Sparrows discriminate between diets differing in valine or lysine concentrations

Area of Science:

• Animal Nutrition
• Behavioral Ecology
• Nutritional Physiology

Background:

• Nutrient selection is crucial for animal survival and reproduction.
• Amino acid deficiencies can significantly impact an animal's behavior and physiology.
• Understanding dietary choices in birds provides insights into nutritional self-regulation.

Purpose of the Study:

• To investigate how White-crowned Sparrows (WCS) choose between diets differing in essential amino acids (valine and lysine).
• To determine the speed and accuracy of dietary selection in response to nutrient deficiencies.
• To assess the influence of amino acid form (crystalline vs. protein-bound) and acclimation on food choice.

Main Methods:

• WCS were offered pairs of semi-synthetic diets, adequate or subadequate in valine or lysine.
• Body mass and total daily food intake (TDFI) were monitored.
• Dietary choices and latency to achieve nutritional balance were recorded.
• Effects of amino acid form and dietary acclimation were examined.

Main Results:

• WCS rapidly selected dietary ratios to maintain body mass within 2-4 days.
• Initial food intake decreased proportionally to subadequate diet consumption.
• Valine deficiency showed longer latency and greater initial intake reduction than lysine deficiency.
• Malnourished birds recovered body mass and intake faster with valine than lysine deficiency.
• Amino acid form had minimal impact; acclimation to crystalline amino acids temporarily increased choice latency.

Conclusions:

• WCS exhibit remarkable ability to self-regulate diet selection to meet amino acid requirements.
• Choice dynamics vary slightly between different amino acids and dietary forms.
• These precise dietary selection mechanisms are ecologically significant for free-living WCS, ensuring nutritional adequacy.