Impact of Natural Heat Stress on Pregnant Rabbits: Behavioral, Physiological, and Reproductive Changes and the Ameliorative Role of Curcumin and Vitamin D₃

This study evaluated the effects of heat stress on productive performance, physiology, reproduction, and oxidative status in pregnant New Zealand White (NZW) rabbit does, as well as the potential synergistic effects of curcumin and vitamin D3 (Cur + VD₃) supplementation in alleviating these stress-induced impairments. Eighty multiparous does (12-18 months old) were assigned to a 2 × 2 factorial design involving two ambient temperatures (indoor vs. outdoor) and two supplementation levels (with or without Cur + VD₃). Outdoor does experienced severe heat stress (THI = 33.22) compared to indoor thermal comfort conditions (THI = 25.13). The supplement (Cur + VD₃) was administered orally at 1 mL/kg body weight. Heat stress significantly decreased body weight, milk yield, litter size, weight at weaning, and behavioral activity. Conversely, rectal temperature, respiration rate, and mortality increased. Supplementation with Cur + VD₃ showed improved body weight, reproductive parameters, milk yield, and behavior, while reducing mortality (0% vs. 5%) compared to treatment without these additives. Physiologically, Cur + VD₃ lowered rectal temperature and respiration rate. In conclusion, combined curcumin and vitamin D₃ supplementation is an effective nutritional strategy to improve heat stress tolerance and maintain productivity in pregnant rabbits exposed to high ambient temperatures.