Effects of genotype, wilting, and additives on the nutritive value and fermentation of bermudagrass silage

Bermudagrass is the main warm-season grass species used for livestock production in the southeastern United States; however, when it is ensiled, the silage fermentation parameters are often less than desirable. The objective of this study was to investigate the effects of management practices on the nutritive value and fermentation characteristics of bermudagrass silage. In Exp. 1, treatments were the factorial combinations of 2 bermudagrass genotypes, 'Jiggs' (Cynodon dactylon) and 'Tifton 85' (Cynodon sp.), 4 additives, and 2 DM concentrations at ensiling. The additives were 1) untreated control (deionized water), 2) Ecosyl, 3) B500, or 4) sugarcane molasses. The 2 DM concentrations at ensiling were low DM (22% DM) or high DM (53% DM). Treatments were replicated 3 times in a completely randomized design. Silage treated with molasses had a lesser (P < 0.05) pH and greater (P < 0.01) lactate concentrations than the control, Ecosyl, and B500 in silage with low DM concentrations and greater (P < 0.01) in vitro true digestibility (IVTD) and lesser (P < 0.01) ADF concentrations than the other treatments at either DM concentration. Silage treated with B500 had the greatest (P < 0.01) aerobic stability, whereas that treated with molasses had the least aerobic stability. However, all treatments presented long aerobic stability (>= 150 h). Jiggs had lesser (P < 0.01) ADF and NDF and NDF digestibility (NDFD) concentrations than Tifton 85 and Tifton 85 had greater (P < 0.01) IVTD than Jiggs in the silage with a high DM concentration. In Exp. 2, Jiggs silage treated with either molasses (20 g molasses [DM]/kg forage [as-fed basis]) or nothing (control, untreated silage) was fed to 16 beef heifers (Bos sp.) in individual drylot pens in a completely randomized design with 8 replicates for voluntary DMI, in vivo apparent DM digestibility, and NDFD evaluations. There were no differences (P = 0.36) among treatments in NDFD; however, there was a trend (P < 0.08) for greater in vivo apparent DM digestibility and DMI in heifers fed the molasses-treated silage. Microbial inoculants had decreased effects on Jiggs and Tifton 85 bermudagrass silage ensiled at a low DM concentration; however, adding molasses was an effective management practice to improve its nutritive value and fermentation characteristics.