WINTER BONUS MAGAZINE 2026

Processing Effective processing ensures that maize kernels are adequately broken so that nutrients, particularly starch, are available for digestion. If kernels are not properly processed, they may pass through the animal undigested, reducing feed efficiency. Farmers can prevent this by ensuring kernels are properly cracked, ideally split in half, and by slightly increasing cutting height to reduce indigestible fibre content. For the farmer, improved digestibility means cows can extract more nutrients and energy from the feed, leading to increased productivity and higher milk yield. Compaction and oxygen removal Once harvested, the focus shifts to compaction, which is essential for removing oxygen from the silage mass. Oxygen is one of the main causes of nutrient loss, as it allows plant respiration and aerobic microorganisms to continue consuming valuable sugars. Effective compaction reduces porosity, limits oxygen penetration, and creates the anaerobic conditions necessary for proper fermentation. This is achieved by spreading the forage in thin layers and packing continuously with heavy machinery to reach a high density. Poor compaction results in air pockets within the silage, leading to heating, dry matter losses, and reduced feed quality. The fermentation process Following compaction, preservation of the silage depends on rapid and efficient fermentation under anaerobic conditions, where a range of organic acids is produced that directly influence feed quality, cow health, and ultimately milk production. Lactic acid is the most important, as it rapidly lowers the pH, stabilises the silage, and preserves valuable nutrients, resulting in highly palatable feed that drives higher dry matter intake (DMI). Increased intake provides more energy to the cow, directly supporting higher milk yield as well as improved butterfat and protein levels. Moderate levels of acetic acid play a supportive role by improving aerobic stability, inhibiting the growth of yeasts and moulds, and reducing heating and spoilage during feed-out, which helps maintain consistent intake and stable milk production; however, excessive levels can reduce palatability and depress intake. Propionic acid also contributes to controlling mould growth and maintaining feed stability, ensuring cows receive consistent, good-quality feed, which is essential for steady milk output. Figure 2: Timeline of pH reduction during the four phases of maize silage fermentation In contrast, when fermentation conditions are not optimal, such as when silage is too wet, too dry, or poorly compacted, undesirable fermentation pathways dominate, leading to the production of butyric acid and high levels of ammonia. Butyric acid is particularly harmful, producing foul-smelling, unpalatable silage that significantly reduces intake and can contribute to metabolic disorders such as ketosis, negatively affecting rumen efficiency and energy utilisation. High ammonia levels indicate excessive protein breakdown, reducing the nutritional value of the silage and limiting milk protein production. The combined effect of reduced intake, poorer nutrient availability, and metabolic stress, results in a clear decline in both milk yield and milk quality. For the dairy farmer, this not only means lower production per cow, but also increased feed wastage and the need for costly supplementation. In practical terms, well-managed fermentation maximises intake and milk production, while poor fermentation directly limits cow performance, health, and overall farm profitability. Sealing and storage protocols Proper sealing and storage are equally critical in maintaining silage quality. Once the silo is filled, it must be sealed immediately to prevent oxygen from entering. 1. High-quality covers : Plastic covers, properly secured with weights such as tires, help maintain anaerobic conditions throughout storage. 2. Advanced films: Oxygen-barrier films can further reduce oxygen infiltration and dry matter losses. 3. Spoilage risks: Poor sealing or damaged covers allow oxygen to enter the silage, encouraging the growth of moulds and yeasts, particularly in the upper layers of the silo. www.agribonus.co.za Winter 2026 BONUS 89