Evaluation of High-Moisture Ear Corn as a Roughage Source in Finishing Diets Fed to Beef Steers

The objective of this study was to evaluate the feedlot performance, rumination activity, and carcass characteristics of high moisture ear corn (HMEC) as a roughage source in finishing diets fed to beef steers. Backgrounded steers (n = 191; initial shrunk weight [4% BW] = 449 kg  23.9 kg) were assigned randomly to 1 of 24 pens (8 steers/pen) with pens randomly assigned to one of four dietary treatments (6 pens/treatment): control diet with hay fed at 10% roughage equivalency (RE; HAY10), or HMEC at either 14% (EAR14), 10% (EAR10), or 6% (EAR6) RE. High-moisture ear corn was assumed to contain 18% RE based on initial starch assay. Activity data were collected through 24-hour observation periods. Diet particle size (PSPS) was analyzed using a Penn State Shaker Box and physically effective NDF (peNDF) was calculated by multiplying the amount of feed that remains above the 1.18mm screen (as a percentage of the total) by the NDF of the feedstuff. All data were analyzed as a randomized complete block design (RCBD) with fixed effects for treatment and a random effect for replicate, with pens serving as the experimental unit. Linear and quadratic contrasts were used to evaluate the effects of increased HMEC inclusion; mean separation was conducted when there was an overall F-test with P ≤ 0.05. One steer died during the study from causes unrelated to dietary treatment; data were analyzed on a deads excluded basis. Decreased HMEC resulted in a linear reduction (P ≤ 0.05) in dry matter intake (DMI). Treatment tended to affect ADG quadratically (P = 0.08) with EAR10 gaining the fastest, EAR6 the slowest (1.61, 1.59, 1.67, and 1.63 kg/d for HAY10, EAR6, EAR10, and EAR14, respectively). Greater HMEC inclusion resulted in a linear increase (P ≤ 0.02) in feed efficiency (G:F; 0.145, 0.153, 0.151, and 0.146 for HAY10, EAR6, EAR10, and EAR14 respectively). Dietary treatment tended (P ≤ 0.07) to affect rib fat quadratically. Dietary treatments had no effect on the distribution of USDA Yield or Quality grades, nor on liver abscess incidence. A linear increase (P ≤ 0.04) in resting behavior was observed on d 46 as RE decreased. Ruminating and chewing behavior on d 46 linearly increased (P ≤ 0.03) as dietary RE increased. Diet affected PSPS (P < 0.01) as HAY10 had smaller diet proportions remaining on the 8 and 4 mm screens and greater proportions in the pan compared to the HMEC treatments. The findings indicate that HMEC, particularly EAR10, may enhance carcass weights compared diets containing hay as a roughage source.