PSXIII-28 Effects of replacing dry-rolled flint corn with reconstituted corn grain silage in supplements for beef cattle finished on pasture provided on different days after mixing

Abstract The study was carried out to assess how replacing dry-rolled flint corn (DRC) with reconstituted corn grain silage (RCGS) in a supplement, exposed in aerobic conditions for different periods before delivery to cattle (fresh, 3 d, or 6 d), affects the performance of Nelore bulls intensively finished on pasture with high supplementation. Nellore bulls [n = 864; body weight (BW) = 408 ± 35 kg; 22 mo old) were used in a randomized block design and distributed into 12 paddocks (10 ha, n = 6; 8 ha, n = 6; 8 bulls/ha). The treatments consisted of control (CON; DRC supplement); T0 (70% of DRC replaced with RCGS and provided after mixing); T3 (70% DRC replaced with RCGS and provided 3 d after mixing); and T6 (70% of DRC replaced with RCGS and provided 6 d after mixing). The control supplement was composed of 67.3% DRC, 11.0% cottonseed whole, 17.4% cottonseed cake, and 4.30% mineral premix. The RCGS was inoculated using Lactobacillus hilgardii (CNCM I-4785) + Lactobacillus buchneri (NCIMB 40788), both at 1.5x105 cfu/g, and opened after 60 d of storage in silos bag (61% DM). Bulls were fed ad libitum for 102 d. Intake was measured daily. Performance data was calculated considering supplement intake (DMIsup) and initial carcass dressing was considered 50%. All data were analyzed as orthogonal contrasts using SAS: C1: CON vs T0; L: linear effect of exposure time; Q: quadratic effect of exposure time. Orthogonal contrasts were analyzed considering P 0.05 as significant effect and P ≤ 0.10 as tendency. Bulls consuming RCGS supplements tended to exhibit a linear response in DMIsup (% BW) over the day of supplement air exposure. No effect was detected in the other assessments for L and Q contrasts (P ≥ 0.11). Bulls consuming fresh RCGS supplement tended to have heavier final BW (P = 0.06) and to consume 5% less supplement (P = 0.09; Table 1). The average daily gain (ADG) was 3.9% greater for T0 animals in comparison with CON (P = 0.03). Supplement intake as % BW was 5.4% less (P 0.01), and feed efficiency was 10.5% better for cattle consuming fresh supplement in comparison with CON (P 0.01). Hot carcass weight tended to be greater for T0 bulls compared with CON bulls (P = 0.09) and carcass ADG presented the same behavior (P = 0.09). Carcass feed to gain (F:G) was 7.17% better for T0 bulls compared with CON bulls (P 0.01). Fecal starch and feces pH presented better results for T0 in comparison with CON (P 0.01). Nellore cattle consuming fresh RCGS supplement had better ADG, carcass characteristics, and feed efficiency than cattle consuming DRC supplement. Cattle consuming air-exposed RCGS supplements performed similarly to cattle consuming fresh RCGS supplement.