Influences of Organic Acid Salts and Bacterial Additives on Fermentation Profile, Aerobic Stability, and In Vitro Digestibility of Total Mixed Ration Silage Prepared with Wet Hulless Barley Distillers’ Grains

This study aimed to investigate the impacts of three organic acid salts and two bacterial additives on the fermentation profile, in vitro digestibility and gas production, and aerobic stability of total mixed ration (TMR) silage prepared with 10% fresh weight (FW) of wet hulless barley distillers’ grains (WHDG), 35% FW of common vetch, 15% FW of whole-crop oat, 10% FW of hulless barley straw, and 30% FW of mixed concentrate. The total mixed ration (555 g kg⁻¹ FW) was ensiled with six treatments: (1) no additives (control); (2) calcium propionate (CAP; 0.5% FW); (3) potassium sorbate (POS; 0.1% FW); (4) sodium diacetate (SDA; 0.5% FW); (5) <i>Lactobacillus buchneri</i> (LB; 1 × 10⁶ cfu g⁻¹ FW); and (6) <i>Lactobacillus casei</i> (LAC; 1 × 10⁶ cfu g⁻¹ FW). All silos (20 L) were opened for the fermentation profile and in vitro digestibility analysis after 95 days of fermentation, and then subjected to an aerobic stability experiment for 14 days. All the TMR silage was well preserved with a low pH (4.32~4.51), acceptable levels of butyric acid (1.34~1.56 g kg⁻¹ dry matter), and ammonia nitrogen (69.1~87.1 g kg⁻¹ total nitrogen). All the groups were steady during aerobic exposure, while the SDA treatment was more stable with lower populations of undesirable microorganisms on day 14. The CAP, POS, and SDA treatments evidently (<i>p</i> < 0.05) enhanced the in vitro digestibility of dry matter (54.8~57.5 vs. 48.4%) and neutral detergent fiber (48.4~51.6 vs. 41.1%) compared to the control. By comprehensive consideration, SDA is recommended as additive to enhance fermentation quality, aerobic stability, and in vitro digestibility of TMR silage containing 10% FW of WHDG.