Importance of prenatal nutrition to the development of a precocial chick

Abstract

The developmental maturity of hatchling birds varies greatly across the altricial-precocial continuum and these differences are related to the relative proportions of yolk and albumen in a species' egg. In general, the more precocial the chick the greater the proportion of yolk in its egg. Egg composition can also vary within species with unknown consequences for the developing embryo. The present research sought to determine the importance of egg composition to avian development by experimentally removing 1, 2, 4, 8, 12, or 16% of the albumen from eggs of domestic fowl (Gallus gallus). Experimental chicks were paired to control chicks whose eggs were matched on the basis of original mass and laid by the same female but no albumen was removed from their eggs prior to incubation. Decreased levels of albumen significantly decreased chick size at hatch. Experimental subjects, however, had similar growth to controls after 20 days of ad-lib access to food, although sex differences between pairs indicated that the growth of females may be affected differentially by albumen removal. Righting responses were retarded in experimental subjects for the 2 and 4% albumen-removal groups. Egg composition can have important consequences for chick survival simply by influencing body size at hatch and it is suggested that the practice of using overall egg size as a measure of egg "quality" needs to be broadened by considering what is inside the egg as well. In addition, the unique opportunity presented by using an avian model to assess directly the specific influences of protein (albumen) and of fat (yolk) on growth and behavioral development is explored.

Chronic Moderate Hypoxia and Protein Malnutrition Both Induce Growth Retardation, But Have Distinct Effects on Arterial Endothelium-Dependent Reactivity in the Chicken Embryo

“…The eggs of chickens contain yolk, which consists of water, fat, and proteins and primarily determines the degree of development of the chick at hatching. The other component of the egg, albumen, mainly (approximately 95%) contains water and amino acids, which are used by the developing embryo for wholebody protein synthesis and growth (23,32,33). As previously shown (23,34), extraction of albumen from the egg was found to reduce total embryonic weight toward the end of incubation.…”

“…The other component of the egg, albumen, mainly (approximately 95%) contains water and amino acids, which are used by the developing embryo for wholebody protein synthesis and growth (23,32,33). As previously shown (23,34), extraction of albumen from the egg was found to reduce total embryonic weight toward the end of incubation. Similar to exposure to chronic hypoxia, relative brain weight was spared, indicating that growth was reduced in a disproportionate way in both models.…”

“…The albumen content of a separate set of eggs (n ϭ 18) was determined using the methods described by Hill (23). In brief, eggs were weighed and subsequently hard-boiled.…”

“…In the model of chronic moderate hypoxia, the embryo is constantly exposed to low oxygen levels from d 6 to 19. However, the effects of albumen removal may occur primarily during the second half of incubation (23). This may be of importance considering that insults may affect developing organ systems like the cardiovascular system at critical time points.…”

Maternal effects of egg size on emuDromaius novaehollandiaeegg composition and hatchling phenotype

“…Studies examining the effects of water loss from eggs during incubation have shown that differences in wet embryo mass tend to be correlated with water content of the embryo and that eggs losing the most water tend to produce embryos with the lowest mass (Davis et al, 1988;Tullett and Burton, 1982). Removing albumen from chicken Gallus gallus eggs caused a reduction in hatchling size (Hill, 1993;Finkler et al, 1998) and resulted in hatchlings with a reduced yolkfree wet body mass (Finkler et al, 1998). Though hatchlings emerging from eggs from which albumen had been removed were smaller (i.e.…”