Plasma levels of luteinizing hormone (LH) and prolactin associated with parental behavior were measured in the Antarctic winter breeding emperor penguin, Aptenodytes forsteri. Males exclusively incubate the egg while females exclusively brood the nonhomeothermic young; both sexes alternate in rearing the homeothermic young. Birds were sampled on arrival from the sea through egg laying, incubati...

The phenotype of a mother and the environment that she provides might differentially affect the phenotypes of her sons and daughters, leading to change in sexual size dimorphism. Whereas these maternal effects should evolve to accommodate the adaptations of both the maternal and offspring generations, the mechanisms by which this is accomplished are rarely known. In birds, females adjust the on...

Objective: In recent years, antibiotics have been used widely in the glob to prevent and treat bacterial diseases. They injected into eggs to eliminate pathogens and prevention of egg transmission of disease, but the adverse effects of drugs have always been a major concern. There is little information available about the safety of tetracycline drugs in the embryonated eggs of the birds. The ob...

An experiment was conducted to determine the effect of time of oviposition, generally representing different positions in the normal egg laying sequence, on egg weight loss during storage and incubation, and on fertility and fertile hatchability of eggs from mid-lay (42 wk) and old (67 wk) broiler breeders. A total of 1,800 eggs (900 eggs per flock age) were collected during 10 consecutive days...

Avian brood parasites, including cuckoos and cowbirds, have multiple negative effects on their hosts. We analysed the effects of Shiny Cowbird Molothrus bonariensis parasitism on different components (e.g. egg losses, hatching success, chick survival and nest abandonment) of House Wren Troglodytes aedon reproductive success. We also conducted an experiment to discriminate between two mechanisms...

Objective: In recent years, antiviral drugs have been used widely in the glob to prevent and treat viral diseases. They injected into eggs to eliminate pathogens and prevent of egg transmission of disease, but the adverse effects of drugs have always been a major concern. There is little information available about the safety of antiviral drugs in the embryonated eggs of birds. The objective of...

Objective: In recent years, antiviral drugs have been used widely in the glob to prevent and treat viral diseases. They injected into eggs to eliminate pathogens and prevent of egg transmission of disease, but the adverse effects of drugs have always been a major concern. There is little information available about the safety of antiviral drugs in the embryonated eggs of birds. The objective of...

objective: in recent years, antiviral drugs have been used widely in the glob to prevent and treat viral diseases. they injected into eggs to eliminate pathogens and prevent of egg transmission of disease, but the adverse effects of drugs have always been a major concern. there is little information available about the safety of antiviral drugs in the embryonated eggs of birds. the objective of...

Birds use contact incubation to warm their eggs above ambient temperature required for embryonic development. In contrast, birds in the industry as well many breeding programs and scientific studies are incubated conventional incubators that via circulating air. This means have different thermal properties than a incubator. light of previous showing small differences can affect chicks post-hatc...

Birds stand out from other egg-laying amniotes by producing relatively small numbers of large eggs with very short incubation periods (average 11-85 d). This aspect promotes high survivorship by limiting exposure to predation and environmental perturbation, allows for larger more fit young, and facilitates rapid attainment of adult size. Birds are living dinosaurs; their rapid development has b...