Note on the Pattern of Diurnal Fluctuations of Some Physiological Responses in Shaded and Unshaded Karakachanska Sheep

1 Institute of Animal Science , BG-2230 Kostinbrod, Bulgaria
2 Institute of Mountainous Animal Breeding and Agriculture, BG-5600 Troyan, Bulgaria


ALEXIEV, Y., D. GUDEV, S. POPOVA-RALCHEVA, P. MONEVA and I. YANKOV, 2005. Note on the pattern of diurnal fluctuations of some physiological responses in shaded and unshaded Karakachanska sheep. Bulg. J. Agric. Sci., 11:737-745

Five Karakachanska ewes were exposed to direct solar radiation (32°C) or kept in shade for 14 hours before and following shearing. Rectal temperature, respiratory rate and heart rate were recorded from 7 a.m. to 9 p.m. Plasma levels, of indol, cholesterol, urea and total protein were determined at 8 a.m. and 2 p.m. Direct solar radiation caused significant increase of rectal temperature, respiratory rate and heart rate in shorn ewes, but had no effect on rectal temperature in unshorn ewes. However unshorn ewes exposed to sun showed an enhanced respiratory activity. The shorn ewes kept in shade hadlower rectal temperature and respiratory rate than the unshorn ewes. Heart rate was higher in shorn ewes either exposed to sun or kept in shade.
Plasma indol, cholesterol, urea and total protein were unaffected by the exposure to heat. Despite the general opinion that Karakachanska sheep is resistant to the abiotic environmental factors, present data suggest that this sheep breed is vulnerable to solar radiation during the first days following shearing.

Key words: diurnal fluctuations, Karakachanska sheep, shaded, physiological response