Calcium digestibility studies utilizing acid-insoluble ash measurements

Area of Science:

• Animal Nutrition
• Poultry Science
• Digestive Physiology

Background:

• Calcium is crucial for laying hens, impacting eggshell quality and bone health.
• Accurate measurement of calcium digestibility is essential for formulating optimal diets.
• Two common methods for assessing calcium digestibility are total collection (TC) and acid-insoluble ash (AIA).

Purpose of the Study:

• To evaluate calcium digestibility in laying hens across a range of daily calcium intakes.
• To compare the calcium digestibility values obtained using the TC and AIA methods.
• To investigate the influence of silica as a filler on calcium digestibility measurements.

Main Methods:

• Laying hens were fed diets with daily calcium intakes from 2.0 to 4.5 g, using limestone as the calcium source.
• Silica (washed sand) was added as a filler to diets with lower calcium intakes.
• Calcium digestibility was determined using both the total collection (TC) method and the acid-insoluble ash (AIA) indicator method.

Main Results:

• Calcium digestibility decreased linearly with increasing daily calcium intake for both methods.
• The AIA method consistently yielded higher calcium digestibility values compared to the TC method across all intake levels.
• The discrepancy between the TC and AIA methods was significantly correlated with dietary silica levels.

Conclusions:

• Calcium digestibility in laying hens is inversely related to calcium intake.
• The AIA method provides higher estimates of calcium digestibility than the TC method.
• Dietary silica content can influence the difference observed between TC and AIA methods for calcium digestibility assessment.