Nano-encapsulated vitamin D3 supplementation effects on reproductive performance, egg quality, and blood indexes in breeding pigeons.

Calcium homeostasis is indispensable for optimal egg production in poultry, and vitamin D3 (VD3) plays a pivotal role in regulating calcium metabolism and maintaining overall reproductive health. This study aimed to evaluate the effects of nano-encapsulated VD3 supplementation in drinking water on reproductive performance, egg quality, endocrine profiles, and antioxidant capacity of breeding White King pigeons. A total of 216 three-year-old pigeon pairs were randomly allocated into four groups, receiving 0, 1,000, 2,000, or 4,000 IU/L of nano-encapsulated VD3 for 13 weeks. The results demonstrated that a moderate supplementation level (2,000 IU/L) significantly improved egg mass, fertilization rate, plasma concentrations of luteinizing hormone (LH), estradiol (E2), and testosterone (T), as well as the activities of antioxidant enzymes [glutathione peroxidase (GSH-Px) and total superoxide dismutase (T-SOD)], while reducing malondialdehyde (MDA) concentrations (P < 0.05). This dosage also optimized the growth performance of squabs. Although the highest dosage (4,000 IU/L) further enhanced eggshell thickness and strength (P < 0.05), it did not confer additional benefits for reproductive success and slightly reduced squab weight gain. Serum calcium concentrations remained stable across all groups, indicating sufficient dietary calcium supply. Collectively, these findings suggest that a balanced VD3 supplementation strategy, particularly at 2,000 IU/L, can effectively improve reproductive outcomes and offspring health in breeding pigeons, while excessive supplementation may lead to diminishing returns. This study provides novel insights into the optimal VD3 requirement for breeding pigeons and offers practical guidance for pigeon production.