1. Despite considerable recent interest in plasma and yolk testosterone (T) in female birds, relatively little is known about environmental regulation of female T, individual variation in female T or the relationship between plasma and yolk T. 2. In breeding females of a wild population of dark-eyed junco ( Junco hyemalis ), we assessed variation in the responsiveness of the hypothalamo-pituita...

This experiment was designed to compare powdered egg yolk with fresh egg yolk in an extender for cryopreservation of Zebu bull semen. Sperm motility, plasma membrane integrity and viability were assessed at different stages of cryopreservation (post-dilution, pre-freezing and post-thawing). Sperm plasma membrane integrity remained similar at all the stages of cryopreservation. Sperm motility an...

this experiment was conducted to evaluate the addition of seminal plasma to coated spermatozoa after 72 h. semen was collected from four taleshi rams by artificial vagina. to prepare coated spermatozoa, semen was collected in tube containing tris-fructose-15% egg yolk. after initial evaluation, the samples were mixed and centrifuged. after removal of supernatant and dilution, samples were divid...

Semen from four Holstein bulls was evaluated to compare effects of four extender treatments on postthaw semen quality. Extender fractions A and B, either heated whole milk or 20% egg yolk-citrate, were combined to yield the extender treatments 1) milk and milk, 2) milk and egg yolk-citrate, 3) egg yolk-citrate and milk, and 4) egg yolk-citrate and egg yolk-citrate. Semen was evaluated at thawin...

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...

Cryopreservation of spermatozoa from endangered species is a valuable tool for genetic management. Previous studies showed the feasibility of cryopreservation of spermatozoa from various endangered gazelles but have also revealed difficulties with available protocols for semen freezing in Cuvier's gazelle (Gazella cuvieri). Experiments were carried out to investigate the effect of (a) 5% or 20%...

Recent studies have indicated that egg yolk immunoglobulins (Ig) can be used for therapeutic purposes and that yolk Ig levels are increased after molting of laying hens. The present study was performed to compare between the effects of two methods of induced molting namely alfalfa and zinc methods on serum and yolk IgY concentrations as well as their effects on the egg quality and immune status...

The toxicity of the herbicide Erbitox E30, a commercial formulation of 2-methyl-4-chlorophenoxyacetic acid (MCPA) containing 28% MCPA as sodium-potassium salt and 72% of unknown ingredients, was tested on chick embryos. Sterile aqueous solutions of MCPA were injected into the air chamber at doses of 0, 1.5, 3.0, 6.0, 9.0, or 10.5 mg/egg on day 0 or on day 4 of incubation. The mortality rate for...

The mass of residual yolk sac expressed as a percentage of initial mass of the egg from which the chick hatched decreased sharply in the first 2 days post-hatching. A gradual reduction occurred between 3 and 10 days after which a sharp decline was noted between 11 and 13 days post-hatching. The highest number of chicks with unabsorbed yolk sac was noted on day 5 post-hatching followed by days 6...