title: Effect of steam-flaked sorghum grain density on performance, mill production rate, and subacute acidosis in feedlot steers.
abstract: Two trials were conducted to determine the effects of steam-flaked sorghum grain bulk density on animal performance, cost of production, and propensity to induce ruminal acidosis in feedlot steers. In Trial 1, 336 yearling steers (343 kg; SEM = .346) were fed diets for 125 d that contained sorghum grain (82.5%, DM basis) flaked to .283 (L), .322 (M), or .361 (H) kg/L (i.e., 22, 25, and 28 lb/bu). Steers fed L consumed 3.2% less DM than those fed H (linear, P < .05), resulting in 6.9% lower ADG (linear, P = .02) and 3.6% lower gain efficiency (linear, P < .15). Sorghum grain flaked to M and L had 16 and 46% greater starch gelatinization than H (measured using differential scanning calorimetry; linear, P = .002). Dressing percentage increased linearly (P < .05) with increasing flake density, but no other carcass measurements were affected by treatment. Increasing flake density increased mill production rate linearly (P < .01), resulting in the lowest energy usage per unit of flaked grain for the H treatment. Trial 2 was an acidosis challenge study that incorporated six ruminally cannulated steers (422 kg; SEM = .129) into a replicated 3 x 3 Latin square experiment. Reducing flake density resulted in linear reductions in ruminal pH following intake challenge at 3, 33, and 36 h after the d-12 challenge (P < .05). There was a linear increase in the area between the pH vs time curve and a line at pH 5.5 (P < .01) and 5.0 (P = .09) with decreasing flake density (28.0, 25.2, and 18.2 pH-hours below 5.5 and 9.6, 7.3, and 3.9 pH-hours below 5.0 for L, M, and H, respectively). Cattle consuming L also tended to have higher VFA concentrations (mM) at 36 h after challenge (P = .12). There was no significant treatment effect on ruminal lactate. Flaking sorghum grain to .283 and .322 kg/L resulted in reduced intake and poorer animal performance compared with .361 kg/L (58.7% starch gelatinization), higher susceptibility to subacute acidosis, and higher costs of production.
authors.affiliation: Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506, USA.
authors.forename: C D
authors.initials: CD
authors.lastname: Reinhardt
authors.forename: R T
authors.initials: RT
authors.lastname: Brandt
authors.forename: K C
authors.initials: KC
authors.lastname: Behnke
authors.forename: A S
authors.initials: AS
authors.lastname: Freeman
authors.forename: T P
authors.initials: TP
authors.lastname: Eck
mesh_terms: D000138:Acidosis / Q000453:epidemiology / Q000209:etiology / Q000662:veterinary*; D000818:Animals; D002151:Calorimetry / Q000662:veterinary; D002417:Cattle / Q000254:growth & development* / Q000502:physiology; D002418:Cattle Diseases / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology; D004032:Diet / Q000662:veterinary; D002523:Edible Grain / Q000592:standards*; D005232:Fatty Acids, Volatile / Q000032:analysis; D005511:Food Handling / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D007773:Lactates / Q000032:analysis; D008297:Male; D011897:Random Allocation; D012307:Risk Factors; D012417:Rumen / Q000737:chemistry
chemical_list: D005232:Fatty Acids, Volatile; D007773:Lactates