Gastrocnemius Muscle Structural and Functional Changes Associated with Domestication in the Turkey

Area of Science:

• Animal Science
• Muscle Biology
• Comparative Physiology

Background:

• Selective breeding in domestic turkeys has led to significantly increased muscle mass compared to wild counterparts.
• Understanding the structural and functional adaptations underlying this muscle hypertrophy is crucial for poultry science.

Purpose of the Study:

• To characterize muscle structural and functional differences in the lateral gastrocnemius (LG) muscle between wild and domestic turkeys.
• To investigate age-related changes in domestic turkey muscle structure and performance.
• To determine the impact of selection for muscle mass on force production and tissue composition.

Main Methods:

• Comparison of peak isometric force production in the LG muscle.
• Measurement of whole muscle and individual fiber cross-sectional area (CSA).
• Quantification and structural analysis of connective tissue collagen using scanning electron microscopy.

Main Results:

• Domestic turkey LG muscles exhibit similar specific force (force per CSA) as wild turkeys.
• Domestic turkeys possess a greater number of smaller muscle fibers compared to wild turkeys.
• Lower collagen concentration and altered endomysium texture were observed in domestic turkey muscle.

Conclusions:

• Selection for muscle mass in domestic turkeys results in more, smaller fibers, not larger ones.
• While muscle structure is altered, body scaling significantly influences functional differences in hind limb performance.
• The study clarifies the structural basis of muscle hypertrophy and its functional consequences in selectively bred turkeys.