Nutritive value of distillers dried grains with solubles from barley, corn and wheat for growing rabbits

Due to their fibrous nature, distillers dried grains with solubles (DDGS) from the bioethanol industry could be considered an interesting feedstuff for rabbit nutrition. To characterize the DDGS available in the Iberian Peninsula the chemical, amino acid and fatty acid composition of eight DDGS batches (2, 2 and 4 from barley, corn and wheat grains, respectively) was performed. Five diets were formulated to determine the nutritive value of DDGS in growing rabbits by the substitution method: a control diet and four experimental diets containing 200 g of the DDGS being evaluated kg−1 dry mater (DM) [DDGS from national barley, national corn, Brazilian corn and national wheat grains]. The digestibility trial was performed using 60 three-way crossbred fattening rabbits (12 per diet), aged 42 days with average live weight of 1.49 kg (S.E.: 0.033 kg). DDGS can be characterized as a raw material really rich in fibre (neutral detergent fibre and neutral detergent soluble fibre) and crude protein (CP, on av. 352, 208 and 318 g kg−1 DM, respectively). Barley DDGS had higher fibre and lower protein contents than wheat DDGS (+25 g of acid detergent fibre and −91 g of CP kg−1 DM, respectively; P < 0.05), as well as the highest ash content (on av. +16 g kg−1 DM; P < 0.05). Corn DDGS had intermediate fibre and protein values between barley and wheat DDGS, but were the richest in ether extract (on av. +70 g kg−1 DM). DDGS' protein was richer in proline, phenylalanine, valine and arginine for barley DDGS (107, 55, 54 and 51 g kg−1 CP, respectively), in leucine, alanine and histidine for corn DDGS (114, 75 and 27 g kg−1 CP, respectively), and in glutamic acid for wheat DDGS (290 g kg−1 CP). Barley DDGS was richer in saturated (236 g kg−1 total fatty acids), corn DDGS in monounsaturated (278 g kg−1 total fatty acids) and wheat DDGS in polyunsaturated fatty acids (615 g kg−1 total fatty acids). Barley DDGS was characterized by the lowest nutritive value traits of DDGS evaluated (11.9 MJ digestible energy (DE) and 168 g digestible protein (DP) kg−1 DM). In spite of higher protein and lower fibre content of the Brazilian corn (+1.7 g CP and −31 g neutral detergent fibre kg−1 DM), no significant differences for the nutritive value of both corn DDGS were observed (on av. 15.3 MJ DE and 208 g DP kg−1 DM). Wheat DDGS might be considered as the DDGS with the highest nutritive value of those evaluated (15.7 MJ DE and 263 g DP kg−1 DM).