Effects of late gestation distillers grains supplementation on fall-calving beef cow performance and steer calf growth and carcass characteristics

Fall-calving, mature Angus and Simmental × Angus cows (n = 251 total) and their progeny were used to evaluate the effects of late gestation dried distillers grains plus solubles (DDGS) supplementation on cow performance and progeny growth and carcass characteristics. Cows were blocked by breed and allotted to 12 tall fescue pastures (6.8 ha average). Pastures were randomly assigned to 1 of 2 treatments: cows were offered 2.1 kg DM DDGS·cow⁻¹·d⁻¹ (SUP; CP = 23%, fat = 7%; n = 6 pastures) or were not offered a supplement (CON; n = 6 pastures) 69 ± 9 d before expected calving date. Cows remained on treatments until calving. Once weekly, cows that had calved were removed from treatment pastures and were moved to new tall fescue pastures (21.6 ha average) where cows from both treatments were comingled without further supplementation. Cows (n = 74) were removed from study for calving more than 30 d after expected calving date, calf loss and injury, or euthanasia. Cow BW and BCS were recorded at the beginning of the supplementation period, after calving, and at breeding. Calf BW was taken at birth and early weaning (82 ± 14 d of age). After weaning, 71 steer progeny (representative of dam breed and treatment pastures) were transitioned to a common feedlot diet with individual feed intake monitored using the GrowSafe feeding system. Steers were slaughtered at 47 ± 4 d after a minimum 12th rib fat thickness (back fat) estimation of 0.6 cm, with cattle being shipped in 3 groups. Forage availability was not different between treatments (P = 0.69). Cows offered SUP gained more BW and BCS (P ≤ 0.02) during the supplementation period. There were no differences (P ≥ 0.12) in calving date, calf birth or weaning BW, or preweaning ADG. Cow BW at breeding was not different (P = 0.19); however, BCS at breeding was greater (P < 0.01) for cows offered supplement. No differences (P ≥ 0.11) in milk production, AI conception, or overall pregnancy rate were detected. For steer progeny, initial feedlot BW, final BW, and days on feed were not different (P ≥ 0.35); no difference (P = 0.77) in feedlot ADG was detected. Feedlot DMI and G:F were not different (P ≥ 0.52) across treatments. No differences (P = 0.62) in morbidity were observed in the feedlot. No differences (P ≥ 0.19) were detected for HCW, LM area, marbling score, or yield grade. Prepartum DDGS supplementation improved cow BW and BCS but did not alter milk production, subsequent reproduction, or subsequent calf performance or carcass characteristics.