SEASONAL RHYTHMS OF CUTANEOUS AND RESPIRATORY WATER LOSSES AS MECHANISMS FOR THERMOREGULATION BY DESERT SHEEP AND GOATS | ||
| Veterinary Medical Journal (Giza) | ||
| Volume 44, Issue 2, April 1996, Pages 425-433 PDF (6.32 M) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/vmjg.1996.376544 | ||
| Authors | ||
| AZAMEL A.* ; EL-SAYED A.; EL-SHERIF A. | ||
| Division of Animal and Poultry Production, Desert Rescarch Center, Matareya, Cairo, Egypt.. | ||
| Abstract | ||
| The present work was initiated to examine the seasonal rates of evaporative water loss (through skin and respiration) on 5 adult Barki rams and 5 bucks in relation to body temperature Season affected significantly (p < 0.01) both rates of respiratory water loss (RWL) and cutaneous water loss (CWL) in sheep and goats. Considering winter as starting occasion, average indoor relative humidity (RH) and ambient temperature (AT) increased steadily up to summer and then declined slightly in autumn. In both species, the seasonal trend of RWL rate was ascendant with those of RH and AT. At the same time, average CWL of sheep decreased inversely to that of CWL. Such descending trend of CWL was observed in goats only from spring to autumn. Goats showed the lowest rate of CWL in winter in order to minimize the resultant heat loss in the cold season. Consistently, goats in winter could elevate their rectal temperature (RT) more than sheep did (0.7 vs. 0.2°C) from 08.00 to 1400 hr. Goats as well were more tolerant to a mild heat load in summer than sheep as judged by the lower increase in RT (0.2 vs. 0.5°C), regardless of the sheep enhanced more water evaporation than goats did. Negative ambient-body temperature gradients in sheep and goats pointed to the outward heat flow to the environment over the different seasons with highest rates in winter and lowest ones in summer. In cold winter, positive coat-skin temperature gradients indicated a mechanism of inward heat transfer from a warmer coat surface to skin of sheep and goats. However, it seemed that each species has a particular pattern of thermoregulation | ||
| Keywords | ||
| Evaporative water loss; sheep; goats; thermoregulation | ||
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