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At least 73 records · Page 4Linked to original sources

PubMed1991

Relationship between thinning of eggshells and reduction in number of eggs produced after administration of some saluretic drugs in domestic fowls.

1. The effect of some diuretic drugs (acetazolamide, hydrochlorothiazide, chlorthalidone, furosemide, ethacrynic acid and amiloride) on eggshell formation and egg production in domestic fowls were investigated. All of the tested compounds significantly inhibited eggshell formation, furosemide being the most potent drug. 2. The number of laid eggs was also reduced by several of the diuretics. There was a correlation between reduction of shell thickness and number of eggs (r = 0.77; P less than 0.01). 3. If the tested diuretics were subdivided into two groups according to their different modes of action, where furosemide, ethacrynic acid and amiloride represent sodium transport inhibitors, and acetazolamide, hydrochlorothiazide and chlorthalidone (contributory action of the two latter) are inhibitors of carbanhydrase, the highest correlation coefficient (r = 0.96) between reduction of shell thickness and egg production was found for sodium transport inhibitors. The corresponding correlation coefficient for carbanhydrase inhibitors (r = 0.44) was not significant. 4. The probable mechanisms of action of the diuretics on eggshell formation and ovulation are discussed.

Animals↗

PubMed1990

Optimal dietary level of 1 alpha,25-dihydroxycholecalciferol for eggshell quality in laying hens.

The optimal dietary level of 1 alpha,25-dihydroxycholecalciferol [1,25-(OH)2D3] for eggshell quality was established. White Leghorn hens, 59 wk of age, were fed one of eight diets that contained the same basal ingredients, including 3.1% calcium, but different levels (microgram/kg) or forms of calciferol supplements: no calciferol supplement of any form (56 hens); 27.5 (control) or 55.0 micrograms of cholecalciferol (56 hens each); 3, 5, or 7 micrograms of 1,25-(OH)2D3 (28 hens each); 5 micrograms of 24,25-dihydroxycholecalciferol [24,25-(OH)2D3] with 28 hens; 5 micrograms each of 1,25-(OH)2D3 and 24,25-(OH)2D3 (28 hens). All groups were fed the control diet prior to the 21-wk treatment. The group fed 5 micrograms 1,25-(OH)2D3/kg diet ranked first in specific gravity (SG), e.g., 1.081 versus 1.077 for the control group at Week 21 (P less than .05). The group fed 7 micrograms 1,25-(OH)2D3/kg consumed 30% less feed and laid 20% fewer eggs than the control, but shell quality was not affected. The groups receiving no calciferol supplement or receiving only 24,25-(OH)2D3 laid eggs with significantly lower SG than the control after 2 wk of treatment (1.072 or less versus 1.082 at Week 2). The rest of the treatment groups mentioned were comparable to the control in eggshell quality and egg production. Groups fed the combination of 1,25-(OH)2D3 and 24,25-(OH)2D3 per kilogram of feed, or 1,25-(OH)2D3 alone at 5 micrograms/kg, had significantly higher tibial weights relative to the control group. All groups receiving the diets without cholecalciferol supplementation had markedly reduced hatchability. It was concluded that the optimal dietary level of 1,25-(OH)2D3 for improving eggshell quality without affecting egg production was approximately 5 micrograms/kg and the toxic level was 7 micrograms/kg.

Animals↗

PubMed1990

Effect of cimetidine on eggshell quality and plasma 25-hydroxycholecalciferol in laying hens.

Experiments were conducted to investigate the effect of feeding cimetidine (CIMET), ranging from 0 to 750 mg/kg, on vitamin D3 metabolism and eggshell calcification in laying hens fed two levels of vitamin D3 (500 and 2,000 ICU/kg). Final BW and feed intake were not significantly affected by either CIMET or vitamin D3 level. Feeding 500 and 750 mg of CIMET significantly decreased total egg production in hens fed either level of vitamin D3, but no differences were observed at lower CIMET levels. Tibia ash decreased significantly in hens fed 150 to 750 mg of CIMET, regardless of the vitamin D3 level. Plasma Ca and inorganic P concentrations were decreased in hens fed high CIMET levels (500 and 750 mg/kg) at Week 2, but no differences were observed at Week 4. Feeding CIMET (500 and 750 mg/kg) significantly decreased plasma 25-hydroxycholecalciferol (25-OHD3) levels at Week 2 in hens fed both vitamin D3 diets but not at Week 4. Eggshell breaking force, shell thickness, and percentage shell weight were decreased significantly by CIMET in all experiments; however, in one experiment, shell quality recovered by Week 8. These results suggest that the CIMET-induced reduction in bone mineralization, eggshell quality, and plasma 25-OHD3 levels could be due to interference of CIMET with vitamin D3 metabolism in vitamin D3-replete laying hens. Shell quality decreased in CIMET-treated hens fed the higher vitamin D diet even though 250-HD3 plasma levels were three times higher than in hens fed the lower vitamin D diet, suggesting that CIMET affected shell quality through some mechanism other than inhibition of 250-HD3 synthesis.

Animal Feed↗

PubMed1990

Influence of vitamin D3, 1 alpha-hydroxyvitamin D3, and 1,25-dihydroxyvitamin D3 on eggshell quality, tibia strength, and various production parameters in commercial laying hens.

Four hundred 53-wk-old Hyline W36 laying hens were randomly allocated to 10 treatments. The effects of feeding two vitamin D3 metabolites, 1 alpha-hydroxyvitamin D3 [1 alpha-(OH) D3] and 1,25-dihydroxyvitamin D3 [1,25-(OH)2 D3], each at five dietary levels (0, .75, 1.50, 3.00, and 4.50 micrograms/kg of feed) were determined on eggshell quality and tibia strength in commercial laying hens (Experiment 1). In Experiment 2, 1,440 Hyline W36 65-wk-old laying hens were used to determine the effects of four levels of vitamin D3 (0, 500, 1,000, and 1,500 ICU vitamin D3/kg) and three levels of dietary 1,25-(OH)2 D3 (0, .5, and 1.0 microgram/kg of feed) on eggshell quality, tibia strength, and egg production. In Experiment 1, neither 1,25-(OH)2 D3 nor 1 alpha-(OH) D3 affected eggshell quality or production criteria. Tibia weight was increased by adding either 1,25-(OH)2 D3 or 1 alpha-(OH) D3. In Experiment 2, 1,25-(OH)2 D3 increased percentage of shell, shell weight, and egg breaking strength when 0 ICU D3/kg was fed but had no effect at higher levels of vitamin D3. Egg production, feed consumption, and egg weight were also increased with supplemental 1,25-(OH)2 D3 when 0 ICU D3/kg was fed. Tibia weight and tibia breaking strength were also increased by adding 1,25-(OH)2 D3 to the diet. The commercial laying hen metabolizes sufficient 1,25-(OH)2 D3 from dietary vitamin D3 to maintain shell quality but not enough to maintain tibia strength.

Animals↗

PubMed1991

Effects of selection for growth and selection diet on eggshell quality and embryonic development in Japanese quail.

Decreased hatchability in Japanese quail following selection for growth and relative improvements in hatchability following selection during goitrogen treatment were investigated. An unselected quail line (Line C) and lines selected for high 4-wk body weight while being fed diets containing either 20% CP and .2% thiouracil (TU) (Line T), or 28% CP and no TU (Lines P and H-CD) were used. Egg weight loss between 0 and 4, and 0 and 14 days of incubation, hatchability, and developmental stage of embryonic mortalities were determined in Experiment 1. Length of the incubation period, and percentages of body water and dry body weight were determined for 10- and 14-day embryos and 18-day-old chicks in Experiment 2. Eggshell quality was determined in Experiment 3. Hatchability was lower in selected than in unselected quail due to increased early and late embryonic mortality. Egg weight loss during incubation was greater in Line P than in Line C eggs. Weight loss, measured across lines, was lower in eggs that hatched than in those in which embryos died early. Percentage body water was higher in Line C than in Lines P and T at 14 and 18 days of incubation; however, percentage body water in Line T was lower than Line P at 14 days. Percentage of dry body weight was greater in Lines P and T than in Line C at 14 and 18 days. Eggshell thickness was greater in Line H-CD when compared with Line C. Increases in eggshell permeability occurring during selection for growth were associated with increased embryonic mortality and decreased hatchability.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Inheritance of tinted eggshell colors in white-shell stocks.

The present study was conducted to study the genetics of tinted eggshell colors in two breeds of chickens laying white-shell eggs. Reciprocal crosses were made between an inbred White Leghorn line (ES) and an inbred Ancona line (ANC). The F1 birds were intercrossed and F1 females were backcrossed to each of the original lines. Eggshell color from each resultant group was measured using a Minolta chromometer, and a value (e) representing the color intensity adjusted by hue and saturation was used as the measurement criterion. Age, hatch group, and crosses each contributed significantly to the variation seen in eggshell color. Distribution comparisons indicated that two major autosomal loci affected the trait in these lines: one gene having incomplete dominance controls the amount of pigment deposition; the second completely inhibits pigment deposition when homozygous recessive. A test of goodness of fit supported this hypothesis. Genetic components were estimated by linear models. Epistasis, dominance, and additive effects contributed significantly to this trait. No sex-linked effects were noted.

Analysis of Variance↗

PubMed1991

Collection and separation of Aedes taeniorhynchus eggshells from mangrove soil.

Two methods to separate eggshells of Aedes taeniorhynchus from mangrove soil were compared. Selective sieving, using nested sieves with 0.185 and 0.170-mm screen openings, and water flotation both removed over 99% of the soil. However, water flotation recovered a significantly greater percentage of eggshells (62% vs. 34%). There was no significant difference in the recovery rate of viable eggs and new and old eggshells using water flotation.

Aedes↗

PubMedDate not supplied

F strain Mycoplasma gallisepticum vaccination of post-production-peak commercial Leghorns and its effect on egg and eggshell quality.

Forty-five-week-old commercial leghorns negative for antibodies to Mycoplasma gallisepticum (MG) and M. synoviae were vaccinated with high-passage F strain MG (FMG). Hens were confined in modified Horsfall-Bauer isolation units through 60 weeks of age. Egg production (% hen day) and parameters of egg and eggshell quality were monitored, including egg weight, eggshell strength, Haugh unit score, pimpling, and blood/meat spot incidence. Egg production was significantly lower (P less than 0.05) for FMG vaccinates than controls (down 5.76% and 5.80% in Trials 1 and 2, respectively). However, vaccinates and controls did not differ significantly in eggshell strength, shell thickness, pimpling, or blood/meat spot incidence. Haugh unit scores were significantly (P less than 0.05) greater for FMG vaccinates. At necropsy, all reproductive tracts appeared grossly normal. These studies suggest that high-passage FMG vaccination of post-production-peak hens does not adversely affect oviduct function.

Animals↗

PubMed2025

Oocyte surface proteins EGG-1 and EGG-2 are required for eggshell integrity in Caenorhabditis elegans.

Metazoan eggs are surrounded by a specialized coat of extracellular matrix that mediates sperm-egg interactions. This coat is rapidly remodeled after fertilization to form a barrier that prevents polyspermy, protects against environmental insults, and provides structural support to the developing embryo. In C. elegans several oocyte surface proteins have been identified that mediate these events. However, whether two of these proteins, EGG-1 and EGG-2, are required for fertilization or downstream events has been unclear. Here, we address this question using more recent advances in genome editing tools through the creation of egg-1 egg-2 deletions of the endogenous loci. We found that egg-1 egg-2 oocytes are fertilization competent and form rudimentary eggshells. While the integrity of the egg-1 egg-2 eggshells are compromised and often rupture within the uterus, surprisingly, some embryos are capable of undergoing several rounds of cell division. Overall, our findings demonstrate that EGG-1 and EGG-2 are not required for fertilization but are involved in post-fertilization processes.

Caenorhabditis elegans↗

PubMed1975

Eggshell aspiration in infants.

Two infants inhaled eggshell fragments. The first aspirated a small fragment into the upper part of the trachea and resuscitation attempts resulted in descent of the foreign body to the right lower lobe bronchus. Two attempts at bronchoscopy were unsuccessful and spontaneous disintegration occurred. The second infant aspirated an eggshell fragment to the entrance of the larynx where it was removed by laryngoscopy. Laryngeal or tracheal foreign body in infants under 1 year of age are rare, and the diagnosis and removal are difficult.

Animals↗

PubMed1978

Some observations on the calcium ion binding to the eggshell matrix.

The calcified matrix of the hen eggshell has been demineralized with the EDTA. Aliquots of this material are soluble in water and have been characterized by column chromatography and by chemical analyses. Of particular interest is the high hexosamine and uronic acid content, which confirms the protein-polysaccharide nature of this water-soluble material. The calcium ion binding to the eggshell matrix has been studied by the equilibrium dialysis technique at different pH values, with both free and blocked carboxylic groups. The material with the free carboxylic side chain groups binds more calcium ions with increasing pH value. When the carboxylic groups have been previously blocked with a water-soluble carbodiimide, the calcium ion binding rapidly decreases. The residual capacity to bind calcium ions in the material with the carboxylic functions modified is probably due to the sulfate ions. In agreement with previous observations on other calcified substrates, the calcium ion binding seems to depend on the presence of ionized carboxylic functions of the matrix.

Amino Acids↗

PubMed1990

Multiple proteins are produced from the dec-1 eggshell gene in Drosophila by alternative RNA splicing and proteolytic cleavage events.

The defective chorion-1 gene (dec-1) in Drosophila encodes follicle cell proteins necessary for proper eggshell assembly. A distinctive feature of the gene is the production of multiple products by both alternative RNA splicing and proteolytic processing events. DNA and protein sequencing studies have revealed several dec-1 protein products. The predominant translation product, fc106, has a vitelline membrane-like N-terminal domain followed by a glutamine, methionine-rich central region, largely in the form of 26 amino acid repeats. During late stage 10 the N-terminal portion of fc106 is cleaved, yielding s80, a major eggshell protein. Conceptual translation of the DNA sequence as well as molecular analyses of several dec-1 mutants suggest that the less abundant alternatively spliced RNAs encode primary translation products with different carboxy terminal ends. These results are discussed with respect to previous genetic analyses of dec-1 mutants as well as with respect to potential protein-protein interactions which may underlie stabilization of this complex extracellular structure.

Amino Acid Sequence↗

PubMed1986

Eggshell conductance--Fick's or Stefan's law?

The diffusion of gases through the avian eggshell has usually been interpreted as an example of Fick's law, and this appears to be the best explanation for gas exchange through narrow long pores. Many eggshells, however, contain more elaborate pores, of which the funnel-shaped type is the most common. It is suggested that most of the resistance to diffusion through these types of pores is best explained by Stefan's law of diffusion through apertures. The implications of this theory to the understanding of pore functions are discussed.

Animals↗

PubMed1988

Diffusive resistance of avian eggshell pores.

Resistance to gas diffusion through the avian eggshell resides in the microscopic pores which penetrate the shell. We calculated the resistance to water vapor diffusion of individual pores in the shells of 23 species of avian eggs, based on measurements of pore dimensions taken from drawings of 321 pore casts published by Tyler (1962, 1964, 1965) and Tyler and Simkiss (1959). Diffusive resistances were calculated from Fick's first law, using a 100-segment model of each pore. In addition, we added 2 series resistances, calculated from Stefan's law, to account for boundary layer resistances at the inner and outer pore apertures. Convective resistances for the same 100-segment model were computed from Poiseuille's law. A special, symmetrically branching model is presented for the diffusive resistance of the branched pores of ostrich eggshells, based on the drawings of Tyler and Simkiss (1959). The total aperture resistance was less than 6.2% of total pore resistance, while the outside aperture effect was on average only 1.5%. The calculated average pore conductance for all species was 5.4 micrograms (day Torr)-1, about three times higher than the average value of 1.6 micrograms (day Torr)-1 obtained by dividing measured shell conductance by the number of pores (Ar and Rahn, 1985). A possible explanation for this discrepancy is advanced. However, it is to be noted that in spite of the discrepancy, both calculated and functional values of pore conductance appear to be independent of egg mass.

Animals↗

PubMed1989

The relationship between eggshell porosity and air space gas tensions measured before and during the parafoetal period and their effects on the hatching process in the domestic fowl.

The partial pressure of gases in the air space were measured before and during the parafoetal period for domestic fowl eggs of the same initial weight but varying in eggshell conductance. Embryos developed and hatched normally from eggs with a wide range of shell conductance and resultant air space gas partial pressures. Air space PO2 levels measured just before pipping ranged from 55 to 65 mm Hg in low and high conductance eggs, respectively, whilst PCO2 levels ranged from 75 to 55 mm Hg. With increasing shell conductance embryos membrane-penetrated and pipped the shell later, but hatch time was unaffected. Membrane penetration and external pipping appeared to occur in response to the partial pressures of gas in the air space but not in response to one particular level of air space PO2 or PCO2. During the parafoetal stage air space PO2 decreased at about 3.8 mm Hg/h and air space PCO2 increased at about 1.8 mm Hg/h and these rates of change were unaffected by eggshell conductance.

Animals↗

PubMed1991

Three-dimensional reconstruction of innermost chorion layer of Drosophila grimshawi and Drosophila melanogaster eggshell mutant fs(1)384.

A low-resolution three-dimensional structure of the crystalline innermost chorionic layer (ICL) of the Hawaiian species Drosophila grimshawi and the Drosophila melanogaster eggshell mutant fs(1)384 has been calculated from electron microscope images of tilted negatively stained specimens. The isolated ICL of Drosophila grimshawi is a three-layer structure, about 36 nm thick, whereas the ICL of Drosophila melanogaster eggshell mutant fs(1)384 is a single layer, about 12 nm thick. Each unit in both crystalline structures includes octamers made up of four heterodimers. Crosslinks between the structural elements, both within and between unit cells form an interconnecting network, apparently important in maintaining the integrity of the layer. A model which may account for the ICL self-assembly formation in vivo and the ICL observed lattice polymorphism is proposed, combining data from the three-dimensional reconstruction work and secondary structure features of the ICL component proteins s36 and s38.

Animals↗

PubMed1989

A preliminary study of the translocation of aldicarb across the duck eggshell.

The duck eggshell has the reputation of being more permeable than that of the domestic hen. If this is true, the developing embryo could be at greater risk from xenobiotic agents, since toxicants picked up on the feathers could be transferred to the embryo during incubation. This study looked for such an effect on the developing embryo after the application of aldicarb to the eggshell. At 72 hr, the eggs were painted with 3, 7, 11, or 15 microM aldicarb in 500 microliters water. The eggs were then incubated to Day 24. The gross morphological measurements were then recorded. A similar study was made using domestic hen eggs; these were treated after 36 hr incubation and incubated to Day 17. Direct injection into the yolk sac of both species was used for further comparison. There was a statistically significant reduction (P less than 0.01) in the middle web toe length with 11 and 15 microM aldicarb and the tarsometatarsus length with 7, 11, and 15 microM. Compared with the duck control group, the group given 15 microM aldicarb had reductions of approximately 8% in the tarsometatarsus and approximately 9% in the middle web toe. No statistically significant changes were produced in the chick embryos.

Aldicarb↗

PubMed1987

Possible eggshell protein gene from Schistosoma mansoni.

We have identified and sequenced a cDNA clone of a mRNA found only in mature female schistosomes. This mRNA is not detectably synthesized by female worms from single sex infections (unisexual females), by males or by the developing miracidia in the eggs. The clone hybridises to a highly abundant polyadenylated mRNA of approximately 1500 nucleotides. The nucleotide sequence of the clone predicts a polypeptide comprising two repetitive regions. A pentapeptide repeat with the consensus sequence Gly-Tyr-Asp-Lys-Tyr, and a region rich in histidine residues. Hybrid selected mRNA translated in vitro with [3H]tyrosine as labelled amino acid yields a polypeptide of 48 kDa (p48) that corresponds to the major [3H]tyrosine labelled translation product of female worm total mRNA. p48 does not label with [35S]methionine and is absent from the translation products of male and unisexual female mRNAs. The amino acid sequence of p48 has significant homologies to silk moth chorion proteins and we suggest that it is one of the major components of the schistosome eggshell probably accounting for the high level of [3H]tyrosine incorporation into the vitellaria of Schistosoma mansoni. The tyrosine content of the polypeptide suggests that it may play a role in phenol oxidase mediated cross-linking of the schistosome eggshell and in support of this we find that mushroom phenol oxidase will cause the specific cross-linking of p48 in in vitro translation products.

Animals↗