Effects of fatty acid salts on fermentation characteristics, bacterial diversity and aerobic stability of mixed silage prepared with alfalfa, rice straw and wheat bran.

Abstract

The objective was to determine effects of potassium diformate (PD), sodium diacetate (SD) and calcium propionate (CAP) on dynamics of microbial community, fermentation characteristics and aerobic stability of silage comprised of a mixture of alfalfa (AF), rice straw (RS) and wheat bran (MF). Treatments included control (C), PD [5.5g kg-1 fresh weight (FW)], SD (7g kg-1 FW), and CAP (10g kg-1 FW), which were ensiled for 1, 3, 5, 7, 15, 30 and 45 days in vacuum-sealed polythene bags. After day 1 of ensiling, the most dominant bacterial species in all silages was Weissella cibaria, whereas Lactobacillus parabrevis, L. nodensis, L. plantarum and L. paralimentarius were dominant species after 5 and 15 days of ensiling, and ultimately Pseudomonas putida and Stenotrophomonas maltophilia became dominant after 45 days. The positive correlation between PD and L. plantarum supported the lowest pH, butyric acid, ammonia nitrogen, neutral and acid detergent fiber, and hemicellulose content, and high water-soluble carbohydrates and crude protein content in PD silage. In addition, SD and CAP enriched the abundance of L. parabrevis and mainly increased lactic acid (LA) and acetic acid (AA). CAP increased abundance of L. acetotolerans after 45 days of ensiling with more LA and AA than other treatments. The succession of the bacterial community of mixed silage was modulated by the three fatty acid salts; furthermore, PD and CAP further improved fermentation quality by accelerating the decrease in pH and the increase in LA. The chemical additives prolonged the aerobic stability more than 16 days. © 2021 Society of Chemical Industry.