Effects of supplemental corn vs. corn fortified with soya-bean meal or urea fed with low-quality mixed grass hay on forage intake, particulate passage rate and neutral detergent fiber digestion in beef heifers

Abstract

One experiment was conducted to determine the influence of supplemental corn with either nonprotein nitrogen or plant protein on dry matter (DM) and neutral detergent fiber (NDF) digestion, feed intake, particle passage and forage intake by beef heifers. Mixed grass hay ( Agropyron spp./ Bromus spp.) was fed ad libitum and animals received either a supplement of cracked corn (CON), corn and soya-bean meal (3:2; SBM) or corn and urea (19:1; UREA). Twelve yearling crossbred heifers (average initial weight 256 kg; four per treatment) were randomly allotted to one of the supplement groups (0.63 kg per head day −1) in a split-plot design with three sampling periods. Fecal output, particulate passage and forage intake were measured and used to estimate DM and NDF digestibility. Forage or total intake, particulate passage rate, gastrointestinal DM fill, intestinal transit time and gastrointestinal mean retention time were unaffected ( P>0.10) by supplement. Dry matter and NDF digestibilities differed ( P<0.05) among supplement groups with SBM resulting in the highest and CON the lowest digestibility.