Effects of Sorting Steers by Body Weight into Calf-Fed, Summer Yearling, and Fall Yearling Feeding Systems1

Two years of data (288 steers/yr) were used to determine if sorting cattle by BW into different production systems would decrease overweight carcasses (> 431 kg) and hot carcass weight (HCW) variation. At receiving, steers were assigned randomly into sorted or unsorted groups (n = 144 steers/group). Within a group, steers were assigned to 1 of 3 feeding times: 1) calf-fed (entering the feedlot at receiving), 2) summer yearling (grazed during winter and entering the feedlot in May) and 3) fall yearling (grazed during winter and summer and entering the feedlot in September). Unsorted steers were assigned randomly to a feeding time. Sorted steers were assigned to a feeding time based on BW, with the heaviest one-third fed as calf-fed steers and the remaining steers grazing in the winter. After winter grazing, the heaviest one-half of the remaining sorted steers were fed as summer yearlings and the lightest one-half grazed summer grass and entered the feedlot in September. On feedlot entry, steers were assigned randomly to 6 pens/treatment. This experiment was analyzed as a completely randomized design with a 2 × 3 factorial arrangement of treatments and with pen as the experimental unit. By design, interactions (P < 0.05) were observed for initial feedlot BW and HCW. In addition, interactions (P < 0.05) were observed for G:F and percentage of overweight carcasses. Sorted fall yearlings had fewer overweight carcasses (6.40 vs. 35.42%). Regardless of whether they were sorted or unsorted, calf-fed steers and summer yearlings did not produce many overweight carcasses. Sorting into a production system decreased HCW variation and percentage of overweight carcasses.