Tocopherol more bioavailable than tocopheryl-acetate as a source of vitamin E for broilers

Area of Science:

• Animal Nutrition
• Biochemistry
• Nutritional Physiology

Background:

• Vitamin E is crucial for animal health, typically supplemented as tocopheryl-acetate (T-Ac) due to tocopherol's (T) instability.
• T-Ac bioavailability is dependent on intestinal hydrolysis, a step that may limit vitamin E absorption efficiency.
• Understanding the comparative absorption efficiency of T-Ac and T is vital for optimizing vitamin E supplementation in animal diets.

Purpose of the Study:

• To compare the absorption efficiency of tocopheryl-acetate (T-Ac) versus tocopherol (T) in broilers.
• To evaluate two distinct test procedures (2-day and 4-day feeding periods) for assessing vitamin E absorption.
• To investigate the dose-dependency and potential saturation of T-Ac hydrolysis in broiler models.

Main Methods:

• Broilers were fed diets supplemented with varying levels of T-Ac or T for either 2 or 4 days.
• Serum and liver samples were collected post-feeding for vitamin E analysis.
• Data were analyzed using linear regression and dose-response models to determine relative efficiencies and saturation points.

Main Results:

• Both 2-day and 4-day test procedures provided reliable data for vitamin E absorption.
• T-Ac demonstrated a relative efficiency of 0.24 to 0.37 compared to T, indicating lower bioavailability.
• T-Ac hydrolysis appeared dose-dependent and potentially saturable at doses above 50 ppm with short-term feeding, while T showed no saturation.

Conclusions:

• Tocopherol (T) has the potential for significantly higher efficiency and tissue deposition of vitamin E compared to tocopheryl-acetate (T-Ac).
• The development of stable forms of tocopherol could enhance vitamin E delivery to animals.
• T-Ac absorption efficiency is influenced by dose and duration of supplementation, suggesting limitations in its bioavailability.