Effect of hexanoic acid, Lactobacillus plantarum and their combination on the aerobic stability of napier grass silage

Abstract

Aims: The objective of this study was to evaluate the potential of hexanoic acid (Hex) as a silage additive. Methods and Results: The effect of Hex, Lactobacillus plantarum (Lp) and their combination (Hex + Lp) on the aerobic stability of napier grass silage was investigated. Napier grass was ensiled without additives (C) or with Lp, Hex or Hex + Lp for 60 days followed by 7 days of aerobic exposure. After 60 days of ensiling, the Lp silage had the lowest pH and the highest lactic acid (LA) concentration among all silage, whereas the highest water-soluble carbohydrates (WSC) content was observed in Hex + Lp silage, followed by Hex silage. After 60 days of ensiling, the population of yeasts in C and Lp silages was > 3·0 log10 CFU per g FW, while that of Hex and Hex + Lp was <2·0 log10 CFU per g FW. During aerobic exposure, the pH in the Lp and C silages increased (P < 0·05) above 7·0 on day 5. The pH of Hex silage was the lowest among all silages on day 3 and 5, followed by a significant (P < 0·05) increase until 7 days of aerobic exposure. There were no significant changes in pH and AA of Hex + Lp silage over the duration of aerobic exposure. The concentrations of LA in C, Lp and Hex silages decreased while that of Hex + Lp silage remained stable after 3 days of aerobic exposure. The Hex delayed the decline of WSC contents and the increase in yeasts over the aerobic exposure period. Conclusion: Addition of Hex (97 h) and Hex + Lp (>168 h) improved aerobic stability (P < 0·05) as compared to the control (83 h). Significance and Impact of the Study: Hex or in combination with L. plantarum inhibited the proliferation of yeasts during aerobic exposure of napier grass. Thus, Hex is an alternative antifungal additive to improve aerobic stability.