At its best, the process of ensiling should retain as many valuable nutrients and dry matter (DM) from the original forage crop as possible. Once the crop is harvested, that’s as good as the silage quality will ever get.
Even in excellent operations, unfortunate things happen to influence silage quality. For example, the weather doesn’t always cooperate to hit the perfect harvest window or equipment breaks at the most inopportune moment. Even in less-than-ideal scenarios, there are options for dealing with unhygienic silage.
Prevent the worst-case scenario
The most effective way to deal with spoiled silage is to prevent it from happening in the first place. To help, take a hard look at your silage management practices. My colleagues have provided more detail about critical areas in the previous two articles in this series.
Develop contingency plans – plan B, C and even D – for any unforeseen adverse event. It is better to have these plans in place and not need them than for an adverse event to occur and have to scramble to determine the next steps. Time is of the essence at harvest. Take time now to list adverse events that have been experienced in the past or may happen in the future. Then, plan what you would do when it happens again because it probably will.
Yeast is public enemy No. 1 for silage that is already in the silo. Yeast contamination is the primary driver for lack of silage preservation and decreasing aerobic stability. One study showed that a differential temperature of greater than 9 degrees Fahrenheit between the core (16 inches deep) and the surface (6 inches) depth corresponded to a 5-log difference in yeast count. That is a huge difference – a 100,000 times difference.
Ideally, acknowledge when harvest conditions are less than ideal and have a plan to counter the conditions. In these cases, it can pay to use a combination forage inoculant, such as those including Lactobacillus buchneri NCIMB 40788 applied at 400,000 CFU per gram of silage or 600,000 CFU per gram of high-moisture corn (HMC). It has been uniquely reviewed by the U.S. Food and Drug Administration and allowed to claim improved aerobic stability, which makes it ideal for scenarios where a challenging fermentation and risk of aerobic instability are anticipated at feedout.
Another source of contamination is the tires on trucks and tractors during harvest or feedout. Undesirable substances can be tracked into the silage. This can lead to a host of issues depending on what is introduced into the silage. Everything that can be done should be done to maintain the hygienic quality of the feed being preserved.
Evaluate silage color and smell
Silage color and smell can indicate potential fermentation problems. It is important to determine the nature of the challenge before determining the next step
Odor Color Cause
Vinegar Yellowish Acetic acid production (Bacillus, enterobacteria, heterolactic bacteria and possibly clostridia)
Alcohol Normal Ethanol production (Yeast)
Sharp Sweet Normal Propionic acid production
Rancid Butter Greenish Butyric acid production (Clostridium)
Caramel/Tobacco Dark brown to black High temperature, heat damaged
Darkened silage usually indicates heating. These silages have the highest potential for opportunistic microbes such as molds and are typically unacceptable feeds. Mold growth can cause palatability issues and reduce animal performance. Plus, some molds can produce mycotoxins under certain circumstances. Wild yeast fermenting creates the optimal conditions for mold growth in silage.
A clostridial fermentation will likely result when alfalfa, grass or cereal grain silages are harvested at higher-than-recommended moisture levels and ensiled without a good inoculant. This leads to the creation and accumulation of butyric and acetic acids, and biogenic amines and ammonia.
Studies in ruminally and abomasally cannulated steers show that dry matter intake (DMI) decreased by more than 25% as the levels of putrescine and cadaverine, two biogenic amines, increased in the diet.
Throw it out
Most often, visibly moldy silage is not redeemable, and producers would do better to just throw it out. Field case reports show that feeding even small amounts of spoiled silage can lead to reproduction and respiratory problems, herd health issues, reduced feed intake and decreased production.
A Kansas State University study in beef cattle showed including even 25% spoiled silage (as part of a 90% silage ration) had negative effects on nutrient digestibility, and the integrity of the forage mat in the rumen was destroyed.
Dilute and feed to a less sensitive group
As a rule, dilution is not the solution to pollution. Choosing to feed spoiled silage to highly productive herds will inevitably result in lowered feed take and a drop in production. When fed unpalatable silage, cattle will not eat as much. Plus, what they do eat will be lower in important nutrients.
However, small amounts of silage can be fed to a less productive group, such as non-lactating, younger cattle. Do not feed it to dry cows. Take care to use good face management techniques to ensure additional spoilage is not occurring during feedout.
Support the rumen
There are still opportunities to recover your herd’s health and productivity even if spoiled silage made it to the feed bunk.
First, stop feeding the silage and obtain a forage analysis. There may be occasions that merit a more detailed wet chemistry fermentation profile analysis along with mold and yeast counts. This can help you understand if there are mycotoxins present and the specific type.
Next, anticipate rumen challenges in the herd, including Sub Acute Ruminal Acidosis (SARA). Consider adding a rumen-specific active dry yeast to optimize rumen function and support lower gut health.
High-performing herds are very similar to elite athletes. A bad meal or two can knock them off the top of their game. It is much easier to create high-quality silage and enjoy the benefits of health and productivity year-round.