Supplementation of stocker calves grazing native prairie pastures in western Oklahoma: Effects on grazing performance, supplemental efficiency and subsequent feedlot performance and carcass characteristics

Experiment 1 tested the effects of supplementing extruded DDGS cubes and increased stocking rates on intensification of stocker production. This trial was conducted at the Marvin Klemme Range Research Station, (Klemme) and the USDA-ARS Southern Plains Experimental Range (SPER). Supplementation treatments at Klemme were 1) Positive Control (PC) – 1.13 kg/d only during the late summer, 2.4 ha/steer and 2) High Supplement (HS) – 0.75% BW the entire grazing season, 33% increase in stocking; at SPER, 1) Negative Control (NC) – No supplement, 2.0 ha/steer, 2) PC- 0.91 kg/d only during late summer, 2.0 ha/steer, and 3) HS - 0.75% BW the entire grazing season, 33% increase in stocking. Early and overall ADG for HS were greatest (P ˂ 0.001), however with late-season supplementation ADG for PC and HS did not differ (P ≥ 0.47). Increased stocking and season-long supplementation increased (P ≤ 0.001) BW gain/ha. Experiment 2 tested the effects of increased supplementation rate on animal performance and supplemental efficiency. At Klemme steers were supplemented at 0, 0.91, and 1.81 kg/animal/d, at SPER 0, 0.91, 1.81, and 2.72 kg/animal/d. Increased supplementation increased ADG and BW gain/ha (P ≤ 0.05). At SPER, increased supplementation reduced supplemental efficiency quadratically (P ≤ 0.01). Experiment 3 tested the effects of pre-finishing plane of nutrition on feedlot performance and carcass characteristics. Klemme steers from yr 2 of Experiment 1 and all from Experiment 2 were used in Experiment 3. Initial BW entering the feedlot was greater (P ≤ 0.01) for steers on higher supplementation rates. Finishing performance for HS steers from Experiment 1 had a greater AFSBW and reduced DOF, total feed required, and feed cost (P ≤ 0.04). Increased supplementation rate for Klemme steers from Experiment 2, decreased early ADG and feed efficiency linearly while individual DMI increased linearly (P ≤ 0.03). Steers from SPER saw a linear and cubic reduction in early and late finishing ADG (P ≤ 0.01). Carcass traits were generally not influenced (P ≥ 0.08).