The effects of natamycin and hexanoic acid on the bacterial community, mycotoxins concentrations, fermentation profiles, and aerobic stability of high moisture whole-crop corn silage

Abstract

The objective of the study was to evaluate the effects of natamycin, hexanoic acid, and Lactobacillus plantarum on fermentation characteristics, aerobic stability, mycotoxins concentrations, and bacterial community in high moisture whole-crop corn silage. Whole-crop corn was harvested at 1/2 milk lines stage and ensiled without additive (CON), with L. plantarum (LP, 1 ×106 cfu/g FW), natamycin (NAT, 0.2 mg/kg FW), or hexanoic acid (HEX, 0.4 mg/kg FW). The addition of NAT and LP enhanced (P < 0.05) lactic acid (LA) production as compared to CON and HEX silage. HEX depressed LA accumulation leading to higher (P < 0.05) pH and water-soluble carbohydrates (WSC). The HEX and NAT silages had lower (P < 0.05) yeast count and ethanol concentration than CON and LP silages. NAT and LP decreased the concentration of ammonia N as compared to CON silage with the lowest value in LP silage. After 60 d of ensiling, LP silage spoiled within 22 h, NAT silage was stable for 41 h, which was slightly (P > 0.05) longer than CON silage (34 h). The HEX silage showed the longest aerobic stability (>144 h) among all silages. Ensiling decreased zearalenone (ZEN) and deoxynivalenol (DON) concentrations (P < 0.05). The LP and NAT silages had significantly (P < 0.05) lower aflatoxin B1(AFB1), ZEN, and DON concentrations than fresh corn, CON, and HEX silages. All additives depressed the growth of Lactococcus, but increased the relative abundance (RA) of Lactobacillus compared to CON. LP reduced the RA of Leuconostocs, while HEX showed stronger antibacterial abilities to Klebsiella than LP and NAT. In conclusion, HEX improved the aerobic stability, whereas NAT and LP improved fermentation quality by enhancing the proliferation of Lactobacillus during ensiling of high moisture whole-crop corn.