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Effects of sorghum hybrid, microbial inoculation, and storage length on fermentation profile, ruminal starch disappearance and aerobic stability of sorghum silage.

E. M. Paula

T55
Effects of sorghum hybrid, microbial inoculation, and storage length on fermentation profile, ruminal starch disappearance and aerobic stability of sorghum silage.
E. M. Paula*1, T. Fernandes1,2, H. Sultana1, L. Ferraretto1. 1Department of Animal Sciences, University of Florida Gainesville, FL, 2Federal University of Lavras Lavras, MG, Brazil.

Interest in growing sorghum for silage has increased, especially in areas where water supply is an issue for plant growth. Therefore, the objective of this study was to evaluate the effects of 2 sorghum (Sorghum bicolor L.) hybrids (forage vs. sudan), microbial inoculation and storage length on the fermentation profile, DM loss, aerobic stability and ruminal in situ starch disappearance of whole-plant sorghum silage. Whole-plant sorghum (27.9 ± 37% of DM for forage and 23.2 ± 29% of DM for sudan) was ensiled in quintuplicate mini-silo pouches bags untreated (CON) or with the following treatments: Lactobacillus plantarum CH6072, Lactobacillus plantarum LSI, and Pediococcus pentosaceus P6 at 1 × 105 cfu/g of fresh forage (LPPP); Lactobacillus buchneri LB1819 and Lactococcus lactis O224 at 1.5 × 105 cfu/g (LBLL). Silos were allowed to ferment for 0, 15, 30 or 90 d. Data were analyzed as a completely randomized design in 2 × 3 × 4 factorial arrangement of treatments using PROC GLIMMIX of SAS. The model included sorghum cultivar, microbial inoculation, storage length, and their interactions as fixed effects. Lactic acid and total acids were greatest in sudan sorghum silage (P < 0.01). Ammonia-N (as % of total N) was greatest with sorghum sudan (P < 0.01). The acetic acid was greatest in forage sorghum inoculated with LBLL, intermediate in sorghum sudan inoculated with LBLL, and gradually increased in both hybrids with storage length from 15 to 90 d (P < 0.01). Silage aerobic stability was 126 h greater, on average, for LBLL compared with CON and LPPP (P < 0.01). Ruminal in situ starch disappearance was increased from d 15 to 90 (54.5 vs. 59.3% of total starch, respectively; P < 0.04). Overall, microbial inoculation with LBLL improved aerobic stability of both hybrids. Forage sorghum had lower lactic and total acids (P < 0.01), however, it had greater starch digestibility (P = 0.01) than sorghum sudan. Storage length linearly increased starch digestibility of both hybrids, which indicates that storage length may be a useful management tool to optimize starch utilization.

Keywords: aerobic stability, starch disappearance, sorghum silage.