Submitted to: Proceedings of the US Dairy Forage Research Center Information Conference
Publication Type: Proceedings
Publication Acceptance Date: September 16, 1996
Publication Date: N/A
Technical Abstract: Ensiling is a principal means of storing forages for livestock. The dominant additives used to guarantee a good fermentation are inoculants, which supply lactic acid bacteria to the crop. When inoculants are successful, fermentation and the lowering of pH occur more rapidly, final silage pH, acetic acid and ethanol concentrations are reduced, and lactic acid content is increased. These shifts in fermentation improve dry matter recovery but can have mixed effects on the aerobic stability of silages. Improvements in animal performance are modest but greater than might be expected (2 to 4% on average). In reviewing published studies, inoculants have been successful in improving fermentation in approximately two-thirds of all trials whereas animal performance has been improved in 25 to 40% of the trials. The primary reason for inoculant failure appears to be a high natural population of lactic acid bacteria that either prevents the inoculant bacteria from getting established or does an equally good job of fermentation. Other possible factors are low crop sugar content, unsuitability of the inoculant for the crop to which it is applied, or inhibition of the inoculant bacteria by bacteriophage. Research on alfalfa has found that the natural lactic acid bacterial population can be predicted by factors that a farmer can measure: wilting time, average air temperature during wilting, crop moisture content at harvest and rainfall during wilting. This allows farmers to restrict inoculant use to those periods when the inoculant is most likely to succeed. Further research is needed to improve the aerobic stability provided by these products and to understand the mechanisms by which animal performance is enhanced.