194 Effects of feeding increased roughage to feedlot steers the last 56 days of finishing

Abstract

Abstract Finishing cattle are fed high concentrate diets to increase deposition of both muscle and adipose tissue and decrease cost of gain. The objective of this experiment was to evaluate the effects of increased roughage inclusion late in the finishing period on growth performance, carcass traits, and ruminal and fecal characteristics of feedlot steers. Treatments included a control (CON; 6% roughage DM), intermediate (INT; 12% roughage DM), and high (HGH; 18% roughage DM) roughage diets. Crossbred beef steers (n = 54; BW = 289 ± 35.6 kg) were assigned to treatments for the late finishing period in a randomized complete block design (4 pens of INT and HGH, 5 pens of CON; 4 steers per pen). Experimental diets contained prairie hay, Sweet Bran, rolled corn, dry supplement, urea, and a corn steep and molasses-based liquid supplement. The inclusion rate of roughage and rolled corn were adjusted for each treatment diet. Steers in HGH tended to have increased overall DMI (P = 0.07). No differences in final BW, overall ADG, or gain:feed were observed among treatments (P ≥ 0.72). Steers fed HGH had the greatest REA (P = 0.03) and a tendency for a lower yield grade (P = 0.08). Fat thickness, HCW, marbling, liver scores, and KPH did not differ (P ≥ 0.29) among treatments. Steers fed the HGH diet had a lower fecal pH at the end of finishing (P = 0.05) compared to CON and INT steers. Ruminal lactate was increased on d 14 for CON steers compared to other treatments (P < 0.001). No differences were observed for ruminal pH (P ≥ 0.11). Results of this experiment suggest that increasing roughage late in the finishing period does not negatively impact growth performance or carcass characteristics, but may alter ruminal fermentation and post ruminal digestion.