Ileal Digestibility of Amino Acids in Fish Meal-Based Diets for Broiler Starters Using Regression Technique

An experiment was conducted to determine apparent ileal digestibility of crude protein (CP) and amino acids (AA) and digestible CP and AA of fish meal (FM) in 21-d-old broiler chickens using the regression technique. Four diets containing 0, 1, 2, and 3% FM in place of cornstarch were formulated with FM as the sole contributor of CP and AAs in the sequential diets. Eighty 14-d-old broiler chicks were weighed, and sorted by body weight and randomly allotted to the experimental diets with 4 replicates per diet and 5 chicks per replicate. Titanium dioxide was added to the diets at the rate of 5 g/kg diet as an indigestible marker. They were fed the experimental diets till d 21 post hatch when they were killed by asphyxiated with CO2 and digesta from the last two-third of ileum collected. The concentrations of CP and AA in the diets increased as dietary FM increased. Apparent digestibility of CP and AA significantly (P < 0.05) increased with dietary FM inclusion but with a decrease in the 3% FM diet. The digestibility values of CP, lysine and methionine estimated as slopes of the regression of the amount of CP or AA digested dry matter intake dry matter intake (DMI) at the terminal ileum against CP or AA intake dry matter intake (DMI) were 88.7, 97.2 and 97.0% respectively. The digestible amounts of CP, lysine and methionine of FM were 63.63 g, 5361.04 mg and 1801.45 mg. Results of the study suggest a maximum level of 2% inclusion of FM was adequate for broiler starter chicks as higher levels may induce higher endogenous CP and AA flow and hence reduced digestibility of these nutrients.