title: Thermogenic and vocalization responses to cold in the chicken hatchling during normoxia and hypoxia.
abstract: We investigated the vocalization and the thermogenic responses to cold during hypoxia in chicken hatchlings during the first postnatal day. Calls were quantified in number and sound characteristics (amplitude and frequency); the change in oxygen (O2) consumption, measured by an open-flow methodology, represented thermogenesis. The cold challenge consisted of a decrease in ambient temperature (Ta) from ~39 to 28 °C, in steps of 2 °C, or an acute exposure to ~28 °C, either in normoxia or hypoxia (10% O2). Hypoxia lowered thermogenesis and the critical Ta, suggesting a decrease in the set point for thermoregulation. The vocalization response to cold was rapid; did not progress with the duration or intensity of the cold stimulus; was similar in very young (<8 hr old) and older (12-24 hr) hatchlings despite their differences in thermogenic capacity; and was essentially unaffected by hypoxia. We conclude that the hatchling's vocalization in the cold follows a stereotyped pattern not related to the thermogenic regulation of body temperature. The dissociation between vocalization and thermogenesis might carry some advantage in conditions of cold and hypoxia.
authors.affiliation: Department of Physiology, McGill University, 3655 Sir William Osler Promenade, Montreal, Quebec, Canada.
authors.forename: Khalid
authors.initials: K
authors.lastname: Al Awam
authors.forename: Florin
authors.initials: F
authors.lastname: Catana
authors.forename: Jacopo P
authors.initials: JP
authors.lastname: Mortola
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001833:Body Temperature Regulation / Q000502:physiology; D002642:Chick Embryo; D002645:Chickens; D003080:Cold Temperature / Q000009:adverse effects*; D000860:Hypoxia / Q000503:physiopathology*; D022722:Thermogenesis / Q000502:physiology*; D014828:Vocalization, Animal / Q000502:physiology*