Factorial models to estimate isoleucine requirements for broilers.

Area of Science:

• Animal Nutrition
• Poultry Science
• Nutrient Utilization

Background:

• Optimizing amino acid intake is crucial for broiler growth and feed efficiency.
• Isoleucine (Ile) is an essential amino acid that can limit performance if not adequately supplied.
• Accurate models are needed to determine optimal Ile levels for different broiler growth stages.

Purpose of the Study:

• To determine the efficiency of utilization (EU) of isoleucine (Ile) in broiler chickens.
• To develop factorial models for predicting optimal Ile intake across different growth phases.
• To evaluate the impact of partitioning EU for feather and feather-free body on model accuracy.

Main Methods:

• Six dose-response trials were conducted with 640 Ross 308 broiler chickens across initial, grower, and finisher phases.
• Seven levels of Ile and a control treatment were used, with Ile as the first limiting amino acid.
• Efficiency of utilization (EU) was determined for the whole body, or partitioned for feather-free body (Bff) and feather, using two factorial models (M1, M2, M3).

Main Results:

• Partitioned EU values were 53% for feather and 69% for feather-free body.
• Optimal Ile intake estimates varied by model and growth phase, with M1 generally yielding higher values.
• Model M3, utilizing partitioned EU, demonstrated reduced bias compared to other models.

Conclusions:

• Partitioning the efficiency of utilization for feather-free body and feather improves the accuracy of isoleucine requirement models in broilers.
• The developed factorial models provide precise estimates for optimal Ile intake, aiding in feed formulation for different broiler growth stages.
• Model M1, which accounts for body weight gain, tends to estimate higher Ile requirements compared to models focusing solely on protein gain (M2, M3).