Thermal Manipulation: Embryonic Development, Hatchability, and Hatching Quality of Broiler Chicks

Abstract

Here, PRISMA guidelines were utilized to systematically evaluate the publications reporting the effect of thermal manipulation during embryogenesis on incubation performance, hatchability, and hatching quality of broiler chicks. The search and selection of eligible publications was through databases web of science, PubMed, and Scopus. Publications written in English between 2015 and September 2021 were considered. It is evidenced that during TM, key considerations include duration and strength of TM besides stage of embryonic development. The moderate elevation in incubation temperature (38.5–39.5°C) intermittently (3–18 h/d) between E07 and E18 improves the chick’s thermoregulation capacity and reduces any adverse effect of TM on hatchability, and chick quality (e.g., hatch weight and chick length) compared with continuous TM. In addition, high temperature TM (38.5–39.5°C) between E7 and E18 has no significant effect on embryo mortality, hatchability, and chick quality compared to standard incubation temperature (37.8°C). TM above 39.5°C significantly increases and decreases embryo mortality and hatchability, respectively compared with standard incubation temperature. In conclusion, the results of TM studies on embryogenesis, hatchability and hatching quality of broiler chicks are still contradicting, which is a possible limitation for its commercial use.