Effects of dietary concentration of wet distillers grains on health and performance of newly received beef cattle, in vitro methane production and volatile fatty acid concentrations, and in vitro and in situ dry matter disapperance

Three studies were designed to evaluate effects of wet distillers grains with solubles (WDGS) on health and performance of newly received beef cattle, in vitro methane production, volatile fatty acid proportions, and in vitro and in situ DM disappearance. In Exp. 1, 219 beef steers (BW = 209 kg, SE = 2.17 kg) were used in a randomized complete block design receiving study. The 4 dietary treatments (DM basis) were a 65% concentrate, steam-flaked corn (SFC)-based receiving diet that contained 0% WDGS (CON) or 65% concentrate receiving diets that contained 12.5%, 25, or 37.5% WDGS. There were no differences among the 4 treatments in BW (P ≥ 0.61), ADG (P ≥ 0.75), DMI (P ≥ 0.75), and G:F (P ≥ 0.35), and morbidity from bovine respiratory disease was negligible. In Exp. 2, in vitro experiments were conducted to determine the effects of WDGS on IVDMD, total gas and methane production, and molar proportions and total concentrations of VFA. Substrates used for the incubations contained the same major components as the diets used in Exp. 1. Two ruminally cannulated Jersey steers (BW = 405 kg) were adapted to a 60% concentrate diet, and ruminal fluid was collected 4 h after feeding. Total gas production was less (P = 0.03) for the average of the 3 WDGS substrates than for the CON substrate, and there was a linear decrease (P = 0.01) in total gas production as WDGS concentration increased in the substrates. Similarly, there were linear (P < 0.01) and quadratic (P = 0.01) decreases in methane production as WDGS concentration increased, as well as a decrease in methane for the average of the 3 WDGS concentrations relative to CON (P = 0.05). The IVDMD was greater for the average of the 3 WDGS concentrations vs. CON (P ≤ 0.05) at 6 and 12 h, and IVDMD increased (P ≤ 0.05) with increasing WDGS concentration at 6 (linear and quadratic) and 12 h of incubation. At 36 h, there was a tendency (P = 0.06) for the CON substrate to have lower IVDMD than the average of the 3 WDGS treatments, as well as a quadratic tendency (P = 0.08) for increased IVDMD as the concentration of WDGS increased. At 48 h, there was also a quadratic effect (P = 0.05) for an increase in IVDMD with increasing concentrations of WDGS in the substrates. Molar proportion of butyrate increased linearly (P < 0.01) as the concentration of WDGS increased in the substrate, and the average of the 3 substrates containing WDGS had a greater proportion of butyrate (P = 0.03) than CON substrate. There was a tendency for a linear decrease (P < 0.06) in total VFA concentration as WDGS increased in the substrates. In Exp. 3, four ruminally cannulated Jersey crossbred steers (BW = 650 kg) were used in a replicated, 2 x 2 Latin square design. Experimental diets fed to the steers were the CON and 37.5% WDGS diets fed in Exp. 1, and the in situ DM disappearance of SFC and WDGS from both corn and sorghum sources was determined for each diet. The 24-h in situ DM disappearance of the 4 diets fed in Exp. 1 also was measured. There was a tendency (P = 0.08) for greater SFC in situ DM disappearance in the 37.5% WDGS diet relative to the CON diet at 12 h. In addition, in situ DM disappearance tended to be greater (P = 0.07) with SFC in the 37.5% WDGS diet relative to CON diet at 18 h. Corn WDGS had greater in situ DM disappearance (P < 0.04) when incubated in steers fed 37.5% WDGS vs. the CON diet at 18 h. Moreover, there was a tendency (P < 0.01) for greater in situ DM disappearance of corn WDGS in diets containing 37.5% WDGS at 48 h of incubation. Differences or tendencies were noted at 3 (P < 0.08), 12 (P = 0.08), and 18 h (P < 0.01) for greater in situ DM disappearance in diets containing 37.5% WDGS relative to CON. There was a tendency (P = 0.06) for the average of all 4 diets to have greater in situ DM disappearance in steers fed the diet containing 37.5% WDGS relative to CON. Performance data from Exp. 1 indicate that including WDGS in the SFC-based receiving diets can be an effective means of providing a source of protein and energy, as well as beneficial in decreasing in vitro total gas and methane production.