Effects of the Application of Lactobacillus plantarum Inoculant and Potassium Sorbate on the Fermentation Quality, In Vitro Digestibility and Aerobic Stability of Total Mixed Ration Silage Based on Alfalfa Silage

SIMPLE SUMMARY: Ensiling total mixed ration allows preservation and saves labor for small farms. This study evaluated the substitution relationship between lactic acid bacteria (Lactobacillus plantarum) and silage components, and verified the practicality of preservative (potassium sorbate) in total mixed ration silage. The results showed that potassium sorbate greatly improved the preservation efficiency of total mixed ration silages. The alfalfa silage could directly produce an acidic environment for fresh total mixed ration before ensiling and showed comparable function to inoculant in the improvement of fermentation quality. Therefore, the application of the inoculant is not necessary when the total mixed ration contains a certain percentage of silage. These findings could provide guidance for farmers to avoid the blind use of inoculants and the spoilage of total mixed ration silage, which could directly improve economic efficiency. ABSTRACT: This study aimed to evaluate the effect of the application of an inoculant and a preservative on the fermentation quality, in vitro digestibility, and aerobic stability of alfalfa silage-based fermented total mixed ration (TMR). The TMR was ensiled with (1) no additives (control), (2) Lactobacillus plantarum (LP), or (3) potassium sorbate (PS). The V-scores of all silages were higher than 80 points during the 30 days of ensiling. The addition of LP and PS had no effects on the in vitro parameters, such as in vitro digestibility and in vitro gas production (p > 0.05). LP-treated silage showed similar fermentation quality and comparable aerobic stability to the control (110 h). The LP only decreased the ammonia nitrogen (NH(3)-N) content (p < 0.05) during ensiling. The PS significantly increased the pH of TMR silages (p < 0.05). Meanwhile, the addition of PS improved the aerobic stability (>162 h) of TMR silage, indicated by the higher water-soluble carbohydrate content and lower NH(3)-N content in comparison with those in the control after aerobic exposure (p < 0.05). The improvement in fermentation quality is extremely small in terms of applying LP in TMR silage based on a large percentage of other silage ingredients. The PS is effective in conserving unpacked TMR silage and showed the potential to reduce the risk of ruminal acidosis in livestock.