Effect of Solar Radiation and Increased Salinity on Awassi Ewe Adaptation and Production

With the recent changes in environmental patterns with climate change, higher maximum summer temperature, increased solar radiation and lower water quality are anticipated; indicators for such changes are already being detected in Lebanon. With Awassi sheep managed in a transhumant system where animals walk for at least 4 to 5 hours in the summer sun, and little research on the effect of heat/sun stress and water quality in transhumant animals 30 lactating Awassi ewes were assigned from LARI from June to august, the hottest summer months, to 6 treatment groups in a 2x3 factorial treatment arrangement where water salinity (High Salt vs No Salt) and solar/heat stress exposure were tested. Addition of CaCO3 to the feed and MgSO4 added to drinking water of the salt treated ewes (Salt) and drinking water to the control (NoSalt), whereas for solar/heat stress, animals were kept in the sun (Sun) or provided partial (Control) or full shade (Shade). Awassi ewes were allowed two weeks of adaptation to the experimental plot under control conditions of partial shade and diet, and exposed to experimental conditions for 1 month, then followed during 2 weeks of recovery from heat and salt stress. Feed and water intake was measured twice a week on 2 consecutive days to estimate daily intake. Respiration (RR) and heart rate (HR), body temperature (BT), and panting scores (0 to 5) were recorded twice a week AM and PM; and BCS, BW and milk quantity recorded. BCS and body weight did not differ (P<0.05) between all treatment groups. Results showed that animals consumed the entire ration, and Salt animals drank less water per hour (P<.05) than control animals irrespective of the sun exposure or time of measurement (noon vs all day). HR, RR and Panting scores did not differ (P>0.1) between Shade and Control ewes, but was significantly higher (P<0.05) in Sun ewes, however panting scores did not exceeded 2.5 for the duration of the experiment, attesting to the adaptation of the Awassi breed to sun exposure and heat stress. Milk production slightly decreased (P<0.05) in animals exposed to both sun and high salt without difference within the control and Shade ewes. Therefore, Awassi sheep has the potential to withstand the anticipated changes in sun radiation and salt content.