Abstract Inconsistencies in distillers grains deliveries have complicated cattle feeding for feedlot producers and have required diet adjustments during the feeding period. The objective of this study was to determine how the frequency of changing inclusions of modified distillers grains plus solubles (MDGS) throughout the feeding period impacts feedlot cattle performance, carcass characteristics, feeding behavior, and ruminal pH. Steers (n = 229; initial BW = 426 ± 22 kg) were blocked by body weight into one of eight pens, each equipped with five electronic feed bunks (RIC2Discover system; Hokofarm). Treatments for this study included 1) a corn control, 2) 25% MDGS kept at a constant inclusion, and 25% MDGS varying from 15 to 35% on a 3) daily, 4) weekly, or 5) monthly basis. Individual animal dry matter intake (DMI) and feeding behavior data were collected for 131 days during the finishing period. Ruminal pH was evaluated on a subset of steers in one pen (n = 16) for the control, constant, and daily treatments. Data were analyzed using the MIXED procedure of SAS, with treatment and block as fixed effects. Significance was set at P ≤ 0.10. The inclusion of MDGS improved average daily gain (ADG; P ≤ 0.02) and hot carcass weight (HCW; P ≤ 0.06) compared to the control. Cattle fed MDGS constantly had greater ADG compared to weekly variation in MDGS. The HCW for control, constant, daily, weekly, and monthly were 412, 426, 422, 419 and 420 kg, respectively. There was no difference between treatments for DMI (P = 0.42). Cattle fed the control had the lowest G:F and cattle fed constant MDGS had the greatest G:F (P ≤ 0.05), with cattle fed the variable treatments being intermediate. There were no differences between treatments for carcass characteristics (P ≥ 0.12). Dietary treatment impacted the incidence of liver abscesses (P = 0.07), with cattle fed the corn control having the greatest and cattle fed any of the MDGS treatments having lower incidences. For feeding behavior, there were no differences between treatments in number of bunk visits or time spent at the bunk each day (P ≥ 0.19). The day-to-day variation in DMI differed between treatments (P = 0.02), with the control and daily cattle having the highest variation in DMI across days. For the control, constant and daily treatments ruminal pH was 5.87, 6.10 and 6.08, respectively, with the corn control having the lowest pH (P 0.07) compared to constant and daily. Results suggest that varying MDGS had little impact on cattle performance and feeding behavior, and varying weekly had the largest impact on feedlot cattle when compared to daily or monthly variation. However, including MDGS in the diet was beneficial to just feeding corn.
Madison et al. (2026) studied this question.