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At least 37 records · Page 2Linked to original sources
PubMed1987

The relation between sodium chloride concentration in drinking water and egg-shell damage.

1. A significant linear increase in egg-shell defects from 60-week-old laying hens, and corresponding significant linear decreases in various egg-shell-quality measurements, were observed in response to increasing concentrations of sodium chloride in the drinking water, to the maximum concentration of 600 mg/l used in the present study. 2. The incidence of damaged egg shells was increased 3-fold by including NaCl in the drinking water at a concentration of 600 mg/l. 3. Shell defects declined when birds were placed on normal water for 5 weeks but were still 1.4- to 2.1-fold greater than control values. 4. After an induced rest from lay on normal water, shell defects were still 1.3- to 3.2-fold greater in birds which had previously received the NaCl in the drinking water. 5. The increased incidence of shell damage was not related to decreased food intake or increased egg weight or production.

Animals↗
PubMed1986

Categorisation and causes of abnormal egg shells: relationship with stress.

Concern regarding the proportion of brown eggs being laid with abnormal egg shells led to an investigation of the relationship between disturbance or stress and egg shell appearance and quality. The abnormalities fell into two main classes: misshapen or bulging eggs and eggs coated with a superficial layer of amorphous calcium, variously termed dusted, white banded, chalky or pink eggs. Translocation of hens from pens to cages resulted in a decrease in egg production and an increase in the proportion of abnormal eggs over the succeeding 18 d. Disturbance to flocks on deep litter resulted in an increase in the proportion of eggs laid with abnormal shells on the following day, not only in the flocks directly affected but also in an adjacent flock. Exclusion from their nests of birds accustomed to laying in nest boxes resulted in disturbed prelaying behaviour, retention of eggs in the shell gland and an increased proportion of coated eggs. Administration of 0.1, 0.25 or 1.0 mg of adrenaline subcutaneously resulted in the retention of eggs currently in the hens' shell glands and in an increased proportion of eggs with abnormal egg shells being laid during the following 10 d. A dose response effect was apparent. There was evidence that the nature of the particular abnormality produced was dependent on the stage of egg formation at which the disturbance was imposed and, if retention followed, upon the length of time the egg was retained. Disturbances when eggs were only lightly calcified tended to result in misshapen eggs, while those occurring when oviposition was imminent tended to result in coated eggs. Dusted or pink eggs followed moderate retention whereas white banded eggs were seen after prolonged retention. These observations may provide a basis for a non-invasive method of assessing stress in laying hens as well as helping to account for hitherto inexplicable occurrences of declining egg shell quality.

Animals↗
PubMed1979

[Lipids in the egg shell of the ostrich (Struthio camelus) (author's transl)].

The egg shell (with cuticle) of the ostrich contained a total lipid concentration of 0.19 mg/g egg shell; the phospholipids constituted the major portion, among the neutral' lipids cholesterol esters, cholesterol and free fatty acids were identified. The egg shell lipids showed a stimulating effect on the crystal growth of calcium carbonate; the highest rate of crystal growth was observed with the phospholipid fraction.

Animals↗
PubMed1974

Porphyrins in egg shells.

T.l.c. of esterified egg-shell porphyrin shows a mixture containing protoporphyrin with admixture of significant amounts of coproporphyrin, pentacarboxylic porphyrin and uroporphyrin and other, unidentified, porphyrins. This points to porphyrin biosynthesis taking place in the oviduct epithelium.

Animals↗
PubMed1988

Levels of calcium and soluble collagen in turkey egg shell membranes.

1. This experiment examined the effect of weeks in egg production and type of housing confinement of turkey hens on calcium and soluble collagen levels in egg shell membranes; and discussion was given to their apparent relationship to gas exchange in turkey eggs. 2. The high level of acid-soluble collagen in inner and outer egg shell membranes of aging caged hens compared with the same aged floor-penned hens may have a relationship with the low hatchability generally recognized in caged hens. 3. The levels of calcium found in the outer shell membrane are low and appeared to decrease with the age of the hen. 4. There were no differences over time in levels of total collagen and neutral salt-soluble collagen (newly formed collagen) found in egg shell membranes of turkey hens confined in cages or floor pens. 5. It is suggested that the acid-soluble collagen levels found in inner shell membranes may have a relationship in limiting respiratory gas exchange during latter incubation time, and thus limit embryo survival.

Acids↗
PubMed1987

Ultrastructure of Brugia malayi egg shell and its comparison with microfilarial sheath.

Ultrastructure of Brugia malayi egg shell and microfilarial sheath have been compared. They are identical in appearance, thus confirming that the microfilarial sheath is derived from the egg shell. The surface of the egg shell and the microfilarial sheath have distinct electron-dense projections which may have a protective role for the parasite.

Animals↗
PubMed1978

Scanning electron microscope studies of the egg shell in some anostraca (Crustacea: Branchiopoda).

The tertiary shell of the eggs of anostracan crustaceans consists of two layers, an outer cortex and an inner alveolar layer. Scanning electron microscope studies show that, in most species, these layers are separated by a subcortical space which intercommunicates with spaces in the cortex and with the meshwork of the alveolar layer. No evidence was found for direct communication between pores on the surface of Branchipus stagnalis eggs and the subcortical space. No surface pores were found in the eggs of Branchinecta packardi, Chirocephalus diaphanus, Artemia salina, nor in eggs of the notostracan Triops cancriformis. Similarities in structure and possible functions of the egg shells of anostracan crustaceans and certain insects are discussed in relation to similarities in certain features of their environments.

Animals↗
PubMed1983

The production and functional morphology of helminth egg-shells.

The high energy costs of egg-shell production in many helminths suggests that this structure plays an important role in their biology. The mechanical and chemical resistance of the egg-shell and the barrier it provides to the entry and loss of material are important in the survival of the free-living stages within the egg. The presence of egg filaments may increase the availability of infective stages and the operculum may be important in the infective process.

Acanthocephala↗
PubMed1985

Ultrastructure of eggs of Ascaris lumbricoides Linnaeus, 1758. I. Egg-shells.

Under the light microscope the chitin-protein layer of egg-shells in ascarids appears to be a regular, hyaline and nonstructural layer of 1.5 to 2.00 microns in thickness. The outer uterine layer is usually removed during the preparation. The lipid (ascaroside) layer covers the inner surface of the chitinous layer and seems to be irregularly undulated and regularly thick over the whole surface, with the thickness up to 1 micron. In electron micrographs the fibrous structure of the lipid layer is not evident as a rule. This is probably due to washing the lipids away from this layer during the dehydration of deeper layers of egg-shells that are imperfectly fixed with glutaraldehyde. A very low permeability of the egg-shells is typical of geohelminth eggs. The layer lipid shows a distinct lamellate structure only after a prolonged fixation with osmium at higher temperature. This is supported by the studies using the method of freeze-fracturing.

Animals↗
PubMed1971

Structural proteins in the egg-shell of the oriental garden cricket, Gryllus mitratus.

1. The egg-shell of the oriental garden cricket, Gryllus mitratus, contained at least two different types of structural protein in an approximate ratio of 5:1. The major fraction was extracted in a solvent containing dithiothreitol, EDTA and 8m-urea, and was purified to apparent homogeneity as judged by free-boundary electrophoresis and ultracentrifugation. This was designated SH-fraction and its S-carboxymethyl derivative (CM-fraction) was also prepared. The minor fraction, insoluble in the solvent, was designated insoluble residue. 2. The major fraction was a phosphoprotein, rich in serine (29.8mol% of the total amino acids) and phosphate (nearly equimolar to serine), and O-phosphoserine was identified in its partial acid hydrolysate. The content of cystine was rather low (0.9mol%) in spite of the importance of this amino acid residue in the native form of the protein. The insoluble residue contained only a small amount of phosphorus, and its amino acid composition was clearly different from the major fraction. 3. CM-fraction, a fibrous protein with an average molecular weight of 57500, behaved as a typical polyanion owing to the high content of phosphate. SH-fraction and CM-fraction were precipitable from their aqueous solutions by the addition of bivalent metal cations, and the precipitation of CM-fraction by Ca(2+) and Mg(2+) was studied in detail. 4. When SH-fraction was exposed to air, intermolecular disulphide linkages were formed, yielding a net-like gel that changed its volume with changes in Ca(2+), Mg(2+) and Na(+). 5. The possible role of this protein fraction in maintaining the integrity of the egg-shell, and a comparison of its composition and properties with other egg-shell proteins and other phosphoproteins, are discussed.

Amino Acids↗
PubMed1991

The egg-shell of Drosophila melanogaster. VI, Structural analysis of the wax layer in laid eggs.

Utilizing freeze-fracturing conventional electron microscopy and scanning electron microscopy methods, a wax layer was identified, sealing the oocyte of Drosophila melanogaster. In mature egg-shells wax forms a hydrophobic layer surrounding the oocyte and lying between, and in very close contact with the vitelline membrane (interiorly) and the crystalline intermediate chorionic layer (exteriorly). In cross-fractured views it is less than 50 A thick whereas in longitudinal fracturing it reveals smooth fracture faces of a multilayered material in the form of hydrophobic areas or plaques (0.5-1 microns in diameter) which are partially overlapping and highly compressed between the vitelline membrane and the innermost chorionic layer. The evidence for this layer being a wax are the facts that a) it is not preserved in conventional fat-extracting electron microscopy methods, b) it directs laterally the fracture planes during freeze-fracturing and reveals smooth fracture faces. Analysis of the structural features of wax in mature egg-shell in various species of Drosophilidae have shown that the wax layer exhibits indistinguishable (among the species) hydrophobic plaques, which have the same size and thickness with Drosophila melanogaster. These data provide structural evidence explaining the physiological resistance of the insect eggs studied, against water loss or water uptake, whenever they are laid on substrates with extreme environmental conditions. In addition, the data demonstrate how an extracellular substance can be organized to perform that function.

Animals↗
PubMed1992

On the mechanism of penetration of ovicidal fungi through egg-shells of parasitic nematodes. Decomposition of chitinous and ascaroside layers.

The decomposition of egg-shells of Ascaris lumbricoides L. was studied microscopically using topochemical methods in a set of 32 strains of soil ovicidal fungi. It was found that even fungi displaying minimal chitinolytic activity in tests on purified chitin in vitro are able to dissolve chitin of egg-shells during the attack on live eggs. Fungi without any chitinolytic activity penetrate probably only the mechanically damaged eggs. None of the studied fungi was capable of degrading enzymatically the glycolipid (ascaroside) layer of the egg-shell which remained intact after digestion of all other components of the egg.

Animals↗
PubMed1987

Scanning electron microscopy of early dinosaur egg shell structure: a comparison with other rigid sauropsid eggs.

Fossil eggs attributable to dinosaur (probably prosauropod) parentage that have been recovered from the early Jurassic Elliot Formation sediments at the Rooidraai locality possess shells that are similar to those of birds and crocodilians, and distinctly unlike those of chelonians and gekkonids. The preserved shell is very thin, and distinct mammillary processes are lacking, although the inner surface displays an undulating contour. The absence of these processes may be attributable to the inner portion of the shell having been at least partially decalcified during incubation and not preserved in the fossil state. The shells appear to be composed of broadly wedge-shaped, albeit ill-defined calcareous units, and they are similar to those of birds and other dinosaurs in the pattern of cleavage shown by the tabular calcite crystals of the palisade layer, and in the absence of the dominant horizontal lamellae that characterize crocodilian shells. The differential resemblance of these early Jurassic shells to the eggs of other closely related sauropsid taxa may be pertinent to questions concerning the evolution of egg shell structure within this clade.

Alligators and Crocodiles↗
PubMed1989

Responses in egg shell quality to sodium chloride supplementation of the diet and/or drinking water.

1. Supplementing the drinking water of 50-week-old laying hens with sodium chloride (NaCl) concentrations between 0.5 and 2 g/l for 7 weeks significantly increased the incidence of egg shell defects and significantly decreased egg shell quality. Dietary NaCl concentrations between 0 and 2 g/kg had little effect on this response. 2. At similar total NaCl intakes egg shell defects were much greater when the NaCl was obtained from the drinking water rather than from the diet. 3. Hens producing eggs with defective shells as a result of receiving saline drinking water failed to recover the ability to lay eggs with good shells after 8 weeks on normal water. 4. The increased incidence of shell damage was not related to decreased food intake or increased egg weight or production.

Animal Feed↗
PubMed1979

The structure and formation of the egg-shell of Syphacia obvelata Rudolphi (Nematoda: Oxyurida).

The egg of Syphacia obvelata is a flattened elipsoid. The egg-shell consists of 5 layers: external uterine layer, internal uterine layer, vitelline layer, chitinous layer and lipid layer. An operculum is present at one pole of the egg. The opercular groove consists of a break in the uterine layers and the modification of the chitinous layer by the deposition of lipoprotein material. On the curved side of the egg the uterine layers are modified to form alternate ridges and depressions. Discrete spaces are present in the internal uterine layer between the ridges. These are open to the exterior via pores in the external uterine layer. The structure of the uterine layers is quite different on the flattened side of the egg. The morphology of the reproductive system and the formation of the egg-shell is described. It is suggested that the complex structure of the uterine layers of oxyurids forms by a self-assembly process.

Animals↗
PubMed1992

[Effect of the manganese content in laying hen feed with different Ca and mineral levels on the egg shell quality and bone mineralization of hens].

Four experiments with 270, 44, 432 and 66800 Leghorn hens were carried out to investigate the influence of various Mn additions to diets differed in mineral or Ca contents on egg shell quality. The addition of 300 mg Mn/kg diet improved significantly egg shell breaking strength by 4 N over one year. The supply of 50-500 mg Mn/kg diet for 10-24 weeks of the second half of laying year did not influence the egg shell quality. Addition of mineral mixture or Ca grit to layer rations with adequate or higher Mn levels did not influence egg shell strength. High mineral content in a low manganese diet increased number of cracks by 3%. Strength, weight and ash content of tibia were significantly reduced by feeding a low mineral level. Addition of 50-150 mg Mn per kg low mineral diet normalized partially tibia stability in young hens. It was concluded that supplied dietary Manganese influences calcification positively only in young hens. High levels of Ca did not influence the effects of Mn. 50 mg Mn per kg layers mixture have been considered as an essential supply.

Animal Feed↗