Effects of increased dietary roughage during the late finishing period on beef cattle performance, carcass traits, and blood, ruminal, and faecal characteristics

Abstract

Finishing cattle consume diets high in concentrates to efficiently deposit both muscle and adipose tissue while decreasing cost of gain during finishing. Concerns regarding liver abscesses and late finishing period morbidity and death loss have led to interest in increasing dietary roughage concentrations during late finishing. The objective of the current experiment was to evaluate the effects of increased roughage inclusion late in the finishing period on growth performance, carcass traits, blood, inflammation markers, ruminal, and fecal characteristics of feedlot steers. Crossbred beef steers (n = 60; initial body weight; BW = 289 ± 35.6 kg) were blocked by BW and assigned to experimental dietary treatments in a randomized complete block design during the final 58 d on feed. Experimental treatments included control (CON; 6% roughage DM), intermediate (INT; 12% roughage DM), and high (HGH; 18% roughage DM) roughage diets (CON = 5 pens and INT and HGH = 4 pens; 4 steers per pen). All experimental diets contained dry-rolled corn, prairie hay, Sweet Bran (Cargill, Inc., Blair, NE), dry supplement, urea, and a corn steep and molasses-based liquid supplement. The inclusion rate of roughage and dry-rolled corn were adjusted for each experimental treatment diet. Overall dry matter intake (DMI) tended to increase linearly (P = 0.02) with increasing roughage concentration. No differences in BW, overall average daily gain (ADG), or gain to feed (G:F) were observed (P ≥ 0.72). Rib eye area increased linearly with increasing roughage concentration (P = 0.02). Fat thickness, hot carcass weight (HCW), marbling, liver score, and kidney, pelvic, and heart fat (KPH) did not differ (P ≥ 0.29) among treatments. Steers consuming the HGH diet had a lower fecal pH at the end of the finishing period (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) among treatments at any collection. Results from the current experiment suggest that increasing roughage late in the finishing period may not negatively impact growth performance or carcass characteristics but does alter feed intake and may alter fermentation and digestion.