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.     

Microbial contamination of artificially incubated Greater Rhea (Rhea americana) eggs

1. This paper is a report of biological agents that contaminate Greater Rhea (Rhea americana) eggs during artificial incubation. 2. The cleanliness of eggs when collected, and the period of storage prior to incubation, were investigated to assess their effects on microbial contamination and hatchability. 3. A total of 14 bacteria and 4 fungi species were isolated within the egg in the laboratory. 4. Microbial contamination was higher (24%) in very dirty eggs than in eggs which were clean or dirty (16%). Hatching success was lower (30%) for very dirty eggs, compared with 42% for clean or dirty eggs. 5. The percentage of microbial contamination of stored eggs (10%) did not differ significantly from that of non-stored ones (5%). 6. The extreme lower and upper limits of infection rate estimated for artificially incubated Greater Rhea eggs were 4% and 40%, respectively, being higher than in poultry species. 7. It is concluded that collecting eggs soon after laying will reduce the risk of microbial contamination.     

Physical characteristics and chemical composition of Greater Rhea (Rhea americana) eggs from wild and captive populations.

1. Eggs from wild and captive populations of Greater Rhea (Rhea americana) were studied to determine their physical and chemical characteristics. 2. Significant differences were found among populations in almost all chemical parameters studied, whereas within physical parameters only shell weight (as a proportion of the entire egg) and density showed differences. 3. Eggs from wild populations had the highest protein and linolenic acid and the lowest total lipid contents, while cholesterol levels of these eggs and of those from the largest captive area were the lowest.     

Ontogenetic Scaling of the Hindlimb Muscles of the Greater Rhea (Rhea americana)

The greater rhea (Rhea americana) is the largest South American bird. It is a cursorial, flightless species with long powerful legs and reduced forelimbs. The goal of this study was to explore how hindlimb muscles scale with body mass during postnatal growth and to analyze whether the specialized locomotion of this species affects the growth of muscle masses. The mass of 19 muscles and body mass were weighed in 21 specimens ranging from 1‐month‐old individuals to adults. Seventeen muscles scaled with positive allometry with respect to body mass, whereas two muscles scaled isometrically . The predominance of positive allometric growth in hindlimb muscles results in a limb with massive and powerful muscles specialized to support a large body mass and to attain relatively high running speeds. Analysis of muscle mass scaling is a simple and useful way to compare possible differences between locomotor styles, and it is valuable in studies that reconstruct the paleobiology of extinct taxa.     

Effects of storage time on hatchability of artificially incubated Greater Rhea (Rhea americana) eggs

(1) A study was conducted to determine the effects of the length of the storage period on the hatchability of artificially incubated Greater Rhea eggs. Hatchability was evaluated in eggs gathered daily from a captive population and in eggs collected less frequently from a semi-captive population. (2) Eggs form both sites were either immediately incubated after being collected or were stored for 1 to 9 d prior to incubation. (3) The maximum number of days for which an egg could be stored without depressing hatchability (with respect to non-stored eggs) was longer in the eggs collected daily. (4) Eggs collected daily and stored for 4d or more showed total hatchability (28%) and fertile hatchability (43%) which was approximately 30% lower than non-stored eggs or eggs stored for 3 d or less. In the semi-captive population, the total and fertile hatchability of non-stored eggs and of eggs stored for one day were 40% greater than of eggs stored for 2 to 9 d (20 and 34%, respectively). (5) The period for which Greater Rhea eggs could be stored without depressing hatchability varied depending on the frequency of egg collection: non-daily egg collection reduces the possible period of storage.     

Hindlimb bone maturation during postnatal life in the Greater Rhea (Rhea americana,Aves, Palaeognathae): Implications for palaeobiological and zooarchaeological interpretations

The objective of this study was to study the morphological pattern of bone maturation of the hindlimb bones of Rhea americana and find out how it can affect bone morphology after a taphonomic process. Juvenile specimens (n = 10) ranging from one month old to eight months old were studied. For comparison, bones from adults and juveniles from museum specimens (n = 4 and n = 6, respectively) were studied. In fresh bones, ossification centres were identified in the proximal and distal epiphyses of the tibiotarsi and in the proximal epiphysis of the tarsometatarsi, whereas the distal region of the femora and tarsometatarsi showed abundance of cartilage. The development and extension of the ossification centres of the tibiotarsi were different. In the proximal epiphysis, the centre presented less development with respect to the distal epiphysis. In the dry tibiotarsi, the proximal centre was absent and the distal one was well preserved. Both the fresh and dry juvenile tarsometatarsi presented unfused metatarsals and bulkier and wider aspect than the adult ones. The dry femora presented a noticeable excavation between condyles, whereas the dry tarsometatarsi showed the absence of the proximal epiphysis. The femora, tibiotarsi and tarsometatarsi possessed different traits of immaturity, which differentially affect the morphology of the preserved bones during a taphonomic process.     

Morphometry of the heart of greater rhea (Rhea americana americana,Linnaeus, 1758)

Heart diseases in birds are frequent and generate significant production disorders. Morphometry is a valuable tool to provide fundamental information about heart conditions. Few studies have addressed morphological aspects of the heart of ratite birds, such as the Greater rhea. The present study aimed to analyse rhea heart morphometry, comparing young and adult subjects, in order to provide relevant information for the diagnosis of heart disease in this species. Hearts of young (n = 10) and adult (n = 10) female rheas were used in this research. Heart length and width and sternum length were measured using a caliper. Heart length and width and sternum length in adults were approximately three times greater than in young individuals. The left ventricular wall (LVW) was thicker than the right ventricular wall (RVW) at all ages, and the RVW was thicker in adults when compared to young subjects. The basal and middle RVW regions thicken with advancing age, and the thickness of the interventricular septum (ISW) occupies an intermediate position between the LVW and RVW. In general, an increase in rhea heart thickness and size relative to age is observed. The morphometric variations between young and adult rhea hearts observed in the present study may serve as a comparative subsidy for the diagnosis of cardiac abnormalities observed in this species.     

Heritabilities and correlations for egg shell crack frequency,body checking,egg number and egg weight in laying hens

1. Egg shell cracks and body checking were assessed on a total of 25 776 eggs collected from 744 hens of two selected White Leghorn strains between 65 and 72 weeks of age.

2. The sire‐component heritabilities in the two strains, respectively, were 0–59 ± 0.23 and 0.36 ± 0.20 for total cracks and 0.41 ± 0.20 and 0.49 ± 0.22 for body checking. The heritabilities for hole, star and hair cracks ranged from ‐0.03 ± 0.13 to 0.66 ± 0.24.

3. The frequency of total cracks did not bear any significant antagonistic relationship with body checking, egg number and egg weight. Body checking had variable relationship with egg number and egg weight. The correlations of shell cracks and body checking with each other and with egg number and egg weight appeared to vary between the strains.     

Chronic fascioliasis in farmed and wild greater rheas (Rhea americana)

From 50 farmed Rhea americana slaughtered for human consumption, adult forms and eggs of Fasciola hepatica were found in 4. The other three livers were free of flukes but did show lesions caused by larval fluke migration. Histological lesions were similar to those caused by flukes in cattle and sheep. The rheas were from an endemic area of ruminant fascioliasis in Southern Brazil. F. hepatica eggs were also found in faecal samples of wild rheas from another endemic area in Southern Brazil. It is likely that the rheas play a role in the transmission of the disease to ruminants and could be jeopardizing the control of this parasitosis in endemic areas. From the best of our knowledge this is the first report of fascioliasis in R. americana.     

Outbreak of Philophthalmus gralli in four greater rheas (Rhea americana)

Using slit‐lamp biomicroscopy, conjunctival biopsy, and morphological identification, a flock of four Greater rheas (Rhea americana) in Arizona were diagnosed with conjunctivitis secondary to Philophthalmus gralli (P. gralli) infection. Aquatic snails from the exhibit’s water source were identified as Melanoides tuberculatus, a known vector for P. gralli. Comparison of partial sequences of DNA regions from P. gralli adults removed from the rheas and metacercariae from the aquatic snails demonstrated a 100% match, confirming the source of infection. The flock was divided into two treatment groups: the most severely affected rheas received both manual removal of trematodes and praziquantel 1% ointment OU q12 h and the least severely affected rheas were only given praziquantel 1% ointment OU q12 h. The rheas were permanently relocated away from the infected water source and aquatic snails. Initial resolution was seen at 17 weeks in the most severely affected rhea, which had 675 adult P. gralli removed and topical praziquantel. The two rheas that only received topical praziquantel showed resolution within 3 and 15 weeks. Current recommendations for treating P. gralli include: manual removal of trematodes, topical praziquantel 1% ointment, and relocation away from infected water sources and aquatic snails.     

Coefficients for the estimation of fresh weight and volume of Greater Rhea eggs

1. Specific values of constants needed to estimate fresh weight (Kw) and volume (Kv) of Greater Rhea eggs were obtained. 2. The average value for the weight coefficient (Kw) was 0.57, whereas that for volume (Kv) was 0.51. Accuracy of results obtained with these values was +/-2.1% and +/-3.5%, respectively. 3. The fresh weight and volume of Greater Rhea eggs can be easily estimated by means of these specific coefficients when those measurements cannot be taken directly.     

Observations on helminth infections of free-living and captive rheas (Rhea americana) in Brazil

The present work describes helminth infection of eight free-living and 12 captive rheas (Rhea americana) from, respectively, Pantanal of Mato Grosso do Sul State, and Jaboticabal, Sao Paulo State, Brazil. Captive birds were young and had a high mortality rate, while free-living birds were adult and apparently healthy. Infections were evaluated by post-mortem examination of internal organs and recovery of helminths using standard parasitological procedures. Seven species of nematodes (Sicarius uncinipenis, Torquatoides crotophaga, Deletrocephalus dimidiatus, D. cesarpintoi, Paradeletrocephalus minor, Capillaria venteli and Dicheilonema rheae) and two species of cestodes (Houttuynia struthionis and Chapmania tauricolis) were identified. P. minor, which inhabits the large intestine, was the most common helminth in free-living birds (63.9%). In captive rheas, a mean parasitic load of 173 helminths per host was found. The gizzard of these birds was the most parasitized organ and S. uncinipenis was most common (92.5%). Parasitism of free-living and captive birds and associated pathology are discussed.     

Parasites from farmed ostriches (Struthio camelus) and rheas (Rhea americana) in Europe

During a 4-year-period, more than 500 ostriches and several rheas, all born in European countries and raised in Spain and Portugal, have been analyzed for the presence of ectoparasites and endoparasites. A total of 29 parasite species have been found, most of them of the gastrointestinal tract. Some of the helminth species found may represent spureous parasitosis, as only the eggs (of an ascarid and a trematode) were found in some samples. From the organisms identified, the ectoparasites (lice-Struthiolipeurus rheae, S. nandu; mites-Dermoglyphus pachycnemis, Gabucinia bicaudata), helminths (cestoda-Houttuynia struthionis- and nematoda-Libyostrongylus sp., Codiostomum struthionis-) and the ciliate Balantidium struthionis are known as ratite specific parasites. Capillaria eggs and larvae were also found; there are no previous records of this parasite from ostriches, and the data available do not allow to do a temptative specific diagnosis. Among protozoa, most of the species now found are described for the first time in ratites. They include organisms also found in other birds (Trichomonas gallinae, Tetratrichomonas gallinarum, Chilomastix gallinarum, Spironucleus meleagridis and Pleuromonas jaculans), and organisms whose specific status cannot be established until further analysis are performed (Cryptosporidium sp., Eimeria sp. and/or Isospora sp., Entamoeba sp. of the one-nucleate and of the eight-nucleate mature cyst groups, Endolimax sp., Iodamoeba sp., Monocercomonas sp., Retortamonas sp., Giardia sp., Blastocystis sp. and euglenids).     

Aspects of the Macroscopic Testicular and Epididymal Morphology in the Greater Rhea,Rhea Americana (Linneaus – 1758) Birds

The purpose of this research was to study the macroscopic testicular and epididymal morphology of the greater rhea. The testicles of 54 greater rhea bred in captivity were utilized. The samples were collected November 2005 (n = 14), December 2006 (n = 20) and May 2007 (n = 20). During commercial slaughter, the testicles and epididymides were collected and their following morphometric parameters were immediately measured: length, width, thickness, circumference, volume, weight of the parenchyma and the tunica albuginea, also aspects such as shape, cavity implantation, relationship with other organs and vascularization. The testicles presented cylindrical shape, with a thin, dense and transparent tunica albuginea, and the vascularization was accomplished by the testicular artery that ramifies from the cranial rectal artery. In the samples from December 2006 and May 2007, the media from the macroscopic measures of the right testicles were volume 58.7 and 14.7 ml, length 9.87 and 3.5 cm, width 2.4 and 0.6 cm, thickness 2.4 and 0.5 cm, circumference 8.0 and 2.3 cm, parenchyma weight 27.6 and 6.1 g and tunica albuginea weight 1.0 and 0.3 g, P < 0.05, respectively. The epididymides, the media from macroscopic measures December 2006 and May 2007 were volume 7.7 and 3.0 ml, length 5.8 and 1.3 cm, width 0.7 and 0.3 cm, thickness 0.6 and 0.3 cm, circumference 2.5 and 1.2 cm, tissue weight 6.4 and 2.8 g and capsule weight 0.4 and 0.1 g, P < 0.05, respectively. Some measures from the right testicle and epididymis were superior to measures taken from the left ones (P < 0.05), but these were not characterizing asymmetry. The morphometric parameters observed during November 2005 remained on an intermediate situation (P < 0.05); however, they were quantitatively closer to the means of December 2006, which may characterize it as a potential transition period between repose and sexual activity. Morphologically, the testicles and epididymides of greater rhea have common points with other researched birds; however, differences were observed. The testicles and epididymides of the Rhea americana are influenced by the environment, presenting reproductive activity season (November–December) during late spring, early summer and sexual repose season (May) during autumn–winter. The morphometric testicular and epididymal measurements were introduced. The morphometric parameters of testicles and epididymides exhibited differences between winter and spring–summer that could be established like sexual activity season.     

Effect of starting body fat content and genotype of laying hens on the changes in their live weight,body fat content,egg production and egg composition during the first egg-laying period

1. A total 120 laying hens (60 TETRA BLANCA white egg layers and 60 TETRA SL brown egg layers) were selected from 250 TETRA BLANCA and 250 TETRA SL pullets based on their predicted body fat content by means of computed tomography (CT) at 16 weeks of age. Three groups of pullets were chosen for the investigation with the highest (n = 20), lowest (n = 20) and average (n = 20) body fat content.

2. Changes in the live weight, body fat content, egg production and egg composition of the chosen animals were recorded at 32, 52 and 72 weeks of age.

3. Based on the results, it was established that differences in starting body fat content of the hens remained the same during the experimental period. The differences between the two extreme groups were statistically significant at each age.

4. The starting body fat content of the hens affected the rate of egg production, i.e. hens with high starting body fat content produced 11–14 eggs fewer than the hens with a low or average body fat content but had no effect on the composition of the eggs.

5. Genotype affected almost all of the examined traits: TETRA BLANCA hens had lower live weight and higher body fat content during the experimental period and produced fewer eggs with lower albumen and higher yolk, dry matter and crude fat content than the TETRA SL hens.

     

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.     

The effect of variation in egg numbers,body weight and egg weight upon shell thickness

It is expected that when birds consume a diet with a fixed calcium content variation in the rate of egg production, in body weight or in egg weight will lead to variation in calcium consumption. This analysis investigated whether, in a particular experiment, this also led to variation in egg shell thickness. Data from 67 birds over ten consecutive 28‐d periods were considered. Within birds and within periods it was found that the relationships between shell thickness and these production characters varied at different dietary calcium levels and in some cases the partial regression coefficients calculated were different in sign from those expected. However, only comparatively small amounts of variation in shell thickness could be ascribed to yariation in egg numbers, body weight or egg weight and, after regression, significant (P<0.001) differences still existed in shell thickness between birds. In this investigation there was little tendency for the egg shells to become thinner as the birds aged and hence the correlation coefficients between shell thickness and each of the three production characters due to common seasonal or ageing effects were small. The correlation between the angular transformation of the percentage cracked egg shells produced by each bird and its'mean shell thickness was — 0.357.     

Macroscopic and microscopic anatomy of the oviduct in the sexually mature rhea (Rhea americana)

The morphological characteristics of the oviduct of 12 sexually mature rheas (Rhea americana) were studied. Only the left oviduct is developed as a long tube with a length of 122 +/- 23.1 cm, and is subdivided into infundibulum (15.2 +/- 4.0 cm), magnum (63.3 +/- 9.4 cm), isthmus (5.6 +/- 3.1 cm), uterus (16.0 +/- 4.2 cm) and vagina (11.5 +/- 1.4 cm). The mucous membrane of the oviduct, as a whole, possesses luminal folds covered by ciliated columnar epithelium with secretory cells. The infundibulum part presents a cranial opening with thin and long fimbriae with few tubular glands in caudal tubular portion. In the magnum, the largest portion of the oviduct, the folds are thicker and are filled with tubular glands. The isthmus is short and presents less bulky folds and a few tubular glands. A bag-shaped uterus in the cranial area shows thin folds, and in the caudal region (shell gland) more ramified folds with few tubular glands. The vagina has long luminal folds and a thick muscular tunic; no glands with sperm-storage characteristics have been observed. In conclusion, the oviduct in sexually mature rhea has morphological similarities with the other species of birds already described; however it presents its own characteristics to produce a big egg.