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

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 log CFU per g FW, while that of Hex and Hex + Lp was <2·0 log 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.