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The intracellular pH of the shell gland of the domestic fowl was calculated at various stages in egg-shell formation. The calculation is based on the distribution of 5,5-dimethyloxazolidine-2,4-dione between intracellular and extracellular water. The results show a rapid fall in intracellular pH at the time of mineralization and this is interpreted as indicating a removal of protons from the site of calcification.
Comparative data collected over two years are presented which refute the popular press claims that blue-shelled eggs of Araucana chickens have higher protein levels and lower cholesterol levels than market eggs. These comparisons were made between the eggs from the strains of Araucanas and those of White Leghorns and Sex-links. None of the differences found between test groups in % protein/g. albumen and % protein/g. yolk were shown to be consistently related to any one test group type. However, all Araucana test groups were significantly (P less than .01) lower in their total egg protein content than either control group by from 2.8--6.5%. This lower total protein content was the result of a consistent increase in the yolk/albumen ratio of the Araucana eggs over the market eggs. The Araucana eggs were consistently higher in their cholesterol levels on a mg./g. yolk basis than either of the market eggs. These increased concentrattions ranged from 2.0--6.9%.
Two techniques for egg-shell treatment were evaluated for their effects on the quantity and variability of the fluid absorbed by turkey hatching eggs subjected to the temperature-differential method of egg dipping. The use of pin or drill to pierce a uniform hole through the shell and membrane(s) on the large end of each egg caused a significant increase in the quantity of dip solution absorbed. Variability in fluid uptake by the eggs also was reduced significantly. Utilization of dilute acid to remove cuticle completely from the whole egg surface or partially from either end also had similar effects. The techniques described also permit and effective dipping procedure that does not require the preheating step.
Eighteen chickens were immunized subcutaneously with purified type 1 fimbriae from Salmonella enterica serotype Enteritidis at 18 and 21 weeks of age. Evidence of IgG and IgA responses was found in the eggs and in the sera of the immunized hens. Three weeks later, immunized and non-immunized chickens (n=18) were challenged intravenously with 2x10(7) live Salmonella enterica serotype Enteritidis. There was no significant difference in the numbers of eggs laid by immunized and non-immunized birds. The percentage of Salmonella contaminated eggs was significantly higher in the non-immunized group than in the immunized group due to a higher percentage of contamination of the externally disinfected egg shells. There were no statistical differences in the percentages of contaminated yolks and egg whites between control and immunized birds. No differences in the number of colonizing bacteria could be found in the spleen nor in the liver between the immunized and the control groups throughout the experiment. Salmonella was cleared from the ovary of the immunized birds in the second week p.i., in contrast to the control birds where Salmonella was isolated till the third week after infection. Oviducts were significantly more infected in the control group than in the immunized group. Salmonella was cleared from the oviducts at 3 weeks p.i. in the immunized hens but not in the control hens. In conclusion, we demonstrated that the immunization of laying hens with type 1 fimbriae reduced the number of contaminated eggs and reduced the colonization of the reproductive organs.
AIMS: As part of a field-based study of the distribution and persistence of Salmonella infection on commercial egg-laying farms, sampling was carried out on one or more occasions in egg-packing areas of 12 farms infected with Salm. Enteritidis. METHODS AND RESULTS: Salmonellas were isolated by cultural methods. Contamination was common, with Salmonella being found in 23.1% of floor swab samples, 30.8% of grading tables, 23.1% of conveyor belts or rollers and 23.8% of candlers. Four farms were sampled after cleaning and disinfection of packing plants had been carried out on the previous day, and residual contamination was found on 6.9% of samples from grading tables, 16.0% holding/sorting tables, 12.6% of conveyors or rollers, 16.7% of vacuum egg lifters, 21.4% of floor surfaces and 5.0% of egg store floor surfaces. Sterilized eggs passed through five farm packing plants showed a contamination rate of at least 16/5,948 (0.3%) egg passages. CONCLUSIONS: It is apparent that contamination in egg-packing plants may be a significant contributory factor to external contamination of shell eggs, and improved methods of cleaning and disinfecting egg-handling equipment are required. SIGNIFICANCE AND IMPACT OF THE STUDY: The presence of Salmonella contamination in egg-packing plants presents a contamination hazard for eggs from Salmonella-free flocks. Samples from equipment in the packing plant could also be used for screening for detection of Salmonella in the throughout of the plant.
1. On samples from two brown-egg strains between 1967 and 1979, "residual" food consumption (i.e. food consumption corrected for body weight, weight change and egg mass) of laying hens was investigated with respect to variation between sire families and phenotypic correlations with production traits, egg traits, morphological and physiological variables. A similar residual food intake (corrected for body weight and body-weight gain) was obtained for samples of males in some years. 2. Highly significant differences between sire families were observed for residual food consumption in both strains for females and in one strain for males. 3. In females, highly significant positive phenotypic correlations were found in both populations for residual food intake with wattle length and shank temperature, and in one population with shank length and width. On the whole, a negative correlation was observed with egg-shell thickness. For two variables recorded only in one strain, proportion of broken eggs yolk: albumen ratio, there were highly significant positive correlations. 4. For males also, wattle length and shank temperature were positively correlated with residual food intake. 5. The physiological meaning and possible use of correlated variables as criteria for indirect selection for food efficiency of layers are discussed.
In order to investigate the ability of infective larvae of the nematode Baylisascaris transfuga (Rudolphi, 1819) Sprent, 1968 to hatch from the egg-shells and then to migrate in tissues, parenteral infections of mice with embryonated eggs were performed. Two groups of outbred albino mice were infected with approximately 3500 B. transfuga infective eggs subcutaneously (s.c.) or intraperitoneally (i.p.). B. transfuga larvae in the i.p. group rapidly hatched and migrated to the intestine, liver, lungs, brain and carcass. Subcutaneous inoculation of eggs was followed also by migration of hatched larvae in the examined organs. In the s.c. mice, extensive encapsulating reactions involving the subcutaneous tissues and carcass, and containing large numbers of hatched eggs and free motile larvae, were found at the sites of inoculation. Some differences in the migratory behaviour were observed between the two groups. It is shown that B. transfuga infective larvae are able to hatch and migrate in tissues of mice, and tend to settle and/or to be trapped in the intestinal wall and muscles, even after parenteral inoculations of embryonated eggs. These results could provide basic data for further investigations on the migratory pathways of B. transfuga larvae or to perform immunological and therapeutical studies.
1. Two hundred and forty Amber-link pullets were individually caged in a naturally-ventilated laying house and fed one of four isoenergetic, isonitrogenous diets containing 0, 20, 40 or 80 sodium bentonite/kg for 44 weeks. 2. No significant dietary effects were observed between treatments with regard to body weight at 20 or 64 weeks, age at first egg, egg weight, Haugh score or egg shell thickness. 3. Significant positive linear responses were observed with live weight at first egg (P less than 0.01), food consumed/hen d (P less than 0.05) and faecal moisture percentage (P less than 0.01). Significant negative linear (P less than 0.01) responses were observed with bacterial counts in the proximal and distal ends of the intestine. 4. A significant negative quadratic (P less than 0.05) response was noticed with egg production per hen. 5. A significant negative cubic (P less than 0.01) response was found with food conversion ratio (g food/g eggs).
Evidence on the extent of the part played by infected hens' eggs in causing salmonella food-poisoning is inconclusive. The role of freshly cooked shell eggs is currently much exaggerated. Prevention should be sought through improved catering practices and kitchen hygiene, and attempts to eradicate salmonellas from laying flocks are likely to be ineffective.
Six non-S. Enteritidis strains and eleven S. Enteritidis strains of which 8 were isolated from eggs, were tested on their growth behaviour in fresh eggs and in eggs of 2 and 3 weeks old hold at 20 degrees C. The growth of Salmonella at 20 degrees C was measured at days 6, 13 and 23 after inoculation. Taking the average growth of the different S. Enteritidis and of the non-S. Enteritidis strains, we found that both groups grew very well in fresh eggs. S. Enteritidis strains grew as good in eggs of 2 weeks as in fresh eggs, non-S. Enteritidis strains grew less. When keeping the eggs 3 weeks before inoculation, both groups showed still a relatively high growth. Additional experiments were done on the growth of Salmonella in a minimal medium with an iron source together with the iron chelator conalbumin, and in a medium without iron and conalbumin, to overcome variations in viscosity and in egg composition. After 12 hours incubation at 37 degrees C, both S. Enteritidis and non-S. Enteritidis strains grew better in the presence of iron than in the absence. S. Enteritidis egg isolates behaved more variable than S. Enteritidis non-egg isolates in the presence of iron. To check the influence of pH changes during ageing of eggs, we measured the growth of Salmonella in minimal media (with iron) of pH 8, 8.5, 9 and 9.5. All salmonellae seemed to grow well independently of the pH. Thus the fact that Salmonella grew best in fresh egg white and showed a decreasing growth in stored egg white, is probably not due to a pH effect. We also investigated if the presence of the yolk had an influence on the growth of Salmonella. We saw no general correlation so it seems that no components that could promote the growth of Salmonella diffuse from the yolk. We studied the influence of the egg sources on the variability in growth by comparing experiments done in eggs of 3 different sources. For the different strains we found a variable growth. But in general, the most important conclusion of our experiments is that all Salmonella strains do grow better in fresh egg white than in egg white of 2 or 3 weeks old. These results are contradictory with findings in literature (Humphrey et al., 1993) and must be checked with the European guidelines concerning the storage of eggs. Moreover, we found that even non-S. Enteritidis strains can grow well in egg white. These are not found in naturally contaminated eggs. It doesn't seem probable that S. Enteritidis could penetrate the egg shell easier than other serotypes so we suppose that horizontal transmission of Salmonella in eggs is of less importance than the vertical transmission.
Egg production and egg quality are complex sex-limited traits that may benefit from the implementation of marker-assisted selection. The primary objective of the current study was to identify quantitative trait loci (QTL) associated with egg traits, egg production, and body weight in a chicken resource population. Layer (White Leghorn hens) and broiler (Cobb-Cobb roosters) lines were crossed to generate an F2 population of 508 hens over seven hatches. Phenotypes for 29 traits (weekly body weight from hatch to 6 weeks, egg traits including egg, albumen, yolk, and shell weight, shell thickness, shell puncture score, percentage of shell, and egg shell colour at 35 and 55 weeks of age, as well as egg production between 16 and 55 weeks of age) were measured in hens of the resource population. Genotypes of 120 microsatellite markers on 28 autosomal groups were determined, and interval mapping was conducted to identify putative QTL. Eleven QTL tests representing two regions on chromosomes 2 and 4 surpassed the 5% genome-wise significance threshold. These QTL influenced egg colour, egg and albumen weight, percent shell, body weight, and egg production. The chromosome 4 QTL region is consistent with multiple QTL studies that define chromosome 4 as a critical region significantly associated with a variety of traits across multiple resource populations. An additional 64 QTL tests surpassed the 5% chromosome-wise significance threshold.
1. The intracellular pH and the extracellular fluid volume of the shell gland mucosa were determined. 2. The pH value varied little during egg formation, the overall mean being 7.11 +/- 0.02 (n = 34). 3. The lowest pH, 7.01, was found 10 h after oviposition and the highest, 7.22, 18 h after oviposition.
The inner and outer shell membranes (ISM, OSM) of fertile hen's eggs become aerated during the first ten days of incubation. The volume of gas in the compound membrane increases from 0 to 65% by day 11 when practically all of the space between the fibers is gas filled. The amount of gas depends on a balance between the capillary tension produced by fluid menisci in the interstices between fibers and the colloid osmotic tension of the albumen. Capillary tension, measured directly with a pressure plate apparatus, and colloid osmotic pressure, measured with a new technique, are in virtual equilibrium during aeration. These tensions increase from 0.15 bar at laying to 2.25 bar on day 11 because of evaporation from the membranes and active removal of water from the albumen by the embryo. Water leaving the membranes by evaporation is only partly replaced from the albumen. Thus the water contents of the membranes and albumen decrease (ISM: 79 to 56%, OSM: 71 to 52%, albumen: 86 to 58%). As the membranes dry, gas enters the larger pores first. Physiological estimates of effective radius show smaller (x = 1.3 micrograms), bimodally distributed pores in the ISM and larger (x = 3.4 micrograms), unimodally distributed pores in the OSM.
In the green anole (Anolis carolinensis), a lizard with genotypic sex determination, yolk testosterone (T) concentration is greater in male-producing than female-producing eggs at oviposition, but the source and potential effects were not clear from previous studies. If yolk T levels are also sex-specific before eggs are laid, a period during which embryonic steroidogenesis is unlikely, it would strongly suggest that the difference in yolk T is maternally derived. We collected yolk samples from eggs shelling within the oviducts of anesthetized females, and then allowed these females to lay the eggs naturally. Eggs were incubated to hatching to determine sex morphologically, and yolk T concentrations were analyzed by radioimmunoassay. As is the case just after they are laid, yolk T is higher in male than female oviductal eggs. To our knowledge, this is the earliest sex difference reported for any yolk steroid. We suggest that maternally derived yolk T levels could influence sex by differentially affecting male- and female-inducing sperm, because fertilization occurs after yolk deposition and ovulation, while the egg is in the oviduct. Our results, together with those of an increasing number of studies, suggest that a relationship between hormones and vertebrate sex determination may be more widespread than generally appreciated.
From an ontogenetic point of view, invertebrate eggs are generally the most freezing intolerant stage of a species. Development state, water content and acclimation may affect their supercooling ability. In this study, we measured fresh mass, water content and temperature of crystallisation (T(c)) of eggs of the edible land snail Cantareus aspersus, depending on its form ("aspersa"vs. "maxima"), incubation temperature (20, 12 and 7 degrees C) and physiological age (as part of the complete development). We also tested their tolerance to freezing. Despite a high number of individual observations (n=759) and significant differences of fresh mass and water content between both subspecies, no effect of origin, incubation temperature or development state has been found in this study. T(c) remained constant whatever the condition, with an overall mean of -5.40+/-0.24 degrees C (mean+/-SD). We suggest that fresh mass is important, a high water content and a constantly wet surface confer to land snail eggs a poor ability to supercool. Moreover, the presence of ice nucleating agents at the egg surface (microorganisms present in the soil, calcium carbonate crystals of the egg shell) might induce freezing. Thus, considering the present results, to delay hatching by cryopreservation of eggs does not seem possible.
1. Neem kernel meal (NKM) was incorporated into a standard layer diet at 0, 100, 150 and 200 g/kg, replacing parts of the soyabean meal and deoiled rice bran. Each diet was offered to 18 White Leghorn layers (25 weeks, 50% egg production) in individual cages for a period of 12 weeks. 2. Results indicated significantly lower food intakes (P < 0.01), rates of egg production and egg weights in birds fed on the diets with NKM at 150 and 200 g/kg. Fertility and hatchability were also adversely affected by the higher inclusion rates of NKM. 3. Except for lower egg shell weight and shell thickness (P < 0.05) in hens fed NKM at 150 and 200 g/kg, the internal egg quality characteristics were comparable in all groups. 4. Feeding NKM beyond 100 g/kg to laying hens significantly (P < 0.01) reduced the content of haemoglobin, erythrocyte count, packed cell volume, serum calcium and uric acid concentrations. However, the leucocyte count, plasma glucose concentration and serum glutamate oxaloacetate transaminase activity were unaltered. Serum glutamate pyruvate transaminase activity was significantly (P < 0.05) reduced in birds fed NKM at 200 g/kg. 5. Thus NKM at 100 g/kg in a layer diet would appear to be safe and cost-effective.
We present a theoretical and experimental study of the fragmentation of closed thin shells made of a disordered brittle material. Experiments were performed on brown and white hen egg shells under two different loading conditions: impact with a hard wall and explosion by a combustible mixture. Both give rise to power law fragment size distributions. A three-dimensional discrete element model of shells is worked out. Based on simulations of the model, we give evidence that power law fragment mass distributions arise due to an underlying phase transition which proved to be abrupt for explosion and continuous for impact. We demonstrate that the fragmentation of closed shells defines a new universality class of fragmentation phenomena.
Organochlorine residues and shell thicknesses were surveyed in eggs of the clapper rail (Rallus longirostris), purple gallinule (Porphyrula martinica), common gallinule (Gallinula chloropas), and limpkin (Aramus guarauna) from the eastern and southern United States. Clapper rail eggs were collected during 1972-73 in New Jersey, Virginia, and South Carolina. During 1973-74, gallinule eggs were collected in Florida, South Carolina, and Louisiana, and limpkin eggs were collected in Florida. Egg contents were analyzed for residues of organochlorine pesticides, including DDT, TDE, DDE, dieldrin, mirex, heptachlor epoxide, oxychlordane, cis-chlordane (and/or trans-nonachlor), cis-nonachlor, hexachlorobenzene (HCB), toxaphene, and endrin, and for polychlorinated biphenyls (PCBs). Shell thicknesses of recent eggs of these species were compared with archival eggs that had been collected before 1947. With the exception of the limpkin, the majority of eggs analyzed contained residues of p,p'-DDE and PCBs. Geometric means ranged from 0.10 ppm to 1.3 ppm. Small amounts (less than 1.0 ppm) of mirex, dieldrin, cis-chlordane (and/or trans-nonachlor), TDE, and DDT were detected in a few eggs. No evidence of eggshell thinning was found for any of the species studied. DDE residues in clapper rail eggs were higher in New Jersey and Virginia than in South Carolina.