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At least 1,225 records · Page 68Linked to original sources
PubMed1985

Variability of shell conductance and gas exchange of chicken eggs.

In 395 fertilized chicken eggs (strain Warren) obtained from a commercial hatchery the following coefficients of variation (SD/mean) were found: egg shell conductance for water vapor, GH2O, 22%; freshly laid egg weight, W, 8%; the specific conductance, gH2O (= GH2O/W), 22%. In 20 eggs selected for widely varying gH2O (range 57%-195% of the mean, 0.246 mg/(day X torr X g), the specific O2 uptake and the CO2 output, measured on days 16-19 of incubation, showed a maximum at medium gH2O values, decreasing at both lower and higher gH2O. The variations of gH2O in the selected eggs were shown to cause a variation of water loss up to hatching from 9 to 26% (average 15%), and a variation of the O2 tension from 84 to 123 torr, and of the CO2 tension from 18 to 54 torr, in the perichorioallantoic air space on days 16-19 of incubation. Mechanisms responsible for the observed changes in the metabolic rate and for the physiological adjustments to varied egg shell conductance are discussed.

Animals↗
PubMed1988

Gas exchange and development of chicken embryos with widely altered shell conductance from the beginning of incubation.

The O2 uptake of chicken embryos confined in the eggshell (MO2) is governed by a shell diffusive conductance (GO2) and PO2 difference between ambience and air space, suggesting that a relation between GO2 and air space PO2 (PAO2) is hyperbolic at constant MO2. Upon wide alteration of GO2 from the beginning of incubation, the MO2 was measured on day 16 of incubation and the relation between GO2 and PAO2 examined. The MO2 increased hyperbolically with increasing GO2, reached maximum at control conductances and decreased with further increase in GO2. From these changes in MO2 with GO2, an equation was derived predicting PAO2 as a quadratic function of inverse gO2 (mass-specific conductance, i.e., GO2 standardized by fresh egg mass), and the relation between air space PO2 and shell conductance was no longer hyperbolic. The arterialized blood PO2 (PaO2) of the allantoic vein measured individually was also expressed by a quadratic equation of inverse gO2. While for widely altered conductance the MO2 was little related to PaO2, the mass (embryo)-specific O2 uptake increased with PaO2. The excess water loss associated with increased conductance was involved in changes in these variables.

Animals↗
PubMed1995

Effect of estrogen on egg production, shell quality and calcium metabolism in molted hens.

Force-molted White Leghorn laying hens were implanted with 0.25, 0.5, 1 and 3 Compudose 200 pellets (24 mg 17 beta estradiol/pellet). Plasma estradiol increased with increasing E2 dosages in a linear manner and decreased over time in a quadratic manner (P < 0.01). E2 treatment had a nonlinear effect on total plasma calcium. Oviduct weight, shell thickness and egg weight were not significantly affected by exogenous estradiol whereas tibial bone ash percentage was increased at only one dose (P < 0.05:0.5 pellet group). Physiological supplementation with estradiol does not improve shell quality.

Animals↗
PubMed1964

X-RAY DIFFRACTION STUDIES OF THE CRYSTALLINE STRUCTURE OF THE AVIAN EGG SHELL.

From x-ray studies, it is concluded that the avian egg shell is composed of calcium carbonate in the calcite modification. In the main portion (crystalline layer) the calcite occurs in large crystalline areas oriented with the hexagonal axis (17.6 A) inclined at 28 to 16 degrees from the normal of the shell surface. With respect to the other areas, orientation is present over limited areas. The mammilla layer contains crystallites in entirely random orientation.The findings agree with the electron microscope observations by the second author (Heyn, 1936 a and b) according to whom large oriented crystals, spherulites, or dendrites would compose the main layer and small unoriented crystals the mammilla layer.

Animals↗
PubMed2002

Effect of regional changes to shell conductance on oxygen consumption and growth of chicken embryos.

Diffusive and perfusive gas conductances of the shell and chorioallantois of avian eggs are not homogeneous, leading to disequilibrium between the air cell gas and chorioallantoic venous blood. This study measured the embryonic ability to maintain oxygen consumption rate and growth under experimentally enhanced inhomogeneity of diffusive conductance, achieved by waxing half of the eggshell and exposing the other half to graded hyperoxia that doubled the oxygen gradient across the shell. Thus, the overall gas conductance was effectively normal but highly inhomogeneous. No differences were observed between the experimental and the control eggs in respiration, residual yolk or embryo growth rate from day 12 until day 20. The embryo was able to utilise the increase of oxygen in the environment to compensate for the loss of about half of its respiratory surface area under the wax. The results indicate that an even distribution of pores in the eggshell and uniformity of chorioallantoic perfusion are not required for successful avian development.

Animals↗
PubMed2001

Detection of Salmonella enteritidis in shell and liquid eggs using enrichment and plating.

Detection methods using various enrichment and plating media and immunoconcentration for Salmonella enteritidis in shell and liquid eggs were evaluated. For liquid egg samples naturally contaminated with S. enteritidis, pre-enrichment in 225 ml of buffered peptone water with cysteine followed by selective enrichment in 10 ml of tetrathionate broth was the superior, resulting in the detection of S. enteritidis in all samples on six of the seven types of selective agar substrate investigated. This enrichment procedure also enabled detection of S. enteritidis in most of artificially inoculated shell egg and pasteurized liquid egg samples.

Animals↗
PubMed2005

The effect of feeding time on shell quality and oviposition time in broiler breeders.

Three experiments were performed to determine the effect of feeding time on shell quality and oviposition time in broiler breeders. Mean eggshell thickness was increased significantly by 3.5 microm (approximately 1%) per h delay in feeding time when hens were housed in individual cages. However, eggshell thickness was not significantly affected by feeding time when birds were housed on litter floors. Mean oviposition time was delayed relative to lights on by 5 min per h delay in feeding time. Egg weight was not significantly affected by feeding time, suggesting that differences in shell thickness and oviposition times were not due to increased oviducal transit times. Producers who wish to implement delayed feeding may have to turn lights on earlier than usual to compensate for delayed oviposition times.

Animal Feed↗
PubMed1975

Localisation and characterisation of egg shell porphyrins in several avian species.

1. Electron microscopy, infra-red analysis and histochemical techniques have been used to determine the site of pigment deposition, the cellular localisation of pigment and the type of pigment precipitated in the egg shells of quail, White Leghorn, Brown Ranger and Black-Headed gull. 2. Transfer of pigment occurs via the surface epithelial cells of the shell gland. 3. Porphyrins are probably synthesised in the blood. 4. Possible pigment deposition mechanisms are discussed.

Animals↗
PubMed1987

Extraneous egg shell calcification as a measure of stress in poultry.

The incidence of eggs showing abnormal shell calcification amongst those produced by hens kept in individual battery cages, hens kept in battery cages in groups of 3 and hens kept in battery cages in groups of 4 was studied. There was good agreement between observers in the assessment of abnormal eggs. Hens kept in individual cages laid fewer abnormal eggs than hens kept in groups of 3 or 4. There was no significant difference in the incidence of abnormal eggs between hens kept in groups of 3 or 4. The results of this study support the idea that the incidence of eggs showing abnormal calcification may provide a quick and reliable method of measuring stress in hens which lay brown shelled eggs.

Animals↗
PubMed1987

Effect of a single injection of adrenaline on shell ultrastructure in a series of eggs from domestic hens.

1. Adrenaline (1 mg in 1 ml water) was administered subcutaneously to three hens to determine whether any changes in the shell ultrastructure of subsequent eggs would occur. 2. The egg shells were examined in a scanning electron microscope after plasma etching. 3. The first three eggs laid by each bird after adrenaline injection were compared with previously-collected normal eggs from the same birds and also with control eggs collected over the same period from three hens which had received no adrenaline. 4. The first egg laid following adrenaline treatment was essentially normal but both the second and third eggs showed severe structural disorganisation at all levels, from the mamillary caps up to the cuticular layer. 5. Eggs laid 20 d or more after adrenaline treatment had reverted to normal. 6. The findings suggest that the abnormal eggs laid after hens have been exposed to disturbance or stress are likely to be affected in not only their external appearance but also to be of poor structural quality.

Animals↗
PubMed1998

Egg shell colour is affected by laying cage design.

1. When laying hens are stressed some retain their eggs in the shell gland beyond the normal time of laying and this can result in the deposition of extra-cuticular calcium which makes brown eggs appear paler. 2. Three different types of enriched modified cage were compared: the location where eggs were laid was recorded and shell colour was measured using a reflectometer. 3. In 2 types of cage with enclosed nest boxes more eggs (80%) were laid in the nests than in a design with nest hollows in the open part of the cage (41%). 4. The eggs from the cages with enclosed nests were darker (had less extraneous calcium) than those with open nest hollows. This implies that in the designs with nest boxes fewer eggs had been retained and the hens may have been less stressed. 5. The results support previous evidence that to reduce stress and improve welfare it is desirable to provide enclosed nest sites for caged laying hens.

Animals↗
PubMed2000

The effect of changing the excreta moisture of caged laying hens on the excreta and microbial contamination of their egg shells.

1. An experiment that included 1440 caged laying hens in 24 experimental units was conducted to determine the effect of differences in excreta moisture on the proportion of dirty eggs and the microbial contamination of eggs that were ostensibly uncontaminated by excreta. Excreta moisture contents were changed by giving the hens diets that contained 4 different concentrations of sodium. 2. Diets containing 1.6, 5, 10 or 15 g/kg dietary sodium were fed ad libitum to 1140 laying hens for a 12-week feeding period. A sample of excreta was collected from each experimental unit each week and its moisture content determined. All eggs produced were classified as clean or dirty according to the European Community Egg Marketing Regulations. A sample of eggs were collected from each experimental unit on 4 separate occasions in the last 4 weeks of the feeding period and the total bacterial numbers on ostensibly clean egg shells were determined. 3. Increasing dietary sodium concentration gave linear (P<0.01) increases in excreta moisture. Each 100 g/kg increase in excreta moisture increased (P<0.001) dirty egg numbers by 0.52% of the total eggs produced. Increasing excreta moisture gave a linear increase (P<0.001) in the (log-transformed) numbers of microorganisms that contaminated ostensibly clean egg shells.

Animals↗
PubMed2001

Response of foodborne Salmonella spp. marker strains inoculated on egg shell surfaces to disinfectants in a commercial egg washer.

The objective of this study was to determine the effectiveness of an iodine based disinfectant (IBD, Iocide, Biomedical Development Corporation, San Antonio, TX) on Salmonella enteritidis and S. typhimurium inoculated on egg shell surfaces under simulated industry egg processing conditions with a commercial egg washer used as the sanitizer delivery system. Re-circulated egg washer water containing 1.40-2.85 g/l total dissolved solids was obtained from a commercial egg processing. Sanitizing treatments consisted of distilled deionized water (DDW), IBD, and chlorine (CL; 200 ppm). All treatments (DDW, IBD and CL) significantly (p < 0.05) decreased Salmonella spp. populations on the shell compared to dry (no spray) egg controls. However, efficacy of egg sanitizers appeared to be dependent on the level of total dissolved solids in the egg wash water.

Animals↗
PubMed2003

Isolation of Salmonella typhimurium Tn5 mutants defective for survival on egg shell surface using transposon footprinting.

The objective of this study was to screen the genome of Salmonella typhimurium for genes potentially required for survival on egg shell surfaces using a novel transposon footprinting method based on a previously developed Tn5 mutagenesis technique. Since the amplified DNA fragment length should usually be unique for each mutant, the polymerase chain reaction products separated on an agarose gel generate a transposon footprint with each band in the footprint representing the corresponding Tn5 mutant. By comparing the footprints from the pools of S. typhimurium Tn5 mutants before and after inoculation on egg shell surfaces, Tn5 mutants not recovered after selection were rapidly identified for potential isolation and genetic analysis.

Animals↗
PubMed2000

Parathyroid hormone receptor binding property in the shell gland of oviduct of the guineafowl during an oviposition cycle.

Parathyroid hormone (PTH) receptor binding property in the membrane fraction of the endometrium of the shell gland (uterus) of the guineafowl was analyzed by the use of [125I]PTH-related peptide (PTHrP) binding assays. Specificity, reversibility, and saturation of binding were demonstrated. Scatchard plots revealed a single class of binding sites. The equilibrium dissociation constant (Kd) was 0.50 to 1.15 nM in laying birds and 1.07 to 1.16 nM in nonlaying birds. The maximum binding capacity (Bmax) per milligram of membrane protein was 65.2 to 110.9 femtomoles (fmol) in laying birds and 105.8 to 120.6 fmol in nonlaying birds. Both Kd and Bmax values changed within the above range during an oviposition cycle in laying birds, showing a decrease during the period of eggshell formation. No change was found in nonlaying birds. The results suggest that PTH/PTHrP receptors are present in the shell gland of the guineafowl, and their binding may be related to eggshell formation.

Animals↗
PubMed2000

The influence of rapid air cooling and carbon dioxided cooling and subsequent storage in air and carbon dioxide on shell egg quality.

This study examined the effect of rapid cooling with air and CO2 on shell egg quality over 14 wk. The 240 fresh eggs were initially heated to 47 C for 24 h in an incubator, cooled using rapid air cooling or CO2 cooling, and then stored in air or CO2 in 250-mL jars for 14 wk. The CO2 levels were recorded of the jar atmosphere, of the egg air cell, and of the egg albumen. The Haugh units of each egg, pH, and of albumen from five eggs per group were also recorded. Haugh units are a logarithmic, empirical relationship between albumen height and egg weight (Stadelman, 1995). Haugh units for the control eggs averaged 70.8 over 10 wk of the study. The control eggs were of such poor quality that they could not be sampled after 10 wk. The air-cooled and CO2-stored eggs averaged 70.3 Haugh units over the 14-wk storage period; however, the egg quality significantly deteriorated after 10 wk. The CO2-cooled and CO2-stored eggs averaged 75.9 Haugh units over the 14 wk study, with no observable decrease in quality. Rapid air-cooling produces a lower quality egg than rapid cooling with CO2. Subsequent storage of rapidly air-cooled eggs in C02 may increase shelf life, but Haugh units were not statistically different from rapid air-cooled eggs. CO2-cooling and subsequent storage in CO2 increased Haugh units. The shelf life of shell eggs could be extended to greater than 14 wk when the eggs were CO2-cooled and CO2-stored.

Air↗
PubMed2001

The effect of shell egg pasteurization on the protein quality of albumen.

The effect of a low-temperature, extended-time, in-shell pasteurization process on the protein quality of egg albumen was evaluated. Ten dozen fresh chicken eggs were pasteurized in a hot-air oven at 55 C for 180 min. The eggs were refrigerated and broken out for analysis on Days 0, 7, 14, 28, 42, and 56 following pasteurization. There were no significant differences in total or soluble protein over the experimental period for the pasteurized or unpasteurized albumen. Mean protein content was 80.6 +/- 0.5% for the pasteurized albumen and 80.9 +/- 0.5% for the unpasteurized albumen. In vitro digestibility, as measured by the AOAC method, was 82.4 +/- 0.7% for the pasteurized albumen and 81.7 +/- 0.6% for the unpasteurized albumen. There were no significant differences over the experimental period in the digestibility of the samples. Free amino acids and discriminant-computed protein efficiency ratio (DC-PER) also did not differ between the pasteurized and unpasteurized albumens or over the experimental period. The in-shell pasteurization process used had no effect on the protein quality of albumen.

Amino Acids↗