Cow-Calf Commentary for Iowa Cattleman Magazine
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By Erika Lundy, Extension Beef Specialist and Beth Reynolds, Extension Beef Specialist
BMP’s for Small Grain Silages
Small grain annual forages are a valuable feed source for cattle, but harvest and storage practices directly impact feed value. The first step when harvesting an annual forage is to determine if the goal is to optimize quality or yield. As forages mature, yield and fiber increase while protein and digestibility decrease. Energy values of forages can decrease rapidly at a rate of 0.33-1% per day from the vegetative to reproductive stages. Most producers either target a late harvest after the seed head is present to maximize tonnage or an early harvest prior to seed head development to maximize quality. Harvesting at boot stage (seed head enclosed in uppermost leaf) optimizes energy and protein.
If you have a cool season annual in the ground now, you likely have a harvest plan; however, Mother Nature tends to dictate a need for flexibility. Grazing is the lowest cost harvest option but may be limited by factors such as fences or water availability. Haying is a great option to preserve feed, but cool days, damp nights, and humidity in Iowa tend to limit dry down. Because weather dictates harvest schedule and end product quality, many early spring forage harvests are made as silage or baleage.
Ensiling small grains provides a high-quality feed but does require proper management during harvest and in storage for optimum success.
1. Create an environment ideal for fermentation.
When ensiling annual forages, the basic principles for good fermentation hold true. The ensiling process simply creates an anaerobic environment ideal for bacteria to convert sugars and starches into lactic acid, reducing the pH enough to kill most bacteria, preventing further degradation, ultimately preserving the forage. The faster the pH drops, the better the end product. Utilizing an inoculant helps reduce the pH, enhance fermentation, and improve silage dry matter (DM) recovery. This also includes selecting a storage area that minimizes contamination from mud and manure, which often house undesired organisms that can impact fermentation and pose cattle health risks.
2. Ensile at the proper moisture content.
Harvesting at the right DM will make or break silage quality. If too wet, clostridia bacteria grow and cause spoilage and reduce the nutrient content due to insufficient pH drop to stop bacterial growth. In this scenario, bacteria utilize the nutrients, leaving fewer nutrients for the cow. Wet forage is also prone to mold when exposed to oxygen – the easiest characteristic to notice in spoiled silage. If too dry, heat damage can occur during ensiling, making valuable nutrients less digestible. Dry forages are also harder to pack, leading to more oxygen exposure. If targeting harvest to optimize quality, the forage will need time to wilt and reach a target moisture of approximately 65% (or 35% DM). If not wilted, small grains in boot stage tend to be around 80% moisture and will not ensile properly.
3. Get a good pack.
How silage is stored will influence the methods used to adequately pack forage. Packing is key to limiting oxygen and creating an anaerobic environment to achieve ideal fermentation. Research has indicated a direct relationship between packing density and subsequent DM waste. For small grains, stems are hollow, so a ⅜ - ½ inch chop length is recommended to ensure adequate packing density.
4. Cover the silage.
Covering the silage regardless of in a bag, bale sleeve, or bunker has a big impact on spoilage and storage waste. Corn silage data found that in the top 10 inches of an unsealed silage pile, DM waste was nearly 75%, and even 20-30 inches from the top, DM waste still reached 25%. A similar result would be expected for small grains.
5. Continue to manage silage appropriately at feedout.
Proper fermentation takes at least 30 days, so silage should not be fed during this time. When feeding, manage the silage face to minimize surface area exposed to air to reduce spoilage. Recommendations for how much of a silage face should be fed per day range from 8-12 inches at minimum. Ideally, silage would be stored on concrete or asphalt to prevent additional dirt from being picked up in the feeding process. If on an earthen floor, put practices in place to reduce the amount of soil picked up. Beyond not providing any nutrients to the cow, soil often contains bacteria that can lead to health issues and high levels of iron, which leads to mineral absorption imbalances.