Performance of stocker cattle grazing 'Tifton 85' bermudagrass supplemented with dried distillers' grains on per-animal and per-area bases: A twoyear summary

The supply of dried distillers' grains (DDG) generated from the ethanol industry provides great opportunities for feed additives and supplementation of stocker cattle. The objective of this study was to evaluate performance of stocker calves grazing 'Tifton 85' bermudagrass [Cynodon dactylon (L.) Pers.] when supplemented daily with varying levels of DDG. Steers (n = 96 [4 testers pasture-1 yr-1], 363 ± 3.7 kg initial BW, and approximately 15 mo of age) were stratified by BW and randomly allocated to each of 16 pastures (0.7 ± 0.01 ha) across 2 yr (2014 and 2015). Pastures were randomly allocated to each of 4 levels of DDG supplementation for about 110 d at 0, 0.25, 0.5, or 1% BW hd-1 d-1. Steers were group fed daily at 0800 h and weighed every 21 d. Grazer animals were added to pastures based on visual and forage mass assessments to maintain a similar forage allowance among pastures. Data were analyzed using SAS PROC MIXED or PROC GLIMMIX. Least squares means were calculated for treatments and separated using F-protected t tests with the Tukey-Kramer adjustment. Average daily gain was greatest (P < 0.05) from steers offered 1% BW DDG (1.25 kg/d) and least from non-DDG steers (0.77 kg/d), with 0.25 and 0.5% BW being intermediate (1.05 and 1.12 kg/d, respectively). Additional gain from DDG supplementation was greater (P < 0.05) from 1% BW DDG (0.68 kg/d) than from 0.25 and 0.5% BW steers (0.47 and 0.54 kg/d, respectively). There was a trend (P = 0.13) toward increased supplemental feed to additional gain ratios of 4.2, 5.4, and 7.2 for 0.25, 0.5, and 1% BW DDG, respectively, indicating that higher levels of DDG supplementation resulted in substitution of forage in the diet. There was no measurable difference (P = 0.33) in stocking rate (318 kg = 1 steer) among treatments (overall mean = 12.4 hd/ha), whereas gain per area was greatest (P < 0.05) at 1,883 kg/ha from pastures offered DDG at 1% BW followed by intermediate values of 1,268 kg/ha at 0.25% and 1,399 kg/ ha at 0.5% BW. Pastures receiving no supplementation had steers gaining 906 kg/ha. Supplementation of stocker calves with DDG while grazing Tifton 85 bermudagrass is a viable management strategy to optimize gain per animal or per area.