Environmental incubation factors influence embryonic thyroid hormones

Area of Science:

• Avian Endocrinology
• Embryonic Development
• Metabolic Regulation

Background:

• Thyroid hormones play crucial roles in avian embryonic development and metabolism.
• While developmental roles of turkey embryonic thyroid are well-studied, metabolic functions require further investigation.

Purpose of the Study:

• To investigate the metabolic response of turkey embryonic thyroid hormones to environmental factors.
• To determine if genetic background influences thyroid hormone responses to diet and incubation temperature.

Main Methods:

• Assayed embryonic thyroxine (T4) and triiodothyronine (T3) levels using RIA.
• Examined turkey embryos from different genetic lines fed varying iodide diets and incubated at different temperatures.
• Collected samples during the final incubation week when thyroid hormones are elevated.

Main Results:

• Line, maternal diet (iodide supplementation), and incubation temperature interacted significantly to affect embryonic T4 and T3 levels.
• Thyroid hormone ratios (T3:T4) were also influenced by the interplay of genetic line, diet, and incubation conditions.
• Environmental factors demonstrably impact circulating thyroid hormone levels in late-term turkey embryos.

Conclusions:

• Environmental factors, including maternal diet and incubation temperature, can modulate thyroid hormone levels in turkey embryos.
• These modulations suggest a potential for manipulating embryonic thyroid hormone levels through environmental incubation conditions.
• Such manipulation may offer a strategy to enhance turkey embryo hatchability and metabolic function.