PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Egg Shell”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1978

Influence of hen dietary calcium and phosphorus on the integrity of the egg shell as it would influence hatching success and the consequences of preincubation 2, 4, 5-T spraying with and without a high TCDD level.

Commercial strain laying hens were fed practical rations deficient in calcium and/or phosphorus to affect weak shelled eggs. Spraying these eggs prior to incubation with 2, 4, 5-T preparations having extremes in TCDD contamination at 10x recommendation was without effect on all parameters used to evaluate embryological development and subsequent early performance of resultant chicks. Analyses for 2, 4, 5-T residues indicated that the shell though weakened was unaffected as a barrier to herbicide contamination.

2,4,5-Trichlorophenoxyacetic Acid↗
PubMed1975

Effect of chlorinated hydrocarbons on shell gland carbonic anhydrase and egg shell thickness in Japanese quail.

Japanese quail (Coturnix japonica) were fed different levels of pesticide in their diets for 15 weeks. The levels of pesticide used were 25, 50, 100, 200 p.p.m. DDE 25, 50, 100, 200 p.p.m. DDT and 50 p.p.m. PCB. Carbonic anhydrase activities were analyzed in the shell glands and blood; pesticide concentration in the eggs of the first experiment was measured; egg weight, shell weight and shell thickness were also measured. No depression in growth was observed at any levels of pesticides used. Quail fed 200 p.p.m. DDE showed a high mortality rate after 10--12 weeks on the diet, while other levels produced no increase in death rate. Lower levels of DDT and DDE (25 and 50 p.p.m.) had no significant effect on egg shell weight or thickness. Higher levels (100 and 200 p.p.m) of DDT and DDE produced a small increase in shell weight and a 5 per cent decrease in shell thickness and were associated with increased shell breakage. At levels of 25 p.p.m. and 50 p.p.m. DDE, the activity of carbonic anhydrase in the shell gland was significantly increased. At levels of 200 p.p.m. DDE and 100 p.p.m. DDT in the diet, the activity of carbonic anhydrase was decreased by 12--15 per cent. A 50 per cent reduction in carbonic anhydrase activity in the shell gland seemed to be necessary for an increased production of soft shelled eggs when it was induces by sulfanilamide. Pesticide residues in the eggs of Japanes quail up to about 300 p.p.m. DDE and 150 p.p.m. DDT were not associated with any change in egg shell thickness. At about 600 p.p.m. DDE and 500 p.p.m. DDT in the eggs, corresponding to 100 and 200 p.p.m. in the diet, the egg shell thickness was reduced by 5 per cent. PCB at 50 p.p.m. produced a small decrease (4.5 per cent) in shell thickness and an increase in the percentage of cracked eggs.

Animals↗
PubMed1976

Egg-shell formation in Isoparorchis hypselobagri.

Egg-shell formation in Isoparorchis hypselobagri is descirbed. The egg-shell in Isoparorchis hypselobagri is colorless and transparent as in case of Diplodiscus mehrai (Madhavi, 1968). Eleven histochemical tests were used to elucidate the process and it was observed that the basic mechanism of egg-shell formation followed the quinone tanned system as all the three precursors i.e. proteins, phenols and phenolase were present in vitelline globules.

Animals↗
PubMed1976

[Penetration of Staphylococci through the egg-shell].

Penetration of staphylococci through egg-shell structures into the egg content was studied in 490 eggs. A series of experiments proved that staphylococci were able to penetrate through all egg-shell structures in a short time (of 1 hour) after the contamination. According to the results of these experiments, penetration was affected by the presence of cuticle, different shell porosity and high pH of the egg white.

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↗
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↗
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↗
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↗
PubMed1991

Role of magnesium in egg shell formation in the domestic hen.

1. The effects of feeding diets containing various amounts of magnesium on plasma concentration of calcium and magnesium in the domestic hen were investigated. 2. Plasma concentrations of calcium and magnesium decreased during shell formation in all birds. 3. Plasma magnesium content and egg shell thickness were severely reduced in birds given diets containing either 207 or 132 mg Mg++/kg. 4. Using electron microscopy, a precise correlation was observed between the normal distributions of magnesium and organic material across the egg shell of the domestic hen.

Animals↗
PubMed1977

The effect on egg-shell thickness of the inclusion of the calcinogenic plant Solanum malacoxylon in the diet of laying hens.

The leaves of the plant Solanum malacoxylon contain 1,25 dihydroxycholecalciferol, the active form of vitamin D. The effect on egg-shell thickness of supplementing the diet of laying hens with a dry powdered preparation of the leaves (DLSM) has been studied. A significnat increase in shell thickness was evident for eggs laid on the second and subsequent days of the DLSM-regimen but nor for those laid during the first 24 hours. It is suggested that the provision of high doses of the vitamin D metabolite in the form of a DLSM supplement may restore calcium binding protein levels in birds approaching the end of the first laying year and hence improve dietary calcium absorption and consequently egg-shell quality.

Animals↗
PubMed1991

[Chick embryo culture using duck egg shell--first successful hatch ].

The suitability of duck egg shell (DES) for chick embryo culture was investigated. Chick embryos were transferred into DESs with all egg contents after 3 days of normal incubation and cultured. The vessels made of polyethylene cling film were used for shell-less control. Among 35 embryos cultured in DESs, 21 survived until 16 days of incubation (13 days after transfer) and finally 3 newly hatched chicks were obtained at 22 days of incubation. One of them died 4 days later, but remaining two became full-grown cocks showing normal body weight and production of fertile sperms. Among 37 embryos cultured in polyethylene vessels, none survived over the period of 19 days of incubation. It is suggested that DES culture system may be useful for the various experiments using chick embryos.

Animals↗
PubMed1992

Is there lipid peroxidation induced malondialdehyde production during egg shell formation?

The marked increase observed in malondialdehyde concentration of the blood plasma and liver of laying hens during egg shell formation in a previous experiment (Mézes and Lencsés, 1985) were explained as a possible consequence of physiologically controlled lipid peroxidation. In this experiment, 54-week-old laying hens were treated intrauterinally with indomethacin (1.0 and 2.0 mg/kg body mass) after oviposition. Two other groups of hens were treated per os with excess amounts of vitamin E (100 and 200 mg/bird). The higher dose of indomethacin significantly decreased the PGF2 alpha production and malondialdehyde content of the sell gland, as well as the malondialdehyde concentration of the plasma. The excess amount of vitamin E had the same effect. The results suggest that during egg shell formation malondialdehyde is derived from prostanoid biosynthesis rather than from a free-radical initiated lipid peroxidative process. On the other hand, the excess amount of vitamin E inhibited prostaglandin biosynthesis as well as malondialdehyde production.

Animals↗
PubMed1991

Microbial barrier properties of hen egg shells.

Scanning electron micrographs of shell surfaces revealed a highly fissured outer layer with few open pores on brown eggs but many on white eggs. Total removal of the cuticle with solvents was difficult but partial removal with surface etching was possible using concentrated nitric acid. Staining methods to estimate the number of pores were unsatisfactory but it was possible to detect and count pores on micrographs, as pore mouths were usually associated with depressions and cuticle disruptions. Additionally, porosity could be estimated by measuring the distance between pores along fractured edges of samples. Egg shell contents were replaced with nutrient agar and incubated in Escherichia coli broth. Colonies were subsequently isolated from the agar, indicating that the barrier properties of shells and membranes had been compromised. Experiments with isolated inner shell membranes showed that these posed no significant barrier to E. coli. The exposure of whole intact eggs to E. coli broth followed by seep filtration and microbiological analysis of egg contents, indicated that bacteria had entered the eggs. The degree of infection was correlated with the pole of the egg in contact with the E. coli broth and was attributed to the increased porosity of the blunt pole of the egg compared with that of the apex. Similar experiments immersing eggs into broth inoculated with a Salmonella strain resulted in contamination of the egg contents with this organism.

Animals↗
PubMed1976

The development of the oxygen permeability of the avian egg shell and its membranes during incubation.

The 02-permeability of the avian egg shell and shell membranes is initially low (approximately equal to 0.1-10(-6) ml O2 STP-sec-1cm-2-mmHg-1) during incubation but increases about 10-fold after the first week. This increase correlates with a decline in water content of the membranes. A major increase in colloid osmotic pressure (up to 50 cm Hg) occurs and is the suggested cause for the onset of rapid removal of water from the membranes. A high membrane water content correlates with low O2-permeability and vice versa. The final degree of membrane hydration reached during incubation is independent of ambient humidity; that is, the O2-permeability of the shell and its membranes is controlled by conditions inside the egg. An hypothesis is presented to explain the profound increase in O2-permeability while the rate of water loss from the egg remains stable during incubation. The removal of water from the shell membranes by the increased colloid osmotic pressure will increase the number of gas filled channels in the membranes which in turn will increase the O2-permeability. In spite of the change in water content, the water vapor pressure in the shell membranes will always be very close to that of a free water surface and water loss will hence be determined by the ambient humidity and the porosity of the mineral shell.

Animals↗
PubMed1992

Nutritional and environmental factors involved in egg shell quality of laying hens.

1. Two experiments were conducted to assess the effects of lighting regime, dietary calcium source and sodium bicarbonate on production variables and egg shell quality of White Leghorn hens. In both experiments, hens were assigned to one of three lighting programmes that provided evening, morning or intermittent (midnight) lighting supplements in addition to natural daylight. Experimental diets used in the first study were formulated to contain (1) ground oyster shell flour, (2) limestone flour, or (3) and (4) the same +2/3 of the calcium source as hen-size oyster shell grit. The same 4 diets plus those containing hen-size limestone or hen-size limestone and oyster shells were used in experiment II. Additionally, diets in the first experiment contained either 0 or 10 g/kg sodium bicarbonate. 2. Hen-day egg production and food consumption were not affected by any of the experimental treatments. Hens fed on oyster shell diets or exposed to intermittent lighting regimes laid eggs of the highest specific gravity. Shell quality, as measured by specific gravity, was not affected by the addition of dietary sodium bicarbonate. 3. As expected, elevated temperatures (greater than 32 degrees C) significantly reduced egg shell quality. However, this effect was variable particularly in experiment II which used younger hens. 4. The shell quality of eggs from hens exposed to intermittent lighting in experiment II was significantly higher in each of the 4 sampling periods: morning (08.00-12.00), afternoon (12.00-16.00), evening (16.00-20.00) and night (20.00-08.00). 5. It is suggested that midnight lighting programmes provide a means of supporting egg shell quality of older laying hens during the summer months without a significant reduction in egg production.

Animal Nutritional Physiological Phenomena↗