Comparative Effects of Whole, Ground, Dry-Rolled, and Steam-Flaked Corn on Digestion and Growth Performance in Feedlot Cattle

Abstract

AbstractTwo trials were conducted to evaluate four common methods of corn processing for cattle simultaneously. Experimental diets contained 75.3% corn grain. Corn processing treatments were 1) steam-flaked corn (SFC; density = 0.31 kg/L), 2)dry-rolled corn (DRC; density = 0.58 kg/L), 3) ground corn (GC), and 4) whole corn (WC). Treatment effects on feedlot performance were evaluated in a 112-d finishing trial involving 120 crossbred yearling steers (311 kg). Cattle fed WC had less (7%; P<0.10) ADG and carcass yield (0.8%; P<0.10) than cattle fed DRC or GC. Cattle fed SFC had greater (9%; P<0.05) ADG, BW gain efficiency (17%; P<0.01), and carcass yield (1.5%; P<0.01) than cattle fed dry corn treatments. Dietary NEm and NEg were similar (P=0.46) for dry corn treatments, but increased (11.5 and 14.7%, respectively; P<0.01) for SFC. There was an inverse relationship between fecal starch (FS; %) and apparent total tract starch digestion: Total tract starch digestion (%) = 102.4 − 0.72FS (n = 16; r2 = − 0.97; P<0.01). Fecal starch was greater (39%; P<0.01) for WC than for DRC or GC and was less (91.5%; P<0.01) for SFC. Starch digestion was greater (6%; P<0.01) for GC than for DRC. Dry rolling or grinding corn increased (P<0.01) the digestibility of OM (13%), starch (15%), and N (8%) over that of WC. Digestion of OM (13%), starch (14%), and N (7%) was greater (P<0.01) for SFC than for the dry corn treatments. The DE value of the diet was greater (11%; P<0.01) for SFC than for dry corn treatment. The DE value of the diet was also greater (13%; P<0.01) for GC and DRC than for WC. Ruminal pH was greater (7.6%; P<0.01) for WC than for DRC or GC. Ruminal pH was less (P<0.01) for SFC than for dry corn treatments. Steam flaking decreased (P<0.01) ruminal molar proportion of acetate (7%), butyrate (25%), and ruminal acetate to propionate molar ratio (41 %) and increased (P<0.01) ruminal molar proportion of propionate (24%). It was concluded that steam flaking increases the NEm and NEg of corn by 15 and 19%, respectively. Finely grinding corn did not improve the feeding value of corn over that of dry rolling. Under ad libitum conditions, the NE value of WC is only slightly less than that of GC and DRC. However, when intake is restricted, starch digestion and the energy value of WC may markedly decrease.