Body heat storage in steers (Bos taurus) in fluctuating thermal environments

Abstract

Heat stored in the body of cattle subjected to a daily 10 C C range of environmental temperature was measured by calorimetry and thermometry. The daily range of bodycore temperature of the animals was of the order of 0-5 °C but mean skin temperature cycled with a range of approximately 6 °C. Calorimetric estimates of changes in mean body temperature showed good agreement with thermometric estimates when core and mean body temperature changes were weighted in the ratio a: (1 -a) where a was found to be 0-85. This result is consistent with the findings of another study where cattle were subjected to abrupt changes in environmental temperature, the combined best estimate of a from the two studies being 0-86 + 0-014 (s.E.). The 10 °C range of daily environmental fluctuation resulted in a daily variation of approximately 1 °C in mean body temperature, which is equivalent to the amount of heat produced by the animals every 40 min. It is suggested that a weighting factor a = 0-86 could be employed, using thermometry only, to estimate fluctuations in body heat storage which are likely to occur in animals subjected to fluctuating environmental conditions in the field.

Latent heat loss of Holstein cows in a tropical environment: a prediction model

“…However, under too high environmental temperatures the thermal equilibrium can hardly be attained and in these circumstances the heat excess can be stored in the body tissues (Finch, 1985;McLean et al, 1983), thus increasing body temperature.…”

Efeitos da temperatura e da movimentação do ar sobre o isolamento térmico do velo de ovinos em câmara climática

“…Silva & Starling (2003) estimaram média de 48,14 W/m 2 para evaporação na superfície corporal e de 27,24 W/m 2 para evaporação respiratória em ovinos da raça Corriedale do mesmo rebanho submetidos às condições de temperaturas do ar similares às utilizadas neste trabalho. O fluxo de calor latente de aproximadamente 75,38 W/m 2 estimado por esses autores parece não ser suficiente para a manutenção da temperatura corporal estável (Figuras 1 e 3) nesses animais, uma vez que ocorreu elevação da temperatura retal quando a temperatura do ar foi superior a 40 o C, certamente em razão da estocagem de energia térmica (McLean et al, 1983).…”

Heat load alleviation in beef cattle: water application during continuous high temperature exposure

“…To provide a satisfactory method of estimating changes in heat storage, McLean et al (1983b) found that the high temperatures noted on all skin regions (lower trunk, upper limb, lower limb and ear) suggest that the skin of the animals was fully vasodilated when the ambient temperature was high. When the ambient temperature fell; however, the effects of vasoconstriction were apparent with successively lower temperatures recorded on the skin regions.…”

“…When an animal lies down both lower limb and dewlap temperatures can be affected by contact with the floor, the metalwork of the holding stall or with other skin regions and it becomes difficult to distinguish between the effects of postural and thermal influences on these temperatures (McLean et al 1983b).…”

“…This may be due to the animals being able to transfer heat to the pen floor (where excess water may have pooled from the water application events, or where urine and faeces were trapped), the air may have been slightly cooler as hot air rises or the animals were conserving energy to further assist in the dissipation of heat. McLean et al (1983b) reported that both the lower limb and dewlap temperatures can be affected by contact with the floor, holding stall or with other skin regions.…”