Selection for high body weight and correlated responses in reproduction in poultry
2000
Hort, J. | Knizetova, H. | Hyankova, L. (Vyzkumny Ustav Zivocisne Vyroby, Prague-Uhrineves (Czech Republic)
The paper presents a review of current knowledge in the area of causes of reduced egg production in poultry of broiler type resulting from long-term selection for high body weight, i.e. increased occurrence of defective eggs and follicular ovulation into the abdominal cavity at the beginning of laying (so called EODES - erratic oviposition and defective egg syndrome). A direct cause is high ovarian activity, i.e. an increased number of rapidly growing follicles and occurrence of follicles at the same developmental stage. Following their bursting, two or more yolk eggs or eggs with imperfect envelopes are laid. The ovulation into the abdominal cavity is likely to be caused by asynchrony between the oviduct and ovary as a result of lower hormonal control. The primary EODES cause is excessive production of depot fats accompanying long-term selection for higher body weight at early age. It is to suppose that the capacity of storing an increased amount of lipids during reproduction not only in adipose depots but also in growing follicles is an adaptation phenomenon allowing the organism to establish a better physiological equilibrium.
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