The basic principles for making quality silage are harvesting the crop at the proper stage of maturity and moisture content (60 to 70 percent), chopping it finely, filling the silo rapidly, packing it tightly, and covering the silage with black plastic. These keys to success optimize silage yield and nutritional value while minimizing harvesting and storage losses. For example, covering bunker silos will dramatically reduce top spoilage by 65 to 85 percent.
There are a wide variety of silage additives and preservatives, ranging from organic acids and nutritive products to bacterial and enzyme inoculants sold as aids to fermentation. The two most popular types are microbial and non-protein nitrogen additives. Effective bacterial inoculants should stimulate lactic acid production and rapidly lower silage pH in order to preserve the forage dry matter and minimize fermentation losses. The most promising silage inoculants provide at least 100,000 live lactic acid-producing bacteria per gram of ensiled forage and consist of Lactobacillus and Pediococcus species, and/or Streptococcus faecium. These products produce small but significant reductions in silage dry matter losses and enhanced silage stability at feed-out. Silage crops that are difficult to ferment, such as alfalfa, show the greatest response to inoculants, while corn and high grain-containing sorghum silages show the least. Their economic benefit depends on the level of response, feed value of the silage, and cost of product and application.
The ammonia-containing additives—Cold-Flo NPN (anhydrous ammonia) and Pro-Sil (an ammonia, molasses, and mineral suspension)—are the only two corn silage additives currently approved by the Federal Drug Administration for both safety and effectiveness. Thus, extensive university research has been conducted with these products, and both are economically beneficial when properly used. These additives increase the crude protein of silage three to five percentage units, reduce mold and fungus growth, decrease protein degradation in the forage, and substantially increase the lactic acid content and silage stability in the silo and feed bunk. However, apparent dry matter recovery may be reduced somewhat, especially with overly wet silages.
