The role of water for heat dissipation by a Jersey cow and a Corriedale ewe.

Knapp, B.; Robinson, KW

doi:10.1071/ar9540568

Cited by 34 publications

(16 citation statements)

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“…Com respeito às raças de origem européia, têm sido observadas taxas de sudação bastante variáveis: 35 a 265 g.m -2 h -1 em Suffolk (Nogueira et al, 1987), 90,6±5,5 g.m -2 h -1 em Ideal (Silva et al, 1990), 145,2±6,1 a 270,7±45,1 g.m -2 h -1 em Rambouillet (Rai et al 1979). Entretanto, nos ovinos lanados a epiderme é muito permeável à água e ao vapor, sendo quantitativamente muito importante a perspiração insensível, de modo que as taxas de evaporação cutânea geralmente correspondem a um volume de água maior que o secretado pelas glândulas sudoríparas isoladamente.…”

Section: Air Temperatureunclassified

“…De qualquer forma, os resultados obtidos no presente trabalho destacam a importância da evaporação cutânea para ovinos em ambientes quentes, confirmando as observações de Rieck et al (1950), Knapp & Robinson (1954) e, em parte, Hofmeyr et al (1969). A evaporação respiratória é neste caso um mecanismo funcionalmente adequado para respostas intensas durante períodos mais curtos.…”

Section: Air Temperatureunclassified

“…Alguns autores mais antigos (Rieck 1950;Knapp & Robinson, 1954;Brook & Short, 1960 a,b) afirmam que, sob altas temperaturas (30 a 40 o C), a evaporação cutânea chega a ser até três vezes mais intensa que a respiratória. Outros supõem que a evaporação respiratória seja mais importante (Alexander & Williams, 1962;Hofmeyr et al, 1969;Hales, 1974).…”

Section: Introductionunclassified

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Evaporação cutânea e respiratória em ovinos sob altas temperaturas ambientes

Silva

Starling

2003

R. Bras. Zootec.

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RESUMO -Dez ovinos da raça Corriedale foram avaliados para as taxas de evaporação respiratória ( E R ) e cutânea ( E C ). Cada animal foi observado até 10 vezes, sob diferentes condições de temperatura (21,1 a 41,9 o C) e pressão parcial de vapor do ar (1,53 a 3,01 kPa), usando um método gravimétrico para determinar a perda de água. As médias totais foram 0,7599±0,0094 g.h -1 .kg -1 para E R e 1,3029±0,0591 g.h -1 .kg -1 para E C . A evaporação cutânea foi considerada como um fator importante de termólise para ovinos em ambientes quentes. São discutidos os efeitos do sexo, da espessura do velo e da temperatura e umidade do ar.Palavras-chave: evaporação respiratória, evaporação cutânea, ovinos, termorregulação Cutaneous and Respiratory Evaporation Rates of Sheep in Hot EnvironmentsABSTRACT -Ten adult Corriedale sheep were evaluated for respiratory (E R ) and cutaneous (E C ) evaporation rates. The animals were observed about 10 times each by recording changes in their live weigth with high-sensitiviy strain gauges, under different conditions of air temperature (21.1 to 41.9 o C) and partial vapour pressure (1.53 to 3.01 kPa). Average evaporation rates were 0.7599±0.0094 g.h -1 .kg -1 for E R and 1.3029±0.0591 g.h -1 .kg -1 for E C . Cutaneous evaporation was considered as an important heat loss mechanism for sheep in hot environments. There were discussed the effects of sex, fleece thickness, air temperature, and air humidity. IntroduçãoNos ambientes tropicais, a temperatura do ar tende a ser próxima da ou maior que a corporal, o que torna ineficazes os mecanismos de transferência térmica por condução e convecção. Em adição, a carga térmica radiante é freqüentemente muito elevada, de modo que a superfície corporal dos animais tende a apresentar temperaturas bastante altas, dependendo da natureza dessa superfície. No caso de ovinos expostos ao sol, têm sido observadas temperaturas de até 90 o C. Em conseqüência, a evaporação torna-se o mecanismo de termólise mais eficaz nesses ambientes, por não depender do diferencial de temperatura entre o organismo e a atmosfera. De fato, as perdas térmicas por evaporação em ovinos sob estresse de calor podem atingir 90 W.m -2 (Monteith & Unsworth 1990).As evidências encontradas na literatura acerca da importância relativa da evaporação respiratória e da cutânea nos ovinos são conflitantes. Alguns autores mais antigos (Rieck 1950;Knapp & Robinson, 1954; Brook & Short, 1960 a,b) afirmam que, sob altas temperaturas (30 a 40 o C), a evaporação cutânea chega a ser até três vezes mais intensa que a respiratória. Outros supõem que a evaporação respiratória seja mais importante (Alexander & Williams, 1962;Hofmeyr et al., 1969;Hales, 1974).É sabido que os ovinos possuem glândulas sudoríparas do tipo apócrino, associadas aos folículos pilosos primários de lã (Bligh, 1961; Robertshaw, 1966) e alguns autores, como Brook & Short (1960a,b) e Alexander & Williams (1962), determinaram altas taxas de sudação em animais tosquiados mantidos a 40 o C. Silva et al. (1990) observaram animais ...

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Section: Air Temperatureunclassified

Section: Introductionunclassified

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Evaporação cutânea e respiratória em ovinos sob altas temperaturas ambientes

Silva

Starling

2003

R. Bras. Zootec.

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“…One of the earliest papers in 1946 measured water loss through rat skin using an open circuit apparatus 24 . In the 1950s and 1960s, several other investigators measured TEWL on different species such as cattle, sheep, birds, reptiles and small vertebrates 17,25–32 . The first reports of TEWL readings in dogs, published in 1972 and 1973, 33–35 used a cylindrical, nonventilated closed chamber system, although the method did involve internal circulation of the air.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of a hand-held evaporimeter (VapoMeter^®) for the measurement of transepidermal water loss in healthy dogs

Lau-Gillard

Hill

Chesney

et al. 2010

Veterinary Dermatology

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In humans, transepidermal water loss (TEWL) is measured by noninvasive techniques using either open- or closed-chamber instruments. The aim of this study was to investigate the use of a hand-held, closed chamber device (Vapometer) to measure TEWL in canine skin. Repeated measurements obtained from multiple body sites in one short and one long-coated dog had mean coefficients of variation ranging from 20% to 33%. In the short-coated dog, TEWL ranged from a mean of 5.8 g/m(2)/h on the ventral abdomen to 24.4 g/m(2)/h between the shoulders. In the long-coated dog, mean TEWL values ranged from 26.3 g/m(2)/h on the right chest wall to 51.3 g/m(2)/h in the right axilla. TEWL readings differed significantly at different body sites and showed significant day-to-day variation. In a comparison of a further 20 dogs, TEWL readings obtained from the lateral thorax differed significantly between dogs. Furthermore, in seven of the twenty dogs, readings differed significantly when one side was compared with the other. The Vapometer was able to measure TEWL in canine skin and yielded values similar to those previously reported in the literature using other devices. However, for use in clinical studies, the significant site to site, day-to-day and dog to dog variations would make changes induced by disease, drugs, dietary supplements or topical agents very difficult to reliably detect.

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“…Rapid, shallow respiratory movements during heat exposure have been described in sheep (Lee & Robinson, 1941; Lee, 1950; Knapp & Robinson 1954), cattle (Kibler & Brody, 1950;Findlay, 1957), dogs (Richet, 1887; Anrep & Hammouda, 1932) and other species. During intensive heat stress, rapid, shallow breathing becomes slower and deeper (Anrep & Hammouda, 1932;Hemingway, 1938;Findlay, 1957; Bianca, 1962;Alexander & Williams, 1962).…”

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confidence: 99%

Respiratory function during thermal tachypnoea in sheep

Hales¹,

Webster²

1967

The Journal of Physiology

116

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SUMMARY1. Four Merino wethers were exposed to dry bulb temperatures ranging from approximately 20 to 60°C, and the concurrent changes in respiratory frequency, tidal volume, respiratory minute volume, alveolar ventilation, dead space ventilation, carbon dioxide output, rectal temperature, and arterial and mixed venous blood, CO2 content, CO2 partial pressure and pH were established.2. The respiratory response to heat exposure showed two phases. Respiratory minute volume was initially increased by a rise in the respiratory frequency, while tidal volume decreased. After more prolonged exposure there was a second phase in which respiratory minute volume was further increased by an increase in the tidal volume; respiratory frequency was now slower than in the first phase but was still well above control values.3. The increase in respiratory minute volume during the first phase of the response was restricted almost entirely to the respiratory dead space; changes in blood CO2 and pH were slight. In the second phase, respiratory minute volume showed a much greater increase, and a change of alveolar ventilation to about 5 times the control level resulted in severe respiratory alkalosis.4. Contrary to findings in cattle, the slower, deeper form of respiration could be elicited even with rectal temperature in the normal range. This change in respiration appears to be the result of either peripheral thermoreceptor function or mechanical demands of the respiratory system. The neglect of control of acid-base balance during the second phase indicates the existence of a dominant thermal stimulus or modification of respiratory control mechanisms.

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The role of water for heat dissipation by a Jersey cow and a Corriedale ewe.

Cited by 34 publications

References 1 publication

Evaporação cutânea e respiratória em ovinos sob altas temperaturas ambientes

Evaporação cutânea e respiratória em ovinos sob altas temperaturas ambientes

Evaluation of a hand-held evaporimeter (VapoMeter^®) for the measurement of transepidermal water loss in healthy dogs

Respiratory function during thermal tachypnoea in sheep

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The role of water for heat dissipation by a Jersey cow and a Corriedale ewe.

Cited by 34 publications

References 1 publication

Evaporação cutânea e respiratória em ovinos sob altas temperaturas ambientes

Evaporação cutânea e respiratória em ovinos sob altas temperaturas ambientes

Evaluation of a hand-held evaporimeter (VapoMeter®) for the measurement of transepidermal water loss in healthy dogs

Respiratory function during thermal tachypnoea in sheep

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Resources

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Evaluation of a hand-held evaporimeter (VapoMeter^®) for the measurement of transepidermal water loss in healthy dogs