Abstract

Heat stress poses a major challenge to broiler production in semi-arid regions, impairing growth performance, carcass quality and physiological homeostasis. This study evaluated the effects of dietary supplementation with vitamin C (250 mg/kg), betaine (2 g/kg), organic selenium (0.3 mg/kg as selenomethionine) and their combination, provided throughout the 42-day rearing period, on Arbor Acres broilers exposed to natural semi-arid heat stress (34–40 °C, 20–45 % relative humidity) at Ahmadu Bello University, Zaria, Nigeria. Three hundred one-day-old male chicks were randomly assigned to five treatments in a completely randomised design with four replicates each. The combination treatment significantly reduced rectal temperature (40.8–40.9 °C compared to 41.5–41.8 °C in control), heterophil to lymphocyte ratio (0.28 compared to 0.52), serum corticosterone (11.4 ng/ml compared to 18.6 ng/ml) and malondialdehyde (2.9 nmol/ml compared to 5.2 nmol/ml), while increasing superoxide dismutase (17.3 U/ml compared to 12.4 U/ml) and glutathione peroxidase (38.7 U/ml compared to 28.1 U/ml) activities (P < 0.05). Final body weight (2410 g compared to 2105 g) and feed conversion ratio (1.65 compared to 1.83) improved markedly, alongside higher dressing percentage (76.2 % compared to 72.4 %), breast yield (28.9 % compared to 25.8 %) and jejunal villus height (1165 µm compared to 895 µm) and villus: crypt ratio (7.37 compared to 4.84). Individual supplements provided intermediate benefits, with the combination demonstrating clear synergistic effects on antioxidant defence, stress attenuation, nutrient utilisation and intestinal integrity. These findings indicate that combined nutritional modulation effectively alleviates heat stress physiology and sustains productivity in semi-arid broiler production systems.

Keywords

heat stress, broiler chickens, vitamin C, betaine, organic selenium, semi-arid conditions, antioxidant defence, intestinal morphology, growth performance