Determination and prediction of standardized ileal amino acid digestibility of corn distillers dried grains with soubles in broiler chickens

The experiment was conducted to evaluate ileal digestibility of amino acids (AA) in 8 corn distillers dried grains with solubles (DDGS) fed to broilers and to establish prediction equations for standardized ileal digestibility (SID) of AA for broilers based on the physicochemical properties. A total of 1,152 1-day-old male broilers were divided into 2 test stages (from day 9 to 14 and from day 23 to 28). In each stage, 576 broilers were randomly allotted to 1 of 9 diets (8 replicates, 8 birds per replicate) including a nitrogen-free diet and 8 corn DDGS test diets. Titanium dioxide (0.5%) was included in all diets as an external marker. In 8 corn DDGS samples, the contents of aflatoxin B1, deoxynivalenol, zearalenone, and zein were from 1.54 to 15.50 ppb, 0.44 to 5.12 ppm, 127.10 to 1062.46 ppb, and 3.10 to 26.89%, respectively; the content of lysine and methionine (Met) ranged from 0.36 to 0.67% (CV 21.51%) and from 0.16 to 0.74% (CV 58.04%), respectively. The SID of AA, except for valine and alanine, were significantly different (P < 0.05) at day 28. A positive correlation was observed (P < 0.05) between degree of lightness and SID of CP, Met, and total amino acid (TAA) at day 14. A negative correlation was observed (P < 0.05) between mycotoxins and SID of CP, lysine, Met, and TAA at day 28. The R2 value of stepwise regression equations for predicting the SID of AA at day 14 and day 28 was best for glutamic acid (R2 = 1.000 using ether extract, crude fiber, CP, aflatoxin B1, and neutral detergent fiber) and TAA (R2 = 0.904 using ether extract), respectively. In conclusion, this experiment suggested mycotoxin can be used to predict the SID of AA in corn DDGS with reasonable accuracy, and the results of SID and prediction equations could be used to evaluate the digestibility of corn DDGS in broilers.