Bacterial inoculants have been around for many years, but only recently have microbiologists been enlisted to improve on the original strains used in the industry. Today's advanced bacterial inoculants from DuPont Pioneer are capable of delivering higher levels of performance in protecting, preserving and enhancing the quality of silage during all phases of fermentation and feedout.
"In the world of bacterial inoculants, two key families of bacteria are used for silage crops, namely Lactobacillus plantarum and Lactobacillus buchneri," says Scott Dennis, Ph.D., DuPont Pioneer technical services and training manager, global forages. Extreme differences between each family of bacteria influence fermentation success and the ability to perform well under various environments.
Since 1978 DuPont Pioneer microbiologists have been working to understand how these differences can convert into improved and more cost-effective silage. To help measure these variations, microbiologists have developed scientific capabilities to screen and evaluate bacterial strain combinations and then test their performance in the field. This ongoing research and evaluation process has resulted in a continuous progression of new bacterial inoculants designed to be compatible with each major silage crop.
By studying bacterial strains that improve front-end fermentation, microbiologists discovered that some strains of bacteria were better for corn, others were more beneficial for alfalfa and still others paired well with grasses. Matching strains to crops helps drop the pH level more quickly and allows more efficient preservation of dry matter compared to previous inoculant formulations, allowing you to make the most out of your silage.
The basic function of an inoculant is to provide a fast, more efficient fermentation of silage. Quick fermentation preserves silage, maintains a high level of silage quality and results in decreased fermentation losses.
"The fermentation process is both biological and chemical in nature," Dennis states. "One of the most fundamental chemical activities is the production of organic acids that reduce silage pH, with lactic acid being the most important of these acids."
Lowering pH, while eliminating oxygen through good management practices prevents spoilage organisms from growing and stabilizes the silage. Only naturally occurring epiphytes produce organic acids that lower pH, that is, if a bacterial inoculant designed to enhance this process is not added. Although the end result may be an ensiled crop, increased shrink and energy loss are the high risks of allowing only natural bacteria to ferment the crop.
The initial fermentation process is best accomplished when homofermentative bacteria (L. plantarum) convert sugars (the energy source) to lactic acid. Unfortunately, naturally occurring lactic acid bacteria that help reduce the energy costs of preservation. These energy savings directly translate to reduced shrink and allow for greater dry matter recovery of 3-5 percent during the initial phase of fermentation (figure 1).
|Figure 1. Dry matter recovery of Pioneer brand inoculated and control silage in university studies, 1981-1995.
Written by Scott Dennis, Technical Services and Training Manager - Global Forages, DuPont Pioneer.
This article was originally published in August 2013 Progressive Forages e-newsletter, and is reproduced with their permission.