Rats pose a significant threat to stored hay, transforming bales into nesting sites and potential food sources. This infestation results in substantial economic loss through spoilage and contamination, rendering entire stacks unusable. The presence of rat feces and urine introduces serious health hazards, carrying pathogens that can cause diseases like Leptospirosis and Salmonellosis in both livestock and humans. Effective rat control around hay storage requires a layered strategy that focuses first on environmental manipulation, then on physical exclusion, and finally on targeted removal.
Modifying the Storage Environment
The first defense against rat infestation is making the storage area fundamentally unappealing to rodents. Hay bales should never be stacked directly on the ground, as this allows moisture wicking and provides instant, hidden access to the core of the stack. Elevating the hay supply on wooden pallets, rails, or thick wooden beams improves air circulation and prevents ground-level harborage. This creates a visual and physical barrier that rats are reluctant to cross.
Proper spacing is important for discouraging rat activity. Keep hay stacks at least 18 inches away from walls and other vertical surfaces. This gap disrupts the rats’ natural tendency to travel along edges, often called a “rat runway.” Maintaining this perimeter allows for easy inspection and trapping while limiting the rodents’ preferred, covered travel routes.
Impeccable cleanliness must be maintained in the immediate vicinity of the hay supply. Any spilled grain, feed, or trash provides an alternative food source that can support a thriving rat population. Managing the exterior vegetation is an effective deterrent. A three-foot-wide, weed-free zone around the storage building foundation discourages rats from burrowing and setting up exterior nests that provide a staging area for interior entry.
Structural Exclusion and Barriers
Physical barriers form the second layer of defense, blocking entry points into the storage structure. Rats can squeeze through openings as small as a half-inch, while mice require only a quarter-inch gap; therefore, even small cracks must be sealed. Openings around utility lines, vents, or foundation cracks should be filled with gnaw-proof materials like concrete, galvanized sheet metal, or steel wool tightly packed and sealed with high-quality caulk.
For covering larger openings, such as ventilation screens or gaps around stacked hay, hardware cloth is necessary. The mesh size should be no larger than one-half inch to exclude rats, and the material should be 19-gauge or heavier galvanized steel to resist gnawing. Rats can easily chew through softer materials, including plastic, wood, and standard window screening.
Doors are a common, overlooked entry point and require specific reinforcement to prevent access. Installing a metal kick plate or flashing along the bottom edge of wooden doors prevents rats from gnawing their way in. A rodent-proof door sweep, often lined with woven stainless steel mesh, should be installed to eliminate the gap between the door and the threshold, ensuring a tight seal that cannot be chewed through.
Active Population Control Methods
When rats bypass preventative measures, active removal via trapping is the safest and most effective method, especially near livestock feed. Snap traps are recommended as they provide an instant kill and allow for clean disposal, minimizing contamination risk. Place traps directly in confirmed “runways,” perpendicular to the wall with the trigger side facing the wall, to intercept traveling rodents.
For high-activity areas, multiple traps should be set close together, often in pairs or groups of three, to maximize success. Electronic traps that deliver a high-voltage shock are also an effective, humane, and clean option for indoor use. If the rats are exhibiting neophobia (fear of new objects), traps should be placed unset and baited for several days to allow the rodents to become accustomed to the presence of the device before setting them.
Rodenticides are generally discouraged for use near stored hay intended for livestock consumption due to the significant risks involved. The primary concern is contamination of the feed itself, but secondary poisoning also poses a threat to barn cats, dogs, and predatory wildlife. If chemicals are deemed necessary, only first-generation anticoagulant rodenticides (FGARs) or non-anticoagulant options should be considered. They must be secured within tamper-resistant bait stations located well away from the hay.