Responses upon multiple administration of L-thyroxine in hens

Area of Science:

• Comparative physiology
• Avian endocrinology
• Biochemistry

Background:

• L-thyroxine plays a crucial role in avian metabolism and growth.
• Understanding the impact of exogenous L-thyroxine on enzyme profiles is vital for poultry science.
• Breed-specific responses to hormonal treatments can occur in poultry.

Purpose of the Study:

• To investigate the effects of repeated L-thyroxine administration on blood plasma enzyme activities and total protein levels.
• To compare the biochemical responses to L-thyroxine between White Rock and Sussex hen breeds.

Main Methods:

• Repeated intramuscular injections of L-thyroxine were administered to White Rock and Sussex hens.
• Blood plasma samples were collected and analyzed for total protein.
• Enzyme activities including aldolase, alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase were measured.

Main Results:

• Total protein levels significantly decreased in both hen breeds.
• Aldolase activity increased in White Rock hens and delayed in Sussex hens. Alanine aminotransferase activity remained unchanged in White Rock hens but increased in Sussex hens.
• Aspartate aminotransferase activity showed an initial increase in both breeds. Alkaline phosphatase activity increased in White Rock hens but decreased in Sussex hens, with significant inter-breed differences noted.

Conclusions:

• Repeated L-thyroxine injections induce significant alterations in plasma enzyme activities and total protein levels in hens.
• Distinct differences in biochemical responses to L-thyroxine were observed between White Rock and Sussex breeds.
• These findings contribute to understanding the physiological impact of thyroid hormone supplementation in poultry.