggest that each ontogenetic stage may provide specific conditions for the proliferation of certain bacterial taxa. Nerveless, alternative microbiota maintains similar ecological activities; thus, we posit that “stage-specific” changes in microbiota may be regulated to guarantee pivotal host functions.
Background
The river prawn,
Macrobrachium americanum (M. americanum),
is one of the largest prawns of the genus in Latin America and is an amphidromous species distributed along the Pacific coast of ...America. This prawn has commercial value due to its size and taste, making it a good option for aquaculture production. Its culture has been attempted in ponds and concrete tanks, but no successful technique can still support commercial production. Understanding the mechanisms that regulate reproduction at the molecular level is very important. This knowledge can provide tools for manipulating transcripts, which could increase the number or size of animals in the culture. Our understanding of the mechanism that regulates the reproduction of
M. americanum
at the molecular level is limited.
Aim
Perform and analyze the transcriptome assembly of the testes, vas deferens, and terminal ampulla of
M. americanum.
to provide new molecular information about its reproduction.
Methods and Results
The cDNA library was constructed and sequenced for each tissue to identify novel transcripts. A combined transcriptome with the three tissues was assembled using Trinity software. Unigenes were annotated using BLASTx and BLAST2GO. The transcriptome assembly generated 1,059,447 unigenes, of which 7222 genes had significant hits (e-value < 1 × 10
–5
) when compared against the Swiss-Prot database. Around 75 genes were related to sex determination, testis development, spermatogenesis, spermiogenesis, fertilization, maturation of testicular cells, neuropeptides, hormones, hormone receptors, and/or embryogenesis.
Conclusions
These results provide new molecular information about
M. americanum
reproduction, representing a reference point for further genetic studies of this species
.
The effect of dietary protein:energy (P/E) ratio on growth performance, body composition, digestive enzyme activities, hematology, and hepatopancreas histology was tested in the juvenile cauque river ...prawn Macrobrachium americanum. Six diets with two different crude protein levels (350 and 400gkg−1 diet) and three lipid levels (60, 100, and 140gkg−1 diet) were tested on juveniles in a factorial manner (3×2) to provide six different dietary P/E ratios: 17, 18, 19, 20, 21, and 22mgCPkJ−1GEg−1. The indicators of growth performance and nutrition were significantly influenced by the dietary P/E ratio; however, no significant survival differences were observed among treatments. The dietary protein–lipid levels (P/E ratios) influenced significantly the whole body protein, lipid, and carbohydrate contents; lipid content in the whole body increased significantly when the dietary lipid level was increased from 60 to 140gkg−1 at the same protein levels. The total protease activity increased significantly with the increase in dietary protein at each lipid level. Total cholesterol and glucose concentrations in the serum were significantly affected by the different dietary P/E ratios and lipid levels. These results, using the principal component analysis (PCA) with the covariance matrix, suggest that the diet containing 350gkg−1 protein level and 100gkg−1 lipid level with P/E of 18mgCPkJ−1 is optimal for cauque river prawn juveniles.
•Cauque river prawn were fed with dietary protein-energy from 17 up 22 mg CP kJ–1 GE g–1 in the diets•The total protease activity increased with the increase in dietary protein at each lipid level•Total cholesterol and glucose concentrations in the serum were affected by the different dietary P/E ratios (P < 0.05)•The best ratio of dietary protein-energy for growth in prawn was 350 g kg–1 protein with P/E of 18 mg CP kJ–1
One way to approach the nutritional requirements of native shrimp, necessary to consolidate their culture, is to know their biochemical composition. The effect of feeding two levels of lipids (4 and ...12% L) and four levels of proteins (30, 35, 40 and 45% P) in M. tenellum females was evaluated with respect to the biochemical composition of their eggs (EG), larvae (LR), gonad (GO) and hepatopancreas (HP). Total protein (TP), total carbohydrate (TC) and total lipid (TL) were estimated. In EG, L and P levels influence TP and TL; TP increases in diets higher than P35. In LR, there are no differences (p > 0.05) in TP and in TL, only diets L4P40 and L12P30 were different (p < 0.05). In GO, there is no trend in TP differences; in TC there was variation in the range of the data and TL was higher in L4P30 and L4P35. In HP, the diets with L4 obtained the highest TP values (p < 0.05); the L12 diets were higher in TL (p < 0.05). In general, diets with an inclusion of L12 showed the highest TP, TC and TL means, within this lipid level the P30 diet stood out; therefore, it is recommended to use a diet with L12P30 in the formulation of balanced feed for the species.
Macrobrachium tenellum is an omnivorous freshwater prawn living in rivers near the coast and in coastal lagoons with potential to be cultured. It is distributed in rivers, estuaries, and coastal ...lagoons, and in each of those habitats, it has access to food items with different features and nutritional content. In this research, it has been tested if this variety of food availability has an immediate effect on their digestive enzymatic activity once animals are brought to laboratory and fed with different meals. Wild prawns were captured in a river and coastal lagoon, and after acclimation, they were fed with three different experimental diets. Total alkaline protease, trypsin, chymotrypsin, lipase, and α amylase were measured from prawns fed experimental diets at 15 and 30 days. There were significant differences in the enzymatic activity of prawns depending on their original habitat and diet. However, the proportion in which these enzymes are expressed in the prawns from different treatments remains proportional to what was observed in wild specimens, as reported in previous research. We consider that the study of this phenomenon can contribute to a better understanding of the nutritional needs of this species if a species‐specific diet needs to be prepared.
We determined the effect of four concentrations of dietary crude protein, 30.7, 37.2, 41.8 and 46.8% on growth rate, survival and body composition of the juvenile cauque river prawn (Macrobrachium ...americanum). The prawns were hatched in the laboratory from the spawn of one wild ovigerous female. Prawns consuming 37.2% crude protein reached a final weight of 0.58 g (feed conversion ratio of 2.15), which was significantly better than the other treatments. Survival was 100% in all treatments. Protein content in the diets had no significant effect on whole body proximate composition and amino acid profile. Juveniles consuming the 37.2% crude protein diet grew faster than those fed the other diets. Specific growth rate was adjusted to the two‐slope broken‐line regression analysis model to estimate the optimal protein requirement. In conclusion, these results demonstrated that the 37.2% protein level diet is optimal for juvenile cauque river prawn M. americanum in the experimental conditions of this study.
The effect of different proteins and lipids levels on antioxidant response of superoxide dismutase (SOD) was tested in muscle, hepatopancreas and whole-body tissues of cauque river prawn ...Macrobrachium americanum juvenile. Six diets with two crude protein (35 and 40% diet) and three lipid levels (6, 10, and 14% diet) were tested for juveniles in a factorial manner (3 x 2), to provide six different dietary. Juvenile prawns (0.22 + or - 0.03 g) were randomly placed in 18 plastic tanks (160 L), at a density of 15 juveniles per tank (3 tank replicates/treatment). The assay lasted 60 days. SOD activity was significantly different in muscle, hepatopancreas and whole body depending on proteins and lipids levels in the diet. Results indicate that the diet containing 35% protein and 10% lipid provided adequately to while preventing diet-induced oxidative stress and protecting the integrity of the antioxidant response of SOD.
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