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PubMed1994

Egg yolk alpha-livetin (chicken serum albumin) is a cross-reactive allergen in the bird-egg syndrome.

Thirty-one patients with clinical history of egg allergy, bird allergy, or bird and egg allergy were investigated with the use of the immunoblot technique to compare IgE-binding components in bird feather and egg yolk and white extracts. Patients were classified into three groups according to clinical history, skin prick test results, and RAST results. Patients in group I were sensitized to bird feathers and egg yolk, patients in group II to egg white, and patients in group III to bird feather but not to eggs. Patients with bird-egg syndrome were mainly female adults, whereas egg white allergy was mainly observed in children without any obvious sex predisposition. IgE from patients with bird-egg syndrome recognized a 70 kd protein in egg yolk (chicken serum albumin = alpha-livetin) and some major allergens in bird feather extract (70, 95, and 200 kd). Preincubation of pooled sera from patients with bird-egg syndrome with budgerigar or hen feather extract and egg yolk extract, respectively, led to complete blocking of IgE binding to allergens in egg yolk and bird feather extract. On the other hand, IgE from patients with egg white allergy did not react with allergens in egg yolk and bird feather extract, despite strong IgE binding to egg white allergens. Patients in group III displayed no reactivity to bird feather or egg allergens. Our results demonstrate common epitopes of budgerigar and hen feather and egg yolk alpha-livetin. Therefore we assume that alpha-livetin (chicken serum albumin) leads to a cross-sensitization and consequently to the "bird-egg syndrome."

Adolescent↗

PubMed1994

Relationship between shell porosity, shell thickness, egg weight loss, and embryonic development in Japanese quail eggs.

Japanese quail eggs that hatched (H) or pipped (PIP) exhibited less weight loss through 15 d of incubation than did eggs that died late (LD), whereas eggs containing early dead (ED) embryos exhibited the greatest weight loss. The pore concentration at the large end of each egg was greatest in H eggs when compared with all other types. The pore concentration at the equator was greatest in H eggs and least in the eggs of the ED embryos. All other egg types lay statistically between these two types with regard to equator porosity. The small end pore concentration was similar in H, INF, and LD eggs and in the LD, PIP, and ED eggs. The least number was exhibited by the ED eggs and most by the H eggs. The thinnest shells at the small end were exhibited by H eggs, whereas thicker small end shells were exhibited by ED, LD, and PIP egg types. No differences were observed at the large end or equator. The data suggest that ED eggs exhibit excessive weight loss even though shell porosity was lower and shell thickness was similar to other egg types. This suggests that some functional component of the egg such as the shell membrane or albumen may contribute to this excessive weight loss. A similar statement can be made for LD eggs, which experienced greater weight loss through 15 d than did PIP or H eggs.

Animals↗

PubMed1995

Examination of egg number and egg weight variables and their effects on daily management in aviary systems for laying hens.

1. Characteristics of egg numbers and mean egg weight were examined for their usefulness in the daily management of aviary systems for laying hens. 2. A number of 3238 brown Isabrown/Warren hens were housed in 1 compartment, a separated part of the house where the hens could move around freely, of a tiered-wired-floor aviary system (TWF-system). An automatic egg weighing and counting system (EWACS) was used to count and weigh eggs daily from 2 tiers of laying nests on 1 side of the compartment and the number of eggs for the whole compartment were counted daily by the farmer. Each tier was divided into 16 blocks of 5 individual laying nests. Two adjoining blocks were called a group. To prevent hens from walking along all the laying nests in a tier, partitions were placed on the perches in front of the laying nests, between nest groups 2-3, 4-5, and 6-7. 3. After the first 3 weeks of the laying period, the distribution of egg numbers over the nest groups within a tier became stable. If egg numbers were counted daily from only 1 nest group the coefficient of variation was 23.1%. If the eggs from the whole compartment were counted daily, the coefficient of variation for the number of eggs was 2.8%. The nest group, presence of a partition and tier level influenced the daily number of eggs. 4. The distribution of the mean egg weight over the different nest groups within a tier was stable for the whole laying period. The coefficient of variation of the daily mean egg weight for a nest group was 3.1%. The difference in mean egg weight between nest groups was small, between 0.1 and 0.6 g, and the level of tiers and the presence of partitions between nest groups had no effect on the mean egg weight. 5. It could be concluded that egg numbers could not be estimated reliably by taking samples from a group of laying nests or a tier, but that it was necessary to count all the eggs from a compartment. The daily mean egg weight, however, could be estimated reliably on the basis of a sample of eggs from a nest group or a tier. By using EWACS frequent samples could be taken, which diminished the coefficient of variation so that the reliability of the data increased.

Animal Husbandry↗

PubMed1994

Intraspecific variation in egg size and egg composition in birds: effects on offspring fitness.

1. There is little unequivocal evidence to date in support of a positive relationship between egg size and offspring fitness in birds. Although 40 studies (of 34 species) have considered the effect of variation in egg size on chick growth and/or survival up to fledgling only 12 studies have controlled for other characters potentially correlated both with egg size and offspring fitness. Of these only two have reported a significant residual effect of egg size on chick growth (in the roseate tern and European blackbird) and three a residual effect on chick survival (all in seabirds: common tern, lesser black-backed gull and kittiwake). 2. More consistent evidence exists, though from fewer studies, for a positive relationship between egg size and offspring fitness early in the chick-rearing period; chick growth and chick survival being dependent on egg size in 8 of 10 studies and 4 of 5 studies respectively. It is suggested that the most important effect of variation in egg size might be in determining the probability of offspring survival in the first few days after hatching. 3. Egg size explains on average 66% of the variation in chick mass at hatching (n = 35 studies) but only 30% of the variation in chick body size (n = 18). When effects of hatching body size are controlled for chick mass remains significantly correlated with egg size, though the reverse is not true. This supports the hypothesis that large eggs give rise to heavier chicks at hatching, i.e., chicks with more nutrient (yolk) reserves, rather than structurally larger chicks. 4. Egg composition increased isometrically with increasing egg size in about half the studies so far reported (n equals approximately 20). However, in seabirds, and some passerines, larger eggs contain disproportionately more albumen, whilst in some waterfowl percentage yolk content increases with increasing egg size. Changes in albumen content largely reflect variation in the water content of eggs, but changes in yolk content involve variation in lipid content, and therefore in egg 'quality.' The adaptive significance of variation in egg composition is considered; females may adjust egg composition facultatively to maximise the benefits to their offspring of increased reproductive investment. 5. Considerations for future research are discussed with particular emphasis on experimental studies and the application of new techniques.

Animals↗

PubMed1983

Effects of the dwarfing gene (dw) on egg weight, chick weight, and chick weight: egg weight ratio in a commercial broiler strain.

The effects of the dwarfing gene (dw) on egg weight, chick weight, and chick weight: egg weight ratio were studied. Egg weights prior to setting and subsequent chick weights were determined on 1842 chicks from standard-sized broiler dams and 1694 chicks from closely related dwarf dams. Egg weight means were 67.3 and 63.0 g for standard and dwarf dams, respectively. Chick weights expressed as percentage of egg weight were 68.4 and 67.3% for standard and dwarf dam chicks, respectively. Both egg weight and chick weight: egg weight ratio differences were highly significant (P less than .01). Percent hatch weights of male and female chicks, 68.0 and 67.7%, respectively, were also significantly different (P less than .05). Regression analysis of egg weight on chick weight estimated the overall equation: chick weight = -6.13 g + .78 X egg weight. A significant positive linear relationship between chick weight: egg weight ratio and egg weight was detected; males increased more than females and dwarf dam chicks more than standard dam chicks. This suggests that chicks from large eggs utilize egg nutrients more efficiently than those from small eggs. Because the larger eggs come from larger hens, it is speculated that there may be a genetic basis to this phenomenon. It was concluded that egg weight, sex, and dam type each significantly contributed to the variability in chick weight and chick weight: egg weight ratio.

Animals↗

PubMed2004

A general solution for optimal egg size during external fertilization, extended scope for intermediate optimal egg size and the introduction of Don Ottavio 'tango'.

Egg sizes of marine invertebrates vary greatly, both within and between species. Among the proposed causes of this are a trade-off between egg size, egg number and survival probability of offspring, and a selection pressure exerted by sperm limitation during external fertilization. Although larger eggs are indeed a larger target for sperm, producing larger eggs also implies making fewer of them. There has been discussion about whether sperm limitation can (theoretically) and does (in nature) select for larger egg size than under ad libitum sperm. In one specific model, based on a particular fertilization kinetics model and an empirically derived mortality function, the theoretical possibility of a negative shift in optimal egg size with sperm concentration was demonstrated. Here we present a generalized analytical model to explore the effects of survival and fertilization probabilities on optimal egg size. It is demonstrated that incorporating fertilization kinetics greatly increases the scope for intermediate optimal egg size, as opposed to eggs of minimal or maximal size. Second, we present a general analytical qualitative solution to the question whether optimal egg size depends on sperm concentration. It is shown that, under the condition that an intermediate optimal egg size exists, this qualitative outcome of the model (positive, negative or no relation between optimal egg size and sperm limitation) depends on the structure of the fertilization kinetics part of the model. Finally, we evaluate fertilization kinetics models with respect to the general solution, using two previously published kinetics models ('Don Giovanni' and 'Don Ottavio') and a novel alteration of one of them in which sperm concentration covaries with egg concentration (Don Ottavio 'tango'). For all three models the relationship between optimal egg size and sperm concentration is shown to be always negative. This paper thus shows how biologically realistic relationships between egg size on the one hand and survival and fertilization probability on the other hand predict optimal egg size to be intermediate, and that this optimum is in general expected to increase when sperm become more limiting.

Animals↗

PubMed2001

Mechanical forces imposed on echinoid eggs during spawning: mitigation of forces by fibrous networks within egg extracellular layers.

Many echinoderms spawn large numbers of eggs in rapid spawning bouts directly into the water column. During spawning, the eggs pass from the gonad along a narrow oviduct and through a rigid gonopore before reaching the water. As the eggs traverse this pathway, they are exposed to shear stress induced by the development of a velocity gradient within the fluid formed by the eggs. In some species, the diameter of the eggs is larger than the diameter of the gonopore. In these cases, the eggs also experience strain resulting from compression of the egg as it passes through the relatively small gonopore. The magnitude of shear stress experienced by eggs differs among species depending upon the viscosity of the eggs. The degree of strain experienced by eggs differs among species depending upon the relative sizes of the egg and gonopore and also changes within species as they grow. Recent evidence suggests that these forces have the propensity to damage eggs, thereby reducing their fertilizability, or to destroy them. Experimental evidence shows that the jelly coat around the eggs can protect them from shear stresses and reduce the strain imposed on them under a compressive force. Echinoderm eggs are surrounded by a jelly coat that has a composite structure of irregularly arranged fibrous networks embedded in a jelly matrix. These fibrous networks have characteristics that are similar to those of engineered and biological materials that are known to reduce the transmission of mechanical forces to other structures. Given this similarity to other materials, three possible mechanisms for the action of the jelly coat may be identified. First, the apparent viscosity of the eggs of echinoids declines as the rate at which they are sheared during spawning increases. This reduction in viscosity with increasing shear rate (shear-thinning) may, in part, be due to the structure of the jelly coat and its resultant non-Newtonian nature. Second, experimental evidence indicates that the jelly coat preferentially deforms under a compressive load, reducing the transmission of that load to the egg. Third, the jelly (but not the fibers in the coating) may deform in a nearly viscous manner. In this case, the fibers may serve to provide an elastic 'backbone' to the layer and remain in place to stiffen the outer layer of the egg. The composite structure of the jelly coat and the morphology of the fibrous network are likely to be critical to all these mechanisms.

Animals↗

PubMed2000

Relating quality characteristics of aged eggs and fresh eggs to vitelline membrane strength as determined by a texture analyzer.

The TA-XT21 texture analyzer (TA) was used to evaluate vitelline membrane strength (VMS). Fresh and aged (1 wk at 25 C) eggs (n = 48 eggs x 2 replications) were evaluated. Fresh and aged eggs were further divided into two groups of yolk only or whole egg (with intact albumen). Yolk index, Haugh units, pH, broken-out egg weights, VMS, yolk viscosity, and scanning electron microscopy (SEM) images were evaluated. Results from the TA indicated a decrease in VMS in aged eggs compared to fresh eggs and in yolk-only eggs compared to whole eggs. The SEM images indicated a loss of structural integrity in aged eggs as compared to fresh eggs. As expected, aged eggs also had higher albumen and yolk pH, lower Haugh units, lower yolk index, and decreased viscosity compared to fresh eggs. There were no differences in broken-out egg weights or whole egg pH between fresh and aged eggs. As the yolk membrane strength increased, yolk index (r = 0.59) and Haugh units (r = 0.56) decreased, and yolk pH (r = -0.64) and albumen pH (r = -0.57) increased. The study suggests that the TA combined with the modified extrusion cell may be effective in determining VMS. In addition, yolk index, Haugh units, and yolk and albumen pH may be used to predict changes in VMS.

Animals↗

PubMed1972