Yolk steroids of maternal origin have been proposed to influence genetic sex determination in birds, based on sex differences in yolk steroid concentrations of peafowl eggs incubated for 10 days. More recent reports dispute this proposal, as yolk steroids in eggs incubated for 3 days do not show such sex differences. To date, research examining this phenomenon has only analysed incubated eggs, ...

In this study, 100 day-old broiler chicks were divided into two groups, A and B containing 50 birds each. Experimental infection with E. coli was given intra yolk to group A on day-1 of experiment, while group B was kept as control. Parameters studied were examination of yolk sac, yolk sac:body weight ratio, antibody titer against Newcastle disease virus (NDV) and analysis of fractional serum p...

Thyroid hormones (THs) are essential for the correct development of nearly every structure in the body from the very early stages of development, yet the embryonic thyroid gland is not functional at these stages. To clarify the roles of the egg yolk as a source of THs, the TH content in the yolk and the expression of TH regulator genes in the yolk sac membrane were evaluated throughout the 21-d...

We have recently established a unique in vitro experimental model for mitochondrion-rich cell (MRC) research, a ;yolk-ball' incubation system, in which the yolk sac is separated from the embryonic body of Mozambique tilapia embryos and subjected to in vitro incubation. To evaluate the ion-transporting property of the yolk balls, we examined Cl- content and turnover in yolk balls incubated in fr...

abstract  introduction: this experiment was conducted to study the effects of different levels of flaxseed (0, 5, 10 and 15% of diet) and copper (in the form of cupric sulfate pentahydrate, 0 and 250 ppm of diet) on fatty acids and cholesterol in egg yolk of laying hens. methods: a total of 128 white leghorn layers aged 50 weeks were used in a factorial design and randomly assigned to 8 treatme...

one-hundred-sixty-eight 28-wk-old hy-line layers (w-36) were used to evaluate the effect of different levels of linseed (ls) and safflower seed (ss) on antibody titter, blood and yolk cholesterol, yolk fatty acid content and the ratio of omega-6/ omega-3. hens were randomly assaigned in a compeletly randomised design each 3 replicates of 8 hens. they were fed diets contained 0, 4, 7 and 10% ls ...

a participatory rural appraisal technique (prat) was used to obtain information from 132 randomly selected turkey farmers in two out of four agricultural development zones in kwara state, nigeria. data were obtained on socio-occupational status of farmers, their production objectives, experience, flock structure, management practices, marketing and consumption of turkey eggs. the results showed...

Despite the strong interest in hormone-mediated maternal effects two key questions concerning their mechanisms are as yet unanswered: First, whether the deposition of hormones in the egg yolk is coupled with the levels of these hormones in the maternal circulation, and second, whether epigenetic changes as induced by embryonic exposure to maternal yolk hormones impinge on yolk hormone depositio...

The external dimensions, weight and contents (yolk, albumen, shell) of Double Yolked (DY) and Single Yolked (SY) eggs of the duck (Anas platyrhynchos domesticus) were measured and compared. The yolks in DY eggs did not differ in weight (p = 0.144), although each double yolk was significantly lighter than the yolk of a SY egg (p<0.001). DY albumen weight was below that expected of a SY egg of co...

The murine yolk sac, being the first site of embryonic blood cell production, has long been theorized to contain the migrating hematopoietic stem cells (HSC) that seed the liver and initiate hematopoiesis on day 10.0 postcoitus (pc). However, it remains controversial whether yolk sac cells isolated before day 11.0 pc possess any long-term repopulating HSC activity upon transplantation into adul...