Studies on the efficacy of a homofermentative lactic acid-producing bacterial inoculant and commercial, plant cell-wall-degrading enzyme mixtures to enhance the fermentation characteristics and aerobic stability of forages ensiled in temperate and tropical environments.

摘要

A series of studies were conducted to address the hypothesis that addition of silage additives (microbial inoculant or enzymes) improved the ensiling characteristics and aerobic stability of forages ensiled in temperate and tropical environments. In experiment one, a two year study was conducted to evaluate the effect of a microbial inoculant and a commercial enzyme preparation on the ensiling characteristics and aerobic stability of forage sorghum ensiled after 90 d of growth in temperate and tropical environments. In both locations, the microbial inoculant alone or in combination with enzyme enhanced the ensiling characteristics of forage sorghum as evidenced by a decrease in pH; an increase in lactic acid producing-bacterial population and lactic acid content. However, it had either a negative or no effect on the aerobic stability of the resulting silage. Results from experiment two indicated that inoculation also improved the fermentation characteristics, but did not reduce the aerobic deterioration of forage sorghum ensiled at 90 and 110 d of growth in a tropical environment. In experiment three, addition of a microbial inoculant plus enzymes had a positive effect on the fermentation characteristics of Johnson grass ensiled after two regrowth periods in a tropical environment. Findings from experiment four indicated that under in vitro conditions, cell-wall disappearance in forage sorghum and Johnson grass harvested in a tropical climate is increased when treated with enzyme application rates greater than recommended, but activity of the enzyme complex differed between forage species. In experiment five, the NDF disappearance from forage sorghum harvested in a temperate environment, treated with 5 commercial enzyme mixtures and applied at different rates were evaluated. Enzyme preparations differed in their ability to degrade the NDF fraction of forage sorghum, but application rates greater than recommended did not improve NDF disappearance. Results from experiment six indicated that addition of enzyme mixtures did not consistently affect the fermentation characteristics and carbohydrate content of forage sorghum ensiled in a temperate environment.