Abstract #265

# 265
Microbial count, fermentation, and aerobic stability of regular- and brown midrib-corn hybrids ensiled with and without a combo inoculant.
Juan J. Romero*1, Yuchen Zhao2, Youngho Joo3, Jinwoo Park3, Marco A. Balseca-Paredes1, Adam J. Heitman1, Miguel S. Castillo1, 1Department of Crop Science, North Carolina State University, Raleigh, NC, 2Department of Animal Nutrition and Feed Science, China Agricultural University, Beijing, China, 3Department of Animal Science, Gyeongsang National University, Jinju, Korea.

The objective was to evaluate the effects of a combo inoculant on microbial count, fermentation, and aerobic stability of 4 hybrids of corn. Treatment design was the factorial combination of 4 corn-types ensiled with (INO) and without (CON) inoculant. Corn-types were TMF2R737, F2F817 (A and B, respectively; from Mycogen), P2089YHR, and P1449XR (C and D, respectively; from Pioneer). The NDF digestibility of A and C conventional hybrids was ~56.5% compared with 65.5% for B and D brown midrib hybrids. The inoculant added contained Lactobacillus buchneri and Pediococcus pentosaceus (4 × 105 and 1 × 105 cfu/g of fresh corn). Experimental design was a complete randomized block design (3 field blocks) with treatments replicated 2 times (2 plots) within blocks, for a total of 16 experimental units within block. Corn from each plot was chopped, treated or not with inoculant, packed into 7.6L bucket silos, and stored for 100 d. At d 0 there were differences due to hybrids solely. The %DM was 44.0, 38.3, 42.1, and 41.3 for A, B, C, and D, respectively; lactic acid bacteria (LAB) count (log cfu/g of fresh corn) was greatest and similar for B and D (7.7) compared with A (6.7) and C (7.1 ± 0.07); yeast count was greatest in D (6.8 vs. 6.6 ± 0.02) and mold count was lowest in C compared with the others (5.7 vs. 5.9 ± 0.05); and pH was higher for A (5.81) vs. C (5.60) and D (5.70), but B (5.79 ± 0.04) was only higher than C (P ≤ 0.05). At opening, INO increased LAB (from 6.2 to 6.6 ± 0.08) and pH (from 3.80 to 4.02 ± 0.01), and decreased yeast (from 5.10 to 3.74 ± 0.18, P ≤ 0.05) compared with CON. Aerobic stability (h) was extended by INO compared with CON (181 vs. 35 ± 1.1) but to a lesser extent for B (73 vs. 36 ± 1.2; P ≤ 0.05). The DM recovery (%) was higher for A (95.8) vs. B (93.4) and D (93.1), but C (95.0 ± 0.6) was only higher than D (P ≤ 0.05). The results indicate that corn-hybrid had an effect on %DM and DM recovery, and that the combo inoculant used improved silage conservation to different extents depending on hybrid type.

Key Words: corn, microbe, inoculant