Heat stress significantly influences productivity, especially in arid regions where temperatures often exceed the thermoneutral limits of lambs. This study evaluates the effects of rumen-protected fat supplementation as a heat stress mitigation strategy on productive behavior and thermoregulation of Dorper lambs in a hot, dry climate. Twenty-one lambs were assigned to three treatments receiving 0, 50 and 100 g d-1 of rumen-protected fat. For 13 weeks, data were collected on dry matter and water intake, body temperature (monitored by thermography and rectal measurements) and weight gain. Lambs receiving 50 g d-1 of protected fat showed an increase (P < 0.05) in dry matter and water intake and experienced lower rectal and cephalic temperatures compared to the control group. However, the study noted that high levels of protected fat (100 g d-1) could negatively affect intake. These results suggest that protected fat is a viable dietary strategy to improve heat tolerance in lambs, promoting productivity and welfare in adverse thermal environments. Likewise, the use of noninvasive thermography provided information on temperature variation in different regions of the body, although it was less sensitive to changes under conditions of mild heat stress.