METABOLIC AND DIGESTIVE RESPONSES TO ARTIFICIAL SELECTION IN CHICKENS.

Area of Science:

• Animal Science
• Evolutionary Biology
• Genetics

Background:

• Domestic broiler chickens are selectively bred for traits like rapid growth and large muscle mass, diverging significantly from ancestral wild jungle fowl.
• Understanding these divergences offers insights into artificial selection's impact on physiology, energy budgets, and evolutionary trade-offs.

Purpose of the Study:

• To compare physiological and metabolic parameters between domestic broiler chickens and ancestral wild jungle fowl.
• To identify the consequences of conscious and unconscious artificial selection on energy allocation and organ development in chickens.

Main Methods:

• Comparative analysis of growth rate, energy intake, digestive efficiency, and metabolic rate.
• Measurement of organ masses, including intestines, brains, and leg bones.
• Assessment of intestinal nutrient transporter and hydrolase activities and capacities across different ages and body masses.

Main Results:

• Broiler chickens exhibit higher daily energy intake and activity costs than jungle fowl of equivalent size.
• Broilers possess larger gastrointestinal tracts but relatively smaller brains and leg bones compared to jungle fowl.
• Despite generally lower transporter activities, broilers have higher relative intestinal transporter capacities due to enlarged guts.

Conclusions:

• Domestication involves complex selection pressures, including unconscious selection for prerequisite traits and against less essential or competing traits.
• Artificial selection in broiler chickens leads to significant physiological adaptations, impacting energy budgets and organ development.
• Intraspecific comparisons highlight evolutionary trade-offs driven by selective breeding in domestic animals.