Effects of Sodium Formate and Calcium Propionate Additives on the Fermentation Quality and Microbial Community of Wet Brewers Grains after Short-Term Storage

Abstract

The objective of this research was to examine the effect of sodium formate (SF) and calcium propionate (CAP) on the fermentation characteristics and microbial community of wet brewers grains (WBG) after short-term storage. In the laboratory environment, fresh WBG was ensiled with (1) no additive (CON), (2) sodium formate (SF, 3 g/kg fresh weight), and (3) calcium propionate (CAP, 3 g/kg fresh weight) for 20 days. After opening, fermentation characteristics, chemical composition, rumen effective degradability, and the microbial community of ensiled WBG were analyzed. The addition of CAP had no effect on pH and lactic acid concentration and increased the concentrations of propionic acid; the SF group had the lowest pH and acetic acid, butyric acid, and ammonia nitrogen contents and the highest lactic acid concentration. After fermentation, the SF group had the highest contents of dry matter (DM), water-soluble carbohydrates (WSCs), and neutral detergent fiber (NDF). The contents of the three nutrients in the CAP group were significantly higher than those in the CON group. The addition of the two additives had little influence on the crude protein (CP) and acid detergent fiber (ADF) contents of the ensiled WBG. Two additives elevated in situ effective degradability of DM and NDF compared with the parameters detected in the CON group; WBG ensiled with SF had higher effective in situ CP degradability than that in the CON and CAP groups. The results of the principal component analysis indicate that the SF group and two other groups had notable differences in bacterial composition. The analysis of the genus level of the bacterial flora showed that the content of Lactobacillus in the SF group was significantly higher than that in the two other treatment groups, while the content of Clostridium was significantly lower than that in the two other treatment groups. Therefore, the addition of sodium formate can suppress the undesirable microorganisms, improve the fermentation qualities, and ensure that WBG is well preserved after 20 days of ensiling.

Keywords: calcium propionate; fermentation quality; microbial community; sodium formate; wet brewers grains.

Figure 1

Principal component analysis of the bacterial community in wet brewers grains ensiled with sodium formate and calcium propionate after 20 days (CON, control group; SF, sodium formate; CAP, calcium propionate; 1, 2, 3, three replicates for each treatment).

Figure 2

Bacterial community and relative abundance by genus of wet brewers grains ensiled with sodium formate and calcium propionate after 20 days (CON, control group; SF, sodium formate; CAP, calcium propionate; 1, 2, 3, three replicates for each treatment).

Figure 3

LEfse (Linear discriminant analysis Effect Size.) online tool was used to compare the microbial changes in wet brewers grains ensiled with sodium formate and calcium propionate after 20 days (CON, control group; SF, sodium formate; CAP, calcium propionate).