Book contents
- Frontmatter
- Contents
- Preface
- Contributors
- 1 Maternal diet, maternal proteins and egg quality
- 2 Comparative composition and utilisation of yolk lipid by embryonic birds and reptiles
- 3 Oviductal proteins and their influence on embryonic development in birds and reptiles
- 4 Fluxes during embryogenesis
- 5 Eggshell structure and formation in eggs of oviparous reptiles
- 6 Shell structure and formation in avian eggs
- 7 Physical characteristics of reptilian eggs and a comparison with avian eggs
- 8 Egg-shape in birds
- 9 The thermal energetics of incubated bird eggs
- 10 Physiological effects of incubation temperature on embryonic development in reptiles and birds
- 11 Cold torpor, diapause, delayed hatching and aestivation in reptiles and birds
- 12 Physical factors affecting the water exchange of buried reptile eggs
- 13 Physiological and ecological importance of water to embryos of oviparous reptiles
- 14 Roles of water in avian eggs
- 15 Water economy and solute regulation of reptilian and avian embryos
- 16 The avian eggshell as a mediating barrier: respiratory gas fluxes and pressures during development
- 17 Gas exchange across reptilian eggshells
- 18 Metabolism and energetics of reptilian and avian embryos
- 19 Reasons for the dichotomy in egg turning in birds and reptiles
- 20 A comparison of reptilian eggs with those of megapode birds
- 21 Why birds lay eggs
- 22 Influences of incubation requirements on the evolution of viviparity
- 23 Overview of early stages of avian and reptilian development
- 24 Ions and ion regulating mechanisms in the developing fowl embryo
- 25 Electrochemical processes during embryonic development
- 26 Methods for shell-less and semi-shell-less culture of avian and reptilian embryos
- 27 Experimental studies on cultured, shell-less fowl embryos: calcium transport, skeletal development, and cardio-vascular functions
- Index
19 - Reasons for the dichotomy in egg turning in birds and reptiles
Published online by Cambridge University Press: 16 November 2009
- Frontmatter
- Contents
- Preface
- Contributors
- 1 Maternal diet, maternal proteins and egg quality
- 2 Comparative composition and utilisation of yolk lipid by embryonic birds and reptiles
- 3 Oviductal proteins and their influence on embryonic development in birds and reptiles
- 4 Fluxes during embryogenesis
- 5 Eggshell structure and formation in eggs of oviparous reptiles
- 6 Shell structure and formation in avian eggs
- 7 Physical characteristics of reptilian eggs and a comparison with avian eggs
- 8 Egg-shape in birds
- 9 The thermal energetics of incubated bird eggs
- 10 Physiological effects of incubation temperature on embryonic development in reptiles and birds
- 11 Cold torpor, diapause, delayed hatching and aestivation in reptiles and birds
- 12 Physical factors affecting the water exchange of buried reptile eggs
- 13 Physiological and ecological importance of water to embryos of oviparous reptiles
- 14 Roles of water in avian eggs
- 15 Water economy and solute regulation of reptilian and avian embryos
- 16 The avian eggshell as a mediating barrier: respiratory gas fluxes and pressures during development
- 17 Gas exchange across reptilian eggshells
- 18 Metabolism and energetics of reptilian and avian embryos
- 19 Reasons for the dichotomy in egg turning in birds and reptiles
- 20 A comparison of reptilian eggs with those of megapode birds
- 21 Why birds lay eggs
- 22 Influences of incubation requirements on the evolution of viviparity
- 23 Overview of early stages of avian and reptilian development
- 24 Ions and ion regulating mechanisms in the developing fowl embryo
- 25 Electrochemical processes during embryonic development
- 26 Methods for shell-less and semi-shell-less culture of avian and reptilian embryos
- 27 Experimental studies on cultured, shell-less fowl embryos: calcium transport, skeletal development, and cardio-vascular functions
- Index
Summary
Introduction
The need for egg turning during incubation is one of the most dramatic differences between the incubation requirements of birds and reptiles. Almost all avian eggs need to be turned throughout much of incubation (Poulsen, 1953; Drent, 1975) and although there are many studies of the egg turning behaviour in incubating birds (Drent, 1975), these are not discussed here. By stark contrast, reptilian embryos are usually killed by turning during incubation (Ferguson, 1985). Egg turning in birds is thought to prevent deleterious adhesions between the embryo and the shell membranes (New, 1957) but in reptiles such adhession is normal (Ewert, 1985; Ferguson, 1985). This simplistic view of the phenomenon of egg turning is widely accepted yet if the requirement and effects of turning are examined further the situation is not so clear cut. In this chapter, the effects of egg turning on avian and reptilian development are described and some suggestions are made for the physiological basis of turning in birds. The possible evolutionary relationships between tgg turning behaviour in birds and its absence in reptiles, are discussed.
The effects of egg turning on hatchability in birds and reptiles
Avian eggs
The majority of studies of egg turning on avian embryos are concerned with effects on hatchability in poultry (Landauer, 1967; Lundy, 1969). Eycleshymer (1907) first showed that turning rate affected hatchability, although by modern standards the results were poor; 58% of fertile eggs of the fowl (Gallus gallus) hatched after being turned five times a day compared with 45% of eggs turned twice a day and only 15% hatchability of unturned eggs.
- Type
- Chapter
- Information
- Egg IncubationIts Effects on Embryonic Development in Birds and Reptiles, pp. 307 - 324Publisher: Cambridge University PressPrint publication year: 1991
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