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This study was undertaken to determine the digestible protein requirement of Amazonian pintado (Pseudoplatystoma reticulatum × Leiarius marmoratus) during growing phase (290–650 g), and the impact of digestible protein levels to body yield, fillet quality, total ammonia excretion rate, and meat chemical composition. Seven digestible protein levels diets were evaluated, 225, 250, 275, 300, 325, 350, or 375 g kg−1. The experiment was carried out in a completely randomized design with seven treatments (digestible protein levels) and five replicates. The experiment lasted for 72 days. Production performance did not differ between treatments, except for protein efficiency rate, which was highest (P < 0.05) in the fish that received the diet with the lowest digestible protein content. Digestible protein levels above 325 g kg−1 allowed less (P < 0.05) fat accumulation in the carcass. Ammonia excretion rate fitted a quadratic model (P < 0.05). According to the model used, the minimum ammonia excretion value was 0.06225 µg L−1 g−1, corresponding to a digestible protein input of 255 g kg−1. The average fillet color (b*) value was higher (P < 0.05) (15.4) in the group fed 250 g kg−1 digestible protein than in the fish fed 350 g kg−1 digestible protein, whereas the other groups showed intermediate results. Fillet pH, shear force, drip loss, and cooking loss did not differ (P > 0.05) between the digestible protein levels. Digestible protein levels above 325 g kg−1 allowed less fat accumulation in the carcass. Based on the ammonia excretion model, it was recommended 255 g kg−1 of digestible protein level in diets to Amazonian pintado in growing phase. [ABSTRACT FROM AUTHOR]

The golden mussel (Limnoperna fortunei), a mollusc originating from Asia, has caused considerable environmental and economic damage in various Brazilian river basins and reservoirs. Genetic studies that focus on characterizing its invasive potential and the feasibility of control measures are required. The present study identified and characterized 13 new microsatellite markers (of which eight were polymorphic) in L. fortunei using enriched genetic libraries. The analysis performed on 48 individuals from three populations identified 32 alleles, ranging from one to seven alleles per locus. The size of the fragments ranged from 172 to 381 bp. The polymorphic information content values ranged from 0.114 to 0.768, with observed and expected heterozygosity values ranging from 0.043-0.938 to 0.123-0.805, respectively. Six loci showed significant deviation from the Hardy-Weinberg equilibrium, possibly influenced by the heterozygous deficit. The microsatellite primers developed will be useful in studies of the genetic diversity and population structure of L. fortunei and will also contribute to the adoption of control measures for this invasive species in Brazilian and other South American basins. KEY WORDS: golden mussel, genetic diversity, population structure, mollusc, primers, SSR, Limnoperna fortunei, INTRODUCTION The golden mussel Limnoperna fortunei (Dunker, 1857) is a bivalve mollusc of the Mytilidae family, with origins in Southeast Asia, mainly from China (Rtickert et al. 2004), and is [...]

The digestive tract of fish has many morphological adaptations related to habitat and nutrition. Intestinal biometry may reflect these adaptations. Here, we aimed to describe histometric patterns in farmed fish and their relationship with feeding by using a standardized protocol considering cell density by tissue area. Five juvenile specimens of each species (Pseudoplatystoma corruscans, Piaractus mesopotamicus, and Oreochromis niloticus) were used. O. niloticus possessed higher intestinal weight and length besides higher intestinal quotient and intestinal somatic index than the other species. The general histological composition was similar between species. However, P. corruscans showed differences in thickness between the anterior and posterior segments. O. niloticus had thinner serosa and muscularis layers than the other species. The cell density was distinct in both species and segments. Comparing the intestinal segments, O. niloticus displayed the lowest count of granulocytes. Goblet cell density was lower in P. mesopotamicus in all segments. However, the volume of these cells was higher in the anterior and middle anterior segments. Our data demonstrated that intestinal structural plasticity is associated with the difference in feeding habits. Here, we used quantitative standardized histometric criteria to understand the morphophysiological diversity of the fish digestive tract, and this technique can be applied in future studies to evaluate changes in the digestive tracts of vertebrates. [ABSTRACT FROM AUTHOR]

Hybrid cachapinta (Pseudoplatystoma reticulatum × Pseudoplatystoma corruscans) has been a very popular fish and is well accepted by consumers internationally, however, there is a lack of information showing its advantages relative to its parental cachara (P. reticulatum) species. This study was undertaken to compare the processing yield and meat quality characteristics of cachara and the cachapinta hybrid raised in net cages. Cachara's weight was 1.51 ± 0.27 kg and total length was 49.85 ± 6.22 cm at harvest and was not significantly different from hybrid cachapinta that weighed 1.50 ± 0.11 kg and measured 50.83 ± 3.91 cm. Additionally, the two groups were not statistically different on gutted fish dress out (cachara: 89.97 ± 1.28%; cachapinta: 90.23 ± 0.30%) and other processing yield parameters. Skinless shank fillets with an average weight of 503.77 ± 0.10 g (cachara) and 514.41 ± 0.04 g, (hybrid cachapinta) were evaluated for pH, water holding capacity, colour (L*, a*, b*), shear force and lipid oxidation (TBARS). There were no differences in the fillet meat quality between cachara and hybrid cachapinta tested in this study. In conclusion, both genetic groups had similar processing yield and fillet meat quality characteristics when produced in net cages. The perceived improvements in growth and disease-resistance generated by hybrid vigour are the main reasons for interest and use of hybrid fishes. It is difficult to systematically predict processing yield and meat quality obtained from hybrids. Processing yields and meat quality are similar for cachara and hybrid cachapinta produced in net cages. [ABSTRACT FROM AUTHOR]

Jewel tetra (Hyphessobrycon eques) is a freshwater fish found in several rivers and basins in South America. The present study is the first study to create a panel of microsatellite markers for detecting genetic diversity in H. eques and evaluating the application of these markers in Serrapinnus notomelas. In total, 44 individuals were genotyped from the natural (WIL, n = 20) and stock in captivity (CAP, n = 24) population. Moreover, 19 microsatellite markers were obtained, of which only 8 loci presented a high degree polymorphism. In total, 45 alleles were detected, ranging from 126 bp (Hype2G2) to 420 bp (Hype2E2). The Hardy–Weinberg equilibrium (p < 0.05) revealed significant difference in one locus in WIL (Hype1G4) and three loci in CAP (Hype1F4, Hype2C3, and Hype2G2). Null alleles (p < 0.05) were present in only one locus (Hype1G4). The WIL and CAP populations revealed high genetic diversity during FST analysis. The cross-amplification test for S. notomelas revealed that only two loci (Hype2C3 and Hype2G2B) presented satisfactory transferability results. The developed microsatellite primers will be useful in studying the genetic diversity and population structure of H. eques in wild populations and fish farms in the Brazilian and other South American basins. [ABSTRACT FROM AUTHOR]

Keywords: bacteriosis; cachara; fish farm; intestine; probiotic bacteria EN bacteriosis cachara fish farm intestine probiotic bacteria 2348 2352 5 04/19/21 20210501 NES 210501 The Order Siluriformes, in which the I Pseudoplatystoma reticulatum i is inserted, popularly known as "cachara" includes fish with wide distribution in South American hydrographic basins, with differentiated morphological peculiarities and piscivorous eating habits, generally associated with the areas closest to the substrate (Baumgartner et al., 2012; Britski et al., 1986; Ferreira et al., 1998). Bacillus subtilis improves non-specific immunity and survival of Pseudoplatystoma reticulatum challenged with Aeromonas hydrophila during the feeding training phase. [Extracted from the article]

Summary: The objective of this study was to evaluate the effects of cold and room‐temperature storage on the quality of Colossoma macropomum sperm. The experiment was carried out in December (end of Spring), in Nova Mutum‐MT, Brazil, involving nine C. macropomum males (4 years old; 6.4 ± 1.5 kg average weight). The fish were selected and transferred to masonry tanks (4 m3) in a laboratory (water renewal rate: 10 L/s; average water temperature: 28°C). Subsequently, reproduction was induced using 2.5 mg of crude carp pituitary extract/kg and the semen was harvested 240 degree hours after hormonal induction. The following sperm characteristics were analyzed every 5 hr using ImageJ/casa software: total motility (MOT), curvilinear velocity (VCL), average path velocity (VAP), straight‐line velocity (VSL), straightness of sperm path (STR), wobble (WOB), progressive motility (PROG), beat cross frequency (BCF) and total number of spermatozoa (NSPZ). A fresh sample of semen from each animal was kept at room temperature (25.3 ± 1.2°C). For analysis of cooled semen, syringes were kept in cooling boxes at an average temperature of 16.9 ± 2.1°C. The reduction (p < 0.05) of MOT in semen kept at room temperature occurred at 10 hr (13.95%); in cooled semen, however, MOT declined at 15 hr (76.87%). At 15 hr, there was practically no MOT in the semen kept at room temperature (0.20%), whereas in the cooled semen this situation was observed only at 35 hr (2.91%) The MOT of cooled sperm was higher (p < 0.05) at all times (except zero time), compared with the semen maintained at room temperature. At 15 hr, the cooled spermatozoa showed higher (p < 0.05) VCL (142.18 μm/s) and BCF (29.72 Hz) than those maintained at room temperature (VCL: 51.18 μm/s; BCF: 19.57 Hz). After 15 hr, only the cooled sperm showed quality. In conclusion, semen cooling allows for extending the viability of C. macropomum spermatozoa from 5 to 10 hr without compromising their quality in most characteristics. At 15 and 25 hr of cooling, sperm viability is still observed, though with decreased quality. [ABSTRACT FROM AUTHOR]

Brycon orbignyanus is a neotropical fish found in several South American countries. This species has high ecological importance and is included in the list of fish threatened with extinction. In this study, we report the development and characterisation of 12 microsatellite primers of B. orbignyanus for future genetic studies. Screening of the 12 markers in a sample of 35 individuals identified seven polymorphic loci and 22 alleles, with one to three alleles per locus. The polymorphic information content ranged from 0.054 to 0.542, with four loci showing significant deviation from Hardy-Weinberg equilibrium. Two loci possessed null alleles. Cross-species amplification tests in two closely related species showed that 11 loci are transferrable to Brycon gouldingi (B. gouldingi) and nine are transferrable to B. falcatus. The microsatellite primers designed may be used for genetic variability and population structure studies in wild populations, fish farms and restocking programmes of B. orbignyanus and the two related species. [ABSTRACT FROM AUTHOR]

The objective of this work was to evaluate the semen characteristics of C. macropomum fish from three successive semen sample collections taken during the same reproductive cycle. Six breeders (6.4 ± 1.5 kg) induced with crude carp pituitary extract (2.5 mg kg−1) were used. Samples of semen were collected in graduated syringes after a period of 260 degree-hours. The semen was collected from the same males in September 2014 (sample 1), December 2014 (64 days after the first collection - sample 2) and February 2015 (86 days after the second collection - sample 3). The semen volume was higher ( P < 0.05) in the sample 1 (6.7 mL) and sample 2 (3.4 mL) than in the sample 3 (1.0 mL). Sperm concentration and normal sperm did not significantly differ between samples. Likewise, sperm motility, curvilinear velocity, displacement velocity, oscillation and beat cross frequency did not vary, whereas straight-line velocity, straightness and progression were higher ( P < 0.05) in sample 2 (December). In general, despite lower amounts, the semen appeared to be of good quality for all three samples collected during the same reproductive period. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate Ovopel and carp pituitary extract (CPE) in the reproductive induction of Colossoma macropomum males. Nine treatments were tested in triplicate, totaling 27 experimental units. C. macropomum breeders were subjected to the following treatments: 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, and 0.7 Ovopel pellet/kg; 2.5 mg CPE/kg (traditional protocol); and a control treatment (no hormone). Breeders under hormone treatment produced a larger (P < 0.05) semen volume (2.4 ± 0.7 to 4.2 ± 0.3 mL) compared with the control (0.9 ± 0.4 mL). Sperm concentration did not differ significantly among treatments (7.2 × 10 9 ± 1.7 to 10.8 × 10 9 ± 2.6 spermatozoa/mL). Total sperm count was higher (P < 0.05) after treatment with 0.3, 0.4, and 0.6 Ovopel pellet/kg (41.6 ± 9.3 to 42.3 ± 10.5 × 10 9 spermatozoa) than the other Ovopel treatments (20.0 ± 2.4 to 26.9 ± 8.2 × 10 9 spermatozoa) and control (6.6 ± 1.1 × 10 9 spermatozoa), but did not differ significantly from CPE (33.7 ± 3.2 × 10 9 spermatozoa). Sperm motility was higher (P < 0.05) in the CPE treated, and 0.2, 0.3, and 0.7 Ovopel pellet/kg (88.3 ± 2.9 to 90.0 ± 5.0) breeders when compared with the other treatments (70.0 ± 10.0 to 78.3 ± 5.8), except for the 0.4 pellet/kg (81.7 ± 2.9) treatment, which did not differ significantly from any of the treatments. The motility period of the spermatozoa did not differ significantly among treatments (93.5 ± 15.7 to 120.0 ± 7.6 s). For the sperm morphological analysis, occurrence of normal spermatozoa was similar across the treatments, with three sperm abnormalities (short tail, bent tail, and detached head) differing (P < 0.05) among the treatments. Ovopel efficiently induced reproduction of C. macropomum breeders, with treatment using 0.3 and 0.4 Ovopel pellet/kg and CPE providing the best semen characteristics. [ABSTRACT FROM AUTHOR]

The present study evaluated the efficacy of Ocimum basilicum (basil) essential oil in the anesthetic induction and recovery of juvenile tambaqui Colossoma macropomum and verified its physiometabolic effects after biometric handling. Juveniles (86.51 ± 7.82 g) were exposed to different concentrations of basil essential oil: 400, 500, 600, 700, 800, 900, and 1000 μL L−1. Subsequently, the fish were divided into five groups: control (non-handled fish), handling without anesthetic (water only), handling with ethanol (720 μL L−1), and handling with Ocimum basilicum essential oil (400 and 800 μL L−1). The shortest (p < 0.05) time to induce anesthesia was at a concentration of 1000 μL L−1 (222 s). The recovery time from anesthesia did not differ significantly among different concentrations (400–1000 μL L−1). The results of the present study confirm the essential oil of O. basilicum as a new and safe natural anesthetic for juvenile tambaqui. The use of this essential oil in biometrics handling procedures reduces or attenuates the secondary responses to handling stress without showing deleterious effects on the non-specific immune system or metabolism of energy, carbohydrates, and lipids. However, further studies are necessary to determine the exact mechanism of action of this essential oil. • The osmoregulatory response in tambaqui was increased by 800 μL L1 of basil. • Basil does not induce hepatotoxicity or liver damage in juvenile tambaqui. • Anesthesia with basil does not alter the anaerobic metabolism of juvenile tambaqui. • Basil promotes anesthesia in tambaqui without impairing cardiorespiratory functions. [ABSTRACT FROM AUTHOR]

Symbiotics are a combination of prebiotics and probiotics that positively affect the animal by stimulating health-promoting bacteria and thus improving production performance and animal welfare. The aim of this study was to evaluate a water symbiotic on the performance, hematological parameters and intestinal morphometry of Nile tilapia raised in a biofloc technology system (BFT) for the initial grow-out phase. Eighty juveniles (initial weight: 30–35 g) were stocked in eight 100-L tanks (10 fish/box). The fish were evaluated using BFT with and without symbiotics. The symbiotic was added directly to the water on a weekly basis at a dose of 0.2 mg L−1 (commercial recommendation for the product). The experiment was laid out in a completely randomized design with two treatments (BFT with symbiotics and BFT without symbiotics) and four replicates, totaling eight experimental units. The experimental period was 40 days. Final weight, weight gain and the specific growth rate were higher (p <.05) in the fish produced in BFT with symbiotics (77.28 ± 0.61 g; 46.79 ± 0.64 g; 2.33 ± 0.03%) than in those farmed in BFT without symbiotics (73.31 ± 0.73 g; 42.54 ± 0.77 g; 2.17 ± 0.04%). Feed conversion ratio was higher (p <.05) in the group reared in BFT without symbiotic (1.02 ± 0.01) as compared with those farmed in BFT with symbiotics (0.94 ± 0.01). Overall, hematological conditions were better (p <.05) in the fish grown in BFT with symbiotics. There were no major differences in intestinal morphometry between treatments. The inclusion of symbiotics in BFT improved the performance and hematological parameters of Nile tilapia in the initial phase (30 to 77 g) without causing significant changes in intestinal morphometry or intestinal cell density. • The use of symbiotics in BFT improved the performance of Nile tilapia juveniles. • The use of symbiotics in BFT improved the hematological parameters of Nile tilapia. • The concentration of nitrite in the water was reduced in the symbiotic treatment. [ABSTRACT FROM AUTHOR]