Physiological acclimatization of fowls to a hot humid environment

Abstract

1. The resting heart rate of cocks and hens was measured in varying degrees of heat stress, and during acclimatization to heat.2. When the rectal temperature was below 110°F. (43·3° C), the heart rate varied inversely with the severity of the climate up to an air temperature around 99° F. (37·2° C).3. At air temperatures of 99° F. (37·2° C.) and above the heart rate was nearly constant over a wide range of rectal temperatures below 110° F. (43·3° C). It averaged about 50 beats/min. less than in an equable climate.4. Above 110° F. (43·3° C.) there was an increase of about 30 beats/min./° F. (17 beats/min./° C.) rise in rectal temperature. The rate equalled that found in an equable climate, when the rectal temperature reached 111–112° F. (43·9–44·4° C). Over this zone of body temperature the fowls were often agitated.5. In severe heat stress there was a slight fall in the heart rate on acclimatization, but this was small compared with the effect of climate.6. In severe heat stress the heart rate during the day was slightly higher than that at night.7. The relation of these findings to the mechanism of temperature regulation is discussed.

Habituation by the immature fowl in response to repeated injections of corticotrophin

“…Thus the continuous exposure of turkeys to either hot or cold environments leads to a marked increase in the concentration of plasma corticosterone and then over a period of weeks, a progressive decrease until the initial concentration is achieved (El-Halawani et al, 1973). Adaptation also occurs when the stressor is discontinuous: the regular exposure of the adult hen to a hot, humid environment results in hyperthermia developing rapidly but as the number of exposures increases so the degree of hyperthermia declines (Hutchinson and Sykes, 1953). Not all physiological mechanisms that are affected by a stressor adapt at the same rate.…”

The period of adaptation of the fasting metabolic rate of the common fowl to an increase in environmental temperature from 22°C to 28°C

“…Studies of the effect of changes in environmental temperature on body temperature indicate a rapid initial adjustment (Hutchinson and Sykes, 1953), but Hillerman and Wilson (1955) suggest a period of 3 to 5 d for complete adjustment and Whittow et al (1966) observed significantly lower rectal temperatures in birds acclimatised to o° G when compared to birds acclimatised to 31° G. Work carried out with rabbits by Lee (1942) and with rats by Gelineo (1934) showed that alteration in heat production resulting from transfer from lower to higher temperatures required a period of adaptation and that this period varied in different species was shown by Gelineo (1964).…”

The stoichiometric approach in determining total evaporative water loss and the relationship between evaporative and non-evaporative heat loss in two resting bird species: passerine and non-passerine

“…First guidance for the direct weighing method for determines evaporative water loss was obtained from the studies of Hutchinson and Sykes [20] and Hutchinson [21,22] on evaporation in the domestic fowl. Lasiewski et al [15] using new techniques and equipments invented new methods different from the original method.…”