Non-additive dietary effects in juvenile slider turtles, Trachemys scripta

Area of Science:

• Zoology
• Nutritional Ecology
• Herpetology

Background:

• Non-additive dietary effects occur when the nutritional value of a mixed diet differs from the sum of individual components.
• Adult slider turtles (Trachemys scripta) exhibit both positive and negative non-additive dietary effects.
• Juvenile slider turtles undergo ontogenetic diet shifts from carnivorous to herbivorous feeding.

Purpose of the Study:

• To investigate whether juvenile slider turtles experience non-additive dietary effects.
• To identify the underlying mechanisms driving these effects in juvenile turtles.

Main Methods:

• Two feeding trials were conducted with juvenile slider turtles.
• Diets consisted of 100% duckweed (Lemna spp.), 100% animal protein (grass shrimp or crickets), or mixed diets with varying proportions.
• Nutritional gains and intake were monitored.

Main Results:

• A negative non-additive effect was observed in juvenile slider turtles fed mixed diets containing 19% grass shrimp or 22% crickets.
• The positive non-additive effect seen in adults was not observed in juveniles.
• Significant variations in intake and transit time between plant and animal diets were noted.

Conclusions:

• Juvenile slider turtles demonstrate non-additive dietary effects, primarily negative, which differ from adult responses.
• Differences in nutrient intake and digestive transit times likely explain the observed non-additive effects.
• Findings provide insights into the dietary ecology and ontogenetic diet shifts in slider turtles.