Thermoregulation responses of broiler chickens to humidity at different ambient temperatures. II. Four weeks of age
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Two experiments were conducted to investigate the effect of RH (35, 60, and 85%) on thermoregulation of broiler chickens at high (35 ° C) and mild (30 ° C) temperatures at the age of 4 wk. The effects of humidity on rectal temperature (RT) and plumage temperature at back (PBAT) and skin temperature at breast (SBRT) were determined at 1, 4, 8, 16, and 24 h after exposure. The RT, PBAT, and SBRT were all significantly increased by high temperature (35 ° C). Humidity had a significant influence on RT at 35 ° C but not at 30 ° C. The peripheral temperatures (PBAT and SBRT) were significantly affected by humidity but responded differently at high (35 ° C) compared with mild temperature (30 ° C). In conclusion, high humidity above 60% impaired the heat transmission from body core to the periphery at 35 ° C but facilitated it at 30 ° C in 4-wk-old broiler chickens. The effect of humidity on nonevaporative heat loss was depended on air temperature, as nonevaporative heat loss was suppressed by high humidity (>60% RH) at high temperature but enhanced at the mild temperature. The effect of humidity on the relationship between peripheral and core temperature depends on ambient temperature as well as on the age of the broiler chicken. The disturbance of thermal balance could not be determined only by changes in RT or peripheral temperature at a single time point but could be determined by mean body temperature within a certain time frame.Keywords:
Plumage
Skin Temperature
The ambient temperature decrease from 32-35 degrees C to 15-17 degrees C was shown to increase the temperature gradient between the skin surface and its deep layers (2-3 mm from the surface) from 0.13 +/- 0.1 degrees C to 1.29 +/- 0.13 degrees C in humans. Considering the localisation of thermoreceptors in different skin layers, such a considerable gradient can be measured by the thermoregulation system and serve for determination of direction and intensity of heat flow across the skin.
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Skin Temperature
Temperature Gradient
Heat flow
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Human body can operate physiological thermoregulation system when it is exposed to cold or hot environment. Whether it can do the same work when a local part of body is stimulated by different temperatures? The objective of this paper is to prove it. Twelve subjects are recruited to participate in this experiment. After stabilizing in a comfort environment, their palms are stimulated by a pouch of 39, 36, 33, 30, and 27?C. Subject?s skin temperature, heart rate, heat flux of skin, and thermal sensation are recorded. The results indicate that when local part is suffering from harsh temperature, the whole body is doing physiological thermoregulation. Besides, when the local part is stimulated by high temperature and its thermal sensation is warm, the thermal sensation of whole body can be neutral. What is more, human body is more sensitive to cool stimulation than to warm one. The conclusions are significant to reveal and make full use of physiological thermoregulation.
Thermal sensation
Skin Temperature
Thermoreceptor
Sensation
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Summary Clark, A. 1974. Plumage changes in the male Maccoa Duck. Ostrich 45: 251–254. Maccoa Duck Oxyura mi ccoo counts made at various waters in the Transvaal and Orange Free State, South Africa, in which the numbers are separated according to plumage, are presented and discussed in the light of the work done by Siegfried (1968, 1970) on this species. Males invariably outnumber females and the indications are that Transvaal birds move out of the area during winter when most males are in non-breeding plumage. There is little difference in the pattern of plumage changes between Transvaal and Cape birds.
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Plumage aberrations are not uncommon in birds, but there is some confusion in the literature, especially in relation to albinos. Plumage aberrations in birds are better known in Europe and North America than in Australia, where, however, several reports have been published recently. In this paper, we review the various types and causes of plumage aberrations, focussing on those that arise from abnormal incorporation of pigments in growing feathers and thus result in aberrant coloration of the plumage.
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Abstract First-year, but not adult, Indigo Buntings (Passerina cyanea) have a previously unknown supplemental plumage. The presupplemental molt includes all of the rectrices, the outermost but not the innermost primaries, and, typically, the three innermost secondaries and all body feathers. In this molt, young females exchange one adult-femalelike plumage for another, while young males exchange an adult-femalelike plumage for one that matches that of adult males in winter. Thus, in their first year Indigo Buntings wear: first, the juvenile plumage, the body feathers of which begin replacement before the tail is fully grown; second, the first basic plumage, which in both sexes is entirely femalelike in coloration and includes the juvenile remiges and rectrices; third, the supplemental plumage, assumed either prior to fall migration (<10% of individuals) or on the wintering ground (>90% of individuals) and in which obvious sexual dichromatism is first achieved; and fourth, the first alternate plumage, acquired in a prolonged and often incomplete prealternate molt of body feathers that occurs during February, March, and April on the wintering ground and during the spring in the United States. Because almost all of the femalelike first basic plumage of young males is lost in the presupplemental molt, this plumage almost certainly is an adaptation to conditions encountered either in the fall or early in the first winter. Furthermore, the ensuing supplemental plumage cannot be compromised by color requirements of the first breeding season because of the intervening prealternate molt; thus, the adult-malelike plumage produced by the presupplemental molt likely evolved to meet a change in signaling requirements that occurs in early winter. The signaling function of this plumage is unknown. Because this supplemental plumage of young males resembles the winter plumage of adult males and because all feathers grown by young males in their first prealternate molt resemble those of the adult male breeding plumage, the female mimicry hypothesis of Rohwer et al. (1980) is untenable for the subadult breeding plumage of yearling male Indigo Buntings.
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Rectal temperature
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Mean radiant temperature
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Males of many species can breed in distinct alternative phenotypes; for example, in many birds some males breed in dull plumage while others breed in bright plumage. Because females often appear to prefer brighter males, it is unclear why some males breed in dull plumage. Males in dull plumage might enjoy enhanced within-pair reproductive success if they can gain access to better breeding territories, or they might have relatively high extrapair reproductive success if they are better able to intrude on the territories of other males. To test these possibilities, we examined the reproductive consequences of plumage color in the red-backed fairy-wren (Malurus melanocephalus), a species in which males can breed in either bright plumage or dull plumage or serve as nonbreeding auxiliaries. Male plumage color was distributed bimodally and was loosely associated with age, such that some males molted into bright plumage a year or more earlier than others. Both male phenotypes were cuckolded at similar rates, but bright males sired significantly more extrapair young than did dull males, and this effect was independent of age. Thus, 1-year-old males who bred in dull plumage had low seasonal reproductive success compared with same-aged males who bred in bright plumage. These results suggest that males may not reap any fitness benefits by breeding in dull coloration, compared with breeding in bright plumage, but rather may be constrained to breed in suboptimal plumage by the timing of plumage acquisition.
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Abstract This review analyses whether skin temperature represents ambient temperature and serves as a feedforward signal for the thermoregulation system, or whether it is one of the body's temperatures and provides feedback. The body is covered mostly by hairy (non‐glabrous) skin, which is typically insulated from the environment (with clothes in humans and with fur in non‐human mammals). Thermal signals from hairy skin represent a temperature of the insulated superficial layer of the body and provide feedback to the thermoregulation system. It is explained that this feedback is auxiliary, both negative and positive, and that it reduces the system's response time and load error. Non‐hairy (glabrous) skin covers specialized heat‐exchange organs (e.g. the hand), which are also used to explore the environment. In thermoregulation, these organs are primarily effectors. Their main thermosensory‐related role is to assess local temperatures of objects explored; these local temperatures are feedforward signals for various behaviours. Non‐hairy skin also contributes to the feedback for thermoregulation, but this contribution is limited. Autonomic (physiological) thermoregulation does not use feedforward signals. Thermoregulatory behaviours use both feedback and feedforward signals. Implications of these principles to thermopharmacology, a new approach to achieving biological effects by blocking temperature signals with drugs, are discussed.
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Thermoreceptor
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