Gastrointestinal dysbiosis induced by Nocardia sp. infection in tilapia.

Nocardiosis has caused high mortalities among fish cultures; however, the effects of Nocardia infections in the fish gastrointestinal microbiota are unknown. In this research, tilapia was infected with Nocardia sp., to analyze the effect of infection on the gastrointestinal microbiota. Tilapia infected with Nocardia sp. reported a 46 % survival (100 % in non-infected). Moreover, the infection caused severe damage to the stomach microbiota, with a loss of diversity and a significant increase of Proteobacteria (94.8 %), resulting in a negative correlation network between Proteobacteria and other important phyla. Nocardia sp. is an emerging pathogen capable of inducing dysbiosis and causing significant mortalities.

Microbiota plasticity in tilapia gut revealed by meta-analysis evaluating the effect of probiotics, prebiotics, and biofloc.

Tilapia species are among the most cultivated fish worldwide due to their biological advantages but face several challenges, including environmental impact and disease outbreaks. Feed additives, such as probiotics, prebiotics, and other microorganisms, have emerged as strategies to protect against pathogens and promote immune system activation and other host responses, with consequent reductions in antibiotic use. Because these additives also influence tilapia's gut microbiota and positively affect the tilapia culture, we assume it is a flexible annex organ capable of being subject to significant modifications without affecting the biological performance of the host. Therefore, we evaluated the effect of probiotics and other additives ingested by tilapia on its gut microbiota through a meta-analysis of several bioprojects studying the tilapia gut microbiota exposed to feed additives (probiotic, prebiotic, biofloc). A total of 221 tilapia gut microbiota samples from 14 bioprojects were evaluated. Alpha and beta diversity metrics showed no differentiation patterns in relation to the control group, either comparing additives as a group or individually. Results also revealed a control group with a wide dispersion pattern even when these fish did not receive additives. After concatenating the information, the tilapia gut core microbiota was represented by four enriched phyla including Proteobacteria (31%), Fusobacteria (23%), Actinobacteria (19%), and Firmicutes (16%), and seven minor phyla Planctomycetes (1%), Chlamydiae (1%), Chloroflexi (1%), Cyanobacteria (1%), Spirochaetes (1%), Deinococcus Thermus (1%), and Verrucomicrobia (1%). Finally, results suggest that the tilapia gut microbiota is a dynamic microbial community that can plastically respond to feed additives exposure with the potential to influence its taxonomic profile allowing a considerable optimal range of variation, probably guaranteeing its physiological function under different circumstances.

Erythroprotective Potential of Phycobiliproteins Extracted from Porphyridium cruentum.

There are multiple associations between the different blood groups (ABO and RhD) and the incidence of oxidative stress-related diseases, such as certain carcinomas and COVID-19. Bioactive compounds represent an alternative to its prevention and treatment. Phycobiliproteins (PBP) are bioactive compounds present in the microalga Porphyridium cruentum and, despite its antioxidant activity, their inhibitory effect on hemolysis has not been reported. The aim of this work was to evaluate the erythroprotective potential of phycobiliproteins from P. cruentum in different blood groups. The microalga was cultured in F/2 medium under controlled laboratory conditions. Day 10 of culture was determined as the harvest point. The microalgal biomass was lyophilized and a methanolic (MetOH), Tris HCl (T-HCl), and a physiological solution (PS) ultrasound-assisted extraction were performed. Extract pigments were quantified by spectrophotometry. The antioxidant activity of the extracts was evaluated with the ABTS+•, DPPH•, and FRAP methods, finding that the main antioxidant mechanism on the aqueous extracts was HAT (hydrogen atom transfer), while for MetOH it was SET (single electron transfer). The results of the AAPH, hypotonicity, and heat-induced hemolysis revealed a probable relationship between the different antigens (ABO and RhD) with the antihemolytic effect, highlighting the importance of bio-directed drugs.

Longitudinal variations in the gastrointestinal microbiome of the white shrimp, Litopenaeus vannamei.

The shrimp gut is a long digestive structure that includes the Foregut (stomach), Midgut (hepatopancreas) and Hindgut (intestine). Each component has different structural, immunity and digestion roles. Given these three gut digestive tract components' significance, we examined the bacterial compositions of the Foregut, Hindgut, and Midgut digestive fractions. Those bacterial communities' structures were evaluated by sequencing the V3 hypervariable region of the 16S rRNA gene, while the functions were predicted by PICRUSt2 bioinformatics workflow. Also, to avoid contamination with environmental bacteria, shrimp were maintained under strictly controlled conditions. The pairwise differential abundance analysis revealed differences among digestive tract fractions. The families Rhodobacteraceae and Rubritalaceae registered higher abundances in the Foregut fraction, while in the Midgut, the families with a higher proportion were Aeromonadaceae, Beijerinckiaceae and Propionibacteriaceae. Finally, the Cellulomonadaceae family resulted in a higher proportion in the Hindgut. Regarding the predicted functions, amino acid and carbohydrate metabolism pathways were the primary functions registered for Foregut microbiota; conversely, pathways associated with the metabolism of lipids, terpenoids and polyketides, were detected in the Midgut fraction. In the Hindgut, pathways like the metabolism of cofactors and vitamins along with energy metabolism were enriched. Structural changes were followed by significant alterations in functional capabilities, suggesting that each fraction's bacteria communities may carry out specific metabolic functions. Results indicate that white shrimp's gut microbiota is widely related to the fraction analyzed across the digestive tract. Overall, our results suggest a role for the dominant bacteria in each digestive tract fraction, contributing with a novel insight into the bacterial community.

Dry matter, protein, and energy digestibility of diets for juvenile Pacific white leg shrimps (Litopenaeus vannamei) reared at different salinity levels / Digestibilidade da matéria seca, proteína e energia de dietas para camarão juvenil do Pacífico (Litopenaeus vannamei) cultivadas em diferentes níveis de salinidades

ABSTRACT: This study evaluated the effect of low, medium, and high-water salinity (5, 35, and 50 ppt) on the apparent dry matter, protein, and energy digestibility of two formulated and six commercial diets for juvenile whiteleg shrimp, Litopenaeus vannamei, in a 120-day trial. Digestibility was determined in vivo using chromic oxide as an inert diet marker. Hydrostability in pellets varied from 86.8% to 99.9%; dry matter digestibility varied from 49.1% to 64.1%; protein digestibility showed greater variations at all salinities (56.9%-85.8%); and energy digestibility ranged from 70.1 to 86.4%. Salinity had a significant effect on dry matter, protein, and energy digestibility. Using a principal component analysis (PCA) with a covariance matrix, our findings suggested that the E2 (fishmeal-based formulation) diet and 35 ppt salinity provided optimum hydrostability and digestibility to Pacific white leg shrimp juveniles.

RESUMO: Nós medimos o efeito de baixa, normal e alta salinidade (5, 35 e 50ppt) na digestibilidade aparente da matéria seca, proteína e energia em duas dietas formuladas e seis comerciais para camarão juvenil do Pacífico, Litopenaeus vannamei. Os coeficientes de digestibilidade aparente da matéria seca, proteína e energia foram determinados in vivo utilizando o óxido crômico como marcador inerte nas dietas (peso inicial médio de 4g), em um teste de 120 dias. Hidrostabilidade na dieta de 86,8% a 99,9%, os coeficientes de digestibilidade da matéria seca variaram de 49,1 a 64,1%, os coeficientes de digestibilidade da proteína apresentaram maiores variações em todas as salinidades (56,9-85,8%), enquanto os coeficientes de digestibilidade da energia variaram de 70,1 a 86,4%. Efeito significativo da salinidade na digestibilidade da matéria seca, proteína e energia foi encontrado. Esses resultados, usando a análise de componentes principais (PCA) com a matriz de covariância, sugerem que a dieta E2 (fórmula à base de farinha de peixe) e salinidade a 35 ppt é ideal para a hidrostabilidade e digestibilidade das dietas para juvenis de camarão-branco-do-Pacífico.

Implementation and Evaluation of Open-Source Hardware to Monitor Water Quality in Precision Aquaculture.

Precision aquaculture is a new field that allows farmers to have better control over aquaculture processes, facilitating decision-making and improving efficiency. The implementation and evaluation of a low-cost water-quality monitoring system based on open-source hardware, which is easy to rebuild for scientific applications, is reported in this paper. The proposed system measures temperature, dissolved oxygen, and pH, taking records and sending information through a wireless protocol (ZigBee) to a graphical user interface which can display information numerically and graphically, as well as simultaneously storing the information in a database. These variables are very important for aquaculture, as they have a direct influence on critical culture parameters such as growth and survival. Although it is a low-cost system, it offers good quality data and demonstrates efficiency for its use in precision aquaculture.

The implication of metabolically active Vibrio spp. in the digestive tract of Litopenaeus vannamei for its post-larval development.

This work aimed to evaluate the link between the occurrence/abundance of Vibrio populations and bacterial composition in shrimp's intestine (Litopenaeus vannamei) during post-larval ontogenetic development and in its culture water, and the correlation of these with environmental parameters. The total and metabolically active populations of Vibrio in the digestive tract of shrimp during its post-larval development were analysed using quantitative PCR (qPCR) and reverse transcription qPCR targeting the 16S rRNA gene sequence. A lab-scale shrimp bioassay was performed for 80 days in a recirculating aquarium under strictly controlled conditions. The results indicate that the Vibrio population from shrimp's gut is associated with its developmental stage and the environment. Multivariate analyses revealed that the presence of Vibrio spp. drove the studied system, but their metabolically active performance was related to earlier developmental stages in an aqueous environment. Also, the samples taken from water of culture units to compare the influence of the aquatic environment on the intestinal microbial community during shrimp's ontogenetic development showed significant differences. Finally, our results revealed that Vibrio is an important member of shrimp's gut microbiota; however, its metabolic activity seems to be highly regulated, possibly by the host and by the rest of the microbiota.

Dosage and frequency effects of the microalgae Dunaliella sp. on the diet of Litopenaeus vannamei challenged with Vibrio parahaemolyticus.

Carotenoid sources in shrimp diets have shown to be effective for improving survival, growth, reproductive capacity, stress resistance, and also for diminishing disease. Dunaliella sp. is known to have high levels of ß-carotenes, which works as pro-vitamin A, enhancing the immune response in shrimp. However, the administration of Dunaliella sp. in shrimp diet needs to be evaluated to determine the appropriate dose and frequency of administration needed to optimize performance in cultured white shrimp. Diets with three different concentrations of Dunaliella sp. flour (1.5, 2 and 3%) were tested, and each one was administered at three different time frequencies: daily, and at 3- and 7-days intervals. Shrimp fed for 20 days were then infected with Vibrio parahaemolyticus (1 × 106 CFU/mL). Hemolymph parameters including protein, glucose, lactate, cholesterol and triglycerides were analyzed to evaluate shrimp stress status. Additionally, L. vannamei innate non-specific immune response was examined by evaluating the activity of prophenoloxidase (proPO), phenoloxidase (PO) and superoxide dismutase (SOD) in hemolymph; shrimp survival was also recorded. Survival after infection with V. parahaemolyticus was higher for shrimp fed with diets consisting of 2% Dunaliella sp. administered every 3 and 7 days. Shrimp fed a diet consisting of 2% or 3% Dunaliella sp. administered every third day showed positive physiological and immune responses to infection. A decrease in lipid oxidation in plasma triglycerides was observed at 48 h post inoculation in shrimp fed at all diets regimes due to Dunaliella sp. antioxidant action. Experimental results suggest the importance of Dunaliella sp. dosage and feeding frequency in L. vannamei diet to improve the survival and immune response.

Survival of Litopenaeus vannamei shrimp fed on diets supplemented with Dunaliella sp. is improved after challenges by Vibrio parahaemolyticus.

Survival of Litopenaeus vannamei was evaluated during a Vibrio parahaemolyticus infection. This bacteria has been causing significant economic losses in the shrimp industry due to the appearance of early mortality syndrome (EMS), also known as acute hepatopancreatic necrosis disease (AHPND). Control of bacteria in ponds is difficult to achieve with antibiotics due to environmental infections and antibiotic resistance. New methods have been proposed to control and prevent the impact of bacterial infections. The physiological response indicated by plasma biochemical parameters in shrimp can determine their health and stress status. Meanwhile, shrimp immunology is the key factor in establishing strategies to control diseases. Immunostimulants are the best alternative to antibiotics to prevent or minimize disease damage, and at the same time, these stimulants improve the immune system in shrimp. Four diets containing 1.5, 2, 2.5 and 3% of Dunaliella sp. with high ß-carotene content were tested in the present study. After 20days of feeding, organisms were infected with V. parahaemolyticus. Protein, glucose, lactate, triglyceride and cholesterol levels, as well as activity of prophenoloxidase and phenoloxidase, were determined 48 h post-infection (hpi). Shrimp fed a diet with 3% Dunaliella sp. showed the highest survival. Glucose, cholesterol, and triglyceride levels, as well as prophenoloxidase and phenoloxidase activity, were not observed to be suitable indicators during this bacterial infection. The results indicated that the inclusion of Dunaliella sp. in diet increases survival in L. vannamei infected with V. parahaemolyticus.

From microbes to fish the next revolution in food production.

Increasing global population and the consequent increase in demand for food are not a new story. Agroindustrial activities such as livestock help meet this demand. Aquaculture arose decades ago and revolutionized the agroindustrial activity as a significant food generator. However, like livestock, aquaculture is based on finite resources and has been accused of being unsustainable. Abandoning aquaculture is not an option considering the food, foreign exchange, and employment it generates, and therefore must be reinvented. Among the many alternatives suggested to make aquaculture more sustainable, microorganisms have been highlighted as a direct food source for cultured fish and crustaceans, a strategy that promises to revolutionize aquaculture by eliminating waste. Considering waste, as part of a cycle, it can increase stock densities and reduce emissions of contaminants and operational costs.

Navicula sp. Sulfated Polysaccharide Gels Induced by Fe(III): Rheology and Microstructure.

A sulfated polysaccharide extracted from Navicula sp. presented a yield of 4.4 (% w/w dry biomass basis). Analysis of the polysaccharide using gas chromatography showed that this polysaccharide contained glucose (29%), galactose (21%), rhamnose (10%), xylose (5%) and mannose (4%). This polysaccharide presented an average molecular weight of 107 kDa. Scanning electron microscopy (SEM) micrographs showed that the lyophilized Navicula sp. polysaccharide is an amorphous solid with particles of irregular shapes and sharp angles. The polysaccharide at 1% (w/v) solution in water formed gels in the presence of 0.4% (w/v) FeCl3, showing elastic and viscous moduli of 1 and 0.7 Pa, respectively. SEM analysis performed on the lyophilized gel showed a compact pore structure, with a pore size of approximately 150 nm. Very few studies on the gelation of sulfated polysaccharides using trivalent ions exist in the literature, and, to the best of our knowledge, this study is the first to describe the gelation of sulfated polysaccharides extracted from Navicula sp.

Bio-filtration capacity, oxygen consumption and ammonium excretion of Dosinia ponderosa and Chione gnidia (Veneroida: Veneridae) from areas impacted and non-impacted by shrimp aquaculture effluents.

Mollusks are some of the most important, abundant and diverse organisms inhabiting not only aquatic ecosystems, but also terrestrial environments. Recently, they have been used for bioremediation of aquaculture effluents; nevertheless, for that purpose it is necessary to analyze the capacity of a particular species. In this context, an experimental investigation was developed to evaluate the performance of two bivalves C. gnidia and D. ponderosa, collected from areas with or without shrimp aquaculture effluents. For this, the filtration capacity (as clearance rate) as well as the oxygen consumption and ammonia excretion rates were measured following standard methods. The clearance rate was significantly higher for D. ponderosa from impacted areas, when com- pared to C. gnidia, from both areas. Contrarily, the oxygen consumption was greater for C. gnidia from impacted areas compared to D. ponderosa from both areas. The same tendency was observed for the ammonia excretion with the highest rates observed for C. gnidia from impacted areas, whereas no differences were observed among D. ponderosa from both areas. The results suggest that both species developed different strategies to thrive and survive under the impacted conditions; D. ponderosa improved its filtration efficiency, while C. gnidia modified its oxygen consumption and ammonia excretion. We concluded that both species, and particularly D. ponderosa, can be used for bioremediation purposes.

Bio-filtration capacity, oxygen consumption and ammonium excretion of Dosinia ponderosa and Chione gnidia (Veneroida: Veneridae) from areas impacted and non-impacted by shrimp aquaculture effluents / Bio-filtración, consumo de oxígeno y excreción amoniacal de Dosinia ponderosa y Chione gnidia (veneroida: veneridae), en áreas impactadas y no impactadas por efluentes de granjas camaroneras

Mollusks are some of the most important, abundant and diverse organisms inhabiting not only aquatic ecosystems, but also terrestrial environments. Recently, they have been used for bioremediation of aquaculture effluents; nevertheless, for that purpose it is necessary to analyze the capacity of a particular species. In this context, an experimental investigation was developed to evaluate the performance of two bivalves C. gnidia and D. ponderosa, collected from areas with or without shrimp aquaculture effluents. For this, the filtration capacity (as clearance rate) as well as the oxygen consumption and ammonia excretion rates were measured following standard methods. The clearance rate was significantly higher for D. ponderosa from impacted areas, when com- pared to C. gnidia, from both areas. Contrarily, the oxygen consumption was greater for C. gnidia from impacted areas compared to D. ponderosa from both areas. The same tendency was observed for the ammonia excretion with the highest rates observed for C. gnidia from impacted areas, whereas no differences were observed among D. ponderosa from both areas. The results suggest that both species developed different strategies to thrive and survive under the impacted conditions; D. ponderosa improved its filtration efficiency, while C. gnidia modified its oxygen consumption and ammonia excretion. We concluded that both species, and particularly D. ponderosa, can be used for bioremediation purposes.

Los moluscos son algunos de los organismos más importantes, abundantes y diversos que habitan no solo ecosistemas acuáticos sino también terrestres. Recientemente ellos han sido utilizados para la biorremediación de efluentes acuícolas; para este propósito, es necesario conocer la capacidad de especies particulares que funcionan como biorremediadores. En este contexto, se evaluó la eficiencia de filtración (medida como tasa de clarificación), así como las tasas de consumo de oxígeno y excreción amoniacal en los bivalvos D. pon- derosa y C. gnidia recolectados en áreas impactadas y no impactadas por efluentes de granjas camaroneras. La tasa de clarificación fue mayor para D. ponderosa procedente de áreas impactadas, comparada con la de C. fluctifraga en las dos áreas de recolecta. Contrariamente, la tasa de consumo de oxígeno fue superior en C. gnidia en las áreas impactadas al compararla con organismos de áreas no impactadas y con D. ponderosa de las dos áreas de recolecta. La tasa de excreción amoniacal siguió una tendencia similar con valores más altos para C. gnidia en áreas impactadas, mientras que no se observaron diferencias para D. ponderosa entre las áreas de recolecta. Los resultados sugieren que ambas especies desarrollan diferentes estrategias para adaptarse y sobrevivir bajo condiciones de impacto; D. ponderosa mejora su eficiencia de filtración y C. gnidia modifica su consumo de oxígeno y excreción amoniacal. Se concluye que ambas especies, pero sobre todo D. ponderosa pueden ser utilizadas con propósitos de biorremediación.

Apparent carbohydrate and lipid digestibility of feeds for whiteleg shrimp, Litopenaeus vannamei (Decapoda: Penaeidae), cultivated at different salinities.

Whiteleg shrimp, Litopenaeus vannamei is one of the most commercially farmed species worldwide because of its fast growth, good survival rate at high farming densities, and osmoregulatory capacity, which makes it an excellent candidate for cultures at different salinities. The knowledge of shrimp nutritional requirements is critical in the formulation of diets to allow optimal growth at different environmental conditions and development stages. The effect of salinity on apparent digestibility of shrimp feed is not well known, and this information is required in shrimp diet formulation. For this purpose, the apparent digestibility coefficients of carbohydrates (ACD) and lipids (ALD) were determined for juvenile whiteleg shrimps under controlled culture conditions. We evaluated the apparent digestibility of six commercial (D1:37CP, D2:38CP, D3:39CP, D4:34CP, D5:35CP, and D6:37CP) and two experimental (E1:33CP and E2:33CP) diets for juvenile whiteleg shrimp cultivated at three salinities (5, 35 and 50 psu) in 60 L aquariums. ACD and ALD were determined in vivo using chromic oxide as an inert marker. Our results showed that ALD in most cases was over 80%, independent of salinity, except the E1:33CP diet which had 74.0% at 50 psu. Diet D3:39CP showed the highest ALD coefficient (90.1 and 90.6% at 5 and 35 psu, respectively). For ACD, differences were detected between commercial and experimental diets at every salinity level, although salinity effect on ACD was not significant. Diet D4:34CP had the highest coefficient (92.4%) at 5 psu, and E2:33CP at 35 and 50 psu (97.3 and 94.7%). This study demonstrated that there is no significant effect of saline variations on carbohydrate and lipid digestibility by juvenile whiteleg shrimp, under the experimental conditions.

Apparent carbohydrate and lipid digestibility of feeds for whiteleg shrimp, Litopenaeus vannamei (Decapoda: Penaeidae), cultivated at different salinities / Digestibilidad aparente de carbohidratos y lípidos en alimentos para camarón blanco, Litopenaeus vannamei (Decapoda: Penaeidae), cultivados en diferentes salinidades

Whiteleg shrimp, Litopenaeus vannamei is one of the most commercially farmed species worldwide because of its fast growth, good survival rate at high farming densities, and osmoregulatory capacity, which makes it an excellent candidate for cultures at different salinities. The knowledge of shrimp nutritional requirements is critical in the formulation of diets to allow optimal growth at different environmental conditions and development stages. The effect of salinity on apparent digestibility of shrimp feed is not well known, and this information is required in shrimp diet formulation. For this purpose, the apparent digestibility coefficients of carbohydrates (ACD) and lipids (ALD) were determined for juvenile whiteleg shrimps under controlled culture conditions. We evaluated the apparent digestibility of six commercial (D1:37CP, D2:38CP, D3:39CP, D4:34CP, D5:35CP, and D6:37CP) and two experimental (E1:33CP and E2:33CP) diets for juvenile whiteleg shrimp cultivated at three salinities (5, 35 and 50psu) in 60L aquariums. ACD and ALD were determined in vivo using chromic oxide as an inert marker. Our results showed that ALD in most cases was over 80%, independent of salinity, except the E1:33CPdiet which had 74.0% at 50psu. Diet D3:39CP showed the highest ALD coefficient (90.1 and 90.6% at 5 and 35psu, respectively). For ACD, differences were detected between commercial and experimental diets at every salinity level, although salinity effect on ACD was not significant. Diet D4:34CP had the highest coefficient (92.4%) at 5psu, and E2:33CP at 35 and 50psu (97.3 and 94.7%). This study demonstrated that there is no significant effect of saline variations on carbohydrate and lipid digestibility by juvenile whiteleg shrimp, under the experimental conditions. Rev. Biol. Trop. 61 (3): 1201-1213. Epub 2013 September 01.

El camarón blanco, Litopenaeus vannamei, es una de las especies más cultivadas comercialmente en el mundo, debido a su velocidad de crecimiento y tasa de supervivencia en altas densidades de cultivo, y su capacidad de osmoregulación, que lo hacen un excelente candidato para cultivo en diferente salinidades. El conocimiento de los requerimientos nutricionales del camarón es fundamental en la formulación de dietas que permita el crecimiento óptimo en diferentes condiciones ambientales y fases de desarrollo del animal. El efecto de la salinidad sobre la digestibilidad aparente de alimentos comerciales para camarones no está documentado. Esta información es necesaria en el cultivo de camarón para la formulación de los alimentos comerciales. Se determinó la digestibilidad aparente de los carbohidratos (ACD) y lípidos (ALD), en juveniles del camarón blanco L. vannamei cultivado en condiciones controladas. Los tratamientos fueron seis dietas comerciales (D1:37CP, D2:38CP, D3:39CP, D4:34CP, D5:35CP y D6:37CP) y dos dietas experimentales (E1:33CP y E2:33CP) para juveniles de camarón blanco en cultivo, a tres salinidades (5, 35 y 50ups) en acuarios de 60L. Los coeficientes de digestibilidad aparente de los carbohidratos (ACD) y los lípidos (ALD) fueron determinados in vivo utilizando óxido crómico como marcador inerte en la dieta. ALD en la mayoría de los tratamientos fue superior al 80%, independientemente de la salinidad, con excepción de la dieta E1:33CP que presentó 74.0% a salinidad de 50ups. La dieta D3:39CP presentó el mayor coeficiente ALD (90.1 y 90.6 en 5 y 35ups, respectivamente). En ACD, se presentaron diferencias entre dietas comerciales y experimentales en cada nivel de salinidad, aunque la salinidad no presentó un efecto significativo. La dieta D4:34CP presentó el coeficiente de digestibilidad más alto (92.4%) en la salinidad de 5ups, mientras que E2:33CP en salinidades de 35 y 50ups fue de 97.3 y 94.7%, respectivamente. En general, el presente estudio demuestra que en juveniles de camarón blanco la variación de salinidad no afecta significativamente la digestibilidad de lípidos y carbohidratos en las condiciones experimentales de este estudio.

Efecto del nivel proteico de la dieta sobre el desarrollo de juveniles de la langosta australiana Cherax quadricarinatus (Decapoda: Parastacidae) / Effect of diet protein on the development of young Australian lobsters, Cherax quadricarinatus (Decapoda: Parastacidae)

An experimental study was conducted from October to December, 1999, in the aquaculture facilities of CIBNOR SC, at La Paz, BCS. To evaluate the effect of diet protein level on the productive response, in juveniles of the australian lobster, Cherax quadricarinatus, diets with four levels of crude protein (20.45, 28.25, 37.33 y 45.44), were formulated and probed. Growth, grow rate, survival, biomass and food conversion rate were greater in juveniles fed with diets of 37.33 and 45.44 of crude protein. It is concluded that diet protein level affects the productive response of redclaw and a level of 37 of crude protein in the diet is enough to obtain acceptable results.

[Effect of the protein level in the diet on the development of young Australian lobsters, Cherax quadricarinatus (Decapoda: Parastacidae)]. / Efecto del nivel proteico de la dieta sobre el desarrollo de juveniles de la langosta australiana Cherax quadricarinatus (Decapoda: Parastacidae).

An experimental study was conducted from October to December, 1999, in the aquaculture facilities of CIBNOR SC, at La Paz, BCS. To evaluate the effect of diet protein level on the productive response, in juveniles of the australian lobster, Cherax quadricarinatus, diets with four levels of crude protein (20.45, 28.25, 37.33 y 45.44%), were formulated and probed. Growth, grow rate, survival, biomass and food conversion rate were greater in juveniles fed with diets of 37.33 and 45.44% of crude protein. It is concluded that diet protein level affects the productive response of redclaw and a level of 37% of crude protein in the diet is enough to obtain acceptable results.