Egg yolk oil is a natural source of bioactive compounds such as unsaturated fatty acids, oil soluble vitamins, pigments and others. Bioactive compound content in egg yolk oil depends from its content in eggs, from which oil was extracted. Many studies show that bioactive compound content in egg is correlated to the content of these compounds in hen feed, but there is also an opinion that hen ho...

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 woul...

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Effects of F-strain Mycoplasma gallisepticum (FMG) inoculation and 1.5% supplemental dietary poultry fat (PF) on the egg yolk characteristics of commercial layers at 24, 34, 44, 50, and 58 wk of age were investigated. Sham and FMG inoculations were administered at 12 and 22 wk of age and dietary treatments (basal control and basal control with 1.5% supplemental PF) were initiated at 20 wk of ag...

Maternal effects are important in epigenetic determination of offspring phenotypes during all life stages. In the chicken (Gallus gallus domesticus), transgenerational transfer of egg yolk factors may set the stage for morphological and physiological phenotypic differences observed among breeds. To investigate the effect of breed-specific yolk composition on embryonic broiler and layer chicken ...

Maternally derived steroid hormones are known to be present in the yolks of avian eggs; however, the physiological mechanisms involved in their deposition remain largely unexplored. Investigations of steroid production by avian follicles have demonstrated temporal differences in the concentrations of progesterone, 17beta-estradiol, and testosterone during yolk formation. Because yolk is deposit...

Hen egg yolk is normally used as a cryoprotective agent in semen freezing extenders, but its use has sanitary and practical disadvantages. Moreover the protection afforded by egg yolk has not yet been completely elucidated. The objective of this study was to compare the egg yolk plasma fraction to whole egg yolk in stallion freezing extender. Plasma contains mainly Low Density Lipoproteins (LDL...

The effects of broiler breeder age (26, 28, and 30 wk) and incubator relative humidity (43, 53, and 63% RH) on yolk sac weight and composition in broiler hatching eggs between 16 and 19 d of incubation were evaluated. Percentage yolk sac weight was reduced in eggs from the youngest (26 wk) breeder hens and in eggs incubated at 53% RH. Percentage yolk moisture, in eggs from the youngest hens, wa...

Studies of receptor-mediated lipoprotein metabolic pathways in avian species have revealed that physiological intricacies of specific cell types are highly analogous to those in mammals. A prime example for the power of comparative studies across different animal kingdoms, elucidated in the chicken, is that the expression of different lipoprotein receptors in somatic cells and oocytes are the k...

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 woul...