Research note: The effect of a lactic acid bacterial inoculant on the fermentation dynamics of Eragrostis curvula during ensiling

Abstract

Making good quality hay from Eragrostis curvula is a risky operation in many areas in South Africa due mainly to unfavourable weather conditions. Ensiling should therefore be considered as an alternative method for conserving the forage. The aim of this study was to determine if the use of a lactic acid bacterial inoculant when ensiling E. curvula is beneficial in terms of the fermentation dynamics during ensiling and the aerobic stability of the silage. The composition of the fresh chopped grass was 37.8+0.1% dry matter, 50.8±2.3% in vitro organic matter digestibility, 5.8±0.3% crude protein, and 79.2±0.34% neutral detergent fibre on a dry matter basis. Eragrostis curvula was ensiled in eighteen mini silos (three replications x six periods) for each of the control and inoculated treatments to follow the fermentation dynamics during ensiling. The pH of the control silage on day 1, 2, 4, 8, 16 and 122 of ensiling was 5.90, 5.08, 4.81, 4.76, 4.67 and 4.33, and that of the inoculated silage was 5.12, 4.34, 4.24, 4.30, 4.14 and 4.0 respectively. The ammonia nitrogen as percentage of total nitrogen of the control and inoculated silage differed (P<0.05) and was 14.4% and 10.9% respectively. The butyric acid content of the control and inoculated silage was 2.77% and 0.16% (P<0.05), and the lactic acid content 2.22% and 3.15% (P<0.05) respectively. Addition of the lactic acid bacterial inoculant to E. curvula at ensiling resulted in a more rapid drop in pH and better preservation compared to the control silage. Both silages were stable when exposed to air for five days.

Additional index words:

• Bacterial additive
• fermentation dynamics
• silage
• subtropical grass