Chemical composition and prediction of amino acid content of maize- and wheat-Distillers’ Dried Grains with Soluble

Abstract

The objective of the study reported here was to examine the relationship between the chemical components of maize- and wheat-Distillers’ Dried Grains with Solubles (DDGS) as well as develop prediction equations for the individual amino acids (AA) using the crude protein (CP) content of the feedstuff. Relationship between AA and CP of maize- and wheat-DDGS and their associated probability values were determined by correlation analysis. Prediction models for individual AA of maize- and wheat-DDGS from CP were developed using regression analysis. The chemical composition of maize- and wheat-DDGS varied among sources with coefficient of variation (CV) ranging from 8.5 to 53.5% for total P and Ca, respectively in maize-DDGS and 10.8 to 37.8% for CP and ADF, respectively in wheat-DDGS. Of the indispensable amino acids, Lys, Met and Trp were most variable in maize-DDGS with CV of 13.1, 12.0, 10.3%, respectively, whereas Lys, Phe and Met were the most variable indispensable AA in wheat-DDGS with CV of 20.2, 17.3, and 16.9% respectively. On the average, standard error of the estimate (SEE) was greater for models predicting AA from CP of wheat-DDGS. For maize-DDGS, r2 ranged from 0.24 to 0.66 and the SEE ranged from 0.038 to 0.169 whereas r2 values ranged from 0.62 to 0.94 and SEE ranged from 0.049 to 0.158 for wheat-DDGS. In a validation exercise using independent data, the mean absolute deviations between predicted and analyzed AA values were within 10% of the predicted AA value for most of the AA. It was concluded that the AA of both maize- and wheat-DDGS can be predicted from their CP contents but only the AA in wheat-DDGS could be predicted with acceptable accuracy.