Nutritional value of wheat and corn distiller's dried grain with solubles: Digestibility and digestible contents of energy, amino acids and phosphorus, nutrient excretion and growth performance of grower-finisher pigs

Two experiments were conducted to evaluate the nutritional value of distiller's dried grains with solubles (DDGS) samples derived from corn, wheat and a wheat/corn blend (4:1). Specifically, the digestibility and digestible contents of energy, amino acids (AA) and P, N and P excretion, and growth performance were determined in grower-finisher pigs. In exp. 1, 12 ileal cannulated barrows (64.6 +/- 6.4 kg) had restricted access (2.6 x maintenance) to a wheat-control diet or one of three diets containing 40% DDGS sample of corn, wheat or wheat/corn origin that replaced wheat. For energy, apparent total tract digestibility was highest for wheat (85%; P < 0.05) and did not differ among the DDGS samples (77 to 79%; P > 0.10). Total tract digestible energy (DE) was higher for corn DDGS (4292 kcal kg(-1) DM; P < 0.05) than wheat/corn DDGS, wheat DDGS and wheat samples (4038, 4019 and 3807). For lysine, apparent ileal digestibility (AID) was highest for wheat (71%; P < 0.05) and did not differ among DDGS samples (59 to 63%; P > 0.10). The AID lysine content was highest for corn DDGS (0.51% DM; P < 0.05), intermediate for wheat/corn DDGS and wheat DDGS (0.45 and 0.42), and lowest for wheat (0.37%). For P, total tract digestibility was lowest for wheat (15%; P < 0.05) and did not differ among DDGS samples (53 to 56%; P > 0.10). Total N excretion was highest for wheat/corn DDGS and wheat DDGS (55 and 58 g d(-1); P < 0.05), intermediate for corn DDGS (44) and lowest for wheat (36). Total P excretion did not differ among DDGS (I I g d(-1)) and was lowest for wheat (8; P < 0.05). In exp. 2, 100 pigs (52.0 +/- 3.3 kg) were fed a wheat-pea control diet or one of three diets containing 25% of the three DDGS samples (3.375 Mcal DE kg(-1); 2.50 g SID lysine Mcal(-1) DE) for 5 wk. Overall, average daily feed intake (ADFI) and daily gain (ADG) were higher for pigs fed the wheat control diet than the DDGS-containing diets (P < 0.05), but feed efficiency did not differ (P > 0.10). In summary, the digestible nutrient content of wheat DDGS is lower than corn DDGS and higher than wheat. Following pre-characterization of digestible nutrient profile, feeding DDGS reduced growth performance indicating that further research is required to improve the nutritional value of DDGS.