This study assessed how environmental stress affected the growth performance and haematological parameters of Uda rams in tropical climates. Over the course of a year, sixteen Uda rams were observed in normal housing. Dry bulb temperature (DBT), wet bulb temperature (WBT), relative humidity (RH), Temperature–Humidity Index (THI), Black Globe–Humidity Index (BGHI), and Thermal Comfort Index (TCI) were among the meteorological characteristics that were noted. Red and white blood cell counts (RBC and WBC), packed cell volume (PCV), hemoglobin concentration (Hb), and red blood cell indices (MCV, MCH, and MCHC) were all measured in blood samples. Feed intake, body weight gain, and feed conversion ratio (FCR) were among the performance metrics evaluated. Results revealed significant negative correlations between Hb, PCV, and WBC with all environmental stress indicators, demonstrating that elevated temperature and humidity adversely affect immune function. Rectal temperature (RT) and respiratory rate (RR) were inversely related to RBC and WBC, indicating heat-induced physiological stress. Haematological indices were significantly associated with growth performance: RBC, PCV, and Hb were positively correlated with improved FCR and body weight gain, whereas MCV and MCHC showed negative correlations with feed intake, weight gain, and FCR. Regression analyses confirmed that increased RT and RR corresponded to reduced Hb and WBC levels, suggesting diminished oxygen-carrying capacity under heat stress. The findings highlight that high ambient temperatures and humidity compromise health and productivity in Uda rams by suppressing erythron activity and immune function. Haematological indices, together with RT, RR, and body temperature, were effective indicators of thermal stress and physiological adaptability. This study underscores the importance of integrating environmental monitoring with haematology to improve management practices, welfare, and performance of small ruminants in tropical climates.
