Effects of Flooring on Lameness in Dairy Cattle
Published on Wed, 11/04/2009 - 11:38am
Lameness constitutes a significant burden on dairy herds. Severe mobility problems may force the producer to cull potentially productive cows. Less severe impairments can lead to delayed estrous, difficulty with natural breeding, lower milk yield, shortened lactation and weight loss. These issues directly impact profitability, and failure to recognize the underlying factor may again cause the dairyman to cull cows with good potential for productivity.
Many nutritional, environmental, and to a limited extent genetic factors can play a role in lameness. The type of flooring material utilized as well as its design and maintenance can contribute significantly to the prevention (or development) of foot problems.
Ninety percent of lameness cases involve the foot, with 90% of those cases occurring in a back foot. A basic familiarity with hoof anatomy is helpful for understanding these pathologies.
The bovine foot contains many tendons, nerves and blood vessels. These structures are protected on the front and sides by a hard outer casing, the hoof horn. A less rigid sole covers the underside. Both structures are made of keratin, the same substance that forms bovine hair and horns as well as human hair and fingernails. The junction between the horn-forming tissue of the hoof wall and the sole is called the white line. Posterior to the sole is the bulb (heel), which consists of soft, rubbery horn.
Anatomically sound feet and legs distribute the animal’s weight fairly evenly over the hoof wall and sole, with the outside claw of the rear foot bearing somewhat more weight than the inside. The bulb normally does not bear significant weight.
Common Flooring-Associated Foot Conditions
Hooves and soles are constantly being worn down during the cow’s daily activity. New growth to replace lost or damaged tissue is also an ongoing process. Repetitive compression and relaxation of soft tissues during weight bearing enhances circulation in the feet.
Foot breakdowns can result when anatomic irregularities, disease or environmental factors weaken the hoof or cause an imbalance between growth and wear. Frequent weight bearing on hard surfaces can stimulate hoof overgrowth, predisposing to white line disease and ulcers. Abrasive surfaces can promote toe wear leading to thinning of the soles and increased vulnerability to toe lesions. Excessive exposure to moisture, particularly in the form of urine and/or manure slurry, can soften the external structures of the foot, increasing wear while promoting dermatitis and heel horn erosions.
An ulcer results when erosion through the sole exposes underlying soft tissue or bone. Most are painful. The outer aspect of the rear foot is most commonly affected. Ulcers are frequently associated with laminitis, but excessive mechanical stress and overexposure to moisture also promote ulceration with or without underlying laminitis.
The terms ulcer and abscess are often used interchangeably, but this is incorrect. An abscess is an infection beneath the skin that normally results in pain and swelling. Ulcers promote abscess formation by creating an opportunity for bacteria to invade exposed tissues. Since the infection responsible for the abscess did not create the ulcer simple infection control measures, while often necessary, do not ensure resolution of the ulcer or address the underlying causative factor(s).
White line disease is generally believed to result when bacteria or fungi invade the junction between the hard tissues of the hoof horn and the adjacent soft tissues. Mechanical stress due to hoof overgrowth leads to traction on the white line, predisposing to this condition. As with ulcers, infection-control measures may improve the worst symptoms but are unlikely to address any underlying mechanical problem.
Thin soles and toe lesions result when hoof wear exceeds growth. Prolonged exposure to abrasive surfaces can promote excessive wear. Overly hard hooves are prone to cracking, particularly if they are also thin. Exceedingly soft soles, on the other hand, are more susceptible to wear, and thus to excessive thinness. Thin soles and toes are likely more vulnerable to ulcers, punctures and other injuries.
Digital dermatitis (heel warts) is believed to be primarily an infectious condition. Anything affecting the integrity of the skin, including pronounced wear and overexposure to moisture, can increase vulnerability to these lesions.
Heel erosions become readily apparent when bacteria and debris invade cracks in the bulb and leads to the formation of new sole material in the underlying space. The result is two layers of sole with a contaminated pouch in between. Again, however, the infectious process normally begins only after abnormal mechanical stress and/or prolonged exposure to moisture initiates breakdown of the bulb.
On Your Feet, Soldier!
A cow with access to a comfortable stall in a satisfactory environment will spend 10-14 hours lying down each day. Logically, the other 10 or more hours will be spent standing or walking, making flooring an important consideration for the entire barn.
Excessively smooth flooring will afford the cow poor footing, particularly when wet. Rough and unyielding surfaces may cause discomfort while promoting excessive wear and foot lesions. Either circumstance will cause cows to avoid weight bearing and thus not fully avail themselves of feed or water. Lack of exercise may also diminish circulation in the foot, which delays healing of existing problems and predisposes the cow to further injury.
Different flooring types may be appropriate in different sections of the barn. Cows are likely to spend considerable time near feed bunks and water troughs. Assuming adequate space is provided animals should normally be fairly relaxed at these locations. Comfort may be a priority over traction in this scenario, with the understanding that some degree of both is required.
Cows may be more rushed near loading shoots and milking platforms. Some may be less than cooperative with their handlers’ agenda at these locations! Where running and frequent changes of direction may occur, providing a surface with more traction may be appropriate even at the expense of greater abrasiveness. Use of epoxy floor coatings or non-slip aggregates, while cost-prohibitive or undesirable for entire buildings, might make sense in these limited areas.
There are multiple flooring options the dairyman can utilize to enhance cow footing while controlling wear. Producers must consider utility, cost, and durability when choosing among these options.
The vast majority of dairy barn floors are made all or partially of concrete. The material is relatively inexpensive, versatile, durable and widely available.
A concrete floor with a smooth finishes offers cows little traction, particularly when wet. Falls and reluctance to walk are a common result. Floors textured with a broom or using excessive aggregate are highly abrasive, a problem also exacerbated by a wet surface.
Most experts recommend adding grooves to a concrete floor to enhance traction while avoiding excessive abrasiveness. Recommendations regarding spacing, pattern and depth of the grooves vary and research to support these recommendations is limited. Options include creating parallel grooves using a float at the time of floor construction, sawing parallel grooves into a previously poured floor, or stamping a floor using a metallic grid during curing. Utilizing an experienced contractor is beneficial in each case.
Even properly finished grooved floors may be abrasive at first. Dragging the floor with concrete blocks or a metal bar prior to occupancy may help to eliminate some of the rough edges.
Floor slope is also an important consideration. A level floor will likely have high and low spots, allowing fluid and debris to pool and making cleaning a challenge. Excessively sloped floors, on the other hand, provide poor footing. Slightly different grades are appropriate in different sections of a barn, but in general a 1.5-3% slope is appropriate. Slopes greater than 6% should be avoided.
Slatted floors can be purchased commercially in precast sections. Slats provide texture to the floor while affording drainage and thus eliminating problems with manure slurry. Studies have noted that cows prefer solid floors or more yielding surfaces to slates and that some foot problems actually increase with this flooring type. However, the incidence of dermatitis is lower on these floors and slipping is likely reduced. There is no consensus as to the net effect on foot health.
Reclaimed Rubber Belting
Large rubber conveyer belts are utilized in many industries, primarily mining. Several companies recycle used belts for marketing to the dairy industry. These belts provide soft flooring preferred by cows over concrete. Such belts are most frequently utilized near feed bunks.
Rubber belts can be slippery when wet. As with concrete, grooves can be added to belts to enhance footing, although this can make scraping manure more challenging. Many barns using rubber belts utilize a flush system for cleaning.
Poured concrete floors can be designed with recessed areas to receive belts, although this increases construction costs. Alternately, belts can simply be fastened on top of existing slabs. In either case belts are subject to buckling and failure near the fastener in response to repeated torsion from cow foot traffic and manure-handling equipment. Debris may collect under loose belts.
Most belts are reinforced with internal wires. These wires can protrude through worn belts and cause punctures as well as break off and become lodged in cows’ feet.
Rubber Flooring Mats or Rolls
Several companies offer rubber flooring products specifically for the dairy industry. Most are textured to prevent slippage. Unlike recycled belts, individual manufactured products offer a consistent level of compressibility and do not contain reinforcement wires. As with recycled mats, however, many commercial products are prone to failure near fasteners over time and can present some manure-handling challenges. Although most studies have demonstrated at least some benefit in terms of decreased lameness and increased cow comfort with rubber floors, these products are not inexpensive.
Lameness in dairy cattle can lead to significant direct and indirect expense for producers. Appropriate foot care is essential to minimize this expense. Providing a clean, dry and comfortable floor can help to minimize foot problems, which are the leading cause of lameness. Dairymen should give careful consideration to flooring type and condition when evaluating their existing facilities or undertaking new construction.
Information for this article was derived from materials provided online by Iowa State University Extension (www.extension.iastate.edu) and Louisiana State University Ag Center Extension (www.agctr.lsu.edu), University of Florida IFAS Extension (www.edis.ifas.ufl.edu), The Iowa Beef Center (www.iowabeefcenter.org), and the Merck Veterinary Manual (www.merckvetmanual.com)