Apparent ileal amino acids digestibility of diets with graded levels of corn DDGS and determination of DDGS amino acids digestibility by difference and regression methods in broilers

This study was conducted to determine apparent ileal amino acids digestibility (AIAAD) of diets with different levels of corn distiller's dried grains with solubles (DDGS) and to determine AIAAD of corn DDGS by difference and regression methods in broiler chickens. One hundred and fifty 30-day-old male broiler chickens were used in the experiment. The corn DDGS were incorporated into basal diets at graded levels (0, 4, 8, 12, and 16%). All birds were killed at the age of 35 days and the contents of the lower half of the ileum were collected. AIAAD was calculated using chromic oxide as the indigestible marker. For AIAAD of DDGS determination, difference and regression methods were used. AIAAD of Lys (78.6%) and Met (91.3%) were the significantly highest in the diet without DDGS in comparison with other diets (P < 0.01). AIAAD of the rest of essential and nonessential amino acids were the lowest in the diet with 8% of DDGS in comparison with the diets with 0 or 16% of DDGS (P < 0.01). The apparent ileal crude protein digestibility was also the lowest in the diet with 8% (61.8%) of DDGS (P < 0.01). The highest differences in AIAAD of DDGS determined by the difference method and in the diet without DDGS (basal diet) determined by the regression methods were found in Lys and Met. There were very low differences between DDGS and basal diet in AIAAD of nonessential amino acids, except Ala and Asp. These results show that higher levels of DDGS decrease AIAAD.