Thesis Abstract Levels and forms of vitamin D in broilers diets

Area of Science:

• Animal Science
• Nutritional Biochemistry
• Poultry Science

Background:

• Vitamin D is crucial for calcium and phosphorus metabolism in poultry.
• Cholecalciferol (D3) and 25-hydroxycholecalciferol (25-OHD3) are key vitamin D isoforms.
• Optimizing vitamin D supplementation is vital for broiler health and productivity.

Purpose of the Study:

• To evaluate the effects of different concentrations and combinations of vitamin D3 and 25-OHD3 on broiler performance.
• To assess the impact of these vitamin D isoforms on bone characteristics and physiological parameters.
• To determine the optimal supplementation strategy for broiler nutrition.

Main Methods:

• 1920 Cobb-500 broiler chicks were used in a completely randomized design with six treatments.
• Diets were supplemented with varying levels of vitamin D3 and 25-OHD3, including combined forms.
• Metabolism assays evaluated calcium and phosphorus retention and excretion at different ages.

Main Results:

• Combined D3 and 25-OHD3 supplementation enhanced calcium and phosphorus retention compared to D3 alone.
• 25-OHD3 supplementation improved feed conversion ratio and bone ash content.
• Combined supplementation increased tibial bone density across all study phases.

Conclusions:

• The combination of vitamin D3 and 25-OHD3 positively impacts broiler feed conversion, plasma calcium levels, and bone density.
• This synergistic effect leads to improved calcium and phosphorus retention and reduced phosphorus excretion.
• Supplementation with 25-OHD3, particularly in combination with D3, is beneficial for broiler development regardless of the growth phase.