Forages and Pastures Symposium: Silage Conservation Practices and Management-Effects on Forage Quality, Farm Profitability, and Feed Efficiency

摘要

Silage fermentation is an uncontrolled process affected by a multitudeof forage factors and management practices. In general, undesirablefermentations result in excessive losses of DM and energy, and can resultin an accumulation of unwanted end products that can negatively affectanimal performance. Various types of additives including enzymes,organic acids, and microbial inoculants have been used to maintain andimprove forage quality and improve aerobic stability during ensiling.For example, plant cell wall degrading enzymes have been added tosilage to improve digestibility. However, true pre-digestion of nutrientsin the silo is a questionable goal. Instead, the goal should be to improvethe digestibility of silage when it reaches the rumen and or intestine ofthe cow. Short chain organic acids such as propionic acid, potassiumsorbate, and sodium benzoate have good antifungal properties that cansuppress yeasts that are responsible for initiating aerobic spoilage. Variousmicrobial organisms have also been added to silages to improvefermentation. Originally classified as homolactic acid bacteria, suchorganisms were used to hasten silage fermentation and result in fermentationsthat recovered more DM and energy. Ironically, extremelyefficient fermentations can lead to poor aerobic stability of silages.Over a decade ago, the introduction of L. buchneri, a heterolactic acidbacteria, resulted in a paradigm shift because it was able to anaerobicallyconvert moderate amounts of lactic acid to acetic acid, which is highlyantifungal in nature and thus improved aerobic stability. Changes insilage fermentation and aerobic stability from the use of additives canhave direct and indirect effects on animal performance. This reviewwill give a history of various silage additives, their modes of action andeffects on animal production.