Avian and Poultry Biology Reviews 13 (3), 2002
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Proceedings of the International Congress on Bird Reproduction, Tours, September 1999
Impact of Egg Storage on Embryo Development
M.R. Bakst and V. Akuffo
Germplasm and Gamete Physiology Laboratory, Agricultural Research Service, USA Department of Agriculture, Beltsville Agricultural Research Center, Beltsville, Maryland, USA
ABSTRACT
1. New information is introduced and other information reviewed regarding the impact of egg storage on the integrity of the avian embryo.
2. Morphologically, the blastoderm from an egg which has been stored more than 10 days is often asymmetrical and may have an attenuated appearance.
3. Fresh egg breakouts coupled with the perivitelline layer sperm-hole determination procedure provide detailed information on the male's contribution to overall fertility.
4. The biological basis for embryonic mortality in eggs stored for longer than 10 days remains the subject of speculation.
Maternal and Environmental Influence on Fertility and Embryonic Survival
Vern L. Christensen and Brian D. Fairchild
Department of Poultry Science, North Carolina State University, Raleigh, NC 27695-7608, USA
Reproductive Biology and Conservation of the Endangered Kakapo (Strigops habroptilus) in New Zealand
J.F. Cockrem
Conservation Endocrinology Research Group, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand
ABSTRACT
The kakapo (Strigops habroptilus) is a large, flightless, nocturnal parrot found only in New Zealand. There are currently 34 male and 22 female kakapo alive on several islands off the coast of New Zealand; these totals will increase following a successful breeding season in1999. Kakapo are lek breeders and are the only parrot to show lek behaviour. The male birds prepare display areas called track and bowl systems during early summer. Male kakapo then spend many nights producing low-frequency calls known as booms to attract females for mating. Breeding occurs naturally only once every two to five years, and the intensity and duration of the male booming displays and the proportion of females that lay eggs can vary greatly between years. In some years females visit the lek breeding grounds to mate then lay up to three eggs and incubate the eggs for about 30 days. After the eggs hatch the female feeds the chicks herself for three months, and the chicks continue to remain with the female for some months after fledging. Efforts to save the kakapo began more than 100 years ago, and the kakapo is now the subject of the most intensive single species conservation programme for any bird in New Zealand and perhaps the world. All kakapo have been moved from their original habitats to islands where the adults are safe from mammalian predators. Every kakapo is fitted with a radio transmitter so that it can be located using radio telemetry, and the birds are all caught and checked at approximately yearly intervals. Since 1989 the management of the kakapo has been undertaken according to a recovery plan with clear goals and significant financial support. The recovery plan was revised in 1995, and very intensive management of kakapo breeding was first implemented in 1997 when kakapo bred on Codfish Island. The conservation effort now maximises the chances that every fertile kakapo egg will lead to a successfully fledged kakapo chick. The intensive conservation work has resulted in a marked increase in the breeding success of kakapo over the last three years, and the prospects for the survival of the kakapo are now better than at any time in the last 100 years.
Endocrine Physiology of Reproduction in the Female Chicken: Old Wine in New Bottles
E. Decuypere*, V. Bruggeman, O. Onagbesan and M. Sa®
University of Leuven, Faculty of Agriculture, Kardinaal Mercierlaan 92, 3001 Heverlee, Belgium
ABSTRACT
The reproductive cycle of the hen, characterised by well-ordered ovulation and oviposition cycles and by a strict hierarchical growth of follicles, is a suitable model for the study of folliculogenesis. Under the impact of recent developments inmammalian reproductive endocrinology, emphasis has been put on the role of growth factors in folliculogenesis and steroidogenesis during the last decade.The state of the art will be reviewed here. Moreover, new findings concerning different pathways of steroidogenesis as well as regulation at the hypothalamic/pituitary level are considered. The overall scheme of endocrine physiology of reproduction in the hen may however be subject to variation due to environmental or selection effects. The extreme divergent selection in poultry, for growth on the one hand and for reproductive performance on the other hand, makes the broiler breeder an excellent model for studying the interaction between feed and reproduction. The endocrinological background of this interaction will be reviewed as far as our knowledge reaches in this field. Undoubtedly, much will remain speculative and will await further elucidation. Similarly, strain differences in reproductive performance have been demonstrated between female broiler breeder chickens which were divergently selected for different growth or efficiency characteristics. Only rather recently were the repercussions of this divergent selection for growth characteristics on reproductive endocrinology considered, and the importance of growth factors as a component in the control mechanisms of follicular development in broiler breeder hens was revealed. Since these factors may have been inadvertently altered by selection for growth, and because of their pleiotropic activity (also in reproductive endocrinology) they may lie at the base of correlated responses in reproduction that occur with continued selection for growth and food efficiency in broiler breeds.
The Avian Embryo, a Model for the Role of Cellular Interactions in Development; the Example of Neural Crest-Derived Pigment Cells
Elisabeth Dupin* and Nicole M. Le Douarin
Institut d'Embryologie du CNRS et du ColleÁge de France, 49 bis Avenue Belle Gabrielle, 94736 Nogent-sur-Marne cedex, France.
ABSTRACT
We have been using neural crest development as a model for understanding the molecular basis of cell migration and lineage diversification during embryogenesis, and to explore the roles of inherited information and cell-to-cell interactions in this process. Techniques allowing the migratory crest cells to be followed during the entire developmental period have given a significant impetus to research carried out in the avian embryo. One of the most striking results to arise from this experimental approach is probably the demonstration of the considerable importance of the developmental relationships existing between the neural crest cells and the embryonic tissues in which they migrate and differentiate. Concerning the nature of these interactions, much progress has been recently provided by the combination of molecular biology, experimental embryology and in vitro cell culture studies. As an example of the role of extrinsic cues in cellular specification, we review here several lines of investigations which have led to the identification of two ligand-receptors i.e., Steel=c-kit and endothelin3=endothelin receptors as crucial signals for regulating the early developmental stages of neural crest-derived pigment cells.
Key words: neural crest, quail, chick, embryo, pigment cell, Stem Cell Factor, endothelin.
Manipulating the Avian Genome
Robert J. Etches
Origen Therapeutics Inc, 1450 Rollins Road, Burlingame, CA 94010, USA
Present and Future of the European Legislation Concerning
Poultry Breeding
J.M. Faure
Station de Recherches Avicoles, INRA Centre de Tours, 37380 Nouzilly, France
Managing the Incubation Environment in Commercial Hatcheries to Meet the Requirements of the Embryo
N. A. French
British United Turkeys Ltd., Hockenhull Hall, Tarvin, Chester CH3 8LE, UK
ABSTRACT
The opportunities for improving hatching performance in commercial hatcheries by modifying the incubation conditions to meet the requirements of individual batches of eggs are discussed. A brief review of the available evidence that such a strategy can be used to improve results highlighted the paucity of data available. However, there is evidence that manipulating incubator humidity to match shell conductance can improve performance although this has yet to be widely used in the chicken and turkey industries because of the logistical problems of weighing large numbers of eggs. The technique is more widely used in ostrich hatcheries where smaller numbers of eggs are incubated and the high value of the chicks can justify the expense. In large hatcheries a more simplistic approach may be required, batching eggs by age of the breeder flock. Further technological advances in incubator design may be required before it becomes practical to adjust incubation conditions to meet the requirements of each batch of eggs.
Breeding Birds as a Commodity
P.J. Sharp
Division of Integrative Biology, Roslin Institute (Edinburgh), Midlothian EH25 9PS, Scotland, UK
ABSTRACT
1. Understanding of the physiology, molecular genetics and developmental biology of avian reproduction is essential for advances in the efficient breeding of birds for commercial gain.
2. Reproduction is controlled at the central nervous level by gonadotrophin releasing hormone-I (GnRH-I) and prolactin.
3. The activity of GnRH-I neurones can be manipulated photoperiodically, through understanding of the physiology of photorefractoriness, to prevent premature onset, or to enhance persistency of reproductive function.
4. Active immunisation against prolactin releasing hormone, vasoactive intestinal peptide, delays the development of photorefractoriness and enhances persistency of reproductive function.
5. The creation of molecular maps of the chicken genome makes it possible to identify quantitative trait loci for reproductive traits, which will be used to identify DNA sequences for marker assisted selection. Polymorphisms in alleles of physiological candidate genes for reproductive efficiency might also be useful for marker assisted selection.
6. New understanding of the developmental biology of the chicken opens up the prospect of developing methods to control sex ratios, and to make transgenic birds. Transgenic technology will be used to introduce genes for disease resistance, and to make proteins for biomedical applications.
7. Nuclear transfer technology might be applied to save endangered species from extinction.
Body Weight, Obesity, and Reproduction in Meat-Type Chickens
Paul B. Siegel
Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, VA 24061-0306, USA
ABSTRACT
This paper provides an overview of relationships between body weight, obesity, and reproduction in meat-type chickens. A historical perspective describes the current situation and the conundrums that preclude solutions without human intervention.
Endangered Avian Species Captive Propagation: An Overview of Functions and Techniques
Michel Saint Jalme
Laboratoire de Conservation des EspeÁces Animales, MuseÂum National d'Histoire Naturelle, Parc Zoologique de CleÁres, 76690 CleÁres, France
ABSTRACT
Birds species, like plants and other animals are facing an unprecedented decline. About11% of bird species are threatened with extinction. Captive breeding as a conservation tool can be used as a substitute for wild populations in research and education, to provide demographic and genetic reservoirs for reinforcing or founding wild populations, and as a last resort for species that have no immediate opportunity for survival in nature. Candidates for captive propagation are zoos, private breeders, state agencies, conservation foundations and research centres within or outside of universities. The problems in managing endangered species have motivated conservation biologists to conduct research in many disciplines such as behaviour, physiology, endocrinology, genetics, husbandry, nutrition and veterinary medicine. In addition, an increasing number of techniques for increasing reproductive success, improving genetic management and enhancing reintroduction success have been employed. Breeding success has been improved by improved knowledge of factors that trigger reproduction and stimulate replacement clutches, as well as by improvements in artificial incubation and artificial insemination. Assuming that the correct social behaviour group is constituted and the animals start to breed, genetic problems are likely to occur in species with only a few remaining individuals. Once numbers are low, genetic variability is reduced and this brings about diminished ability to respond to environmental change. Recent advances in molecular genetics have enabled studies in taxonomy to be carried out in order to determine species, subspecies and population boundaries. They have also contributed to the theoretical development of small population genetics and demographics aimed at improving ex-situ population management. Captive birds are often hand-reared, but since many behaviours are acquired from the parents, or by experience in the wild, artificial rearing by hand could affect the survival potential of released animals. In order to prevent imprinting on humans and other detrimental effects of hand-rearing techniques, parents, foster-parents, puppets or costumes have been used to rear chicks. Finally, recent developments in research on training programmes to find food, to fly, to avoid specific dangers, or to recognise and to avoid predators, appear to have substantially increased release success in reintroduction programmes.
Avian Sperm : Egg Interaction : Mechanisms and Practical Application for Analysis of Fertility
Graham J Wishart
Avian Reproduction Group, University of Abertay Dundee, Bell Street, Dundee DD1 1HG, Scotland, UK
Prolactin and its Receptor in Galliformes
D. Zadworny1, N. Kansaku1, G. BeÂdeÂcarrats1, D. GueÂmeneÂ2 and U. Kuhnlein1
1McGill University, Dept. Animal Science, Montreal, Canada
2INRA-SRA, Nouzilly, France