Using supplementation and growth-promoting management strategies for intensification of stocker steer production on rangelands in the southern Great Plains

Objectives Our objectives were to evaluate the man-agement strategies of supplementation with extruded dried distillers grains cubes (DDG) and use of a growth-promoting implant on performance of growing steers graz-ing native range over 2 yr. Materials and Methods In Exp. 1 we compared (n = 140 steers per year; BW = 239 ± 21 kg) positive con-trol (PC): late-summer supplementation with 1.13 kg of DDG/d (as-fed basis) and stocking at 2.4 ha/steer; and high supplement (HS): DDG at 0.75% (2.1 kg as fed/d) of BW all summer with a 1.6 ha/steer stocking rate. In Exp. 2 we compared (n = 125 steers per year; BW = 225 ± 23 kg) negative control (NC): no supplement and stocking at 2.0 ha/steer; PC: late-summer supplementation with 0.91 kg of DDG as fed per day and stocking at 2.0 ha/ steer; and HS with stocking at 1.4 ha/steer. Before graz-ing, steers were implanted with a trenbolone acetate–es-tradiol (TBA/E) combination in Exp. 1 and progesterone and estradiol (PG/E) implant in Exp. 2. In mid-summer, one-third of steers in each pasture were either not reim-planted or reimplanted with TBA/E or PG/E. Economic returns were estimated using partial budgeting. Data from each experiment were analyzed using PROC MIXED in SAS 9.4 (SAS Institute Inc., Cary, NC) as a split-plot experiment. Results and Discussion Forage biomass and nutri-tive quality did not differ among treatments at any sam-pling date. The HS treatment increased early summer and overall ADG at both locations, but late-season ADG did not differ between PC and HS. The HS treatment pro-duced the greatest BW gain per hectare and system net returns because the greater supplementation rate support-ed both increased stocking rate and greater season-long ADG. Mid-summer reimplanting with TBA/E increased late-summer ADG, but ADG did not differ between PG/E and non-reimplanted steers in either Exp. Implications and Applications Reimplantation with TBA/E and DDG supplementation can intensify stocker cattle production on native range by increasing gain per hectare and net returns, but the long-term ecological im-pacts of these systems require study.