Rhea Americana Research Articles

Antifungal susceptibility of emerging opportunistic yeasts and yeast-like fungi from Rhea americana

Opportunistic yeasts and yeast-like fungi have been recognized as important pathogens in high-risk patients. This study aimed to evaluate the presence of these microorganisms in the microbiota of captive rheas and to investigate the antifungal susceptibility of the isolated strains. Isolates representing Magnusiomyces capitatus (Geotrichum capitatum, n = 11), Trichosporon mucoides (n = 11), Trichosporon asteroides (n = 5), Rhodotorula mucilaginosa (n = 4), Trichosporon asahii (n = 3), Trichosporon cutaneum (n = 3), and Trichosporon ovoides (n = 3) were obtained from the oropharynx, cloaca, and feces of 58 animals. Most of the isolates were susceptible to antifungals in vitro; however, resistance against fluconazole (n = 1) and itraconazole (n = 2) was detected among T. mucoides. This study indicates that healthy rheas can be reservoirs of opportunistic pathogens. Primary resistance to azoles in T. mucoides obtained from these animals demonstrates the potential risk to humans.

Effect of passage through the gut of Greater Rheas on the germination of seeds of plants of cerrado and caatinga grasslands

Frugivorous seed-dispersers play an important role in the maintenance or regeneration of plant populations and communities. Greater Rheas are potentially one of the most import dispersers of seeds in South American grassland biomes owing to their capacity to swallow large seeds and their habitat of walking long distances each day. We studied the potential role of Greater Rheas in the dispersion of seeds of plants of the cerrado and caatinga grassland biomes through germination experiments. We evaluated the rate of seed germination and the mean time of germination of passage through the gut (seeds that passed through the digestive system of Rheas) compared with a control (seeds extracted directly from fruits). Nine species of plant from cerrado grasslands and three plant species from caatinga grasslands were tested. All three caatinga plant species germinated at a lower rate and took longer to germinate after passage through the gut, whereas two of nine cerrado plant species germinated at a higher rate and in less time after passage through the gut. Greater Rheas are probably good dispersers of some of the plant species we examined and may therefore be important in maintenance and regeneration of habitat. Future experiments will investigate the factors causing the variation in germination of seeds seen in this experiment.

The influence of diet composition on egg and chick traits in captive Greater Rhea females

1. This study was conducted to evaluate the influence of diet composition on egg number, physical and chemical characteristics of eggs and weight and survival of chicks throughout a breeding season in a captive-bred population of greater rheas (Rhea americana). 2. From August to December, individuals were offered two diets: processed feed for rheas and processed feed for chicken (which is the feed most commonly offered to farmed rheas in Argentina). Reproductive performance of 15 females was monitored and female body weight was recorded before egg-laying onset. Within each experimental group, the following variables were determined: egg morphometric variables and percentage of components, fatty acid composition, hatching success and initial weight of chicks and mortality during the first week of life. 3. Females that were fed on processed feed for rheas delayed onset of laying and reduced laying period and number of eggs produced. However, females of this group laid larger eggs, with higher percentages of yolk and yolk lipids, and exhibited higher hatching success and chick weight compared with those that received chicken diet. Survivorship of chicks in their first week of life was not affected by composition of the diet offered to parental female. 4. Some reproductive parameters of captive greater rhea females fed on processed feed for rheas were higher than those of individuals receiving processed feed for chicken.

Behavioral responses to short-term transport in male and female Greater Rheas (Rhea americana) reared in captivity

Animal transport is an indispensable practice in species that need to be moved for management or commercial purposes. However, transport may have negative effects on individuals' welfare. The aims of the present work were to determine if the behavioral responses of adult Greater Rheas (Rhea americana) bred in captivity are sensitive to short-term transport and if males and females differ in their posttransport behavioral activity and recovery. Eight males and 8 females were placed in individual pens and allowed 6 d to habituate (d 1 to 6) before transport procedure. On the transport day (d 7), half of the birds (4 males and 4 females) were randomly assigned to a transport group that was captured and handled to be placed into the crates, exposed to a 30-min transport stressor, and immediately returned to their pens. Four transports with 1 different male and female each time were performed. The other half remained undisturbed and were used as controls. Behavior of all individuals was video-recorded during habituation days, after transport on d 7, and on the 2 following days (d 8 and 9) to evaluate pre- and posttransport behavioral activity for 2 h per day. No significant behavioral changes were observed during the last 2 d of the habituation period (d 5 and 6), suggesting that Greater Rheas were adapted to the housing conditions before transport. After transportation, several behaviors were affected: transported males and females showed null resting, transported females also showed reduced preening and increased vigilance (P < 0.05), whereas transported males showed increased drinking (P < 0.05) compared with their respective control groups. The results suggest that behavioral responses of captive-bred Greater Rheas are sensitive to short-term transport (which includes handling) and that males and females differ in their posttransport behavioral activity, recovering their overall basal levels on the third day posttransportation.

Detection of Candida species resistant to azoles in the microbiota of rheas (Rhea americana): possible implications for human and animal health

There is growing interest in breeding rheas (Rhea americana) in Brazil. However, there are no data on the yeast microbiota of the gastrointestinal tract of this avian species, and the phenotypic characteristics of these yeasts are not known. Therefore, the aim of this work was to isolate Candida species from the digestive tract of rheas and to evaluate the in vitro antifungal susceptibility and secretion of phospholipases of the recovered isolates. For this purpose, 58 rheas from breeding operations in the cities of Fortaleza and Mossoró, north-eastern Brazil, were used. Samples were gathered from the oropharynx and cloaca of the animals using sterile swabs. Stool samples were collected from their pens by scraping with a scalpel blade. For the primary isolation, the material was seeded onto 2 % Sabouraud dextrose agar supplemented with chloramphenicol (0.5 g l(-1)). The isolates were identified based on morphological and biochemical features. After identification, all the strains were submitted to antifungal susceptibility testing for amphotericin B, itraconazole and fluconazole. The phospholipase activity of the Candida species isolates was also tested by culturing on egg yolk agar. Candida species were isolated from at least one anatomical site in 36/58 birds (14/17 juveniles and 22/41 adults) and in 6/10 faecal samples. Mostly, only a single species was isolated from each collection site (36/56 positive sites), with up to three species being observed only in four cases (4/56). A total of 77 isolates were obtained, belonging to the species Candida parapsilosis sensu lato (19), Candida albicans (18), Candida tropicalis (13), Candida guilliermondii (12), Candida krusei (10) and Candida famata (5). C. albicans was more prevalent in the oropharynx of the juvenile rheas when compared with adult ones (P<0.001). All tested isolates were susceptible to amphotericin B, but 16 isolates were simultaneously resistant to the two azole derivatives (11/18 C. albicans, 1/10 C. krusei, 2/19 C. parapsilosis sensu lato and 2/13 C. tropicalis). C. albicans presented a particularly high resistance rate to fluconazole (15/18) and itraconazole (13/18). Finally, 23/77 strains secreted phospholipases. In summary, healthy rheas carry potentially pathogenic Candida species in their gastrointestinal tract, including azole-resistant strains that secrete phospholipases, and are prone to disseminating them in the environment. Thus, breeding and handling these animals may have some implications for human and animal health.

Landbird Assemblages in Different Agricultural Landscapes: A Case Study in the Pampas of Central Argentina

A combination of elements (e.g., crops and pasture lands, strips of roadside vegetation, woodlots, temporary wetlands) increases the heterogeneity of rural landscapes. Agricultural landscapes range from homogeneous, dominated by a single element (i.e., pure cropland or pure pastoral farming) to heterogeneous, dominated by two or more elements (i.e., mixed farming). In this study we characterized landbird assemblages in various agricultural landscapes (cropland, pastoral, and mixed landscapes) in the Pampas of central Argentina, surveying along transects to quantify species richness, composition, and abundance. Mixed landscapes were more heterogeneous than pastoral areas and cropland. Species richness, particularly of generalists, was greater in mixed landscapes. Richness of grassland specialists (species of increased conservation concern in the Pampas) was lower in croplands than in pastoral and mixed landscapes. An indicator-species analysis supported the association of some grassland specialists (Rhea americana, Asthenes hudsoni, Embernagra platensis, Pseudoleistes virescens) with pastoral landscapes. Our results suggest that maintaining landscape heterogeneity throughout the Pampas (i.e., mixed landscapes) is important for preserving species richness of birds. But several threatened grassland specialists inhabiting the Pampas, such as Rhea americana and Asthenes hudsoni, are found exclusively in pastoral landscapes, so the long-term survival of these species will depend on the conservation of this landscape type.

AN INDIVIDUAL‐BASED MODEL TO ESTIMATE THE DAILY ENERGETIC COST OF GREATER RHEAS AND ITS CONTRIBUTION ON POPULATION RECRUITMENT

Abstract An individual‐based model for estimating the energetic costs in Rhea americana was developed considering their sexual and seasonal differences in the behavioral activities. The model includes as variables the individual's characteristics, as well as corporal weight, the time spent on different activities, and the cost associated with each activity. We estimated the daily energetic demand of an adult rhea based on the activities individuals normally develop during postreproductive, nonreproductive, and reproductive seasons, differentiating between sexes. The time spent in each activity for one given animal was calculated from field observations of individuals and the estimations of energetic costs for each activity were obtained from specialized literature. The model built varied between sexes because males and females have different reproductive costs. Both models have the same general formulation but they differ in the cost associated with reproduction. In Greater Rheas, while males assume all of the incubation, the females only lay eggs communally in a single nest. Also the possibility that the individual reproduces or not was considered. The model does not allow to determine whether the energetic costs associated with the breeding are the reason why few individuals try to reproduce but it indicates that there is a clear difference in the daily energetic costs of individuals which reproduce and those which do not reproduce. Other activities associated with parental care posthatching, not taken into account here, would increase these differences, and would explain the low number of breeding attempts observed at wild.

Corticosterone stress response of Greater Rhea (Rhea americana) during short-term road transport

The effect of transport stress on blood corticosterone levels in captive Greater Rheas was investigated. Twelve adult individuals (7 males; 5 females) were loaded in pairs inside wooden crates and transported along a paved road for 30 min. Blood samples were taken before the individuals were introduced into the crate (baseline value) and immediately after they were unloaded (30 min after capture). To assess whether corticosterone levels were affected by the blood sampling procedure per se, another 6 (nontransport) control birds (3 males; 3 females) were also captured and sampled at the same times as their transported counterparts. Plasma corticosterone concentrations were measured using a commercially available corticosterone (125)I radio-immunoassay kit. Baseline corticosterone levels were similar in the control and transported birds (9.0 ± 1.6 and 10.4 ± 0.8 ng/mL, respectively). Transportation induced a highly significant (P < 0.001), more than 40-fold increase in the corticosterone levels (433.6 ± 35.4 ng/mL) that was about 5 times higher (P < 0.001) than in their nontransported counterparts (88.4 ± 14.8 ng/mL). The present findings suggest that Greater Rhea is a species highly sensitive to stressful manipulations. Both blood sampling and transportation induced highly significant adrenocortical responses. Considering that transportation is one of the unavoidable common practices in the management of Greater Rheas and, as shown in the present study, that it induces a significant 40-fold corticosterone stress response, efforts should focus on helping to generate management transport standards for optimization of the welfare of this ratite.

Gastrointestinal parasites in greater rheas (Rhea americana) and lesser rheas (Rhea pennata) from Argentina

Few data exist on the parasites of ratites, especially from regions within their natural range. It is only recently that extensive studies on the parasites of ostriches (Struthio camelus) have been published, mainly from European countries where commercial farming has expanded. Two species of ratites are native in South America: the lesser rhea also known as Darwin's rhea (Rhea pennata) and the greater rhea (Rhea americana). Both species are considered near threatened by the IUCN and are included in the CITES’ Appendices I and II, respectively. Parasitological studies have conservation implications, as they allow us to assess the risk of transmission of pathogens from farmed ratites to wild populations. In this study 92 faecal samples from greater rheas and 55 faecal samples from lesser rheas from different localities in Argentine were analyzed to determine their gastrointestinal parasites. In greater rheas the protozoa (Balantidium coli-like and Entamoeba spp.) and helminths (Fasciola hepatica and Deletrocephalus spp.). The protozoa had not previously been cited as parasites of greater rheas in South America. Cysts and/or trophozoites of B. coli-like were found in 16.3% of the samples, while the prevalence of the remaining parasites was below 10%. Lesser rheas harbored the protozoa B. coli-like, Entamoeba spp. and Chilomastix spp. as well as F. hepatica and nematode eggs and larvae. B. coli-like cysts were found in 20.0% of the samples, while the prevalence of the other parasites remained below 5%. Some of them had not been cited as infecting lesser rheas yet.

THIAFENTANIL-DEXMEDETOMIDINE-TELAZOL ANESTHESIA IN GREATER RHEAS (RHEA AMERICANA)

Ratite anesthetic events are often dangerous because these birds use their powerful legs and clawed feet as a defense, and physical restraint can result in self-trauma or injury to handlers. Although various combinations of opioids, alpha-2 adrenergic agonists, and dissociative agents have been employed in ratites, few effective chemical immobilization protocols have been documented for rheas (Rhea spp.). An intramuscular, remote-delivered combination of thiafentanil (0.30 +/- 0.08 mg/kg), dexmedetomidine (7.31 +/- 2.72 microg/kg), and tiletamine-zolazepam (5.09 +/- 2.31 mg/kg) was utilized in eight adult (four male, four female) greater rheas (Rhea americana). Smooth inductions were observed. During clinical procedures, birds were intubated and maintained on isoflurane gas, and atipamezole was administered to antagonize the dexmedetomidine. At recovery, naltrexone was administered to antagonize the thiafentanil, and midazolam was administered to smooth crate recoveries until release. This low-volume, high-potency, reversible drug combination demonstrated safe inductions and smooth recoveries and proved to be a reliable anesthetic regimen for greater rheas.

Gross morphology of rhea oropharyngeal cavity

The rhea (Rhea americana americana) is an american bird belonging to Ratite's family. Studies related to its morphology are still scarce. This study aims to describe the macroscopic structures of the oropharyngeal cavity. Five heads (2 to 6 months old) formalin preserved were anatomically dissected to expose the oropharynx. The oropharynx of the rhea was "bell-shaped" composed by the maxillary and mandibular rhamphotheca. The roof and floor presented two distinct regions different in colour of the mucosa. The rostral region was pale pink contrasting to grey coloured caudal region. The median longitudinal ridge extended rostrally from the apex of the choana to the tip of the beak in the roof and it is clearly more prominent and rigid than the homolog in the floor that appeared thin and stretched merely along the rostral portion of the regio interramalis. The floor was formed by the interramal region, (regio interramalis) tongue and laryngeal mound containing glove-shaped glottis. This study confirmed the basic morphology of the oropharinx of the rhea. However, important morphological information not previously described is highlighted and contradictory information present in the literature is clarified.

Using environmental enrichment to reduce the expression of abnormal behaviours in Greater rhea Rhea americana at Belo Horizonte Zoo

Animals kept by zoos may express abnormal behaviours that are indicators of poor welfare. Environmental enrichment is a technique of providing items to animals that stimulate the expression of normal behaviours. The aim of this study was to evaluate the effects of providing simple environmental enrichment in the reduction of the expression of abnormal behaviour in captive‐born Greater rhea Rhea americana at Belo Horizonte Zoo, south‐eastern Brazil. As enrichment, fruit and vegetables were scatter fed to a group of seven birds from April to September 2009, and the behaviour of the birds was recorded using scan sampling with instantaneous recording of behaviour every 1 minute for 1 hour daily (90 hours of observation). The study was divided into three phases: baseline, enrichment and post‐enrichment. The abnormal behaviours ‘pacing’, ‘eating faeces’ and ‘escaping behaviour’ reduced during the enrichment phase, but only the first two behaviours differed significantly between the phases; ‘walking’ and ‘foraging’, both positive behaviours, increased during the enrichment phase. These results showed that the implementation of simple environmental enrichment can stimulate the Greater rhea to exhibit more natural behaviours and improve their welfare.

Effect of atmospheric conditions on protein tyrosine phosphorylation in stallion sperm

individual variation of samples following cryopreservation. Cholesterol is known to play an important role as cryoprotectant in semen freezing. Egg yolk of greater rhea (Rhea americana) is known to have 4.54 times more cholesterol than the chicken egg yolk. The aim of this work was to compare the use of two commercial extenders using chicken egg yolk and substituting Rhea egg yolk to chicken egg yolk, in order to maximize the cryoprotectant effect of cholesterol. Semen was collected six times from each of six Criollo breed stallions during the non-breeding season using a Hannover model artificial vagina and an estrous mare. The ejaculate was evaluated for total and progressive motility; concentration was determined with a Neubauer counting chamber. Sperm morphology slides were stained with Cerovsky stain. After evaluation, semen samples were divided in two aliquots and diluted 1:1 in one of the centrifugation extenders: A (extender with glycerol) or B (extender with methylformamide). The semen samples were centrifuged at 400 g for 10min and 90–95% of the supernatant (extender plus seminal plasma) was removed. All samples were re-suspended to a final concentration of 100 106 sperm/ml either in extender A with or without rhea egg yolk or extender B with or without rhea egg yolk. Extended semen were packaged into 0.5-ml straws and frozen 3 cm above liquid nitrogen level for 20 min. Samples were then plunged into liquid nitrogen and stored at 196C. Semen samples were examined earliest one week after freezing for total and progressive motility and for physical and functional membrane integrity (HOST and CFDA-PI fluorescence). Differences between treatments were computed using Prism5 (GraphPad, USA) and an analysis of the 2x2 factorial design was done using the Bonferroni test as post-test; the significance was set at 5%. Both extenders, with or without Rhea egg yolk, showed no significant difference in total or progressive motility, although there was a difference (P 1⁄4 0.05) between extenders when different extenders were compared, no matter if they were supplemented with Rhea egg yolk or not. Membrane integrity was not significantly different. The present results show that Rhea americana egg yolk might be an alternative supplement to stallion semen extenders, although there is no improvement of semen quality in comparison to egg yolk.

Detecção sorológica e microbiológica de Salmonella spp. em emas (Rhea americana)

The fast agglutination screening test, using S. Typhimurium as the antigen, was compared with the standard bacterial method to identify rheas (Rhea americana) contaminated with Salmonella spp.at slaughter.Seventy birds were serologically tested for Salmonella enterica Pullorum using a commercial antigen.Of these, 66 were also submitted to a macroagglutination test, using a strain of Salmonella Typhimurium isolated from rheas.All birds did not react with the commercial S. Pullorum antigen, but 37 were positive for the FAST-ST.The isolation of Salmonella spp. was verified in 66 (94.2%) birds. 85.7% were found in liver samples, 60% in feces and 42.3% in cloacal swabs.A total of 16.6% were identified as being S. enterica enterica rugosa, 35.9% as S. Typhimurium, 46.5% as S.Newport and 0.9% as S. Anatum. An insignificant concordance between the results of bacterial isolation and the serological response was observed (k=0.016).The detection of Salmonella spp. by bacteriological and serological methods in samples from rheas must be deemed important, because birds without a clinical manifestation can be significant sources of salmonellas in food infections.

Use of Rhea americana egg yolk to substitute chicken egg yolk in stallion semen extenders

Use of Rhea americana egg yolk to substitute chicken egg yolk in stallion semen extenders

Avaliação da infestação de piolhos mastigadores (Struthiolipeurus rheae) em emas (Rhea americana) mantidas em criadouro comercial no estado do Piauí

We evaluated the level of infestation of biting lice (Struthiolipeurus rheae) in emus (Rhea americana) kept in a breeding business in the state of Piaui. We used 16 emus, 12 adults, six of them were males and six females. Only four of emus analyzed were young. Were collected randomly, two wings and two feathers of the base of the neck of each animal, which were placed in plastic bags. Later, lice were counted, preserved in jars with alcohol 70oGL and sent to the Laboratory of Animal Health of Federal University of Piaui for identification. In samples obtained from adult emus, met a total of 77 lice, and the incidence of the wing feathers collected, 84.4% (65), significantly higher than in the feathers of the lower neck, 15.6% (12 ). No lice were found in young animals born in brooder. The adult rheas showed a high degree of infestation by S. rhea. The artificial incubation of the animals prevented the infestation of young emus S. Rhea. The high infestation S. rhea prevents the commercial use of emu feathers. This is the first record of occurrence of S. rhea in rheas in the state of Piaui.

Establishment and maintenance of persistent infection by picobirnavirus in greater rhea (Rhea Americana)

A study aimed to determine the infection model that picobirnavirus (PBV) established in birds was conducted in a farm of greater rheas in Córdoba, Argentina. Analysis of stools collected during a longitudinal study involving seven birds provided evidence that PBV is acquired very early in life and establishes a persistent infection in the host, which is characterized by intermingled periods of high, low and silent viral activity. Genomic analysis indicated that the rheas excreted virus with nucleotide sequence identity between 90.5-100% and that more than one PBV strain with different electropherotype profiles could be involve in the infection. This report provides the first evidence of persistent infection of PBV in birds. The natural history of PBV infection has begun to be understood, and it appears that asymptomatic PBV-infected mammals and birds could persistently excrete the virus in stool samples, contributing to wide circulation of the virus in the environment.

Efficiency of the cloacal sexing technique in greater rhea chicks (Rhea americana)

1. The feasibility and accuracy of the cloacal sexing technique in greater rhea chicks was assessed using chicks of two captive populations of greater rhea in Córdoba, Argentina. 2. A total of 46 greater rhea chicks of 2 to 3 months of age were randomly arranged into three groups and the members of each group were sexed by a different operator. 3. A feather of each chick was plucked for sexing through a molecular method and results were used as controls. 4. Sex was correctly assigned by cloacal inspection in 98% of the cases. Chick manipulation was easily performed and no infections or traumatic lesions were observed a posteriori. 5. Cloacal sexing of rhea chicks up to 3 months of age does not affect animal welfare and should be considered an efficient alternative to molecular methods.

Visitor Influence on the Behavior of Captive Greater Rheas (Rhea americana, Rheidae Aves)

Visitors can affect and reduce the welfare of nonhuman animals. The Belo Horizonte Zoo, Brazil, had a group of greater rheas intended for reintroduction to the wild. Because this group received public visitation, evaluating its effect on the birds' behavior and welfare was important. The study conducted 60 hr of behavioral observations: 30 with, and 30 without, visitors in front of the birds' enclosure. The study, conducted April–December 2009, collected data using scan sampling with instantaneous recording of behavior every minute. The study collected data on public behavior, visitor density, and time spent observing the birds. More than 4,000 persons visited the birds' enclosure: 9.86 s average time spent. Public behaviors most expressed were walking-watching-talking and stopped-watching-talking; visitors or not, greater rheas' most expressed behaviors (inversed between treatments) were foraging and walking alert; defecating/urinating and other behaviors differed statistically between treatments. Walking alert was most expressed in the presence of visitors; defecating/urinating and other behaviors were most expressed in their absence. Greater rheas seemed to habituate to visitors. Birds' behaviors differed little in visitors' presence or absence.

Gross anatomical features of the tongue, lingual skeleton and laryngeal mound of Rhea americana (Palaeognathae, Aves): morpho-functional considerations

The tongue body of Rhea americana is triangular and partially pigmented with each caudo-lateral margin displaying a round, sub-divided lingual papilla. The tongue root is a smooth, non-pigmented tract of mucosa. The tongue body is supported by the paraglossum and distal half of the rostral projection of the basihyal (RPB), and the tongue root by the proximal half of the RPB, body of the basihyal and proximal ceratobranchials. An urohyal is absent; however, peculiar to R. americana, the caudal margin of the cricoid body displays a median projection, which may represent the remnant of the urohyal incorporated into the cricoid. The laryngeal mound is less elevated, the arytenoid cartilages are smaller than in other ratites, and the caudal margin displays pharyngeal papillae that vary in shape and number. The unique morphology of the lingual skeleton and its positioning within the tongue of R. americana, the rostral insertion of the M. ceratoglossus, the absence of the urohyal (enhanced ventroflexion) and the caudal positioning and mobile attachment of the ensheathed basihyal to the paraglossum would appear to allow independent movement of the tongue body relative to the hyobranchial apparatus. Additionally, the deeply indented base and rostral oval opening in the paraglossum limits the length of cartilage present in the midline of the tongue body. This may allow the tongue the necessary flexibility for the lingual papillae to clean the choana. The cleaning action of the tongue would occur simultaneously with the previously described role of this organ and associated structures during feeding. Thus, the so-called reduced, ancestral tongue of R. americana may be structurally and functionally more complex than previously believed.