Nutrient composition, digestibility and energy value of distillers dried grains with solubles and condensed distillers solubles fed to growing pigs and evaluation of prediction methods

This study had two objectives: (1) to determine the nutritional value of 13 batches of distillers dried grains with solubles (DDGS) and 5 batches of condensed distillers solubles (CDS), and (2) to evaluate the prediction of the nutritional value of DDGS by using either mean values per DDGS type or lab measurements as potential predictors of nutrient content. The DDGS batches were derived from either wheat (n = 3), corn (n = 3) or a mixture of grains (n = 7). The CDS batches were mainly wheat-based. The batches were collected from 11 European ethanol plants. Six barrows per dietary treatment were placed in individual metabolism cages and fed either a basic diet or a diet in which 30% of the basic diet was replaced by DDGS or CDS. Chromium oxide (4 g/kg) was included in the feed as an external marker. Fecal and ileal samples were collected and the apparent fecal digestibility (AFD) and apparent ileal digestibility (AID) of the diets were calculated using the indicator method. Consequently, AFD and AID values for DDGS and CDS were calculated through difference. Nutrient components, color measurements and in vitro protein values were evaluated as variables to predict the AFD, AID and net energy (NE) value of DDGS by means of multiple regression analysis. The DDGS corn samples had a higher gross energy and crude fat (CFAT) content (P < 0.001) and were more red (a*; P = 0.002) and yellow (b*; P = 0.003) than the DDGS wheat and DDGS mix samples. The NE value was also higher for DDGS corn (P < 0.001). Large variation existed between DDGS samples in amino acid digestibility (particularly of Lysine), even when DDGS was produced from the same type of grain. Hence, the use of mean values for each DDGS type did not result in a good estimation of the nutritional value. The NE value of DDGS could be predicted by the color parameter b* (R2 = 71.1; P < 0.001) and CFAT (R2 = 76.2; P < 0.001), or by combining CFAT and acid detergent fiber (R2 = 94.0; P < 0.001). No good prediction equations could be established for the amino acid digestibility. The CDS samples also showed high variation in nutrient and amino acid composition and digestibility, which limits their usability in practical pig feed formulation.