Cold weather and alfalfa silage: Strategies for successful fermentation
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EmailLow temperatures can be an obstacle when it comes to haylage production, but with optimal management practices, these challenges can be effectively addressed.
As many dairies across the state get ready to harvest haylage, the unpredictable Michigan weather can shift into cold spells. This not only impacts our plans for BBQ but can also present unique challenges for forage preservation.
Recent studies discuss the importance of addressing cold weather challenges in silage production. For instance, research indicates that low temperatures can delay fermentation and alter microbial communities within the silage, leading to reduced quality. This risk can start to increase when the temperature drops below 60 degrees Fahrenheit. Cold weather can significantly impact the fermentation process, affecting silage quality and, ultimately, herd nutrition. Understanding these effects and implementing appropriate strategies is crucial for maintaining high-quality forage.
Optimal silage fermentation occurs between 68 F and 86 F. When temperatures fall below 50 F, the activity of beneficial lactic acid bacteria slows considerably. These bacteria are crucial for a rapid pH drop, which ultimately drives the rapid preservation of the forage thus limiting the loss of nutritional value. When their activity is slowed, it can lead to delayed pH reduction, increasing risk of spoilage and greater protein degradation due to undesirable microbial activity.
Although we can maintain some control, harvesting hay or alfalfa for haylage should be driven by the maturity of the forage. In other words, if the forage is ready to meet your goals for quality, the delay of the harvest results in a loss of nutritional value. Suboptimal conditions increase the importance of being on point with the basics: Moisture content, exposure after harvest and optimal storage.
When harvesting alfalfa for haylage, the recommendation is to harvest at a moisture level between 60% and 65% (35-40% dry matter). Moisture levels outside this range can hinder fermentation, especially in cold conditions. Overly wet forage may lead to clostridial fermentation, while excessively dry forage can result in inadequate packing and oxygen infiltration.
Once the forage is cut, there is an additional consideration when temperature is suboptimal, and wilting can potentially take longer due to reduced evaporation rates. Once the forage has achieved optimal moisture, the goal should be to focus on reducing the time between chopping and storing. For wet haylage, the exposure to oxygen allows the continual respiration of the plant which reduces the sugars content in the forage. Sugar content is key as it fuels the fermentation process; bacteria metabolize it to lactic acid, rapidly reducing the pH. As bacterial efficacy is reduced in cold weather, reducing the sugar content will aggravate the optimal fermentation process for preservation. MSU Extension recommends that once the proper moisture is achieved the forage should be chopped, stored and covered as quickly as possible in order to limit oxygen exposure and continual degradation.
Whether using bunkers, bags or wrapped bales, ensure the forage is packed tightly and sealed adequately. Oxygen exposure is particularly detrimental when fermentation is slow, as is common in cold weather. Proper sealing minimizes aerobic spoilage and preserves feed quality. Ensure that there are no leaks or tears in the plastic and if using bunks or drive-over piles, use tires with sidewalls close together to weigh down the plastic and avoid air pockets.
After ensuring the basics are addressed, the next step in your cold weather harvest toolbox could be the use of proven forage inoculants. In general, inoculants provide beneficial bacterial populations to the forage to optimize and accelerate the fermentation process, reducing the loss of nutritional value. Although inoculation is typically beneficial under most conditions, its benefit will become especially important when harvesting in cold weather when the natural bacteria on the forage is negatively impacted by temperature. There are a variety of commercially available inoculants that are science-based and proven to help in achieving the goals of preservation, but when temperature is under 68 F it’s important to select inoculants that are proven to be tolerant to colder conditions. Studies underscore the effectiveness of lactic acid bacteria such as L. Plantarum and L. Buchnerii in enhancing the fermentation of alfalfa haylage under low-temperature conditions. These inoculants help initiate rapid fermentation, reducing the window for spoilage organisms to proliferate. Be sure to ask your agronomist, nutritionist or forage supplier how the recommended product works under low temperature conditions to help you make the right decision. You can also reach out to MSU Extension through the Ask Extension platform where experts can provide science-based information to address questions.
Cold weather presents obstacles during forage harvest when it comes to haylage production, but with optimal management practices, these challenges can be effectively addressed. Staying focused on the basics (moisture, exposure and storage) can go a long way in reducing the adverse effects of the lower temperatures during the preservation process. Additionally, selecting appropriate, research-based cold tolerant inoculants can provide producers with an important safeguard to maintain forage quality.
For additional information or guidance on forage management in cold conditions, contact your local MSU Extension office or visit our MSU Extension Forage website.