Preparing for the 2022 corn harvest
As summer comes to an end, soon dairies will begin harvesting corn silage from 2022 corn crops. During harvest many decisions that affect nutritive value and operations over the next year will be made in a short, stressful time span. To optimize silage production and nutritional value, some key factors should be considered before and during harvest. It’s also recommended that producers have group discussions on harvest with nutritionists, agronomists, and crop consultants.
Harvest timing and considerations
Monitoring plant maturity is key for maximizing corn silage nutritive value and ensuring proper fermentation. Harvesting too early or too late may compromise these aspects and negatively impact resulting silage, so harvest timing is critical. Harvesting corn forage within 33 to 37 percent dry matter and kernels with 2/3 to 3/4 milk line helps account for variation and ensure that silage will have adequate starch content and water for fermentation. Harvesting plants too early may decrease starch concentrations in corn silage, making producers more reliant on purchased starch sources. However, harvesting corn plants too late reduces the digestibility of fiber, as indigestible fractions accumulate, and starch, as kernels become harder. Greater plant maturity may also limit silage fermentation, since more mature plants with a greater dry matter harms bacterial growth.
After the desired plant maturity is reached, producers should also maximize kernel breakage during harvest. Broken kernels increase the accessibility of starch to bacteria in the rumen of dairy cows, increasing starch digestibility. Whole or mostly whole kernels are less accessible since rumen bacteria cannot bypass the hull of corn kernels. The proportion of broken kernels and degree of kernel breakage are determined by roll gap settings of the kernel processer in harvesters. Generally, a smaller roll gap setting yields more broken kernels. However, the rollers of a kernel processer can wear over time, so roller gap settings may not represent the true gap between rollers. Producers should monitor kernel breakage throughout the harvest, especially overtime or during changes to the harvester and fields.
Packing corn silage is vital to fermentation and nutrient preservation. Silage fermentation requires the removal of oxygen from the forage mass, so anaerobic bacteria can dominate and curb undesirable fermentation. Good packing density helps exclude oxygen from the forage mass and can jumpstart desirable silage fermentation. Packing density depends on many factors, including forage layer thickness, tractor weight, forage delivery rate, forage particle size, and forage dry matter concentration. Producer planning prior to harvest can ensure adequate tractor weight is available and help coordinate appropriate layer thickness and the rate of forage delivery.
Forage particle size and forage dry matter concentration can be controlled during harvest and directly impact packing density. Forage with long, coarse particles or with a high dry matter make packing more difficult and may increase the amount of oxygen left in the silo after sealing. It is critical for producers to make sure forage is not too dry and that forage particle size will not interfere with packing. If these problems are unavoidable, special care should be taken to make sure silage is packed as densely as possible and silage should be monitored during feeding for undesirable fermentation.
Another important aspect during harvest is maintaining worker safety and avoiding practices that may cause safety concerns in the future. First, it is important to remind workers during harvest to keep track of their surroundings and ensure they know where equipment and others are relative to them. Harvest requires the coordination of many large pieces of equipment and increases traffic around the dairy, increasing the potential for accidents.
Another thing to consider is how silo dimensions will affect silo safety during feed out. Although it may be tempting to make tall silos to maximize space, this increases the likelihood that the silo face may collapse when workers remove material, even when using silage facers. So, producers should be conscious of silo size and make sure enough space is available to make silos appropriately sized without being too tall.
Luiz Ferraretto is the ruminant nutrition extension specialist, University of Wisconsin-Madison, Division of Extension while Diepersloot is a graduate research assistant, University of Wisconsin-Madison