Effects of replacing partially dry-rolled corn and soybean meal with different levels of dried distillers grains with solubles on growth performance, dietary energetics, and carcass characteristics in hairy lambs fed a finishing diet

While there is very little empirical data with feedlot lambs, the current standards assigns the same energy value to distillers dry grain with solubles (DDGS) and corn. Since the basis of energy of corn is starch while in DDGS are the proteins and fat content, in the vast majority of the studies comparisons were made between in non-isoenergetic diets, situation that make it difficult to accurately determine the feeding value of DDGS included at high levels. For the latter, the objective of this experiment was to determine in isoenergetic diets the effects of replacing partially dry-rolled corn (DRC) and soybean meal (SBM) with different levels (0, 15, 30 and 45%) of dried distillers grains with solubles (DDGS) on growth performance, dietary energetics, carcass characteristics, and visceral mass in finishing hairy lambs. DDGS substitution improved (linear P=0.04) final weight and average daily gain, but as a consequence of a tendency (P=0.06) to increase dry matter intake (DMI) with DDGS substitution, there were no advantages (P≥0.33) on gain efficiency, dietary energetic or observed-to-expected DMI. DDGS substitution did not affect dressing percentage and backfat thickness, but increased (linear, P≤0.03) hot carcass weight and kidney, pelvic and heart fat (KPH) and decreased (linear, P=0.05) longissimus muscle area (LM). There were not treatments effects on carcass composition, but increased DDGS level in substitution tended to linearly decrease, as a percentage of cold carcass weight, muscle (P=0.08) and increase carcass fat (linear, P=0.10). There were no effects of substitution with DDGS on wholesale cuts. Replacing corn and SBM with DDGS increased (linear P=0.03) empty body weight (EBW, as percentage of full weight) but influence on organ weights as a proportion of EBW (g/kg EBW) were small. The feeding value of DDGS is similar to that of dry-rolled corn (∼9.62MJ ENm/kg), this feeding value decreases as the inclusion level of DDGS increases beyond 30% because to the removal of starch instead NDF and the potential reduction of digestibility of fat. The drastically change of source of energy (fat and protein instead starch) can affect the deposition of body fat and the area of LM. Based on DMI and performance observed in the present study, DDGS is a suitable substitute for a portion of the dry-rolled corn and SBM in a finishing diet; however, at high levels of inclusion, it tends to decrease the LM area and increase the KPH.