תפריט נגישות
ניגודיות עדינהניגודיות גבוהה
מונוכרום
הדגשת קישורים
חסימת אנימציה
פונט קריא
סגור
איפוס הגדרות נגישות
להורדת מודול נגישות חינם תפריט נגישותניגודיות עדינהניגודיות גבוההמונוכרוםהדגשת קישוריםחסימת אנימציהפונט קריאסגוראיפוס הגדרות נגישותלהורדת מודול נגישות חינםBirds are endotherms, able to maintain their body temperature within a narrow range. However, an alteration in body temperature as a result of exposure to extreme environmental conditions may lead to a cascade of irreversible thermoregulatory events that could be lethal for the bird. To sustain thermal tolerance and avoid the deleterious consequences of thermal stresses, three direct responses are elicited: the rapid thermal stress response; acclimation; and epigenetic temperature adaptation. Although domestic fowl respond to changes in the environment with the same mechanisms as other endotherms, their intensive production causes them to face serious difficulties in coping with extreme environmental changes. Recent decades have seen significant progress in the genetic selection, on the one hand, of fast-growing meat-type broiler chickens and turkeys and, on the other hand, of egg-producing laying hens. However, the significant improvements in body and muscle growth and in egg production have not necessarily been accompanied by equivalent growth of specific visceral organs, and the probable consequence is a reduced ability to cope with extreme changes in environmental temperatures. This chapter will focus on: a. body temperature development in chickens during embryogenesis; b. the control of body temperature during acute and chronic exposure to various environmental conditions; and c. the efficacy of controlling body temperature, as affected by thermal conditioning (epigenetic temperature adaptation) experience during perinatal period.
Birds are endotherms, able to maintain their body temperature within a narrow range. However, an alteration in body temperature as a result of exposure to extreme environmental conditions may lead to a cascade of irreversible thermoregulatory events that could be lethal for the bird. To sustain thermal tolerance and avoid the deleterious consequences of thermal stresses, three direct responses are elicited: the rapid thermal stress response; acclimation; and epigenetic temperature adaptation. Although domestic fowl respond to changes in the environment with the same mechanisms as other endotherms, their intensive production causes them to face serious difficulties in coping with extreme environmental changes. Recent decades have seen significant progress in the genetic selection, on the one hand, of fast-growing meat-type broiler chickens and turkeys and, on the other hand, of egg-producing laying hens. However, the significant improvements in body and muscle growth and in egg production have not necessarily been accompanied by equivalent growth of specific visceral organs, and the probable consequence is a reduced ability to cope with extreme changes in environmental temperatures. This chapter will focus on: a. body temperature development in chickens during embryogenesis; b. the control of body temperature during acute and chronic exposure to various environmental conditions; and c. the efficacy of controlling body temperature, as affected by thermal conditioning (epigenetic temperature adaptation) experience during perinatal period.
