Inclusion of corn ethanol byproducts in non-forage diets and their effects on feed intake, digestibility, growth performance, and blood parameters of young Nellore bulls

Context Distillers grains can be used in ruminant diets as sources of protein and energy. Recent technology has allowed to remove the fiber of the corn grain before fermentation. Fiber can be combined with condensed distillers solubles to obtain other new ethanol byproducts, such as dry fiber plus solubles (DFS). The animal response to new byproducts needs to be evaluated. Aims This study aimed to evaluate the effects of DFS and dry distillers grains plus solubles (DDGS) on feed intake, digestibility, performance, and blood metabolites of growing beef cattle, to partially replace ground corn and completely replace soybean meal and cottonseed cake in non-forage diets. Methods Twenty-four young Nellore bulls (initial body weight of 276 ± 37 kg, and age of 12 ± 3 months) were randomly distributed into 12 pens, using a completely randomized block design. Treatments were: (1) CON – control diet with conventional ingredients (soybean hulls, ground corn, soybean meal, cottonseed cake, urea and mineral mix; CP in diet = 148 g/kg); (2) DFS – diet with inclusion of 30% DFS (CP in diet = 143 g/kg); and (3) DDGS – diet with inclusion of 30% DDGS (CP in diet = 185 g/kg). The CON diet was formulated to an average daily gain (ADG) of 0.8 kg. Keys results The inclusion of DFS and DDGS increased dry matter intake (DMI; kg per animal per day) compared with CON diet (P = 0.021); however, DMI was not affected when measured in g per kg BW (P > 0.05). The CP, ether extract (EE) and NDF intake were highest for DDGS, intermediate for DFS and lowest for CON (P < 0.010). The inclusion of DFS and DDGS improved nutrient digestibility compared to the CON diet (P < 0.05). The ADG and feed conversion were higher (P < 0.05) for the animals receiving the DDGS compared to CON and DFS, which did not differ from each other. The total predicted metabolizable protein supply was highest for DDGS, intermediate for DFS, and lowest for CON (P < 0.001). Treatments showed no effects on serum indicators (P > 0.05), though trends were observed for urea (P = 0.070) and albumin (P = 0.087) levels. Conclusions The inclusion of 30% DDGS supports greater productive performance, likely due to the increased supply of nutrients, particularly metabolizable protein and net energy. Implications Corn ethanol byproducts (DDGS and DFS) can completely replace protein sources and partially replace corn in non-forage diets.