Introduction
Properly designed freestall barns encourage cows to deposit manure in the alleyways between the rows of stalls. This keeps the bedding area for the cows cleaner and drier, which helps to keep the cows cleaner, drier and healthier.
Just as important as clean bedding for overall cow health and comfort, clean alleyways are necessary to reduce exposing cows to bacteria that can cause infections such mastitis and digital dermatitis. Keeping alleyways clean requires the periodic removal of manure that collects there.
Dairy producers have two main options for cleaning and removing the manure from their freestall barn alleyways, including:
- Flush
- Scrape or vacuum
Flush systems utilize water to remove the manure from the alleyways, whereas scrape and vacuum systems do not.
Flush Systems
Flush systems release a fast-moving flow of water from one end of the alley to a receiving gutter at the other end of the alley. As the water rushes through the alley, it collects the manure and transports it to the receiving gutter, which then conveys the liquid to a processing system or long-term storage.
Flush systems require a water supply, recycle system consisting of pumps and pipes, flush tanks, and sloped alleys to allow the water and manure to flow from one end of the barn to the other. The flush water must be released at a specific flow rate and velocity to effectively clean the alleys.
In a typical flush system with a 2-5% alley slope and a 10” curb, a flow velocity of 5 feet per second at a 3” depth is common. This may vary based on the bedding used. Consult a design professional to recommend the right combination of flow rate, slope and flow velocity.
The flush water does not have to be fresh water, but it does need to be capable of conveying solids. Recycled flush water can be used to flush the barns again and again using liquid-solid separation equipment, such as Rotary Drum Separators. This type of equipment removes the majority of the manure fibers from the liquid. Dairies can then choose to use the recovered liquid to supplement their flush water.
Because flush systems rely on water to clean the alleys, precautions should be taken to ensure the system can operate when the temperatures remain below freezing.
Scrape Systems
Scrape systems push or drag manure down the barn alley to a reception pit or cross gutter channel for conveyance to a reception tank via flush flume or horizontal auger. These systems can be manual or automatic. Manure can also be scraped directly into a reception tank.
Manual
Manual scrape systems can be as simple as a large-diameter tire cut in half, attached to a three-point hitch frame and then pushed by a skid steer through the alleys, or they can consist of a scraper blade pulled by a tractor. Scrapers should be kept in good condition to ensure manure is removed completely from the alleys and including the vertical surface of curbing.
Automatic
Automatic, mechanical scraping systems can consist of a scraper blade that spans the width of the barn alley and is pulled by a chain, cable or rope system that runs the length of the alley. The system, driven by electric motors, is programmed to travel up and down the alley at set timed intervals, pushing or dragging manure with it to the reception pit. When using alley scrapers with sand bedding, be sure to implement a rigorous maintenance program to ensure reliable operation.
Vacuum tanks
Vacuums tanks are a type of scrape system that collects the manure and transports it to a storage location or lagoon. These are available as vacuum scraper trucks or as trailed implements. Manure vacuums feature a scraper blade attached to a wheeled collecting tank. The scraper collects the manure across the width of the alley, and the vacuum system suctions the material collected by the scraper up into the tank. When the tank is full, it can be unloaded into the manure storage area. Vacuum tanks are especially well suited to large facilities where manure needs to be conveyed to a central processing facility.
Choosing the Best Freestall Cleaning Method
Every dairy has different manure handling needs, so there is not one best option when it comes to managing the manure in freestall barn alleyways. Each of the systems above has its pros and cons in terms of capital cost, labor, fuel, upkeep and more. Tractor scrape and vacuum systems require the use of an operator, whereas automatic scrapers and flush systems can be set to run at timed intervals or started with the push of a button. Flush systems and tractor scrape systems can see high energy and fuel costs, whereas automatic systems can have higher maintenance costs.
Barn design, available equipment and individual preference play a large role in which manure cleaning method offers the most value to a dairy.
In addition, the bedding type should be taken into account, as ultimately some of the bedding material will make its way into the alley. Finally, the dairy producer should consider their plans for the manure after it has been removed from the barn. All of these factors will help dictate what alley cleaning method is best for a dairy.
