Stimulation of Adrenals During the Critical Periods of Development and Production in Fowls

SummaryThe functional reserves of the organism realized through influence on the adaptation systems during the critical periods of development could be of considerable importance in improving the adaptability of poultry to intensive conditions. The efficiency of such an approach is considered taking the investigations of the hypothalamo-hypophysial-adrenal system (HHAS) in hens as an example. Seven periods are distinguished in the development of the HHAS, including two critical ones: from 13th up to 19th day of embryogenesis and the 3rd week of the postembryonic development. These two periods are associated with the regulatory reorganization of interactions between the components of the system. The exposure of the organism to repeated cooling during the critical periods results in a steady rise of HHAS activity and, simultaneously, in higher viability of embryos and chicks. A new regime for cooling eggs of broiler crosses during incubation has been outlined based on the result of low temperature stress “imprinting”, which stimulates broiler development.