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Body temperature and vasomotor responses in Scottish Blackface and Tasmanian Merino sheep subjected to slow cooling

Published online by Cambridge University Press:  02 September 2010

J. Slee
J. Slee
Affiliation:
A.R.C. Animal Breeding Research Organisation, Edinburgh 9
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Extract

1. Scottish Blackface and Tasmanian Merino one-year-old males were exposed to cold in climate chambers. The environmental temperature fell slowly from +10°C to −15°C in the first experiment when the sheep were in full fleece and from +30°C to −5°C in the second experiment when the same sheep were closely shorn. In the second experiment each sheep received two identical exposures separated by one day spent in a cool environment. Rectal temperatures and skin temperatures on the body and the extremities were recorded.

2. In experiment 1 skin temperatures on the feet and ears generally fell sharply due to vasoconstriction, especially in the Blackface sheep. The Blackface sheep showed earlier and more intense vasoconstriction than the Merinos.

3. In experiment 2 foot and ear skin temperatures fell smoothly with gradual vasoconstriction. In contrast to experiment 1, both breeds were similar in the time of onset of vasoconstriction. Foot temperatures, however, were significantly higher and vasoconstriction correspondingly later during the second exposure of experiment 2 than during the first exposure.

4. The skin temperature at which vasoconstriction occurred remained similar irrespective of breed, shearing or exposure occasion. But the ambient temperature at vasoconstriction was significantly influenced by all these variables.

5. Cold-induced vasodilatations were more frequent in experiment 1 than in experiment 2.

6. Retarded vasoconstriction among the Merinos in experiment 1 could, except for two sheep, be accounted for by their superior fleece cover. In experiment 2, the delayed foot vasoconstriction on second exposure was attributed to increased blood flow resulting from acclimatization.

Type
Research Article
Information
Animal Production , Volume 10 , Issue 3 , August 1968 , pp. 265 - 282
Copyright
Copyright © British Society of Animal Science 1968

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References

REFERENCES

Armstrong, D. C., Blaxter, K. L., Clapperton, J. L., Graham, N. McC. and Wainman, F. W. 1960. Heat production and heat emission of two breeds of sheep. J. agric. Sci., Camb. 55: 395–401.CrossRefGoogle Scholar
Baker, P. T. and Daniels, F. 1956. Relationship between skinfold thickness and body cooling for two hours at 15°C. J. appl. Physiol. 8: 409–416.CrossRefGoogle Scholar
BlaxterK, L. K, L., Graham, N. McC, Wainman, F. W. and Armstrong, D. G. 1959. Environmental temperature, energy metabolism and heat regulation in sheep. II. The partition of heat losses in closely clipped sheep. J. agric. Sci., Camb. 52: 25–40.CrossRefGoogle Scholar
Blaxter, K.L., Graham, N. McC. and Wainman, F. W. 1959. Environmental temperature, energy metabolism and heat regulation in sheep. III. The metabolism and thermal exchanges of sheep with fleeces. J. agric. Sci. Camb. 52: 41–49.CrossRefGoogle Scholar
Blaxter, K. L. 1962. The energy metabolism of ruminants. Hutchinson, London.Google Scholar
Burton, A. C. and Edholm, O. G. 1955. In Man in a cold environment. Arnold, London.Google Scholar
Daniel, P. M. and Prichard, M. M. L. 1956. Arterio-venous anastomoses in the external ear. Q. Jl exp. Physiol. 41: 107–123.CrossRefGoogle Scholar
Edwards, M. A. 1967. The role of arteriovenous anastomoses in coldinduced vasodilatation, rewarming and reactive hyperemia as determined by 24 clearance. Can. J. Physiol. Pharmac. 45: 39–48.CrossRefGoogle Scholar
Hertzman, A. B. 1959. Vasomotor regulation of cutaneous circulation. Phvsiol. Rev. 39: 280–306.CrossRefGoogle ScholarPubMed
Joyce, J. P. and Blaxter, K. L. 1964. The effect of air movement, air temperature and infrared radiation on the energy requirements of sheep. Br. J. Nutr. 18: 5–27.CrossRefGoogle ScholarPubMed
Keatinge, W. R. 1957. The effect of general chilling on the vasodilator response to cold. J. Physiol., Lond. 139: 497–507.CrossRefGoogle ScholarPubMed
Lewis, T. 1930. Observations upon the reactions of the vessels of the human skin to cold. Heart 15: 177–208.Google Scholar
Lewis, T. 1931. Supplementary notes upon the reactions of the vessels of the human skin to cold. Heart 15: 351–358.Google Scholar
Molyneux, G. S. 1965. Observations on the structure, distribution and significance of arterio-venous anastomoses in sheep skin. In Biology of the Skin and Hair Growth. Angus and Robertson, Sydney.Google Scholar
Slee, J. 1964. Comparative responses of Tasmanian Merino and Scottish Blackface sheep to a falling environmental temperature. Proc. Aust. Soc. Anim. Prod. V: 188–189.Google Scholar
Slee, J. 1966. Variation in the responses of shorn sheep to cold exposure. Anim. Prod. 8: 425–434.Google Scholar
Slee, J. and Sykes, A. R. 1967. Acclimatization of Scottish Blackface sheep to cold. 1. Rectal temperature responses. Anim. Prod. 9: 333–347.Google Scholar
Sykes, A. R. and Slee, J. 1968. Acclimatization of Scottish Blackface sheep to cold. 2. Skin temperature, heart rate, respiration rate, shivering intensity and skinfold thickness. Anim. Prod. 10: 17–35.CrossRefGoogle Scholar
Webster, A. J. F. 1966. The establishment of thermal equilibrium in sheep exposed to cold environments. Res. vet. Sci. 7: 454–465.CrossRefGoogle ScholarPubMed
Webster, A. J. F. and Blaxter, K. L. 1966. The thermal regulation of 2 breeds of sheep exposed to air temperatures below freezing point. Res. vet. Sci. 7: 466–479.CrossRefGoogle ScholarPubMed