Ontogenetic variation in the marine foraging of Atlantic salmon functionally links genomic diversity with a major life history polymorphism.

The ecological role of heritable phenotypic variation in free-living populations remains largely unknown. Knowledge of the genetic basis of functional ecological processes can link genomic and phenotypic diversity, providing insight into polymorphism evolution and how populations respond to environmental changes. By quantifying the marine diet of Atlantic salmon, we assessed how foraging behaviour changes along the ontogeny, and in relation to genetic variation in two loci with major effects on age at maturity (six6 and vgll3). We used a two-component, zero-inflated negative binomial model to simultaneously quantify foraging frequency and foraging outcome, separately for fish and crustaceans diets. We found that older salmon forage for both prey types more actively (as evidenced by increased foraging frequency), but with a decreased efficiency (as evidenced by fewer prey in the diet), suggesting an age-dependent shift in foraging dynamics. The vgll3 locus was linked to age-dependent changes in foraging behaviour: Younger salmon with vgll3LL (the genotype associated with late maturation) tended to forage crustaceans more often than those with vgll3EE (the genotype associated with early maturation), whereas the pattern was reversed in older salmon. Vgll3 LL genotype was also linked to a marginal increase in fish acquisition, especially in younger salmon, while six6 was not a factor explaining the diet variation. Our results suggest a functional role for marine feeding behaviour linking genomic diversity at vgll3 with age at maturity among salmon, with potential age-dependent trade-offs maintaining the genetic variation. A shared genetic basis between dietary ecology and age at maturity likely subjects Atlantic salmon populations to evolution induced by bottom-up changes in marine productivity.

Optimization of dilution rate and mixed carbon feed for continuous production of recombinant plant sucrose:sucrose 1-fructosyltransferase in Komagataella phaffii.

The trisaccharide 1-kestose, a major constituent of commercial fructooligosaccharide (FOS) formulations, shows a superior prebiotic effect compared to higher-chain FOS. The plant sucrose:sucrose 1-fructosyltransferases (1-SST) are extensively used for selective synthesis of lower chain FOS. In this study, enhanced recombinant (r) 1-SST production was achieved in Komagataella phaffii (formerly Pichia pastoris) containing three copies of a codon-optimized Festuca arundinacea 1-SST gene. R1-SST production reached 47 U/mL at the shake-flask level after a 96-h methanol induction phase. A chemostat-based strain characterization methodology was adopted to assess the influence of specific growth rate (µ) on cell-specific r1-SST productivity (Qp) and cell-specific oxygen uptake rate (Qo) under two different feeding strategies across dilution rates from 0.02 to 0.05 h-1. The methanol-sorbitol co-feeding strategy significantly reduced Qo by 46 ± 2.4% compared to methanol-only feeding without compromising r1-SST productivity. Based on the data, a dilution rate of 0.025 h-1 was applied for continuous cultivation of recombinant cells to achieve a sustained r1-SST productivity of 5000 ± 64.4 U/L/h for 15 days.

The fate of Cu and Zn along the feed-animal-excreta-effluent continuum in swine systems according to feed and effluent treatment strategies.

Copper (Cu) and zinc (Zn) have negative environmental impacts as they accumulate in the soil after pig manure is spread. Cu and Zn are essential elements in pig nutrition but due to their low retention rate, more than 90% of ingested Cu and Zn are excreted. A better understanding of the behaviour of these elements throughout the animal-manure-soil continuum according to feed composition and manure management chain is thus required to propose alternative ways to reduce these environmental impacts. The aim of this study was to determine the fate of Cu and Zn throughout this continuum by studying the effect of Cu and Zn contents in animal feed and in the manure management chain based on anaerobic digestion and composting. Faeces were collected from 24 finishing pigs fed with 4 different Cu and Zn dietary levels and sources of supplementation. Samples of faeces were exposed to mesophilic anaerobic digestion or to 5-week composting with straw. Concentrations of Cu and Zn in the faeces were highly dependent on dietary supplies and ranged from 38 to 188 mg Cu/kg DM and from 191 to 728 mg Zn/kg DM. Degradation of a significant fraction of organic matter during treatment led to a significant increase in Cu and Zn concentration relative to the product's dry matter (DM) content, which. Cu and Zn concentrations relative to DM content were twice as high after treatment whatever the content and the form of Cu and Zn dietary supplementation. Otherwise, effluent treatment tended to reduce the possible availability of Cu and Zn in final organic products according to water-extractible contents. This study clearly shows that feed management is the main lever for reducing the amount of Cu and Zn amount in pig effluents and hence in the soil. Appropriate treatment could also facilitate the supply of organic fertilisers to areas with soil deficiency, but feed strategies need to be adapted to the treatment chain to enable the production of good quality organic products that respect EU regulations.

Microplastic concentrations and risk assessment in water, sediment and invertebrates from Simon's Town, South Africa.

Plastic pollution is an ever-increasing threat globally and poor waste management in South Africa has caused an increase in plastic leakage into the environment. Plastic waste in the environment are categorized according to size and plastic particles smaller than 5 mm in size are regarded as microplastics (MPs), and little to no research has been done on MPs pollution within the marine coastal environment and rocky shores in South Africa. Sampling was done in February 2020 at a rocky shore within Simon's Town Marina, Cape Town. MPs were extracted from collected water (n = 5), sediment (n = 5) and biota (n ≤ 30) samples. The extracted MPs were further classified based on shape, colour, size and an attenuated total reflectance Fourier-transform infrared (ATR-FTIR) instrument was utilized for polymer type identification The risks posed by MPs because of concentration at which they occurred and chemical composition were assessed in all the sample types. As expected, MPs were higher in sediment (38 ± 2 MP/kg) than in water (0.37 ± 0.06 MP/L) as the area has low water energy, allowing MP particles to settle within the sediment. Filter-feeding organisms had the lowest average MP particle concentrations (0.28 ± 0.04 MP/g) but displayed the highest variation of MP particle colours due to the non-selective feeding strategy, where other feeding strategies ingested mostly black/grey particles. The dominant MP size was between 100 µm and 500 µm in size for all samples combined, with the most abundant MP polymer type being nylon (27.27 %), polyethylene terephthalate (PET) (18.18 %) and natural MP particles such as cotton (18.18 %). The risk assessment indicated that polymer type poses a greater risk of MP pollution than MP concentrations.

The effects of Bacillus subtilis on the immunity, mucosal tissue morphology, immune-related gene transcriptions, and intestinal microbiota in flounder (Paralichthys olivaceus) with two feeding methods: Continuous versus discontinuous feeding.

Probiotics as dietary additives can improve weight gain, feed efficiency, and disease resistance in cultured fish. In this research, we evaluated and compared the effects of Bacillus subtilis on immunity, mucosal tissue morphology, immune-related gene transcriptions, and intestinal microbiota in flounder (Paralichthys olivaceus) by a 30-day feeding experiment based on a continuous feeding schedule (E1) and a discontinuous feeding schedule (E2). As a result, the use of B. subtilis exerted the best positive effects on survival rate, enzyme activity, mucosal tissue morphology, immune-related gene transcriptions, and intestinal microbiota in flounders. Alkaline phosphatase (AKP), lysozyme (LZM), and superoxide dismutase (SOD) activities in the liver of E2 were higher than those of E1 (P < 0.05). Furthermore, the villi length in the intestinal tract and the fold length in the stomach of E2 were also higher than in E1 (P < 0.05). The il-1 expression levels in the spleen were significantly increased in E2 (P < 0.05) compared to E1. We performed 16 S rRNA sequencing analysis to find that Bacillus in E1 (1.06%) and E2 (1.01%) had higher relative abundances than in E0 (0.053%) at the end of the experiments, indicating that short-term application of B. subtilis with the continuous or discontinuous feeding method can allow both the adaptation of the ecosystem to the presence of probiotics by the establishment of new species in the gut microbiota and the ability these new probiotic species to perform corresponding functions. No significant differences in the ability of probiotic establishment were observed between E1 and E2. Our findings provided a unique perspective to explore the mechanism of immune enhancement with probiotics and to screen the optimal administration strategy in aquaculture application for probiotic use. Together, these results point to some level of enhancement in immune status by continuous and discontinuous feeding after a short-term feeding period, which could be used as a prophylactic strategy for flounder health management.

Microplastic ingestion in marine mesozooplankton species associated with functional feeding traits.

Microplastic (MP, <5 mm) contamination in the ocean raises concern for zooplankton, as their prey and MPs fall within the same size range. This study aimed to evaluate the ingestion capacity of MPs among a diverse array of mesozooplankton taxonomic groups and species from the central Mexican Pacific, focusing on two functional traits: trophic group and feeding strategy. A total of 20 taxa belonging to eight taxonomic groups, 13 which were identified to species level, were exposed to microspheres (Ms) ranging in size from 38 to 53 µm, at a concentration of 100 Ms/mL. All experimental treatments were placed in 620 mL bottles and rotated on a plankton wheel for 2 h. The results demonstrate that the capacity to ingest MPs is closely related to the trophic group and the feeding strategy of each species, independent of taxonomic group. Omnivores and omnivore-herbivores which generate feeding currents were the most susceptible to MPs ingestion, while highly carnivorous species with active feeding strategies were the least prone. These findings highlight the importance of evaluating MP ingestion by zooplankton at the species level, due to the variability of feeding strategies within taxonomic groups, and the need for continued trait-based research at the species level. A more detailed understanding of zooplankton feeding behavior, especially in ecologically significant species, could enhance trait-based modeling at a biogeographic scale, predicting areas with the highest risk of MP ingestion by zooplankton communities and evaluating global impacts.

Distribution of microplastics in seafloor sediments and their differential assimilation in nearshore benthic molluscs along the south-west coast of India.

Spatial and temporal distribution of microplastics (MPs) in the nearshore seafloor sediments along the Southwest coast of India and their patterns of accumulation in selected infaunal and epibenthic molluscs with diverse feeding strategies were investigated. Along the 300-km coastal stretch, which is one of the most productive and biodiversity rich regions of the eastern Arabian Sea, notable levels of MP contamination in both sediment (617.7 items/kg dry weight) and molluscs (5.39 items/g) was recorded. The concentration of MPs in sediments also varied seasonally, with a higher prevalence during the post-monsoon season. Among the four molluscan groups studied, the highest MP abundance was recorded among scavenging gastropod Pseudominolia biangulosa (9.13 items/g), followed by microcarnivore scaphopod Tesseracme quadrapicalis (5.96 items/g). In comparison, the suspension feeding bivalve, Anadara hankeyana and deposit feeding clam Jitlada philippinarum had lesser accumulation of MPs (2.98 items/g and 3.50 items/g respectively). The majority of MPs in sediments and within molluscs were less than 250 µm in size (89.14%) and were predominantly fibres and fragments. Chemical characterisation of MPs revealed eleven types of polymers dominated by polyethylene (PE) and polypropylene (PP). Present study identified positive correlations between ingested MP polymers and the feeding strategies of molluscs. Higher values for the ecological risk assessment indices (PHI, PLI and PERI) in most of the stations indicated the severity of plastic pollution in the region. Molluscs being a major contributor to the benthic food web is also a connecting link to higher trophic levels. Hence understanding the specificity in the MPs accumulation pattern within this group has far reaching significance in utilizing them as potential bioindicators for pollution studies in marine ecosystems.

Optimization of Culture Media and Feeding Strategy for High Titer Production of an Adenoviral Vector in HEK 293 Fed-Batch Culture.

Adenoviruses are efficient and safe vectors for delivering target antigens and adenovirus-based vaccines have been used against a wide variety of pathogens, including tuberculosis and COVID-19. Cost-effective and scalable biomanufacturing processes are critical for the commercialization of adenovirus-vectored vaccines. Adenoviral vectors are commonly produced through the infection of batch cultures at low cell density cultures, mostly because infections at high cell densities result in reduced cell-specific virus productivity and does not improve volumetric productivity. In this study, we have investigated the feasibility of improving the volumetric productivity by infecting fed-batch cultures at high cell densities. Four commercial and one in-house developed serum-free media were first tested for supporting growth of HEK 293 cells and production of adenovirus type 5 (Ad5) in batch culture. Two best media were then selected for development of fed-batch culture to improve cell growth and virus productivity. A maximum viable cell density up to 16 × 106 cells/mL was achieved in shake flask fed-batch cultures using the selected media and commercial or in-house developed feeds. The volumetric virus productivity was improved by up to six folds, reaching 3.0 × 1010 total viral particles/mL in the fed-batch culture cultivated with the media and feeds developed in house and infected at a cell density of 5 × 106 cells/mL. Additional rounds of optimization of media and feed were required to maintain the improved titer when the fed-batch culture was scaled up in a bench scale (3 L) bioreactor. Overall, the results suggested that fed-batch culture is a simple and feasible process to significantly improve the volumetric productivity of Ad5 through optimization and balance of nutrients in culture media and feeds.

Enteral feeding strategies in patients with acute gastrointestinal injury: From limited to progressive to open feeding.

Acute gastrointestinal injury (AGI) is very common in critically ill patients, and its severity is positively correlated with mortality. Critically ill patients with digestive and absorption dysfunction caused by AGI face higher nutritional risks, making nutritional support particularly important. Early enteral nutrition (EN) support is extremely important because it can promote the recovery of intestinal function, protect the intestinal mucosal barrier, reduce microbiota translocation, reduce postoperative complications, shorten hospital stay, and improve clinical prognosis. In recent years, many nutritional guidelines have been proposed for critically ill patients; however, there are few recommendations for the implementation of EN in patients with AGI, and their quality of evidence is low. The use of EN feeding strategies in critically ill patients with AGI remains controversial. The aim of this review was to elaborate on how EN feeding strategies should transition from limited to progressive to open feeding and explain the time window for this transition.

Fed-batch fermentation of Mucor circinelloides reveals significant improvement in biomass and lipid accumulation through performance evaluation, chemical analysis, and expression profiling.

This study aimed to improve the lipid and biomass yields of Mucor circinelloides WJ11 by implementing four different fed-batch fermentation strategies, varied in time and glucose concentration (S1-S4). The S1 fermentation strategy yielded the highest biomass, lipid, and fatty acid content (22 ± 0.7 g/L, 53 ± 1.2 %, and 28 ± 1.6 %) after 120 and 144 h, respectively. The γ-linolenic acid titer of 0.75 ± 0.0 g/L was greatest in S3 after 48 h. Quantitative reverse transcription polymerase chain reaction (RT-qPCR) was used to analyze the transcription of key genes involved in lipid accumulation. The glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and ATP-citrate lyase genes showed increased expression levels. Fourier-transform infrared (FTIR) spectroscopy was used to analyze the biochemical profile during fermentation strategies. Optimal abiotic factors for production efficiency included pH 6.5, 25-26 °C, 15 % (v/v) inoculum, 500 rpm, 20 %-30 % dissolved oxygen, and 120 h fermentation. Glucose co-feeding offers valuable insights to develop effective fermentation strategies for lipid production.

Highly efficient production of 2-phenylethanol by wild-type Saccharomyces bayanus strain.

2-Phenylethanol (2-PE) is a highly valuable aromatic alcohol utilized in fragrance, cosmetics and food industries. Due to the toxic by-products from chemical synthesis and the low productivity of the extraction method, bioproduction of 2-PE by yeast is considered promising. In this study, a wild-type Saccharomyces bayanus L1 strain producing 2-PE was isolated from soy sauce mash. Transcriptional analysis showed that 2-PE was synthesized via the Ehrlich pathway and Shikimate pathway in S. bayanus L1. By improving the fermentation conditions in shaking flasks, the maximum 2-PE titer reached 4.2 g/L with a productivity of 0.058 g/L/h within 72 h. In fed-batch fermentation, S. bayanus L1 strain produced 6.5 g/L of 2-PE within 60 h, achieving a productivity of 0.108 g/L/h. These findings suggest that S. bayanus L1 strain is an efficient 2-PE producer, paving the way for highly efficient 2-PE production.

Data quantifying the behaviour of macro and trace elements along the feed - manure - treated waste continuum in pig production.

Manure from animal production is commonly spread on agricultural soil as an organic fertiliser to provide macro and trace elements to crops. However, some trace elements can accumulate in the soil and become toxic to plants and microorganisms. These elements include copper (Cu) and zinc (Zn), which can be applied in large quantities when pig manure is spread. The feeding strategy and manure management (e.g. through treatment chains) are two mechanisms identified to better control the use of these elements, but their fate from the feed to the soil in pig production remains poorly documented. Better understanding the fate of Cu and Zn, as well as that of other trace and macro elements, along the feed - excreta - waste chain is required to develop alternative ways to reduce their environmental impacts. This dataset provides insight into the composition (Cu, Zn and other trace and macro elements) of organic products along two contrasting manure management chains: (1) only storage or (2) in-building separation, anaerobic digestion (AD) of solids, and digestate drying. Feed, raw slurry, liquid and solid phases after separation of the manure and AD products were sampled and then analysed to measure their total compound contents.

High-throughput sequencing and fatty acid profile analyses of the Black Amur bream (Megalobrama terminalis) reveal variation in dietary niche associated with geographic segregation.

Fish dietary niche is a core focus, and it reflects the diversity of resources, habitats, or environments occupied by a species. However, whether geographic segregation among different populations triggers dietary diversification and concomitant fish niche shift remains unknown. In the present study, we selected the Black Amur bream (Megalobrama terminalis) is a migratory fish species that plays an important role in the material transfer and energy cycling of river ecosystems, inhabiting southern China drainage with multiple geographic populations. Here, we utilized the combined analyses of 18S rDNA high-throughput sequencing in fish gut contents and fatty acid (FA) in muscle tissues to evaluate potential spatial patterns of habitat and resource use for M. terminalis in three rivers of southern China. Our results showed that prey items of the Xijiang (XR) population (Pearl River) exhibited the highest species diversity and richness among the three geographic populations. Moreover, diet composition of M. terminalis was affected by spatial differences associated with geographic segregation. Analyses of FA biomarkers indicated that the highest levels of C16:0, C18:3n-3, and C18:2n-6c were found in Wanquan (WS) population (Wanquan River). The XR population exhibited a distinct FA profile characterized by higher amounts of arachidonic acid (ARA) and docosahexaenoic acid (DHA). The Moyang (MY) population (Moyang River) acted as the linkage between WS and XR populations and consisted of middle levels of saturated FAs (SFAs) and polyunsaturated FAs (PUFAs). The XR population displayed a greater FA niche width compared with WS population. Furthermore, we observed a close positive relationship between the niche width and α-diversity indices of dietary resources for FA proflies. Our study provides valued information to develop different conservation strategies among different populations and improve fisheries management for M. terminalis and other endemic species in local rivers.

A Comparative Study Between the Early and Late Enteral Nutrition After Gastrointestinal Anastomosis Operations.

INTRODUCTION: Intestinal anastomosis is a surgical procedure crucial for restoring the integrity of the digestive system and finds widespread application in addressing diverse gastrointestinal disorders such as tumors, inflammatory conditions, and traumatic injuries. The timing of restarting feeding after the surgery is a debated topic due to its potential impact on patient recovery. Early enteral feeding, administered soon after surgery, aims to counteract the negative effects of prolonged fasting and improve outcomes. OBJECTIVE: This study analyzed the early and late enteral feeding following gastrointestinal anastomosis surgery. METHODS: Forty patients undergoing abdominal surgery were prospectively randomized into early or late feeding groups. Demographics, laboratory values, operative time, blood loss, transfusion rates, nasogastric tube (NGT) removal, hospital stay, gastrointestinal recovery, postoperative body mass index (BMI), and complications were compared. Data was organized in Excel and analyzed using the Statistical Package for the Social Sciences (IBM SPSS Statistics for Windows, IBM Corp., Version 27.0, Armonk, NY). Qualitative data were presented with numbers and percentages, while parametric quantitative data used means, standard deviations, and ranges. Non-parametric quantitative data were represented with medians and interquartile ranges. Chi-square tests were used for comparing two qualitative groups with predicted counts less than 5, while independent t-tests and Mann-Whitney tests were employed for comparing two quantitative groups with parametric and non-parametric distributions, respectively. The analysis used a 95% confidence interval, a 5% margin of error, and considered P values less than 0.05 as significant. RESULTS: Early feeding was associated with significantly shorter NGT removal times (p=0.005) and hospital stays (p=0.001) than late feeding. Postprandial potassium levels were higher in the early group (p=0.007), while CRP levels were significantly lower (p=0.004). No significant differences were found in operative time, blood loss, transfusion rates, gastrointestinal recovery, postoperative BMI, or complication rates between groups. CONCLUSIONS: Early enteral feeding appears safe and effective after gastrointestinal anastomosis surgery, potentially reducing hospital stay and improving inflammatory markers without increasing adverse events.

Trophic plasticity of a tropical seabird revealed through DNA metabarcoding and stable isotope analyses.

DNA metabarcoding and stable isotope analysis have significantly advanced our understanding of marine trophic ecology, aiding systematic research on foraging habits and species conservation. In this study, we employed these methods to analyse faecal and blood samples, respectively, to compare the trophic ecology of two Red-billed Tropicbird (Phaethonaethereus; Linnaeus, 1758) colonies on Mexican islands in the Pacific. Trophic patterns among different breeding stages were also examined at both colonies. Dietary analysis reveals a preference for epipelagic fish, cephalopods, and small crustaceans, with variations between colonies and breeding stages. Isotopic values (δ15N and δ13C) align with DNA metabarcoding results, with wider niches during incubation stages. Differences in diet are linked to environmental conditions and trophic plasticity among breeding stages, influenced by changing physiological requirements and prey availability. Variations in dietary profiles reflect contrasting environmental conditions affecting local prey availability.

Feeding Strategies with Multi-Strain Probiotics Affect Growth, Health Condition, and Disease Resistance in Asian Seabass (Lates calcarifer).

A 16-week feeding trial was done to examine the impacts of continuous feeding (CF) or pulse-feeding (PF) of multi-strain probiotics on Asian seabass (Lates calcarifer, 30.0 ± 0.1 g) juveniles. In this study, three different multi-strain probiotic mixtures were added to a basal diet, including (I) a mixture of different strains of Lactobacillus plantarum, (II) a mixture of the first probiotic (I) + L. delbrueckii sub bulgaricus, L. rhamnosus and L. acidophilus, and (III) a mixture of the second probiotic (II) + two quorum quenching (QQ) bacteria (Bacillus thuringiensis QQ1 and B. cereus QQ2). CF (every day) or PF (every two weeks) strategies were applied for using the abovementioned probiotics to design seven experimental groups including C (control, without probiotics), CF-I (continuous feeding of fish with the probiotic mixture I), CF-II (continuous feeding of fish with the probiotic mixture II), CF-III (continuous feeding of fish with the probiotic mixture III), PF-I (pulse-feeding of fish with the probiotic mixture I), PF-II (pulse-feeding of fish with the probiotic mixture II), and PF-III (pulse-feeding of fish with the probiotic mixture III). Four hundred and twenty fish were stocked into 21 circular polyethylene tanks with 220 L volume (20 fish/tank). Each dietary treatment had three replicates. Tanks were supplied with seawater (temperature = 30.5 °C, salinity = 45 g L-1) in a flow-throw system. Fish in CF-I, CF-II, and CF-III had higher growth rate (ca. 113-145%) and better feed conversion ratio than fish fed C and PF-I (P < 0.05). Fish in the CF-III group had the highest protease activity. Continuous feeding strategy resulted in a higher amount of glutathione and catalase activities in both the liver and plasma as well as higher superoxide dismutase activity in the liver of fish. Pulse-feeding strategy resulted in lower plasma lactate dehydrogenase and aspartate aminotransferase levels than the CF strategy. Regardless of feeding strategy, different probiotic mixtures significantly enhanced blood hemoglobin and hematocrit levels compared to the control. Continuous feeding with the multi-strain probiotics resulted in a higher survival rate against Vibrio harveyi than the PF method. Continuous feeding induced higher mRNA transcription levels of granulocyte-macrophage colony-forming cells and interleukin 10 genes in the gut of fish than PF strategy. In conclusion, continuous feeding with multi-strain probiotics is better than pulse-feeding on growth, feed utilization, antioxidant capacity, and the gut's immune-related genes and led to higher resistance of L. calcarifer in challenge with V. harveyi.

Trophic ecology of Acestrorhynchus falcirostris Cuvier, 1819 in island lakes on the lower stretch of the Solimões River, Amazon Basin / Ecologia trófica de Acestrorhynchus falcirostris Cuvier, 1819 em lagos de ilha no trecho inferior do Rio Solimões, Bacia Amazônica

Abstract The aim objective of this study was to determine the trophic ecology of juvenile and adult Acestrorhynchus falcirostris during the rising and flood (high-water) period in six island lakes adjacent to the Solimões River. As such, we investigated: i) the trophic position, through the fractional trophic niche; ii) the niche breadth; iii) niche overlap and iv) the food strategy of the species. The specimens were collected during the years 2014 to 2017, using gillnets with mesh sizes ranging from 30 to 120mm between opposite knots. Through the analysis of stomach contents, the preference in the consumption of items of animal origin was observed. Juveniles consumed insects in greater proportions (IAi% = 50%), while adults consumed fish (IAi%=99,98%). Despite the large supply of food items available in the high-water period, juveniles were the only ones to consume items of allochthonous origin, such as insects. Juveniles presented a different dietary strategy and dietary composition to adults. Juveniles were omnivores with a generalist strategy, while adults were piscivores with a specialist strategy. Thus, the food composition, niche breadth, trophic position and feeding strategy of Acestrorhynchus falcirostris change due to the stage of development.

Resumo O objetivo deste estudo foi determinar a ecologia trófica de juvenis e adultos de Acestrorhynchus falcirostris durante o período de enchente e cheia em seis lagos de ilha adjacentes ao rio Solimões. Assim, investigamos: i) a posição trófica, através do nicho trófico fracional; ii) a largura de nicho; iii) sobreposição de nicho; iv) a estratégia alimentar. Os espécimes foram coletados durante os anos de 2014 a 2017, utilizando redes de emalhar com malha variando de 30 a 120mm entre nós opostos. Por meio da análise do conteúdo estomacal, observamos a preferência no consumo de itens de origem animal. Os juvenis consumiram insetos em maiores proporções (IAi% = 50%), enquanto os adultos consumiram preferencialmente peixes (IAi% = 99,98%). Apesar da grande oferta de alimentos disponíveis no período da cheia, os juvenis eram os únicos a consumir itens de origem alóctone, como por exemplo, os insetos. Os juvenis apresentaram uma estratégia alimentar e composição alimentar diferente para os adultos. Os juvenis foram considerados onívoros com uma estratégia generalista, enquanto os adultos foram considerados piscívoros com uma estratégia alimentar mais especialista. Assim, a composição alimentar, amplitude do nicho, posição trófica e a estratégia alimentar de Acestrorhynchus falcirostris muda em função do estágio de desenvolvimento.

Trophic ecology of Acestrorhynchus falcirostris Cuvier, 1819 in island lakes on the lower stretch of the Solimões River, Amazon Basin

Abstract The aim objective of this study was to determine the trophic ecology of juvenile and adult Acestrorhynchus falcirostris during the rising and flood (high-water) period in six island lakes adjacent to the Solimões River. As such, we investigated: i) the trophic position, through the fractional trophic niche; ii) the niche breadth; iii) niche overlap and iv) the food strategy of the species. The specimens were collected during the years 2014 to 2017, using gillnets with mesh sizes ranging from 30 to 120mm between opposite knots. Through the analysis of stomach contents, the preference in the consumption of items of animal origin was observed. Juveniles consumed insects in greater proportions (IAi% = 50%), while adults consumed fish (IAi%=99,98%). Despite the large supply of food items available in the high-water period, juveniles were the only ones to consume items of allochthonous origin, such as insects. Juveniles presented a different dietary strategy and dietary composition to adults. Juveniles were omnivores with a generalist strategy, while adults were piscivores with a specialist strategy. Thus, the food composition, niche breadth, trophic position and feeding strategy of Acestrorhynchus falcirostris change due to the stage of development.

Resumo O objetivo deste estudo foi determinar a ecologia trófica de juvenis e adultos de Acestrorhynchus falcirostris durante o período de enchente e cheia em seis lagos de ilha adjacentes ao rio Solimões. Assim, investigamos: i) a posição trófica, através do nicho trófico fracional; ii) a largura de nicho; iii) sobreposição de nicho; iv) a estratégia alimentar. Os espécimes foram coletados durante os anos de 2014 a 2017, utilizando redes de emalhar com malha variando de 30 a 120mm entre nós opostos. Por meio da análise do conteúdo estomacal, observamos a preferência no consumo de itens de origem animal. Os juvenis consumiram insetos em maiores proporções (IAi% = 50%), enquanto os adultos consumiram preferencialmente peixes (IAi% = 99,98%). Apesar da grande oferta de alimentos disponíveis no período da cheia, os juvenis eram os únicos a consumir itens de origem alóctone, como por exemplo, os insetos. Os juvenis apresentaram uma estratégia alimentar e composição alimentar diferente para os adultos. Os juvenis foram considerados onívoros com uma estratégia generalista, enquanto os adultos foram considerados piscívoros com uma estratégia alimentar mais especialista. Assim, a composição alimentar, amplitude do nicho, posição trófica e a estratégia alimentar de Acestrorhynchus falcirostris muda em função do estágio de desenvolvimento.

Food deprivation does not affect growth performance of juvenile tambacu / Privação alimentar não afeta o crescimento de juvenis de tambacu

The objective of this study was to evaluate the efficiency of food deprivation on the growth performance of the commercially important hybrid fish tambacu (Piaractus mesopotamicus male × Colossoma macropomum female). For this, 171 juveniles of average length 8 cm and 11.4 g body mass were distributed in nine tanks, and allocated to three treatments: the fish were fed every day (control), fed for six days followed by one day of food deprivation (6F/1D) and fed for five days followed by two days of food deprivation (5F/2D). After 77 days, all animals achieved similar growth rates. Only animals submitted to two days of food deprivation presented hyperphagia. There was a reduction in total feed consumption of 3.8% and 10.8% for the 6F/1D and 5F/2D treatments, respectively. Our results suggest that juvenile tambacu exhibit total compensatory growth when submitted to food deprivation, and that a two-day deprivation could significantly reduce production costs for tambacu farmers.

O objetivo do estudo foi avaliar a eficiência da privação alimentar sobre o desempenho zootécnico de tambacu (Piaractus mesopotamicus x Colossoma macropomum). Para isso, 171 animais (massa: 11,4 ± 1.5 g; comprimento total: 8.0 ± 0.4 cm) foram alocados em nove tanques (19 peixes/tanque; n=3). Os peixes foram alimentados todos os dias (controle), alimentados durante seis dias seguidos de um dia de privação alimentar (6F/1D) e durante cinco dias seguidos de dois dias de privação alimentar (5F/2D). Após 77 dias, todos os animais alcançaram índices de crescimento similares. Somente os animais submetidos a dois dias de privação apresentaram hiperfagia. Houve redução do consumo total de ração em 3,8 e 10,8% para os tratamentos 6F/1D e 5F/2D, respectivamente. Os nossos resultados demonstram que os juvenis de tambacu exibiram crescimento compensatório total quando submetidos a privação alimentar, e a estratégia de 2 dias de privação alimentar pode reduzir significativamente os custos de produção de tambacu.

Fortifying pork liver mixture: Evaluation of protein quality and iron bioavailability - Part 2 / Mistura fortificadora a base de fígado suíno: avaliação da qualidade protéica e da biodisponibilidade de ferro - Parte 2

ABSTRACT Objective To evaluate the protein quality and iron bioavailability of a fortifying mixture based on pork liver. Methods Determinations of protein efficiency ratio, net protein utilization, true digestibility and hemoglobin regeneration efficiency by depletion and repletion were performed. In the depletion phase, the animals (male Wistar rats) received an iron-free AIN-93G diet and in the repletion phase they received the following diets: standard AIN-93G diet, fortifying mixture and standard diet containing heptahydrated ferrous sulfate for comparison. Results For standard AIN-93G diet and fortifying mixture the results were 3.75 and 4.04 for protein efficiency ratio and 3.53 and 3.63 for net protein retention, showing that the presence of pork liver in the diet promoted an increase in protein efficiency ratio and net protein retention (not statistically significant). True digestibility results obtained with the fortifying mixture (97.16%) were higher than those obtained with the standard AIN-93G diet (casein), but without significant difference. The hemoglobin regeneration efficiency values obtained for standard AIN-93G diet, fortifying mixture and standard diet containing heptahydrated ferrous sulfate were 50.69, 31.96 and 29.96%, respectively, showing a statistically significant difference between the control (standard AIN-93G diet) and test (fortifying mixture and standard diet containing heptahydrated ferrous sulfate) samples, but not between the test samples. Conclusion The fortifying mixture showed a high protein efficiency ratio value of 4.04 and a high relative biological value (108%) and it can be added to soups, creams and meats in day-care centers for the prevention of iron-deficiency in children of school age.

RESUMO Objetivo Avaliar a qualidade protéica e a biodisponibilidade de ferro de uma mistura fortificadora a base de fígado suíno. Métodos Foram determinados coeficiente de eficácia protéica, retenção protéica líquida, digestibilidade verdadeira e de eficiência da regeneração de hemoglobina (depleção e repleção). Na fase de depleção os animais (ratos da linhagem Wistar) receberam dieta (AIN-93G) isenta de ferro e na fase de repleção receberam as dietas: padrão AIN-93G (dietas padrão AIN-93G), mistura fortificadora e dieta-padrão com sulfato ferroso heptahidratado para comparação. Resultados Para dietas padrão AIN-93G e mistura fortificadora os resultados foram respectivamente 3,75 e 4,04 para coeficiente de eficácia protéica e 3,53 e 3,63 para retenção protéica líquida mostrando que a presença de fígado suíno promoveu aumento dos valores de coeficiente de eficácia protéica e retenção protéica líquida (sem diferença estatística). Resultados de digestibilidade verdadeira obtidos com a dieta mistura fortificadora (97,16%) foram maiores do que os obtidos com a dietas padrão AIN-93G (caseína), também sem diferença estatística. Os resultados de eficiência da regeneração de hemoglobina para dietas padrão AIN-93G, mistura fortificadora e sulfato ferroso heptahidratado foram respectivamente 50,69; 31,96 e 29,96% apresentando diferença estatística significativa entre a amostra controle (dietas padrão AIN-93G) e as amostras testes (mistura fortificadora e sulfato ferroso heptahidratado), porém não entre as amostras testes. Conclusão A mistura fortificadora se mostrou com alto coeficiente de eficácia protéica (4,04) e alto valor biológico relativo (108%) podendo ser adicionada às sopas, cremes, carnes em creches na prevenção e controle da anemia ferropriva em crianças em idade escolar.