Evaluación de oligosacáridos de manano (MOS) en dietas balanceadas para juveniles de pejelagarto (Atractosteus tropicus)

Background: Prebiotics are polysaccharides that cannot be digested by the host; however, they generate benefits by stimulating the activity of beneficial microorganisms in the digestive system, which can maximize weight gain, feed conversion, and stimulate the immune response. Mannan oligosaccharides (MOS) have been evaluated in several fish species of commercial importance. Goals: Determine inclusion effects of diffe­rent MOS levels in balanced diets for juveniles of Atractosteus tropicus on the growth, productive parameters, survival, somatic indexes, and activity of digestive enzymes. Methods: Six experimental diets including MOS (0.0, 0.2, 0.4, 0.6, and 0.8%) and a trout control diet (DC) were designed, manufactured, and evaluated in triplicate during 62 days. A hundred and eighty juveniles (5.11 ± 0.08 g) were distributed in a recirculation system with 18 tanks of 70 L with a flow of 10 L min-1. Results: The 0.2% MOS diet produced the highest va­lues in weight gained (WG), specific growth rate (SGR), and protein efficiency rate (PER) and the lowest value in feed conversion rate (FCR). Survival in all treatments was greater than 96%. The hepatosomatic index was higher for the 0.4% treatment, while the viscerosomatic index was higher for the 0.4% and 0.6% treatments. All the enzymatic activities (acid protease, alkaline protease, trypsin, chymotrypsin, leucine aminopeptidase, carboxypeptidases, lipases, α-amylase, acid phosphatases, and alkaline phosphatases) showed significant differences by the inclusion of MOS in the diet. Conclusions: Supplementation of 0.2% MOS in diets for juveniles of A. tropicus, generates benefits in growth and productive performance. The inclusion of MOS in diets for juveniles of A. tropicus modifies somatic indices and the activity of digestive enzymes of juveniles.Antecedentes. Los prebióticos, son ingrediente no digerible que benefician al huésped, estimulando selectivamente el crecimiento y la actividad de bacterias benéficas en el sistema digestivo. La eliminación de las colonizaciones bacterianas, estimula la respuesta inmune, maximiza la ganancia de peso, la conversión alimenticia y mejora la resistencia a enfermedades y al estrés. En este contexto, el Manano oligosacárido (MOS) ha sido empleado en varias especies de importancia comercial. Objetivo. Es así que se pretende determinar el efecto de los diferentes niveles de MOS en dietas balanceadas para juveniles de A. tropicus. Métodos. Se diseñó un experimento simple completamente aleatorizado con seis tratamientos, los cuales se evaluaron por triplicado, empleando diferentes porcentajes de MOS (0, 0.2, 0.4, 0.6 y 0.8%) y una dieta control de trucha (DCo). Se seleccionaron 180 juveniles (5.11 ± 0.08 g), que se distribuyeron en un sistema de recirculación. Resultados. La supervivencia en todos los tratamientos fue del 100%, mientras que la dieta 0.2% MOS presentó los valores más altos en crecimiento promedio diario (AWD), tasa de eficiencia proteínica (PER), ganancia en peso (DWR) y tasa específica de crecimiento (SGR), además se presentaron las mayores actividades enzimáticas digestivas (proteasa ácida, proteasa alcalina, tripsina, quimotripsina, leucina aminopeptidasa, y ?-amilasa). Conclusiones.  La suplementación con 0.2% de MOS en dietas para juveniles de pejelagarto, puede ser considerada como un suplemento dietético beneficioso para mejorar el crecimiento y la capacidad digestiva de los juveniles de A. tropicus

Larval Development in Tropical Gar (Atractosteus tropicus) Is Dependent on the Embryonic Thermal Regime: Ecological Implications under a Climate Change Context

In ectotherm species, environmental temperature plays a key role in development, growth, and survival. Thus, determining how temperature affects fish populations is of utmost importance to accurately predict the risk of climate change over fisheries and aquaculture, critical to warrant nutrition and food security in the coming years. Here, the potential effects of abnormal thermal regimes (24, 28 and 32 C; TR24, TR28, and TR32, respectively) exclusively applied during embryogenesis in tropical gar (Atractosteus tropicus) has been explored to decipher the potential consequences on hatching and growth from fertilization to 16 days post-fertilization (dpf), while effects on skeletal development and body morphology were explored at fertilization and 16 dpf. Egg incubation at higher temperatures induced an early hatching and mouth opening. A higher hatching rate was obtained in eggs incubated at 28 C when compared to those at 24 C. No differences were found in fish survival at 16 dpf, with values ranging from 84.89 to 88.86%, but increased wet body weight and standard length were found in larvae from TR24 and TR32 groups. Thermal regime during embryogenesis also altered the rate at which the skeletal development occurs. Larvae from the TR32 group showed an advanced skeletal development, with a higher development of cartilaginous structures at hatching but reduced at 16 dpf when compared with the TR24 and TR28 groups. Furthermore, this advanced skeletal development seemed to determine the fish body morphology. Based on biometric measures, a principal component analysis showed how along development, larvae from each thermal regime were clustered together, but with each population remaining clearly separated from each other. The current study shows how changes in temperature may induce craniofacial and morphological alterations in fish during early stages and contribute to understanding the possible effects of global warming in early development of fish and its ecological implications.Versión del edito

Larval Development in Tropical Gar (Atractosteus tropicus) Is Dependent on the Embryonic Thermal Regime: Ecological Implications under a Climate Change Context

This article belongs to the Special Issue Current Advances and Challenges in Fisheries and Aquaculture Science: Feature Papers for the New Journey of Fishes[EN] In ectotherm species, environmental temperature plays a key role in development, growth, and survival. Thus, determining how temperature affects fish populations is of utmost importance to accurately predict the risk of climate change over fisheries and aquaculture, critical to warrant nutrition and food security in the coming years. Here, the potential effects of abnormal thermal regimes (24, 28 and 32 °C; TR24, TR28, and TR32, respectively) exclusively applied during embryogenesis in tropical gar (Atractosteus tropicus) has been explored to decipher the potential consequences on hatching and growth from fertilization to 16 days post-fertilization (dpf), while effects on skeletal development and body morphology were explored at fertilization and 16 dpf. Egg incubation at higher temperatures induced an early hatching and mouth opening. A higher hatching rate was obtained in eggs incubated at 28 °C when compared to those at 24 °C. No differences were found in fish survival at 16 dpf, with values ranging from 84.89 to 88.86%, but increased wet body weight and standard length were found in larvae from TR24 and TR32 groups. Thermal regime during embryogenesis also altered the rate at which the skeletal development occurs. Larvae from the TR32 group showed an advanced skeletal development, with a higher development of cartilaginous structures at hatching but reduced at 16 dpf when compared with the TR24 and TR28 groups. Furthermore, this advanced skeletal development seemed to determine the fish body morphology. Based on biometric measures, a principal component analysis showed how along development, larvae from each thermal regime were clustered together, but with each population remaining clearly separated from each other. The current study shows how changes in temperature may induce craniofacial and morphological alterations in fish during early stages and contribute to understanding the possible effects of global warming in early development of fish and its ecological implicationsSIThis work was partially funded by “Study of the digestive physiology in larvae and juveniles of tropical gar (Atractosteus tropicus) based on histological, biochemical and molecular techniques” project (Ref. CB-2016-01-282765) from the National Council for Science and Technology (CONACyT) of Mexico. I.F. acknowledges the funding from the MICIU and the European Social Fund, “The European Social Fund invests in your future” through the Ramón y Cajal (Ref. RYC2018-025337-I) contract from the Plan Estatal de Investigación Científica y Técnica e Innovación 2017–2020Authors also thanks the support from the RED LARVAplus “Estrategias de desarrollo y mejora de la producción de larvas de peces en Iberoamérica” (117RT0521) funded by the Programa Iberoamericano de Ciencia y Tecnología para el Desarrollo (CYTED

Effect of β-Glucans in Diets on Growth, Survival, Digestive Enzyme Activity, and Immune System and Intestinal Barrier Gene Expression for Tropical Gar (Atractosteus tropicus) Juveniles

The application of β-1,3/1,6-glucan derived from yeast at five concentrations (0%, 0.5%, 1.0%, 1.5%, and 2.0%) in formulated diets was evaluated in juveniles for its effects on the growth, survival, digestive enzymatic activity, and expression of genes associated with the immune system (interlukin-10 (IL-10), transforming growth factor (TGF), occludin (OCC), mucin2 (MUC2), lysozyme (LYS), and nucleotide-binding and oligomerization domain 2 (NOD2)) in tropical gar (Atractosteus tropicus). For the experiment, three replicates of 30 fish per experimental unit (70 L) were cultivated for 62 days. The growth results showed no statistically significant differences in relation to weight and total length between treatments. The activity of digestive enzymes (alkaline proteases, trypsin, leucine aminopeptidase, and amylase) did not show significant differences between treatments, except for chymotrypsin activity, where fish fed 1.0% and 1.5% of β-glucans showed higher activities compared with the rest of the treatments. On the other hand, the analysis of gene expression did not show significant differences between treatments, although a tendency of increase in the expression of IL-10, TGF, MUC2, and OCC was observed with an addition of 1.5% of the prebiotic, but there was a decrease in the fish fed with 2% of the prebiotic. It is possible to include concentrations of between 0.5% and 1.5% of β-glucans in the diets for A. tropicus, with no detectable adverse effects on growth, survival, digestive enzyme activity, or specific gene expression. β-glucan 1,3/1,6 added at 1.0% and 1.5% in the diet significantly increases chymotrypsin activity.info:eu-repo/semantics/publishedVersio

Evaluation of Mannan oligosaccharides (MOS) in balanced diets for tropical gar juveniles (Atractosteus tropicus)

Antecedentes: Los prebióticos son polisacáridos no digestibles por el huésped, pero, por otro lado, son los encargados de estimular la actividad de microorganismos benéficos en el sistema digestivo, lo que puede maximizar la ganancia en peso, la conversión alimenticia y la activación de la respuesta inmune. Los oligosacáridos de manano (MOS) han sido evaluados en varias especies de peces de importancia comercial. Objetivos: Determinar el efecto de diferentes niveles de MOS integrados en dietas balanceadas para juveniles de Atractosteus tropicus sobre el crecimiento, parámetros productivos, supervivencia, índices somáticos y actividad de enzimas digestivas. Métodos: Se evaluaron por triplicado seis dietas experimentales con inclusión de MOS (0.0, 0.2, 0.4, 0.6 y 0.8%) y una dieta control de trucha (DC) durante 62 días. Se distribuyeron 180 juveniles (5.11 ± 0.08 g) en un sistema de recirculación con 18 tanques de 70 L con flujo de 10 L min-1. Resultados: La supervivencia en todos los tratamientos fue superior al 96%. La dieta 0.2% de MOS presentó los valores más altos en peso ganado (WG), tasa específica de crecimiento (SGR) y tasa de eficiencia proteínica (PER), y el menor valor en tasa de conversión alimenticia (FCR). El índice hepatosomático (HSI) fue mayor para el tratamiento 0.4%, mientras que el índice viscerosomático fue mayor para los tratamientos 0.4% y 0.6%. Todas las actividades enzimáticas determinadas mostraron diferencias entre tratamientos (proteasa ácida, proteasa alcalina, tripsina, quimotripsina, leucina aminopeptidasa, carboxipeptidasas, lipasas, α-amilasa, fosfatasas ácidas y fosfatasas alcalinas). Conclusiones: La suplementación de 0.2% de MOS en dietas para juveniles de A. tropicus genera beneficios en el crecimiento y el rendimiento productivo. La inclusión de MOS en dietas para juveniles de A. tropicus modifica los índices somáticos y la actividad de enzimas digestivas en juveniles.Background: Prebiotics are polysaccharides that cannot be digested by the host; however, they generate benefits by stimulating the activity of beneficial microorganisms in the digestive system, which can maximize weight gain, feed conversion, and stimulate the immune response. Mannan oligosaccharides (MOS) have been evaluated in several fish species of commercial importance. Goals: Determine inclusion effects of different MOS levels in balanced diets for juveniles of Atractosteus tropicus on the growth, productive parameters, survival, somatic indexes, and activity of digestive enzymes. Methods: Six experimental diets including MOS (0.0, 0.2, 0.4, 0.6, and 0.8%) and a trout control diet (DC) were designed, manufactured, and evaluated in triplicate during 62 days. A hundred and eighty juveniles (5.11 ± 0.08 g) were distributed in a recirculation system with 18 tanks of 70 L with a flow of 10 L min-1. Results: The 0.2% MOS diet produced the highest values in weight gained (WG), specific growth rate (SGR), and protein efficiency rate (PER) and the lowest value in feed conversion rate (FCR). Survival in all treatments was greater than 96%. The hepatosomatic index was higher for the 0.4% treatment, while the viscerosomatic index was higher for the 0.4% and 0.6% treatments. All the enzymatic activities (acid protease, alkaline protease, trypsin, chymotrypsin, leucine aminopeptidase, carboxypeptidases, lipases, α-amylase, acid phosphatases, and alkaline phosphatases) showed significant differences by the inclusion of MOS in the diet. Conclusions: Supplementation of 0.2% MOS in diets for juveniles of A. tropicus, generates benefits in growth and productive performance. The inclusion of MOS in diets for juveniles of A. tropicus modifies somatic indices and the activity of digestive enzymes of juveniles.info:eu-repo/semantics/publishedVersio

High-throughput sequencing of the 16S rRNA gene to analyze the gut microbiome in juvenile and adult tropical gar (Atractosteus tropicus)

Tropical gar (Atractosteus tropicus) is freshwater and estuarine fish, inhabiting the Earth since the Mesozoic era and undergoing limited physiological variation ever since. Besides its recognized cultural and scientific relevance, the species has seen remarkable growth in its economic impact due to pisciculture. In this study, we present the first report of the whole taxonomic composition of microbial communities in gut contents in juveniles and adults of A. tropicus, by sex and origin (wild and cultivated). For this study, 508 genera were identified, with the most and least abundant being Cetobacterium and Paludibacter, respectively. Fusobacteria, Proteobacteria, Firmicutes, and Bacteroidetes phyla are the core gut microbiome of A. tropicus juvenile and adult by sex and origin. Deinococcus-Thermus phylum sequence was only identified in wild-type males. In the phylogenetic trees reconstruction Lactococcus lactis strains CAU929 and CAU6600, Cp6 and CAU9951, Cetobacterium strain H69, Aeromonas hydrophila strain P5 and WR-5-3-2, Aeromonas sobria strain CP DC28 and Aeromonas hydrophila were identified, some of them with probiotic potential within the three dominant phyla in core gut microbiome in A. tropicus adults, especially in wild-type organisms. Myroides genus was recognized in microbiota gut of the cultivated juvenile A. tropicus. Nevertheless, Alpha diversity indicated that the highest gut microbiota abundance and richness is found in cultivated juvenile and wild-type adult A. tropicus female, rather than adult wild-type males and the least gut microbiota abundance and richness is found in a cultivated adult of A. tropicus for both sexes.The authors thank the Mexican National Council of Science and Technology for the postgraduate studies thesis scholarship and the mixed scholarship granted to carry out the research internship at the University of Valencia (Spain). This research received external funding from the Mexican National Council of Science and Technology "Strengthening of the Master's Degree in Environmental Sciences for its Permanence in the National Register of Quality Graduates of CONACYT" Reg. No. TAB-2014-C29-245836 and the Project "Estudio de la fisiología digestiva en larvas y juveniles de pejelagarto (Atractosteus tropicus) con base en técnicas histológicas, bioquímicas y moleculares" Reg. No. CB-2016-01-282765.Peer reviewe

Esquemas de alimentación para larvicultura de pejelagarto (Atractosteus tropicus Gill): crecimiento, supervivencia y canibalismo

The design of specific feed based on digestive physiology, and an adequate feeding schedule, are important to reduce cannibalism and increase survival rate in larvae fish. The first objective of this study was evaluating growth, survival and cannibalism during tropical gar (Atractosteus tropicus Gill) larviculture, using four feeding schedules: CT (10 day co-feeding of Artemia nauplii and commercial trout feed), T1 (commercial trout feed), T2 (10 day co-feeding of Artemia nauplii and A. tropicus larvae designed feed) and T3 (A. tropicus larvae designed feed). The second objective was to determinate correlation between survival and cannibalism, using a linear regression model. We observed better growth and survival in the co-feeding treatments CT and T2. Cannibalism was observed in all treatments, with higher presence in T1 and T3 (treatments without Artemia nauplii co-feeding). It was observed a strong correlation between survival and cannibalism (r = -0.88, p < 0.05), demonstrating that cannibalism has a considerable effect on survival rate. We concluded that T2 represent the best alternative for A. tropicus feeding during larviculture, since they present better growth and less cannibalism.El diseño de dietas con base en la fisiología digestiva, así como un adecuado esquema de alimentación, permiten la disminución del canibalismo y el incremento de la supervivencia en la etapa larvaria de peces. Por lo anterior, el objetivo fue evaluar el crecimiento, supervivencia y canibalismo en la larvicultura del pejelagarto (Atractosteus tropicus Gill) bajo cuatro esquemas de alimentación: CT (co-alimentación con nauplio de Artemia por 10 días y dieta comercial de trucha), T1 (alimentación con la dieta comercial de trucha desde la apertura de la boca), T2 (co-alimentación con nauplio de Artemia y dieta diseñada para larvas de A. tropicus por 10 días) y T3 (alimentación con la dieta diseñada para A. tropicus desde la apertura de la boca), así como determinar la correlación entre el canibalismo y la supervivencia mediante un modelo de regresión lineal. Los mejores crecimientos y supervivencias se obtuvieron en los tratamientos T2 y CT. En todos los tratamientos se presentó canibalismo, siendo más alto cuando no se co-alimentó con nauplio de Artemia (T1 y T3). Se encontró una fuerte correlación (r = -0.88, p < 0.05) entre la supervivencia y el canibalismo, lo que demuestra que el canibalismo tiene efecto sobre la supervivencia. El tratamiento T2 representa la mejor alternativa para la larvicultura de A. tropicus, con mayor crecimiento y menor canibalismo

Inclusion of Mannan-Oligosaccharides in Diets for Tropical Gar <i>Atractosteus tropicus</i> Larvae: Effects on Growth, Digestive Enzymes, and Expression of Intestinal Barrier Genes

Mannan-oligosaccharides (MOS) are non-digestible carbohydrates, and their use in aquaculture as prebiotics is well documented. The objective of this work was to test whether MOS supplemented in the diet of A. tropicus larvae (2, 4, and 6 g kg−1) influence growth parameters, the activity of digestive enzymes, and the expression of genes related to the intestinal barrier. The highest total length was observed in larvae fed 6 g kg−1 MOS compared to control larvae. Trypsin activity increased with the addition of MOS to the diets, but leucine aminopeptidase activity only increased with 6 g kg−1 MOS. Lipase and α-amylase activities increased in larvae fed with 2 and 4 g kg−1 MOS. The expression of zo-2 was higher with the 6 g kg−1 MOS treatment. The cl-3 transcripts were lower with 2 g kg−1 MOS but higher with 6 g kg−1 MOS. All tested concentrations of MOS increased the expression of muc-2. In this study, incorporating mannan-oligosaccharides into the diet of A. tropicus larvae had a positive effect, and the concentration of 6 g kg−1 produced the best results. Therefore, including this prebiotic in the diets for the culture of A. tropicus larvae is suitable

Aclimatación en cautiverio del sargo Archosargus probatocephalus (Perciformes: Sparidae)

The sheepshead (Archosargus probatocephalus) is a priority species for mariculture development in southeastern México. The objective of the study was to reproduce in captivity two sheepshead batches, one in captivity for 12 months and another of wild breeders. The batch in captivity was formed by 36 organisms, in a water recirculation system with salinity of 10 psu, with the increase in their length and weight determined each month; in addition, sexual maturity was promoted by gradually increasing the salinity of the system up to 35 psu, after which spawning was induced with an intramuscular injection of 500 UI kg-1 of chorionic and serum gonadotropin hormone. On the other hand, 15 wild breeders were collected from the Alvarado Veracruz lagoon, inducing them to spawn in the same way. The average increase in length of the organisms conditioned to captivity was 0.064 ± 0.02 cm d-1 with average weight of 1.97 ± 0.4 g d-1, sexually maturing in the month of January. Both batches spawned; the eggs obtained had an average diameter of 817.3 ± 20.9 µm, average yolk sac volume of 243 ± 11 µL, average oil drop diameter of 203.5 ± 16.5 and average notochordal length of the eleuteroembryos of 1.65 ± 0.25 mm. It is possible to achieve maturation of the sheepshead in captivity, as well as obtain quality larvae from the induction of breeders in captivity and wild ones in the reproductive season.El sargo (Archosargus probatocephalus) es una especie prioritaria para el desarrollo de la maricultura en el sureste mexicano. El objetivo del estudio fue reproducir en cautiverio dos lotes de sargos, uno en cautiverio por 12 meses y otro de reproductores silvestres. El lote en cautiverio se formó por 36 organismos, en un sistema de recirculación de agua con salinidad de 10 psu, a los que se les determinó el incremento en longitud y peso cada mes, además se promovió la madurez sexual incrementando de forma gradual la salinidad del sistema hasta 35 psu, para luego inducir el desove con una inyección intramuscular de 500 UI kg-1 de hormona gonadotropina coriónica y sérica. Por otra parte, se colectaron 15 reproductores silvestres de la laguna de Alvarado Veracruz, induciéndolos al desove de la misma forma. El incremento promedio en longitud de los organismos acondicionados al cautiverio fue de 0.064 ± 0.02 cm d-1 con peso promedio de 1.97 ± 0.4 g d-1, madurando sexualmente en el mes de enero. Ambos lotes desovaron, los huevos obtenidos tuvieron un diámetro promedio de 817.3 ± 20.9 µm, volumen del saco vitelino promedio de 243 ± 11 µL, diámetro promedio de la gota de aceite de 203.5 ± 16.5 y longitud notocordal promedio de los eleuteroembriones de 1.65 ± 0.25 mm. Es posible lograr la maduración en cautiverio del sargo, así como, obtener larvas de calidad a partir de la inducción de reproductores en cautiverio y silvestres en la época reproductiva

EFFECT OF STOCKING DENSITY ON PRODUCTIVE PERFORMANCE OF JUVENILE OF THE BLACKSTRIPE CICHLID Vieja fenestrata (CICHLIFORMES: CICHLIDAE)

Background: Native fish species are a developing alternative for sustainable aquaculture worldwide and in Mexico, the southern region is leading the efforts in freshwater species. Objective: To assess the effect of different stocking densities on the productive performance of native fish juveniles of blackstripe cichlid (Vieja fenestrata). Methodology: A one-factor randomized experimental design was used, evaluating in triplicate four stocking densities, 0.5 (L), 2 (M), 4 (H) and 6 (S) juvenile L-1. The experiment lasted 30 days. Wet weight and total length were registered every 15 days and growth performance indices were obtained. Results: Growth and survival were superior (P<0.05) for densities L and M. However, the M density showed a higher (P<0.05) growth rate, weight gain, and condition factor. Implications: The stocking density showed an apparent effect on the growth and survival of juveniles of the blackstripe cichlid, with the M density showing the best results; however, a cost-benefit assessment is required before starting production of this tropical native species. Conclusion: Our results suggest that a territorial and/or food competition was probably responsible for the survival and growth obtained. Although more studies are required, it appears that Vieja fenestrata showed the typical patrons of behaviour of another most famous cichlids, as Nile tilapia, with high levels of aggression that depend on stoking density