Dry Rainy Season Research Articles

Seasonal dynamics of Amblyomma cajennense (Fabricius, 1787) sensu stricto in a degraded area of the Amazon biome, with notes on Rickettsia amblyommatis infection

BackgroundThe tick Amblyomma cajennense sensu stricto (A. cajennense s.s.) frequently parasitizes animals and humans in the Amazon biome, in addition to being a vector of Rickettsia amblyommatis. In the present study, we evaluated both the population dynamics of A. cajennense s.s. in a degraded area of the Amazon biome and the presence of rickettsial organisms in this tick population.MethodsThe study was carried out in a rural area of the Santa Inês municipality (altitude: 24 m a.s.l.), Maranhão state, Brazil. Ticks were collected from the environment for 24 consecutive months, from June 2021 to May 2023. The region is characterized by two warm seasons: a rainy season (November–May) and a dry season (June–October). We characterized the temporal activity of A. cajennense s.s. on the vegetation by examining questing activity for each life stage (larvae, nymphs, adults [males and females]) in relation to the dry and rainy season. Ticks collected in this study were randomly selected and individually tested by a TaqMan real-time PCR assay that targeted a 147-bp fragment of the rickettsial gltA gene.ResultsOverall, 1843 (62.4%) adults (52.6% females, 47.4% males), 1110 (37.6%) nymphs and 398 larval clusters were collected. All adult females and nymphs were morphologically identified as A. cajennense s.s. Larval activity was observed from April to December, with a peak from June to September (dry season); nymph abundance peaked from September to November (transition period between dry and rainy seasons); and adult ticks were abundant from October to May (spring/summer/early autumn). The infection rate by R. amblyommatis in A. cajennense s.s. ticks was at least 7% (7/99).ConclusionOur data suggest a 1-year generation pattern for A. cajennense s.s., with a well-defined seasonality of larvae, nymphs and adults in the Amazon biome. Larvae predominate during the dry season, nymphs are most abundant in the dry-rainy season transition and adults are most abundant in the rainy season. The presence of R. amblyommatis in adult ticks suggests that animals and humans in the study region are at risk of infection by this species belonging to the spotted fever group of Rickettsia.Graphical

Short-term protein-energy supplementation at weaning or in the transition of dry-rainy season on performance of Nellore calves kept on Mombaça or Marandu grasses

Short-term protein-energy supplementation at weaning or in the transition of dry-rainy season on performance of Nellore calves kept on Mombaça or Marandu grasses

Air Pollution and Meteorological Parameters in SARS-CoV-2 Virus Spread and Transition

The purpose of this small study is to evaluate the meteorological parameters and air pollutants on the prevalence of SARS-CoV-2 in urban areas to identify conditions that can prevent or prevent future infection waves. According to studies, all meteorological parameters are significantly associated with SARS-CoV-2 cases. (Temperature, mainly affects solar radiation, UV Index (UVI), and wind speed) as well as air pollution parameters (Especially O3, SO2, and CO), but to a lesser extent. CO, SO2, and NO2 (mobility markers that refer to human interaction) it was reported all year round. It can be inferred that meteorological phenomena mainly affect the virus, both in its spread and inactivation: High relative humidity, low temperatures, low solar radiation, and low Wind speed can cause the virus to persist in the air, then, cold and dry rainy seasons can be dangerous for people who are outdoors. CO, SO2 and NO2 can be used to predict and reduce infections in the new wave of SARS-CoV-2 transmission. Adequate outdoor face masks should be considered to prevent inhalation of air pollutants and SARS-CoV-2.

Rotavirus A, a significant cause of infant diarrhea in Mozambique

Introduction: Rotavirus A (RVA) is a leading cause of acute infant gastroenteritis in Mozambique, responsible for approximately 13,000 annual infant deaths in peri-urban and other areas. Aim: the present review aimed summarize the most relevant and recent literature regarding RVA infection in Mozambique. Methods: the documents were obtained from electronic databases such as PubMed, Google Scholar, Scinapse, Scilit, and Microsoft Academic to find the leading scientific publications related to Mozambique's RVA.Findings: The search allowed us to find 20 peer-reviewed journal articles, three official reports, eight abstracts from national conferences, one thesis, and other documents to supplement the information. Rotavirus frequency ranged between 24 to 42.4%, 34.8% attributable to Mozambique. Most data are hospital-based from Maputo, Sofala, Zambézia, and Nampula provinces. Nampula province shows the highest number of cases. Thus, there might be some bias on the geographical distribution of the virus. The prevalence is high in children less than one year. Regarding the control, the Expanded Program on Immunization (EPI) introduced a monovalent vaccine in September 2015 (Rotarix), which positively impacted the reduction of RVA cases. After vaccine introduction, a high diversity of RVA genotypes was observed, with the predominance of G1P[8] and the emergence of G9P[4], G9P[6], G3P[4]. However, only the whole genome sequence can confirm if it is due to the natural genotypes fluctuation. RVA infection was detected in swine, and a recent analysis reported an RVA strain from children clustered with different animal strains.Conclusion: The scarce yet highly reliable research resources allowed scientists to detect RVA G1P[8] and other genotypes, potential animal reservoirs, and to find that RVA is more prevalent during the transition dry-rainy season, and the virus becomes more frequent when children approach the 11th month, to then decline as they age. It is essential to develop studies providing a broad view of RVA reservoirs as part of the strategy to control its dissemination.Keywords: Rotavirus infections; Children; Diarrhea; Mozambique

Intra-annual colonization of Chironomidae on leaf litter in a Brazilian Cerrado stream

In low-order streams, the processing of allochthonous leaf litter is essential in the carbon/energy flow dynamics. Benthic macroinvertebrates, such as chironomids, play critical roles in the breakdown of allochthonous materials, because their larvae take part in intricate trophic networks and have varied trophic ecologies. We evaluated the effects of intra-annual variability on the input of allochthonous leaf litter, and the interactions of leaf-detritus on the succession of Chironomidae assemblages in the dry, rainy, and transition seasons (rainy-dry and dry-rainy). The study took place in a stream in the Brazilian Cerrado. Leaves were incubated in the stream to ascertain the colonization process by Chironomidae and the loss of leaf litter mass after 90 days. Functional feeding groups (FFG) were less rich and less abundant in the dry and dry-rainy seasons, than in the other seasons. The FFG composition of Chironomidae demonstrated that temporal variation between seasons was affected by the exposure time of the leaf-detritus in the stream, and there was more segregation during the dry and rainy seasons. In conclusion, the colonization of leaf-detritus by Chironomidae larvae depended on how long allochthonous plant material remained in the stream, and the variability of the organic matter dynamics input into the stream.

Importance of interaction rewiring in determining spatial and temporal turnover of tritrophic (Piper‐caterpillar‐parasitoid) metanetworks in the Yucatán Península, México

AbstractNatural history studies documenting spatial and temporal variation of species assemblages and their interactions are critical for understanding biodiversity and community ecology. We characterized caterpillar–parasitoid assemblages on shrubs in the genus Piper across remnants of semi‐evergreen forest in the Yucatán Península during the rainy and rainy–dry seasons. We collected caterpillars feeding on Piper leaves and reared them to adults or parasitoids to: (i) describe tritrophic interactions between Piper, caterpillars, and parasitoids, (ii) compare empirical metanetworks among sites and seasons, and (iii) investigate patterns in species and interaction turnover across spatial and temporal scales to understand the contribution of species composition and interaction rewiring to overall interaction turnover. We found six Piper species supporting 79 species of caterpillars, which in turn hosted 20 species of parasitoids. In total, there were 116 realized trophic interactions. Species and interactions exhibited substantial turnover at temporal and spatial scales. Total interaction turnover was more pronounced across seasons in all sites (>93%), than it was between sites (<91%). We also found that interaction rewiring contributed more to overall interaction turnover than species turnover. The spatial and temporal variation in metanetworks documented here contribute to understanding fine‐scale temporal and spatial turnover in tropical species and interactions and raise important questions about the lability of consumer specialization and the short‐term effects of interaction rewiring on the stability of biotic communities. Our results highlight the importance of tropical food web studies that are based on natural history using consistent field methods to document bi‐ and tripartite interactions.Abstract in Spanish is available with online material.

Rendimiento Y Componentes De Valor Nutritivo De Tres Cultivares Panicum Máximum

Los géneros Panicum variedades como Mombaça, Tobiatá y Colonial se han introducido a diferentes regiones del país con éxito y fracaso debido a que no se tiene la información de su comportamiento a nivel nacional y nos guiamos por la de los países donde se han introducidos con características de clima, suelo y topografía totalmente variante a la de nuestro país. El trabajo se realizó en el Centro de Enseñanzas e Investigaciones Agropecuarias de Tocumen (CEIAT) de la Facultad de Ciencias Agropecuarias de la Universidad de Panamá. El objetivo de este trabajo fue estudiar tres cultivares de Panicum máximum (Massai, Tanzania y Aruana). La siembra fue con semilla gámica a razón de 6.0 kg/ha de semillas gámica, a una distancia de 0.50 cm entre surco y a chorro continuo. El diseño experimental fue de bloque completamente al azar, con cuatro repeticiones. Los cortes se realizaron cada 30 días. El tamaño de las parcelas fue de 9.00 mt2. Aunque las tres especies tuvieron comportamiento aceptable por su rendimiento de materia seca (P<0.05), destaco Panicum maximum cv. Tanzania con 30.00 y 9.40 t/ha para los periodos lluviosos (invierno) y seco (verano), respectivamente, mientras que Panicum maximum cv. Massai resulto superior (P<0.05) en el contenido de proteína bruta (11.30%). En la época seca no se encontraron diferencias significativas en la altura de los cultivares, pero en el periodo lluvioso Panicum maximum cv. Tanzania y Panicum maximum cv. Massai superaron a Panicum maximum cv. Aruana.

Daily evolution of urban heat islands in a Brazilian tropical continental climate during dry and rainy periods

High temperatures are typically recorded in tropical continental climate regions, with heat intensified by urban heat islands. This research attempts to investigate the intensity and maintenance of heat islands in the lower atmosphere and their spatial distribution during different periods of the day using multicriteria modeling. The present study was conducted in Presidente Prudente city, located west of São Paulo State, Brazil, between south latitudes 22°18′ and 22°06′ and west longitudes 51°47′ and 51°34′; its 2019 population is estimated at 228,743 inhabitants (IBGE, 2019). Air temperature and humidity data were recorded by a meteorological network comprising 26 points distributed throughout the intraurban and surrounding country. Data collection took place during both the dry and rainy seasons' most representative months (August and December 2015, respectively), in evenly spaced periods of the day (0 h, 3 h, 6 h, 9 h, 12 h, 15 h, 18 h, and 21 h). For the integration of primary and secondary data, descriptive statistics of simple and multiple linear regression were adopted. Results show that the heat islands' magnitude and continuity in different periods of the day vary according to surface characteristics (land use, relief, and vegetation) and the city's climatic seasonality. The highest and lowest magnitudes were recorded during the dry rainy season, respectively. It is believed that urban heat islands analysis will enable the subsidizing of territorial management and urban planning, and it will lead to a healthier development of cities, which will enhance societal sustainability.

Ground improvement using granular pile anchor system: resistance to heave and uplift pressure

<span lang="EN-GB">Expansive soil is found in many parts of the world where its major drawback is its expansion and shrinking property upon moisture absorption and drying during alternation of rainy-dry seasons. Due to its swelling-shrinkage repeated process, fatigue and distress cause crack to structures. Granular pile anchor (GPA) system is a pioneering technique that is utilised in reinforcing these expansive soils. Granular pile anchor (GPA) system is a pioneering technique that is utilised in reinforcing expansive soils. The GPA provides tensile resistance which arrest the exerted upward forces and hence reducing heave. Previous investigations have only focused on load-displacement relationships by utilizing the pull-out technique. In this technique, an external force pulls the GPA and the corresponding displacements are recorded. The results provide indication of the GPA resistance to the applied force. However, in real conditions the heave and expansion forces were developed as a result of the pressure caused by the water absorption which pushes the entire soil bed in the upward direction along with the GPA. Therefore, this paper is aimed to explore this concept by carrying experimental and numerical investigations on a small scale model for a single pile with a diameter of 4 cm, with lengths of 20 and 40 cm. Ultimately, the reinforced soil exhibits reduction in upward force and heave compared to the unreinforced soil. Also, verifications for the testing shows that the relationship between the upward force and heave exhibits almost linear relationship for both experimental and numerical investigations. Therefore, shallow foundations incorporated with a GPA system proves to effectively lessen the heave that occurs in expansive soils which in turn can solve problems for constructions.</span>

PSXII-40 Encapsulated nitrate to beef cattle growing under grazing system supplemented during the dry-rainy season

Abstract This study evaluated the effects of the encapsulated calcium ammonium nitrate as a partial substitute for soybean meals in the concentrate on performance and rate consumption of Nellore young bulls under grazing conditions, supplemented during the growing phase. Sixty-four Nellore young bulls (initial BW = 246.69 ± 7.43 kg) where allotted into 16 paddocks of 1.0 ha each of Urochloa brizantha, randomly assigned into one of two treatments: (CTL) supplement with 22% CP, without nitrate inclusion and; (ENP): supplement with 22% CP, with a inclusion of 50 g of encapsulated calcium ammonium nitrate to each 100 kg of body weight. The experimental period lasted 84 d, during the dry-rainy transition season. Animals were supplemented with 1.0% of BW, once a day (at 1000 h). Supplementation disappearance rate were evaluated the during continuous 24h after feeding, with intervals of 3 hours. For performance evaluation, animals were weighted every 28 days. Data were analyzed as a completely randomized design, using ANOVA (α = 0.05). There were no differences in ADG (1,039 vs 1,012 kg, P < 0.4468), G:F (0.299 vs 0.331, P < 0.1435) and final BW (336.44 vs 329.86 kg, P < 0.2063). The treatments affected the rate of supplementation disappearance (P < 0.0001). Control animals consumed all supplement offered 9h after fed. On the other hand, animals from the nitrate supplementation consumed only 54.65% in the same period. The nitrate decreased the overall supplement intake (P < 0.0011) with CTL consumed 2.844 kg, while ENP consumed 2.492 kg. The inclusion of 50 g of encapsulated calcium ammonium nitrate to each 100 kg of body weight in the supplement of growing cattle under grazing conditions, on dry-rainy transition season decreases DMI and the rate of supplemental disappearance, however, this not affected the performance.

Seasonal variations and meteoral factors influence in stroke on Nouakchott

The role of meteorological conditions in stroke occurrence has been the subject of several studies in the last ten years. Most of the work was carried out in temperate climates, few studies concerned the tropical climate. We carried out a retrospective study at the Nktt CHS neurology department, going from 01/01/2012 to 31/12/2016. Our inclusion criteria were an age greater than 15 years, all medical imaging confirmed stroke from the Nouakchott region. Daily meteorological information was obtained from the national meteorological service by calculating the monthly and seasonal average of each parameter (mean wind speed, temperature and humidity). The seasons were distributed in the rainy dry season, cold dry season and in the hot season. We collected 1280 patient records, with a sex ratio of 1.24. The average age of patients was 61.59 years, with extremes of 16 to 95 years. The most representative age group was between 70 and 80 years old at 28.3%. The average number of strokes per year was 256 and the average number per month was 21.3. There is a decrease in global incidenc in the rainy season with a minimum in July and a maximum in December and January. The incidence of AVCH decreases during the hot, rainy season. That of DALYs, shows a slight decrease in cold dry season, with a maximum during september. The number of strokes is significantly negatively correlated with humidity. At the end of this work, we observe the seasonal variation in the incidence of stroke as a whole.

FORAGE PRODUCTION AND PRESERVATION OF SPECIES BY ENRICHING CAATINGA WITH GRASSES AND THINNING AREAS INTO STRIPS

ABSTRACT The objective of this study was to evaluate the thinning into strips and the enrichment with exotic grasses in a Caatinga area in order to maintain and increase the biodiversity of native vegetable species and forage production. Two studies were carried out-one in an area of Caatinga thinned into strips and one in an unmanipulated Caatinga area-during the rainy and rainy-dry season transition periods in 2016. The production of herbaceous biomass was evaluated, and the diversity and equability of the two areas were assessed through Shannon-Weaver (H’) and Pielou (J’) indexes. The establishment of massai and buffel grasses at the center and edges of the area thinned into strips was also evaluated. During the rainy season, the production of herbaceous biomass in the area thinned into strips and the unmanipulated area was 1,228 kg ha-1 and 833.33 kg ha-1, while during the rainy-dry transition period, it was 1,973 kg ha-1 and 836.00 kg ha-1, respectively. The indexes remained similar: H’ (1.86) and J’ (0.74) for the area thinned into strips, and H’ (1.77) and J’ (0.85) for the unmanipulated area. The massai grass presented better establishment and development than that by the buffel grass in the center and edges of the area thinned into strips. Thus, thinning into strips increases the biodiversity of an area, and this combined with enrichment through grasses increases the biomass of herbaceous forage.

Morphophysiology of buffel grass grown under different water supplies in the dry and dry-rainy seasons

ABSTRACT The lack of information on the growth of forage grasses in semi-arid environment, especially from the perspective of irrigation, is one of the obstacles to regular forage supply, as well as to the rational use of irrigation water. The objective with this study was to evaluate the leaf gas exchanges, biomass flow and structural characteristics of buffel grass cultivar Gayndah under different water supplies (30, 60, 90 and 120% of the reference evapotranspiration - ETo) during the dry season and dry-rainy season, in completely randomized design in a split-plot scheme with three repetitions. The experiment was conducted in Sobral, CE, Brazil (3° 45’ 00.77” S and 40° 20’ 38.55” W, altitude of 101 m) from September 2015 to January 2016. A higher photosynthetic rate was verified during the dry season, evidencing the adaptability of buffel grass to environments with water restriction. Overall, the best morphogenic and structural characteristics and the biomass production were observed in the dry season. The 90% ETo regime leads to maximum amount of forage accumulation, whereas the 30% ETo allows the maintenance of the cultivar Gayndah of buffel grass in a state of latency during the dry season.

Effects of two different La Niña types on the South American rainfall

The paper tests if the two La Niña (LN) types can be distinguished from each other using their climate impacts on northeastern Brazil (NEB). To this end, all LN events during the 1901–2010 period followed by a wet or dry rainy season (from February to April) in NEB are classified into two categories: WET‐LN and DRY‐LN. The global and regional anomalous atmospheric circulation patterns and the rainfall anomaly patterns in South America associated with the two cases are analysed. The WET‐LN and DRY‐LN events present, respectively, the eastern Pacific LN and central Pacific LN sea surface temperature (SST) anomaly features in the tropical Pacific. On the other hand, the WET‐LN features an interhemispheric SST dipole pattern in the tropical Atlantic, and the DRY‐LN, colder‐than‐normal surface waters in the tropical South Atlantic (TSA) and equatorial Atlantic during MAM(+1). The two analysed cases show regional differential circulation patterns in all seasons. The anomalous wetness over northern and northwestern South America occurs for the WET‐LN type during JJA(0)–DJF(+1) and for the DRY‐LN type, during DJF(+1)–MAM(+1). The anomalous dryness over SESA is more evident for the WET‐LN during JJA(0) and MAM(+1), and for the DRY‐LN, during SON(0). Anomalous dryness occurs in central and eastern South America noted during JJA(0) and DJF(+1) for both cases analysed. The precipitation anomalies in northern South America during DJF(+1) are stronger and more extensive for the DRY‐LN than for the WET‐LN events due to the action of both the anomalous (double) Walker and Hadley cells for the DRY‐LN, in contrast with the exclusive action of an anomalous Walker cell for the WET‐LN case. Also, a double Walker cell drives the dry–wet dipole between northern South America and NEB during MAM(+1) for the DRY‐LN. Our results might be useful mainly for climate monitoring purposes.

Seasonal changes impact soil bacterial communities in a rubber plantation on Hainan Island, China

Rubber plantations have expanded rapidly over the past 20 years in tropical Asia and their impacts on regional ecosystems have garnered much concern. While much attention has been given to the negative impacts on aboveground diversity and function, the belowground bacterial soil community has received much less attention. Here, we investigated the community composition and diversity of soil bacteria of rubber plantations on Hainan Island in south China. The goals of the study were to describe changes in bacterial compositions and diversity across seasons. We found that seasonality defined by differences in rainfall amount strongly influenced bacterial communities. At both the Phylum and Family levels, we found significant differences in the total number of taxa, as well as the composition of the community as a function of season. Diversity of soil samples in the dry-rainy season was highest of three seasons, suggesting that bacterial structure was more sensitive in alternate periods of season. Diversity in the rainy season was substantial lower than in dry season. Results from a redundancy analysis showed that seasonal changes explained the largest part (31.9%) of the total variance of bacterial community composition. In conclusion, seasonal change had the greatest influence on bacterial communities, which overshadowed the effects of soil nutrient as well as other factors, and controls the bacterial communities in soils of RP in tropical region of Hainan.

Occurrence of Aflatoxin M1 in cow milk in El Salvador: Results from a two-year survey.

Aflatoxin M1 (AFM1) is a metabolite of Aflatoxin B1 (AFB1) and is excreted through cow´s milk. AFM1 contamination of milk is extended geographically and there might be seasons-related variations for both prevalence and contents, with higher than average values in regions with long periods of drought like El Salvador. Therefore, this project quantified AFM1 levels in raw cow milk and AFs in cattle feedstuffs, during the transitional dry-rainy seasons of two consecutive years and it determined the variation of occurrence and contents associated to drought. Significant variations were shown from year to year in the prevalence of contamination (30% vs. 20%) and in the average levels of AFM1 in milk (0.056 vs 0.039 μg/kg), associated with drought and increased temperature. The AFs median levels raised significantly with the drought period (from 22.5 to 10.3 μg/kg). A significant relationship was demonstrated between AFs levels and those of AFM1, both in the year with drought and without that condition. AFM1 positive cases and its levels in milk increase in drought and hot conditions, AFs levels in the cattle feed tend to be higher with the same, as well. Both relationship between AFs and AFM1 levels and their association with drought were demonstrated. So that, heat and drought stress conditions can evoke raising effects on both Aflatoxins level and occurrence due to AFM1 in milk is a carryover from AFs contaminated feedstuffs ingested by dairy cows.

Intraseasonal variability of low-level moisture transport over West Africa

The vertically integrated surface-850 hPa atmospheric water vapor flux is investigated, to account for the total low-level moisture flux contribution to rainfall over West Africa (WA), based on NCEP–NCAR reanalysis data. The focus is the contributions to total moisture transport and convergence by the mean circulation, the synoptic ( 10 day) scale anomalies. For WA, the time-mean flow and climate anomalies are comparable. Similarly, for meridional and zonal components, transports by the time-mean and climate anomalies are the largest contributors to mean meridional and zonal moisture transport. While the climate anomalies are responsible for driving moisture poleward from the Atlantic Ocean to the Guinea coast, and westward from the western Atlantic Ocean into the Sahel, the synoptic anomalies contribute to transporting moisture zonally out of the Sahel. Moreover, the spatial distribution of moisture flux convergence reveals a close similarity to the observed 2005 relatively wet and 2006 relatively dry accumulative rainfall. Convergence in WA is mainly the result of moisture transport by the mean flow. An enhanced (weak) flux convergence by the mean flow is characteristic of wet (dry) Sahel rainfall seasons. During wet April-June rainy seasons in the Guinea coast, enhanced convergence due to synoptic anomalies is observed in the region, whereas it is suppressed during dry April-June seasons. In the Sahel, however, during the dry rainy seasons, the convergence region due to synoptic anomalies is displaced southward.

Weight gain and carcass yield in sheep supplemented with multinutrient blocks in transition period dry-rainy season

The aim of this study was to evaluate weight gain and cold carcass yield in sheep supplemented with multinutrient blocks (MNB) fattening phase in the transition period between the dry season and the rainy season. A completely randomized design, in which 16 castrated Colombian hair sheep creoles, managed in rotational grazing (RG) and randomly distributed in four treatments were used as follows: T0: RG; T1: RG + MNB soy based; T2: RG + MNB cotton cake based; and T3: RG + MNB urea based. An analysis of variance was used to determine whether there was a difference between average daily gain and cold carcass yield. For daily gain no significant difference (p>0.05) between treatments was found, but if difference (p?0.05) was found for cold carcass yield. To sell live animals is not necessary supplementation with multinutrient blocks in the transition period between the rainy and dry season.

Effect of supplementation of beef cattle with different protein levels and degradation rates during transition from the dry to rainy season.

The objective of this study was to evaluate the effect of increasing the supply of protein with different degradation rates on the performance and metabolism of growing Nellore cattle reared on Brachiaria brizantha cv. Marandu pasture during the transition period from the dry to rainy season. The experiment was installed on an area of 34 ha, divided into 12 paddocks with an average area of 2.85 ha. In the performance evaluation were utilized 72 recently weaned, non-castrated Nellore cattle with an initial body weight (BW) of 199 kg (SEM = 16). The following supplements were used: energy protein supplement containing 25% crude protein (CP) (C-25) and energy protein supplements containing 40% CP with one third highly degradable CP and two thirds poorly degradable CP (40-1/3NPN), one half highly degradable CP and one half poorly degradable CP (40-1/2NPN), and two thirds highly degradable CP and one third poorly degradable CP (40-2/3NPN). Higher protein degradation rates reduced supplement intake (P < 0.01). In the first period, animals consuming supplement 40-1/3NPN exhibited higher average daily gain (ADG) (0.30 kg/day), similar to that of animals receiving supplement 40-1/2NPN (P = 0.04). In the second period, supplement 40-2/3NPN resulted in lower ADG (0.19 kg/day less than the other supplements). There was no effect of supplement on animal performance in the third period (P > 0.10), when ADG was 0.56 kg/day. In conclusion, the response to supplementation is associated with interactions with characteristics of the forage canopy. Supplementation with a true protein source will be beneficial only during the early stage of the dry-rainy season transition period.

Feeding ecology of immature Lithodoras dorsalis (Valenciennes, 1840) (Siluriformes: Doradidae) in a tidal environment, estuary of the rio Amazonas

Studies of feeding ecology are important for the evaluation of interactive processes in fish communities. This study evaluated the feeding ecology of Lithodoras dorsalis (Doradidae) from streams within the Amazon estuary delta (Brazil), a macro-tidal area, on different pluviometric periods. A total of 371 young specimens was collected during 12 months of sampling (July 2010 to June 2011). The species diet was composed of 28 food items analyzed by Repletion Index, Alimentary Index and Niche Breadth. Young L. dorsalis was classified as herbivore with a frugivory tendency due to the high importance of fruit and seeds in its diet. Food intake varied among sampled months, with the lowest intake being recorded during the rainy-dry season transition period, and the highest at the beginning of the dry season. The importance of food items and the composition of the diet were different throughout the year, probably due to the daily tides that allow fish to access new environments and the pluviometric periods. These results provide important data on the feeding ecology of Amazonian doradids. The study also emphasized the importance of allochthonous resources, derived from the riparian forest, which reinforces the importance of this habitat for the conservation of Neotropical freshwater fishes.