Interactive Effects of Incubation Temperature and In Ovo Feeding on Hatchability, Organ Development, Bone Minerals and Blood Metabolites in Broiler Chicks

Background: Optimal incubation temperature and in ovo feeding strategies during incubation are crucial for ideal performance and welfare of chicks. Objective: This study investigated the effects of incubation temperature and early in ovo feeding on hatchability, internal organ development, bone mineralisation and blood metabolites in broiler chicks. Methods: A total of 1200 eggs from 58-week-old Arbor Acre breeders, averaging 62 ± 1 g, were incubated in separate dual-system automatic incubators (Senjie series DZ 47-53) at specified temperatures and 60% humidity. A total of 400 eggs were randomly assigned to three incubation temperature treatments, with four replicates per treatment, based on predetermined air temperatures of 36.5°C, 37.0°C and 37.5°C, maintained from embryonic day (ED) 1 until ED 18. On ED 10, eggs were candled, and each temperature group was further divided into three subgroups: the first serving as a control, where eggs were perforated but not injected; the second receiving an in ovo injection of glucose solution (5 mg/mL); and the third receiving an in ovo injection of vitamin-D3 solution (25 mg/mL). The supplements were administered 0.2 mL at egg level in the air sac. Results: Hatchability showed a clear temperature-dependent response, reaching a maximum of 89.86% in glucose-injected eggs at 37.5°C and decreasing to 48.33% in vitamin-D3 injected eggs at 36.5°C (p < 0. 05). Bone mineral content was influenced by interactions between incubation temperature and feeding, with calcium highest in glucose-fed chicks incubated at 37.0°C, while phosphorus was highest in control eggs incubated at 36.5°C (p < 0.05). By Day 21, chicks fed vitamin-D3 consistently demonstrated lower cholesterol levels, whereas those fed glucose and controls showed higher alkaline phosphatase activity under increased incubation temperatures (p < 0.05). Conclusion: Optimal results were achieved with glucose injection at 37.0°C and 37.5°C, improving hatchability, intestinal development and bone mineralisation, whereas vitamin-D3 supplementation at lower temperatures negatively impacted hatchability and metabolic balance.