| Abstrakt: |
Finishing cattle are fed diets high in concentrates to promote efficient deposition of both muscle and adipose tissue while decreasing cost of gain during finishing. The continued incidence of liver abscesses and increases in morbidity and mortality in the late finishing period have led to interest in increasing dietary roughage inclusion 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 metabolites, inflammation markers, and ruminal and faecal 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 dry matter; 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 rates of roughage and dry-rolled corn were adjusted for each experimental treatment, in which the increased roughage replaced dry-rolled corn. Overall dry matter intake (DMI) tended to increase linearly (P = 0,02) with increasing roughage inclusion. No differences in BW, overall average daily gain (ADG), or gain to feed ratio (G:F) were observed (P ≥ 0,72). Rib eye area increased linearly with increasing roughage inclusion (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 faecal 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 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. [ABSTRACT FROM AUTHOR] |
