The Influence of Shearing Stress on Thermal Homeostasis and Performance of Barki Ewes in the North Western Desert of Egypt

Abstract

Twenty four adult non-pregnant; non-lactating Barki ewes, aged 3 to 4 years with initial body weight of (35.75 ± 1.15) (kg) were randomly divided to two groups (n=12). Ambient temperature (AT) and relative humidity (RH) were recorded along the trail and temperature humidity index (THI) was estimated. The first group was kept as a control unshorn group while the second group was shorn to inspect the effects of shearing on body weight, physiological responses and thermal homeostasis of shorn ewes. Animals were weighed on days 0, 15, 30 and 45. Rectal temperature (RT), skin temperature (ST) and respiration frequency (RR) were measured on days 0, 1, 3, 15, 30 and 45 andThermal gradients (RT-ST) and (ST-AT) were assessed. Irrespective of the lost fleece weight on day 0, shorn ewes continued to lose more of their weights till day 15 then they started to regain their body weight. Shearing reduced (P<0.05) RT and RR of shorn ewes to lower values than their control mates. It also declined ST of shorn ewes (P>0.05) compared with the control group. Differences in (RT-ST) and ambient (ST-AT) between groups were insignificant. Shorn ewes retained lower values of RT, ST and RR than the controls during the experiment. Results indicated the capacity of shorn Barki ewes to maintain their thermoregulation stability by using energy retention mechanisms andto regain body weight. That might indicate a temporal moderate effect of shearing if it was under mild climatic conditions.