Thin-shelled Eggs Research Articles

MYCOTOXINS IN FOODS AND FEEDS 5-Trichothecenes A-T-2 Toxin السموم الفطرية فى الأغذية والأعلاف 5- الترايکوثيسينات أ- ت-2 توکسيـن

Trichothecenes (TCT) are secondary metabolites commonly found in cereals. They are produced in foods and feeds by various species of Fusarium: Myrothecium, Trichothecium, Trichoderma, Cephalosporium, Cylindrocarpon and Stachybotrys. More than 140 different TCT have now been isolated and described. T-2 toxin is the most cytotoxic mycotoxin of the group TCT. It is produced by Fusarium fungi (F. acuminatum, F. poae and F. sporotrichioides) in cereal crops and processed grains. The commonest clinical signs of alimentary toxic aleukia (ATA) caused by T-2 toxin in humans are weakness, vomiting, diarrhea, nausia and abdominal pain. The major toxic effects of T-2 toxin in ruminants include gastroenteritis, hemorrhages, bloody diarrhea and ruminal ulcers. Reduced feed intake and weight gain, diarrhea and impairment of the immune system are the effects caused by T-2 toxin in pigs. Signs of T-2 toxin in poultry comprised decreased feed intake, growth depression, oral lesions, abnormal feathering, decreased egg production, thinner egg shells and impaired hatchability.

Produção e qualidade de ovos em reprodutoras de frangos de corte com horário de arraçoamento diferenciado

Foi estudada a influência de quatro horários de arraçoamento (único, às 6h30; dual [50% às 6h30 e 50% às 15h30]; único, às 11h; e único, às 15h30) sobre a produção e qualidade dos ovos de reprodutoras de corte, alocados ao acaso, em 48 boxes, com 27 fêmeas Arbor Acres e três machos cada, com 12 repetições. As exigências nutricionais e de manejo atenderam as recomendações da linhagem. Estudaram-se as produções de ovos total (PTOTAL), de ninho (PNINHO), limpos (PLIMPO) e quebrados (PQUEMO) em seis coletas (6h30, 9h, 11h, 13h30, 15h30 e 17h30); peso médio (PESOVO) e gravidade específica do ovo (GE) agrupados em três coletas (9h, 13h30 e 17h30). Foram utilizados a análise de variância, o teste T de Student para comparação das médias referentes a tratamento e coleta, e a análise de regressão polinomial para idade. Houve efeito do horário de arraçoamento e coleta para todas as variáveis, exceto para PQUEMO, em que não foi evidenciado efeito do horário de arraçoamento. Para os arraçoamentos às 6h30 e dual, o maior percentual de ovos produzido (22,78 ± 0,36% e 20,26 ± 0,33%, respectivamente) ocorreu na coleta das 9h, enquanto, para os arraçoamentos às 11h e às 15h30, ocorreu na coleta das 13h30 (20,35 ± 0,39% e 19,25 ± 0,38%, respectivamente). As reprodutoras do sistema dual de arraçoamento e aquelas arraçoadas às 15h30 tiveram PESOVO de 71,0 ± 0,3 g, que, em qualquer coleta, foi, no mínimo, igual aos demais. As médias de GE foram maiores para as aves arraçoadas às 11h (1,0788 ± 0,0002) e às 15h30 (1,0799 ± 0,0002) que as demais. Ovos de reprodutoras mais velhas e aqueles coletados nas primeiras horas do dia foram mais pesados e apresentaram cascas mais finas. O sistema de arraçoamento dual apresentou-se como a melhor alternativa na substituição do sistema de alimentação única às 6h30.

Ultrastructure of eggs of Paracapillaria ( Crossicapillaria) philippinensis and evidence related to its life cycle

The varied ultrastructure of the eggshell of Paracapillaria ( Crossicapillaria) philippinensis, collected from a human sample, is reported from a scanning electron microscopy study. Two distinct egg shapes were identified: typical peanut-shaped and swollen peanut-shaped. Both thick and thin eggshells were detected. Thick eggshells are either fairly smooth or bear a beam-like network in relation to the pillars in their surface ultrastructure. Thin eggshells are transparent allowing visibility of the coiled larva within. Presence of the thin shell provides supportive evidence of autoinfection involved in the life cycle of this medically important parasite.

Microstructure-dictated resistance properties of some Indian dinosaur eggshells: finite element modeling

Finite element modeling (FEM) has been used to evaluate microstructure-controlled stability of selected eggshells of Indian dinosaurs. Our study suggests that under static load the eggshell microstructure of Megaloolithus cylindricus displays a low magnitude of tensile stress over most of the spherolith. The magnitude of this tensile stress is lower than that displayed in M. jabalpurensis, M. baghensis, and Subtiliolithus kachchhensis. In M. cylindricus, a shell thickness matching the length of the spheroliths prevents the failure of eggshells, whereas in M. jabalpurensis and M. baghensis, which have thinner shells, the development of additional subspheroliths compensates for the relatively higher magnitude of tensile stresses. Extremely thin eggshell in S. kachchhensis shows a still higher magnitude of tensile stresses, thereby making it prone to cracking, but the propagation of cracks is apparently checked and stability reinforced by wider spacing of pore canals.

Embryonic exposure to oestrogen causes eggshell thinning and altered shell gland carbonic anhydrase expression in the domestic hen.

Eggshell thinning among wild birds has been an environmental concern for almost half a century. Although the mechanisms for contaminant-induced eggshell thinning are not fully understood, it is generally conceived to originate from exposure of the laying adult female. Here we show that eggshell thinning in the domestic hen is induced by embryonic exposure to the synthetic oestrogen ethynyloestradiol. Previously we reported that exposure of quail embryos to ethynyloestradiol caused histological changes and disrupted localization of carbonic anhydrase in the shell gland in the adult birds, implying a functional disturbance in the shell gland. The objective of this study was to examine whether in ovo exposure to ethynyloestradiol can affect eggshell formation and quality in the domestic hen. When examined at 32 weeks of age, hens exposed to ethynyloestradiol in ovo (20 ng/g egg) produced eggs with thinner eggshells and reduced strength (measured as resistance to deformation) compared with the controls. These changes remained 14 weeks later, confirming a persistent lesion. Ethynyloestradiol also caused a decrease in the number of shell gland capillaries and in the frequency of shell gland capillaries with carbonic anhydrase activity. These data suggested that a disrupted carbonic anhydrase expression was involved in the mechanism for the oestrogen-induced eggshell thinning found in this study. The results support our hypothesis that eggshell thinning in avian wildlife can result from a structural and functional malformation in the shell gland, induced by xeno-oestrogen exposure during embryonic development.

THE INFLUENCE OF LAYING DATE AND MATERNAL AGE ON EGGSHELL THICKNESS AND PORE DENSITY IN YELLOW-EYED PENGUINS

Abstract In many bird species, eggs laid late in the breeding season hatch after a shorter incubation period than eggs that were laid early. The proximate mechanisms that cause these seasonal declines in incubation length remain poorly understood. We tested in Yellow-eyed Penguins (Megadyptes antipodes), Hipfner's hypothesis that late-laid eggs have thinner eggshells with a higher pore density that allow embryos to develop more rapidly than in early-laid eggs. In this species incubation length declines with increasing female age, so we also investigated whether eggshell thickness and pore density varies with female age. In addition, differences in shell thickness and pore density between first- and second-laid eggs of the same clutch were examined. Eggshell thickness did not change with laying date and was not related to length of incubation. In contrast, pore density increased with laying date and was negatively related to incubation length in first-laid eggs. Eggshell thickness and pore density increase...

The Drosophila Female Sterile Mutation twin peaks Is a Novel Allele of tramtrack and Reveals a Requirement for Ttk69 in Epithelial Morphogenesis

The Drosophila gene tramtrack ( ttk) encodes two transcriptional repressors, Ttk69 and Ttk88, which are required for normal embryogenesis and imaginal disc development. Here, we characterize a novel female sterile allele of tramtrack called twin peaks ( ttk twk) that, unlike other tramtrack alleles, has no effect on viability and produces no obvious morphological defects, except during oogenesis. Females homozygous for twin peaks produce small eggs with thin eggshells and short dorsal respiratory appendages. Complementation analyses, immunolocalization, and rescue data demonstrate that these defects are due to loss of Ttk69, which is expressed in the follicle cells and is required for normal chorion production and dorsal follicle-cell migration. Analyses of phenotypes produced by mutations in other loci that regulate eggshell synthesis suggest that the chorion production and follicle-cell migration defects are independent. We present evidence that twin peaks disrupts a promoter or promoters required for late-stage follicle-cell expression of Ttk69. We hypothesize that loss of Ttk69 in all follicle cells disrupts chorion gene expression and lack of function in dorsal anterior follicle cells inhibits morphogenetic changes required for elongating the dorsal appendages.

Effects of Dietary 1,4-Diaminobutane (Putrescine) on Eggshell Quality and Laying Performance of Hens Laying Thin-Shelled Eggs

Experiments were conducted to evaluate the potential for dietary 1,4-diaminobutane (putrescine) to influence eggshell quality and overall laying performance in hens. Forty-eight, 60-wk-old White Leghorn hens laying thin-shelled eggs were fed a corn and soybean meal-based diet supplemented with 0.00 (control), 0.05, 0.10, or 0.15% putrescine for 4 wk. Twelve hens that laid thick-shelled eggs were also fed the control diet. The feeding of supplemental putrescine decreased feed consumption; however, egg weight decreased only at higher levels of supplementation. Increasing dietary levels of putrescine responded quadratically in eggshell deformation, eggshell weight, and eggshell weight as a percentage of egg weight (P < 0.05). There were no significant differences in shell deformation, shell thickness, or shell weight when comparing hens laying thick-shelled eggs and those laying thin-shelled eggs that were fed 0.05% supplemental putrescine. Calcium intake, calcium retention, and calcium balance decreased linearly (P < 0.05) with increasing levels of dietary putrescine. Pancreatic putrescine concentrations were significantly higher (P < 0.05) in hens laying thick-shelled eggs compared with hens laying thin-shelled eggs. It appeared that pancreatic cells synthesized more polyamines in hens laying thick-shelled eggs. This increase in polyamines might have caused improved eggshell quality by increasing calcium transport. It was concluded that 0.05% supplemental putrescine improved eggshell quality; however, higher levels proved to be toxic.

Organochlorine contaminants and biomarker response in double-crested cormorants nesting in Green Bay and Lake Michigan, Wisconsin, USA.

Double-crested cormorant (Phalacrocorax auritus) eggs at pipping and sibling 10-day-old chicks were collected from two colonies in Green Bay, WI, one colony in Lake Michigan, WI, and reference colonies in South Dakota and Minnesota. Egg contents and chicks were analyzed for organochlorine contaminants including polychlorinated biphenyl (PCB) congeners. Livers of embryos and chicks were assayed for hepatic microsomal ethoxyresorufin-O-dealkylase (EROD) activity. Eggshell thickness and the physical dimensions of embryo brains were measured. Concentrations of organochlorines, including p,p'-DDE (p,p'-dichlorodiphenyldichloroethylene), PCBs, and PCB congeners were generally an order of magnitude higher in eggs and chicks from Wisconsin than from reference locations. Total PCBs averaged 10-13 microg/g wet weight in eggs from three Wisconsin colonies compared to 0.9 microg/g PCBs from reference locations. Double-crested cormorant chicks accumulated on average 33-66 microg PCBs/day and 7-12 microg p,p'-DDE/day in the Wisconsin colonies compared to 0 microg PCBs/day and 1 microg p,p'-DDE/day in the reference colonies. At pipping, EROD activity in the livers of cormorant embryos was significantly higher in the Wisconsin colonies and significantly correlated with PCBs and the toxic equivalents (TEQs) of aryl hydrocarbon-active PCB congeners relative to 2,3,7,8-tetrachlorodibenzo-p-dioxin. However, in 10-day-old chicks EROD activity was not consistently different among colonies and was not correlated with PCBs or TEQs. A significant negative relationship between embryo brain asymmetry and the size of the egg suggested that physical constraint might be an important factor influencing the response of this bioindicator. Thinner eggshells in two colonies located near Door County, Wisconsin, suggested that historic p,p'-DDE residues associated with orchards are still an important source of p,p'-DDE in the local environment.

Avian pneumovirus infection of laying hens: Experimental studies

Administration of a virulent strain of avian pneumovirus (APV) to specific pathogen free laying hens by the oculonasal route failed to induce a drop in egg production or any adverse effects on eggshell quality. However, intravenous (i.v.) inoculation of the same strain caused a substantial drop in egg production and a high incidence of soft and thin-shelled eggs. Some respiratory signs were also observed and the hens appeared sick, with diarrhoea being observed in approximately one-half of the hens between 4 and 11 days post-inoculation (p.i.). APV antigen was detected in the oviduct epithelium up to 9 days p.i. This challenge model was then used to investigate the efficacy of live attenuated turkey rhinotracheitis (TRT) vaccine administered alone at 1 day old, or an inactivated TRT vaccine (at 16 weeks), or a combined programme using both vaccines, in protecting against this challenge. Neither the live nor the inactivated vaccine alone protected against clinical signs (respiratory infection or diarrhoea). However, the inactivated, but not the live, vaccine did protect against the effect of the i.v. challenge on laying performance. In contrast, the combined vaccination programme protected completely against both clinical signs and poor egg-laying performance. This protection lasted until at least 60 weeks of age. On the basis of the results with this experimental model, it is concluded that the use of live priming followed by administration of inactivated TRT vaccine is necessary to provide complete protection of laying chickens against APV challenge.

Effects of electromagnetic fields on the reproductive success of American kestrels.

Reduced reproductive success of birds nesting near power lines has been documented but never directly attributed to electromagnetic fields (EMFs). Laboratory studies have identified EMF effects on embryonic development, but reproductive success of wild birds is dependent on additional factors, including fertility, egg size, hatching, and fledging success. We tested whether EMFs affect reproductive success of birds. Captive American kestrels (Falco sparverius) were bred for one season per year for 2 yr under either controlled or EMF conditions. EMF exposure was equivalent to that experienced by wild reproducing kestrels and was weakly associated with reduced egg laying in 1 yr only. In both years fertility was higher, but hatching success was lower in EMF pairs than control pairs. Fledging success was higher in EMF pairs than control pairs in 1995 only. Egg composition and embryonic development were examined in 1 yr only, but hatchlings were measured in both years. EMF eggs were larger, with more yolk, albumen, and water, but had thinner egg shells than control eggs. Late-term EMF embryos were larger and longer than control embryos, although hatchlings were similar in body mass and size. EMF exposure affected reproductive success of kestrels, increasing fertility, egg size, embryonic development, and fledging success but reducing hatching success.

Extreme host specificity by Microdon mutabilis (Diptera: Syrphiae), a social parasite of ants

Larvae of the syrphid fly Microdon mutabilis are social parasites which live up to two years, feeding on ant brood in nests of Formica lemani ants. We questioned why M. mutabilis is extremely localized when its host is widespread and abundant. Like endoparasitic diseases, social parasites must penetrate formidable defences before 'infecting' their hosts. This occurs during the egg stage of M. mutabilis: females are sedentary and oviposit at F. lemani nest entrances, which workers treat as part of their nest, leaving the thin-shelled eggs vulnerable to attack for 10 to 14 days before hatching. We describe experiments which show a strong maternal effect in M. mutabilis. New-laid eggs had > 95% survival when introduced to the individual ant colony that reared each mother fly or to its close neighbours, but survival declined as a sigmoidal logistic function of distance from the mother nest, with F. lemani colonies from 2 and 30 km away killing 80 and > 99% of eggs, respectively, within 24 h. Attacks on eggs also increased in proportion to the delay before introduction to laboratory nests. We suggest that they may be coated with a mimetic chemical disguise that lasts for three to four days after oviposition. The results indicate extreme local adaptation by an M. mutabilis population not simply to one species of host, but to an individual host population and possibly to local strains or family groups within an F. lemani population. This conclusion is discussed in terms of virulence, transmission and coevolution in parasitic diseases.

FINITE ELEMENT ANALYSIS OF STRESSES DURING COOLING OF EGGS WITH DIFFERENT PHYSICAL CHARACTERISTICS

Maximum thermally induced stresses in eggshell under rapid cooling conditions were predicted using a validated axisymmetric finite element model (AFEM). The maximum thermally induced stress in the eggshell occurred immediately upon cooling, i.e., after 1 s of rapid cooling (h = 2839.0 W/m 2 °C or 500 Btu/h-ft 2 -°F). For typical extra-large eggs, the AFEM calculated eggshell stresses were 1.79 MPa (260 psi) and 1.73 MPa (251 psi) for meridional and circumferential directions, respectively. Maximum thermally induced stresses occurred along the outer boundary at the interface between air cell and albumen. Increasing eggshell thickness, air cell size, cooling rate, and the taper angle favored higher thermally induced stresses. Among the ten test cases, Case 7 (M, THIN), which was a medium egg (the maximum principal, i.e., pole to pole, dimension a = 28.5 mm (1.1 in.), minimum principal dimension b = 21.2 mm (0.83 in.), taper angle e = 5°, air cell size = 5% by volume) with thin eggshell (shell thickness, t = 0.305 mm (0.012 in.) under rapid cooling, experienced the smallest maximum thermally induced stress (1.47 MPa or 214 psi). Consequently, an egg with these or similar physical characteristic values is likely to have less damage due to stress-induced cracking during rapid cooling.

Observations on the significance of diagnostic findings in egg-binding of Psittaciformes

Clinical examination of 2192 psittacine birds of both sexes revealed a prevalence of 2.74 per cent (60 birds) of egg-binding. Domesticated species easily bred in captivity were the most commonly...

Underwater nesting by the Australian freshwater turtle Chelodina rugosa: effect of prolonged immersion and eggshell thicknesson incubation period, egg survivorship, and hatchling size

The northern long-necked turtle, Chelodina rugosa, occupies seasonally ephemeral freshwater wetlands in thewet–dry tropics of northern Australia. The species has a highly unusual nesting strategy in that nesting takes place under waterwhen wetland habitats are flooded. Embryonic development proceeds when floodwaters recede during the annual dry seasonand hatchling emergence coincides with the start of the following wet season. This study examined the influence of duration ofimmersion of eggs on hatchling size and hatching success under laboratory conditions. Prolonged immersion of eggs in waterresults in smaller hatchlings and shorter incubation times, but does not increase egg mortality during incubation. Leaching ofcalcium from the eggshell, resulting in reduced availability of calcium to the developing embryo, may explain the smallerhatchlings and shorter incubation period. Hatchlings from thin-shelled eggs, in which shell formation was incomplete, weresmaller and hatched sooner, indicating that the eggshell plays a role in determining hatchling size and incubation period.Thin-shelled and normal eggs had equivalent egg survivorship, indicating that the eggshell is unimportant in egg survivalduring immersion.

Underwater nesting by the Australian freshwater turtle Chelodina rugosa: effect of prolonged immersion and eggshell thicknesson incubation period, egg survivorship, and hatchling size

The northern long-necked turtle, Chelodina rugosa, occupies seasonally ephemeral freshwater wetlands in thewet–dry tropics of northern Australia. The species has a highly unusual nesting strategy in that nesting takes place under waterwhen wetland habitats are flooded. Embryonic development proceeds when floodwaters recede during the annual dry seasonand hatchling emergence coincides with the start of the following wet season. This study examined the influence of duration ofimmersion of eggs on hatchling size and hatching success under laboratory conditions. Prolonged immersion of eggs in waterresults in smaller hatchlings and shorter incubation times, but does not increase egg mortality during incubation. Leaching ofcalcium from the eggshell, resulting in reduced availability of calcium to the developing embryo, may explain the smallerhatchlings and shorter incubation period. Hatchlings from thin-shelled eggs, in which shell formation was incomplete, weresmaller and hatched sooner, indicating that the eggshell plays a role in determining hatchling size and incubation period.Thin-shelled and normal eggs had equivalent egg survivorship, indicating that the eggshell is unimportant in egg survivalduring immersion.

Evolution of viviparity: variation between two sceloporine lizards in the ability to extend egg retention

The evolutionary transition between oviparity and viviparity in squamate reptiles presumably occurs via a gradual increase in the duration of egg retention, the production of thinner eggshells, and increases in the vascularity of maternal and embryonic tissues. The ‘ease’ of this transition may differ among taxa. For example, in the genus Sceloporus, the scalaris species group contains both oviparous and viviparous species, and female Sceloporus scalaris can extend egg retention facultatively in response to the absence of a suitable site for oviposition without impairing embryonic development. In contrast, the undulatus species group contains only oviparous species, and, while female Sceloporus virgatus can extend egg retention, doing so retards embryonic development. I tested several hypotheses that would explain the greater ability of 5. scalaris than S. virgatus to extend egg retention. In this study, female S. scalaris retained eggs for 19 d without affecting the mortality of embryos, total developmental time, or dry mass of hatchlings. In contrast, when female S. virgatus retained eggs for 18 d, embryos had very high mortality and eggs took significantly longer to hatch than control (non‐retained) eggs, although the dry mass of hatchlings was not affected. The ability of S. scalaris females to retain eggs with little negative effect on embryonic development was associated with relatively large chorioallantois, relatively thin eggshells, and relatively small clutch masses. These observations suggest that phylogenetic differences in the ability to extend egg retention may facilitate or constrain the evolution of viviparity in some lineages.

Thinner eggshells of dipper (Cinclus cinclus) eggs from an acidified area compared to a non-acidified area in Norway

Thinner eggshells of dipper (Cinclus cinclus) eggs from an acidified area compared to a non-acidified area in Norway

Thinner eggshells of dipper ( Cinclus cinclus ) eggs from an acidified area compared to a non-acidified area in Norway

Eggs of dippersCinclus cinclus from a chronically acidified area in Southern Norway were compared with eggs from a non-acidified area in Central Norway. There were no differences in egg size, as measured by volume, weight, length and calculated surface area, between the two areas. Eggshells were 7.0% lighter and 6.1% thinner, as measured by the Ratcliffe index and 7.0% as measured by the eggshell index (shell weight/surface area) in Southern Norway than in Central Norway. The Ratcliffe and eggshell indices were highly correlated. Scanning electron micrographs showed that the palisade layer of eggshells of eggs from the acidified area was 10.7% thinner than that of eggshells of eggs from the non-acidified area. Eggshell vapour permeability was not significantly influenced by area. Since the moderately lower thickness in Southern Norway was not accompanied by higher vapour permeability, this indicates that the reduced eggshell thickness did not cause desiccation of dipper eggs in the acidified area. The possibility of underestimating the environmental effects of acidification on dippers is discussed.

Selection for egg shell strength in laying hens using shell membrane characteristics.

1. Divergent selection for attachment strength between the shell membrane and the calcium shell was performed in a White Leghorn strain. Multivariate analysis was used to estimate genetic parameters for shell membrane measurements and shell thickness. The aim was to investigate the possibility of improving shell strength in laying hens by selecting for increased attachment strength. 2. A significant direct selection response for attachment strength was achieved. There was a favourable correlated selection differential in the frequency of cracked eggs which resulted in a nonsignificant but favourable, correlated response. Selection for a strong attachment resulted in a thinner egg shell, and vice versa. Heritabilities were all relatively high (0.30 to 0.70). Most of the genetic correlations were in agreement with the achieved correlated responses. 3. Two factors that probably contributed to the responses in egg shell thickness were an unfavourable genetic correlation between attachment strength and shell thickness, and natural selection against changes in attachment strength, in the form of increased mortality during incubation and hatching. Problems connected with breeding for increased shell strength are discussed.