A herd’s potential for milk production is greatly influenced by the quality of forages we put in storage and how well we preserve them. We have two main goals as we move through the harvest season: Preserve enough feed for our cattle for the next year and preserve as many high-value nutrients as we can throughout the year in storage.
One of the most important things we can do to achieve these goals is to drive a rapid and efficient drop in pH once we put the feed in the silo, bunker or pile. This drop in pH prevents growth of undesired bacteria and preserves those valuable nutrients in the forage that will eventually be converted into meat or milk. As the fermentation process begins, lactic acid-producing bacteria consume sugars, starches and proteins and convert them to lactic acid. The lactic acid lowers the silage pH which, in turn, stops bacterial and yeast activity.
We want this up-front fermentation – and the subsequent drop in pH – to occur as quickly as possible. The longer it takes, the more nutrients get consumed by bacteria and are unavailable to cattle. Consider a haylage that is 40% dry matter (DM) and valued at $92 per ton (as fed). For every 1% increase in DM loss, you lose almost $1 worth of feed per as-fed ton. That means, in a 5,000-ton bunk, every 1% increase in shrink is a loss of $5,000. Shrink on a pile can easily vary by more than 20%. This can have a real impact on true income over feed costs. Shrink means we pay more for a less valuable feedstuff.
Harvesting and packing to preserve nutrients
Driving a rapid drop in silage pH starts in the field. It’s critical to harvest forage at the proper DM content.
When a silage is too wet, detrimental bacteria (such as clostridia) can dominate the fermentation. These bacteria consume high-quality nutrients (lactic acid, protein, etc.) that we want to feed to our cows, and they produce harmful metabolic end products, such as biogenic amines.
When a silage is too dry, it does not pack as well and allows for greater oxygen penetration, bacterial growth and less efficient lactic acid production. During the aerobic phase of ensiling – the phase in which oxygen is still present in the silo prior to fermentation – bacteria consume oxygen and silage nutrients and produce heat, carbon dioxide and water. Once oxygen is eliminated, and the silo enters the anaerobic phase of ensiling, the activity of most bacteria and yeast, specifically those that cause spoilage and degrade feed quality, ceases.
We want to create as dense of a pile as we can to help exclude oxygen and facilitate pH drop. For haylage, target a density greater than 16 pounds of DM per cubic foot. For corn silage, target a density of at least 20 pounds of DM per cubic foot. This requires a combination of proper packing tractor weight and the right amount of time spent packing. Your forage consultant can help you determine whether your packing strategy will help you meet your silage density goals.
Challenges of delayed sealing
The other key to eliminating oxygen is to seal the bunker or pile as quickly as possible so that oxygen does not continue to infiltrate the silage mass. Even on a well-packed pile, when feed is not covered quickly, oxygen can penetrate the surface several feet, especially in the outer edges of piles. As previously mentioned, as long as oxygen is present in the feed, bacteria will continue consuming the nutrients we want for our cows. They also steal the sugars and proteins that fuel lactic acid-producing bacteria, thus slowing lactic acid production and the subsequent pH drop. This often leads to a higher silage pH, loss of silage DM and valuable nutrients, and a less stable pile that we are relying on to support income over feed costs and maximize milk production throughout the next year. Using a quality oxygen barrier plastic can reduce DM loss in the top 3 feet by 40% compared to an uncovered pile and by 10% compared to a conventional 5-mil plastic cover and tires.
Sealing a bunker or pile immediately is easier said than done. Frequently, bunkers and piles cannot get covered right away due to difficult or dangerous weather conditions. High winds, rain and thunderstorms all make for increased difficulty and danger when trying to cover a completed pile. Furthermore, loss of daylight and a fatigued harvest crew can make for a dangerous situation. Protecting the safety of all farm team members is always the most important task in forage harvest and storage.
A recent Vita Plus trial shows that another tool in the silage production toolbox can help preserve nutrients – even in cases of delayed sealing.
In this trial, triticale with 26% DM was ensiled in bucket silos, replicating a difficult ensiling scenario. One set of the bucket silos was sealed immediately and the other set remained open for 24 hours before being sealed. In addition, silages were untreated or treated with an up-front fermenter, which contains Lactobacillus plantarum MTD/1, a lactic acid-producing inoculant bacterium. All silos were opened after 124 days and analyzed.
As shown in Figures 1 and 2, delayed sealing of the untreated silage led to a significantly higher pH and a significantly higher level of butyric acid. The higher pH makes the silage more prone to spoilage, with less sugar and starch available for cows to utilize. Butyric acid is not palatable and is highly likely to reduce intake. Furthermore, spoilage microorganisms may also produce biogenic amines, such as putrescine and cadaverine, creating silage that may be dangerous to feed to cows.
In contrast, the trial showed that silage inoculated with a high-quality up-front fermenter had a lower pH and no butyric acid – even when sealing was delayed.
Maximizing homegrown nutrients is key to improving income over feed costs. Invest the time to create a forage harvest and storage plan that will allow you to preserve as many nutrients as possible while also limiting potential spoilage. Take advantage of technologies proven to improve DM recovery and reduce spoilage, even when conditions are not ideal. And, finally, remember that keeping your team safe is the most important goal.
