Inhibitors of Fermentation in Silage: A Comprehensive Guide
Table of Contents
Silage, a vital feed source for livestock, undergoes a meticulous fermentation process to ensure its quality and nutrient content. One crucial aspect of this process involves the use of inhibitors of fermentation, substances that play a pivotal role in enhancing the stability and preservation of silage. In this article, we explore the different inhibitors of fermentation and their effects on silage quality.
Propionic Acid: A Potent Antimycotic Agent
Propionic acid stands out as a powerful inhibitor of fermentation due to its remarkable antimycotic activity. This property becomes even more potent as the pH levels decrease, making it an ideal candidate for enhancing the aerobic stability of corn silage in instances where the pH is low. Notably, the addition of significant amounts of propionic acid (approximately 1 to 2% of the dry matter) has been shown to improve the aerobic stability of silage. However, it’s important to note that excessive levels of propionic acid can sometimes hinder the fermentation process due to its high acidity. To address this challenge, acid salts such as calcium, sodium, and ammonium propionate have been utilized as effective alternatives.
Nutrient Additives: Ammonia and Urea
Ammonia, as a nutrient additive, brings several advantages to the ensiling process. Its introduction results in the cost-effective addition of crude protein, extended bunk life during feeding, reduced molding and heating during ensiling, and decreased protein degradation within the silo. An equally significant nutrient additive is urea, which is employed to provide a source of economical crude protein in corn silage. While urea’s potential to improve bunk life and decrease proteolysis remains under scrutiny, it has shown promise for enhancing silage quality.
Ammonia, in particular, serves as a catalyst for reducing plant proteolysis. Although ammonia generally stimulates fermentation, the ensiling process is prolonged due to the buffering effect of ammonia. This results in higher overall acid production, which has inconsistent effects on dry matter recovery.
Application of ammonia can occur at various points, such as the chopper, blower, bagger, or bunk. Additionally, molasses and minerals can be combined with these solutions to enhance their effectiveness. Anhydrous ammonia application, at a rate of around 1 kg of N per 100 kg of forage dry matter, can elevate crude protein content from approximately 8% to 12.5% on a dry matter basis. To ensure safe application, it’s recommended to utilize water-ammonia or molasses-ammonia mixes rather than anhydrous ammonia.
Safety in Silage Storage: A Critical Consideration
Ensuring safety during silage storage involves addressing the formation of nitrogen oxides when nitrates degrade in the ensiling process. The result is the production of nitrogen dioxide (NO2), commonly known as “silo gas.” This gas can be highly toxic to both humans and animals when its concentration exceeds 10 to 25 ppm. It’s essential to assume the presence of both carbon dioxide (CO2) and nitrogen dioxide (NO2) in tower silos. Even if exposure isn’t fatal, respiratory tract damage can occur, and relapses are frequent after apparent recovery.
The nature of NO2, which is heavier than air, sometimes makes it visibly evident within silos or around silo openings. The majority of NO2 is released from the silage within the first week of fermentation, with peak production occurring two to three days after ensiling. After the material has been in the silo for over 10 days, NO2 production typically diminishes.
Fermentation in Silage: Controlling Fermentation | A Delicate Balance
Silage fermentation is a process that demands careful control to ensure optimal nutrient preservation. Silage additives come into play to enhance the ensiling process, which can be divided into four distinct phases:
- The Oxygen-Rich Phase: After forage is chopped and packed into the silo, the presence of oxygen persists. Plant respiration and enzyme activity continue until oxygen is depleted. Excessive oxygen can lead to unwanted protein breakdown, heating, and the growth of yeasts and moulds. Eliminating excess oxygen requires swift packing, uniform distribution of forage, and proper chopping.
- Anaerobic Microbial Activity: Under anaerobic conditions, microbial activity dominates this phase. Fermentation hinges on the types of microorganisms present, the available substrate for microbial growth (soluble carbohydrates), and crop moisture. Lactic acid-producing bacteria (LAB) utilise water-soluble carbohydrates to produce lactic acid, which is the primary acid responsible for lowering silage pH. However, if the pH doesn’t drop rapidly, microorganisms like Enterobacteria and Clostridia can lead to undesirable fermentations.
- Lack of Oxygen, Optimal Conditions: In the third phase, the absence of oxygen prevents the growth of yeast and moulds, while the low pH prevents the growth of most bacteria. Under these conditions, silage can be stored for extended periods.
- Feeding Out and Exposure to Air: The fourth stage involves feeding out the silage and exposing it to air. Proper management during feed-out and the use of airtight silos help prevent aerobic spoilage.
Fermentation End Products: Insights from Alfalfa and Corn Silages
To understand the impact of fermentation on silage, let’s examine common fermentation end products in two types of silages:
| Item | Alfalfa Silage | Corn Silage |
|---|---|---|
| pH | 4.3-4.5 | 3.7-4.2 |
| Lactic Acid (%) | 7-8 | 4-7 |
| Acetic Acid (%) | 2-3 | 1-3 |
| Propionic Acid (%) | <0.5 | <0.1 |
| Butyric Acid (%) | <0.5 | 0 |
| Ethanol (%) | 0.5 – 1.0 | 1-3 |
| Ammonia-N (%) | 10-15 | 5 – 7 |
Conclusion: Fermentation in Silage
Inhibitors of fermentation are essential tools in the realm of silage production. Their strategic deployment ensures not only enhanced preservation but also the preservation of nutrient content and overall feed quality. By understanding the science behind these inhibitors, farmers can make informed decisions to create silage that supports healthy and productive livestock.
FAQs: About Fermentation in Silage
- Q: Are inhibitors of fermentation safe for animals?
- A: Yes, when used correctly, inhibitors of fermentation contribute to the overall safety and quality of silage.
- Q: How does ammonia affect the ensiling process?
- A: Ammonia enhances silage by providing a cost-effective source of crude protein, extending bunk life, and reducing molding and heating during ensiling.
- Q: What are the phases of silage fermentation?
- A: Silage fermentation involves four phases: oxygen-rich phase, anaerobic microbial activity, lack of oxygen
For more detials, Contact Us.
