Apparent and standardized ileal digestibility of calcium in wheat and soybean meal for growing quail chicks using direct method

Calcium (Ca) is necessary for bone health and metabolic functions in poultry, however, the extent to which it can be utilized varies among feed ingredients. The goal of this study was to determine the apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of calcium in wheat and soybean meal (SBM) in young quail chicks using a direct method. Three dietary treatments were used in the experiment: a calcium-free basal diet to determine endogenous calcium losses, and two diets with either wheat or SBM as the primary calcium sources. Titanium dioxide was incorporated as an indigestible marker for precise measurement of ileal digestibility. On day 30, a total of 300 male quail chicks were weighed and then randomly assigned to one of the three treatments. Each treatment comprised five replicate pens, with 20 birds per pen. On day 34, the birds were euthanized using carbon dioxide, and ileal digesta samples were collected from the distal two-thirds of the ileum to analyze Ca content. The endogenous ileal Ca loss was determined to be 179 ± 68.6 mg/kg of dry matter intake (DMI), providing a baseline for calculating SID values. The AID of calcium for wheat grain was determined to be 24.3 %, with the SID measuring 31.2 %. However, SBM had higher Ca digestibility, with AID and SID values at 34.6 % and 39.9 %, respectively. Understanding digestibility metrics is crucial for optimizing dietary formulations to ensure adequate Ca intake, particularly when plant-derived sources of Ca are used.