The peripheral layer of the egg has long been recognized as a region with special properties. Several types of experiments argue for the existence of an egg cortex (reviewed in Wilson, 1925; Chambers and Chambers, 1961; Hiramoto, 1970; Vacquier, 1981). We can cite in chronological order: micromanipulations of the egg with rods and micropipettes; low speed centrifugation experiments that stratif...

the present study was conducted to estimate correlations among performance and egg quality traits in iranian native fowl. data were collected from 21,679 birdsat the isfahan native fowl breeding center to derive genetic parameters for performance traits and egg quality traits were measured on eggs of 1,020 birds. genetic correlations of performance and egg quality traits were estimated with a b...

Species' life history traits, including maturation age, number of reproductive bouts, offspring size and number, reflect adaptations to diverse biotic and abiotic selection pressures. A striking example of divergent life histories is the evolution of either iteroparity (breeding multiple times) or semelparity (breed once and die). We analysed published data on salmonid fishes and found that sem...

The general lack of experimental evidence for strong, positive effects of egg size on offspring phenotype has led to suggestions that avian egg size is a neutral trait. To better understand the functional significance of intra-specific variation in egg size as a determinant of offspring fitness within a life-history (sex-specific life-history strategies) and an environmental (poor rearing condi...

The objective of this study was to identify the quantitative trait loci (QTL) affecting carcass traits on chromosome 1 in Japanese quail. The populations comprised of 422 progeny in 9 half-sib families. Phenotypic data on carcass weight, carcass parts, and the internal organs were collected on 422 progeny. Nine half-sib families were genotyped for 8 microsatellite markers covering chromosomes 1...

Seabirds are used frequently as indicators of mercury contamination in marine ecosystems, but few studies have examined the forms of mercury found in seabird tissues. Here we compare concentrations of total and organic mercury in feathers (n=5) of six sympatric nesting seabirds and in egg components of Leach's storm-petrels from Machias Seal Island, New Brunswick, Canada, during the 2006 breedi...

Current egg washing practices use wash water temperatures averaging 49 degrees C and have been found to increase internal egg temperature by 6.7 to 7.8 degrees C. These high temperatures create a more optimal environment for bacterial growth, including Salmonella Enteritidis if it is present. Salmonella Enteritidis is the most common human pathogen associated with shell eggs and egg products. I...

The existence of a coevolutionary process between avian brood parasites and their hosts predicts lower intra-clutch variation in egg appearance host eggs among rejecters as this would favor discrimination parasite by once parasitic mimicry had evolved. So far empirical tests prediction have ignored the fact that different aspects phenotypes may differ relative role environmental vs. genetic det...

When successive stages in the life history of an animal directly overlap, physiological conflicts can arise resulting in carryover effects from one stage to another. The extreme egg-size dimorphism (ESD) of Eudyptes penguins, where the first-laid A-egg is approximately 18-57% smaller than the second-laid B-egg, has interested researchers for decades. Recent studies have linked variation in this...