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At least 73 records · Page 4Linked to original sources
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↗
PubMed1994

Egg shell penetration tendency of different Salmonella serotypes by attached ring color method.

To investigate the extent of Salmonella penetration through the egg shell, 200 eggs were dipped in red (for 3 minutes) and then in green (for 6 minutes) aqueous bland food color solution for the detection of positive penetration test areas. Each egg with positive penetration area, 5 spots of 1 cm in diameter, was marked for the attachment of steel cylinders (1 cm in diameter and height). These cylinders were filled with the test strain of Salmonella. Among 19 serotypes S. pullorum and S. gallinarum were nonmotile while the other 17 were motile. Among a total of 180 eggs (900 points) maximum (30%) penetration was in area III, where salmonellae invaded through cuticle, shell, inner and outer shell membranes, followed by area II (14.77%) and area I (4.6%). It was very well evident that penetration of salmonellae to the contents of eggs was maximum, while in area II the penetration was to outer shell membrane and in the least cases through the cuticle and shell. Penetration in area I is not significant and to some extent in area II as well, while invasion in area III is highly significant.

Animals↗
PubMed1990

Visualization of chitin-protein layer formation in Ascaris lumbricoides egg-shells.

The formation of chitin-protein layer in Ascaris lumbricoides egg-shells was studied using the method of chitin structures visualization by means of derivatives of stilbene-disulfonic acid (Blankophor, Bayer, FRG). Intensive formation of chitin structures in A. lumbricoides egg-shell occurred only in fertilized females in a very short portion of uterus from the site of connection of the oviduct with the uterus up to 25-30 mm distally, i.e. in the section forming about one fifth or less than one sixth of length of adult female uterus. Already 3 mm from the beginning of uterus there was a thin layer on the surface of the fertilized eggs which contained chitin detectable by Blankophor visualization, whereas the chitin-protein layer on the shells could not be demonstrated histologically. The thickness of this chitin-protein complex increased distally. At 25 mm from the beginning of uterus the chitin layer was already complete and its thickness did not increase any more.

Animals↗
PubMed1983

The influence of dietary phosphorus level on laying hen performance, egg shell quality, and various blood parameters.

The influence of dietary phosphorus on hen performance and egg shell quality was investigated. Total dietary phosphorus levels of .17, .23, .30, .40, .50, .70, 1.50, and 2.30% were fed to four body weight groups of 23-week-old White Leghorn hens. Hens consuming the diets containing .17, .23, and .30% phosphorus, all from plant origin, consumed significantly (P less than or equal to .05) less feed, which resulted in poorer performance than hens fed diets supplemented with inorganic phosphorus. Addition of supplemental inorganic phosphorus at levels of .10 to .40% resulted in the best overall hen performance. Plasma phosphorus was directly related to dietary phosphorus level. Egg shell quality as measured by specific gravity was inversely related to dietary phosphorus levels above .50%.

Animals↗
PubMed1984

Egg shell formation by vitelline globules or by uterus. An introspection.

The question of the formation of the egg shell has attracted attention of most of the helminthologists and several different views have been expressed from time to time. The most agreed view which held the vitelline globules responsible for forming precursors of the shell membrane, has now become questionable in view of the fact that there are trematodes in which neither Mehlis' gland nor vitelline glands are present. The authors have demonstrated histochemically and histologically that the proximal part of the uterus has the necessary potentialities to form the egg shell membrane.

Animals↗
PubMed1996

Dietary marine algae promotes efficient deposition of n-3 fatty acids for the production of enriched shell eggs.

Two experiments were conducted to investigate the usefulness of a natural golden marine algae (MA) as a poultry ration supplement for the production of shell eggs rich in n-3 fatty acids (n-3 FA). This MA is unique due to a high concentration of docosahexaenoic acid (DHA; C22:6n-3) and the absence of other n-3 FA normally present in marine oils such as menhaden oil (MO). In the first experiment, 60 24-wk-old Single Comb White Leghorn (SCWL) hens were divided among four dietary treatments, including a typical corn-soybean control (CON); 1.5% MO, supplying 233 mg eicosapentaenoic acid (EPA) and 155 mg DHA per d; 2.4% MA, supplying 200 mg DHA/d; and 4.8% MA, supplying 400 mg DHA/d. A second experiment using 96 56-wk-old SCWL was conducted using the same diets. In both experiments, eggs were collected weekly for 4 wk for determination of egg production parameters and yolk FA content. Each week, yolk samples were extracted, methyl estered, and quantified using gas chromatography. Transient depression in egg and yolk weights were noted early in Experiment 1 in response to dietary 4.8% MA. Although egg and yolk weights were not affected in Experiment 2, egg production was significantly reduced in the 4.8% MA treatment. Egg production was unaffected due to diet or week in Experiment 1. In both experiments, yolk polyunsaturated profiles were significantly influenced by diet. Dietary n-3 FA supplementation significantly increased yolk total N-3 FA with concomitant reductions in yolk n-6 FA. Although hens fed MO were supplied predominantly EPA, the principal yolk FA deposited was DHA. Marine algae also promoted efficient yolk DHA deposition with the highest yolk DHA concentrations attained in eggs from hens fed 4.8% MA. These data indicate that utilization of MA as a direct source of dietary n-3 FA may provide an efficient alternative to current sources of n-3 FA available for the production of poultry products rich in n-3 FA.

Animal Feed↗
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↗
PubMed1983

Blood gases and acid-base status in chicken embryos with naturally varying egg shell conductance.

In chicken eggs selected for widely varying values of specific water vapor conductance, gH2O (= water vapor conductance per freshly laid egg mass), PCO2, pH, PO2 and hematocrit were measured in arterialized blood sampled from an allantoic vein (after 16 days of incubation) or in blood termed 'venous', sampled from an allantoic artery (after 18 days of incubation). Both arterialized and 'venous' PCO2 were inversely related to gH2O. Since the variations of blood plasma pH with PCO2 were smaller than predicted for true plasma, partial compensation by appropriate non-respiratory changes of plasma bicarbonate concentration must have occurred. Only with extremely high and low gH2O a definite alkalosis and acidosis, respectively, were observed. Both arterialized and 'venous' PO2 tended to diminish with decreasing gH2O. The hematocrit value showed a tendency to increase with decreasing gH2O and with decreasing arterialized PO2.

Acid-Base Equilibrium↗
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↗
PubMed1989

Calcium reserve assembly: a basic structural unit of the calcium reserve system of the hen egg shell.

A well-defined proper subregion of the mammillary knob is described, consisting of baseplate (BP), calcium reserve body (CRB), and an integral but distinct CRB cover. The BP extends 14 to 20 microns into the outer shell membrane and rises a few microns above its surface. The organic matrix of the BP is a composite of modified membrane fibers and adjacent components. The distinct CRB matrix is attached to the BP and extends outward in attenuated from, much like the fractal aggregates associated with filter "cakes." The three regions comprise a unit designated as the CRA (calcium reserve assembly, or assemblies). The CRA are fully developed and mineralized by 10.5 to 11 h postoviposition of the previous egg. By 13 h postoviposition a new structure, the crown, is evident. The classical mammillary knob consists of the CRA/crown complex. By hatch time the CRA are partially decalcified, except in the air cell region. Consequently, a zone of separation develops in the affected CRA about midway through the CRB. Estimates of the calcium recovered from the egg shell and of the calcium found in the CRA, excluding the CRA in the air cell region, indicate that more than enough calcium is present in the CRA to meet the drawdown of calcium from the egg shell by the developing embryo. It is concluded that the CRA that are available to the action of the chorioallantoic membrane represent the calcium reserve of the hen egg shell.

Animals↗
PubMed1989

Regulation of net intestinal calcium uptake in hens laying obligatory soft-shelled eggs.

1. Individually caged laying hens had a loop of thread inserted into the shell gland. This resulted in the laying of soft shelled eggs. 2. A balance study was performed for a one week period before and after the operation. After the operation birds with threads consumed less calcium than before. Their requirements for calcium for eggshells decreased, resulting in increases in both calcium excreted and calcium retained. 3. Net calcium extraction in the digestive tract was measured in groups of birds with threads and intact controls, when shelling or not, by examining ratios of Ca to TiO2 in different gut segments. Observations were made during the period following premature oviposition in birds with threads, but within the normal shelling period of control birds. The period of study was at least two weeks after the operation. 4. Birds with threads absorbed less calcium than control birds up to the upper jejunum. 5. Control birds secreted calcium between the upper jejunum and colon, but birds with threads showed little change in absorption in this part of the digestive tract. 6. The increase in calcium absorption in intact birds was a response to the stimulus of shelling an egg or replacing calcium in medullary bone during a pause day, rather than of ovulation.

Animals↗
PubMed1993

Introduction of a fluorescence-microscopic technique for the detection of eggs, egg shells, and mites in scabies.

A technique using the fluorescence microscope can prove helpful in the laboratory diagnosis of scabies. Specimens from fifteen patients with scabies were used in this study. All of the specimens were embedded with glycerine instead of potassium hydroxide (KOH) solution. The specimens were examined at 0 min, 30 min, 1 hr, 6 hrs, 24 hrs, and one week after mounting under light and fluorescence microscopes. Specimens embedded with non-fluorescent glycerine were not clear immediately after mounting but became so after about 1 hr. Eggs and egg shells were easily counted in the specimens under the fluorescence microscope but were very hard to identify under the light microscope. Mites were absent in half of the specimens; only eggs and egg shells were present in those specimens found by the fluorescence microscope. The above findings suggest that the detection of egg shells by the use of fluorescence microscope may be helpful for the diagnosis of scabies, in particular with mite negative specimens. Slides prepared with non-fluorescent glycerine were more stable and could be preserved for a long time. However, this method is time-consuming and requires expensive equipment.

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↗
PubMed1985

[Structure of the hen's egg shell and its changes during incubation. A scanning electron microscope study].

The structure of the hen's egg shell was studied during the incubation. The local differences in the structure of the shell were estimated during the incubation in dependence to the development of the allantochorial vascular system. On the external surface of the shell there is a thin layer, homogenous in the SEM. It remains changeless during the whole period of incubation. The main part of shell is formed by long prisms with their long axes oriented perpendicularly to the external surface of the shell. These prisms are partially twisted round each other, similarly as in the case of the teeth enamel. The inner layer of the shell is formed by a system of fibers forming the three-dimensional network, similar to an air filter. In the middle of incubation, when the embryo's skeleton is still predominantly cartilaginous, is the structure of the shell identical with that one at the beginning of incubation. At the end of incubation, when the embryo's skeleton is already predominantly ossificated, the inner layer of the shell disappears without any trace. By resorption of the shell are the peaks of the prisms of the middle layer of the shell destroyed as well. The above described changes are the best visible in the equator region of the shell. Less developed are they in the region of the sharp pole of the egg. They are not detectable in the region of the blunt pole of the egg. In this region the egg's shell has the same structure during the whole period of incubation. The changes of structure of the shell--the resorption of the inner layer together with partial destruction of the prisms of the middle layer - exactly correspond with extension of the allantochorial vascular system.

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↗