Robotic cleaners more than pass muster when it comes to scraping manure off slatted floor dairy barns.
While a slatted-floor dairy barn may offer manure storage and handling advantages, conventional methods used to keep cow alleys clean and dry on solid floors have serious shortcomings on slats. However, robotic slat cleaners have proven they are up to the job.
You need clean, dry cow alleys, regardless of whether you have slats or solid floors, to help maintain healthy hooves. Clean alleys also prevent cows from dragging manure onto their freestall beds, enhancing udder health.
Conventional automatic alley scrapers effectively push manure through slats, but involve cables or shuttle arms you have to maintain. To avoid creating a hazard to cow traffic, you have to install corner wheels or other drive mechanisms outside the cow area, adding to barn size. Robotic slat cleaners require no cables or drive wheels.
Another drawback to using automatic scrapers on slats is their inability to remove manure from crossovers and holding areas. Scraping them manually is your only option. Robotic slat cleaners can deal with crossovers and the large open areas commonly adjacent to robotic milking units.
To clean areas where manure builds up quickly -- next to the freestall curb, for example, you can program a robotic slat cleaner to scrape them more frequently. Slats, and subsequently your cows, stay cleaner.
Robotic slat cleaners are not intrusive, either. They do their job quietly and have little effect on cow behaviour. If they encounter a cow lying in the alley or other obstacle, they either try to go around it or try several times to push it out of the way. If the cow or obstacle still does not move, the robot shuts down and waits for you to resolve the issue.
Two types of robotic slat cleaners are currently used in Ontario, the JOZ-tech and the Lely Discovery. A third is available in Europe, manufactured by Royal De Boer.
Using a remote control, you walk the JOZ-tech slat cleaner around your barn to layout its initial route. An antenna on the unit picks up signals from a series of floor-mounted transponders for navigation. As it passes over each transponder, the unit receives a programmed command telling it to turn, continue in a straight line and so forth. As well, sensors in the scraper blade's wings keep the unit tracking along the stall curbs and walls. Rear wheels count revolutions to track distance travelled.
If the JOZ-tech is stopped or disorientated, you can steer it by remote control to the next transponder. It can readjust its route from that point.
The Lely Discovery navigates by a combination of a gyroscope, ultrasound device and wheel revolutions. The gyroscope maintains orientation. Ultrasound determines the distance from walls and curbs, and keeps the unit tracking along stall curbs. The wheel revolution count tracks distance.
A trial conducted in January 2010 in a robotic milking barn used Lely Discovery robotic slat cleaners. The robotic slat cleaner in one section of the barn was shut off for 24 hours and manure build-up in the alleys was collected and weighed. More importantly, the effect of the manure build-up and manure transferred to stall beds from the cows' hooves was measured.
To determine the amount of manure on the stall bed, a one-metre (399inch by 39-inch) square divided into a 10-by-l0 grid was placed on top of the stall bed. It was centred under a stall partition, and the squares containing any signs of manure totalled. A second one-metre-square grid was placed on the slatted floor next to the freestall curb, also centred on a partition. The manure within the square was collected and weighed. Data from four locations in one of the four interior rows was collected and averaged at each collection time.
Time-lapse video photography monitored cow behaviour before the robot was turned off, while it was inactive and when it was operating again.
Although trends could be observed in the barn during the data collection, insufficient samples were available to establish these trends statistically. The exception was one evening sampling around 6:30 p.m. with the robotic slat cleaner off and the next day at the same time after it was operating again, as shown in the graph. Squares contained double the amount of manure with the cleaner off than they did with it on. This seemed to indicate cows were indeed dragging more manure into their stall beds.
Stalls were maintained twice a day, early in the morning at about 7 a.m., and late in the evening at about 11 p.m. This explains why manure accumulation on the stall surface did not continue to increase after the 6:30 p.m. sampling. Since the cows were less active overnight, the stall surface was still cleaner at 6:30 a.m. the next morning, even though the amount of manure in the alley had increased significantly to 10 kilograms per square metre from four kilograms.
Manure build-up in the alleys was quite noticeable after 24 hours, and it would only continue to increase. However, with only four samples taken in the barn, this didn't always show on the data. When the scrapers were turned on again, they effectively cleaned the floor.
The time-lapse video photography showed the cows paid little attention to the robot unless it stopped for some reason. It then seemed to become a matter of great concern.
Manure builds up on alleys, especially next to the freestall curb, when it is not pushed through by a scraper. A manure build-up on the slatted floor eventually will lead to increased contamination from cows dragging manure into stalls with their feet and tails. A robotic unit can effectively keep slatted floors clean with little disturbance to your cows' normal behaviour.
House, H.K., 2010. The Why and How of Robotic Slat Cleaners, Proceedings of the First North American Conference on precision Dairy Management, Toronto, March 2-5, 2010.
This article first appeared in The Milk Producer Magazine, January, 2011.
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