Larger dairy units and the introduction of automatic milking systems will increasingly emphasize the importance of reducing risks for lameness, since immobile animals will not fit into a system with low labor input. Despite much effort to reduce lameness worldwide, treatments of lameness do not seem to subside. Previously there was a general assumption that the cow’s feet environment was of primary concern for the outcome of lameness. Hygiene was the final message to prevent infectious claw diseases. At that time, herd problems with digital dermatitis (DD) exploded and were blamed as a cause for most lameness problems.

Today we know that despite these undisputable DD problems, a great deal of lameness is caused by laminitis-related claw horn lesions such as sole ulcer, sole and white line hemorrhages, white line disease, etc. For these diseases the physical environment or traumatic claw lesions are of highest importance. Our experience in the past clearly showed that solid rubber mats in tiestalls reduced the occurrence of laminitis-related sole hemorrhages and sole ulcers, but it was not possible to determine if this was an effect of standing on a soft surface, lying more due to the improved rubber mat comfort, or a combination of the two.

New research allowed us to test rubber mats on cows’ walking comfort and preferences, as well as their influence on claw conformation and claw disease. The main elements were to study locomotion patterns, cow preferences, hygiene, claw conformation and horn quality, weight distribution between and within claws, lameness and claw disorders.

Laminitis
Laminitis is the underlying cause of many claw disorders and lameness. Laminitis is the name of a complex of claw disorders which we can see in the foot and that often shortens the longevity, reduces the production capacity and causes suffering for animals. Laminitis refers to a non-infectious inflammation of the claw corium harming the horn production.

Laminitis has both a metabolic (nutritional) and bio-mechanical (traumatic) background. It is believed that the metabolic component loosens the attachment of the claw bone inside the horn capsule. Provided that the metabolic load is the same, exposure of the cow’s feet to hard flooring and improper loading triggers the process.

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Due to loading and counter-pressure from the ground, the corium between the claw bone and sole horn is squeezed and blood and blood serum leak out and are absorbed in the growing horn. These hemorrhagic spots are weak points for further environmental damage and are identified as sole and white line hemorrhages, sole ulcers, double soles and white line disease.

Flooring in dairy barns
In all types of dairy barns, concrete has been the material used for constructing floors. Concrete is a very good material in many aspects such as engineering, durability and cost. However, concrete as a material is not a given formula because of many differences in compounds and quality; as well, concrete wears and changes with time.

There is no doubt that concrete will continue to be the base for floor construction in the future. But there are also many different materials to lay on top of concrete for different purposes. Examples are different mats and mattresses for freestalls and rubber mats for alleyways, with the purpose to improve cow comfort and performance.

Tracing cows with footprints
A new method where the animals’ footprints were tracked, measured and analyzed was developed, and locomotion patterns for different flooring types were tested in different dairy herds. In our first experiment, the cows were tested on five surfaces: solid concrete, slatted concrete, solid rubber mats, slatted rubber mats and packed sand. For each surface (except for sand) a 32.8 feet-long (10 meter), straight walkway was prepared.

After milking, the cows were kept in a group and individually walked through each surface in one test run. The measurements of the footprints were made manually from four consecutive strides on each floor type, using a ruler and an angle-meter. The time of passing each test course was measured to estimate the walking speed of the cow. Cows’ locomotion score was also assessed.

The results showed that healthy cows walked more efficiently on rubber mats than on concrete floors, and both stride and step length increased significantly compared to a concrete surface. The gait pattern was worst for most parameters on the relatively worn concrete slatted floors, while natural sand and rubber mats gave the best figures.

The speed of cows was lowest on the slatted concrete floor, in comparison with the other floor types. On the concrete slatted floor the strides were shortened and the overlap was considerably “more negative” than on the other surfaces. In comparison with slatted concrete, the cows increased their speed, prolonged their strides and steps, and had a higher overlap when walking on the slatted rubber flooring.

Cows took longer strides on solid rubber mats than on slatted rubber mats. Other trackway elements did not differ significantly between the two types of rubber flooring.

Although no severely lame cows were present, most cow trackway parameters were more pronounced by lameness. Moderately lame (score 2, arched back when walking and standing) cows walked slower than non-lame (score 0) cows and had a shorter stride and a shorter step length than non-lame and mildly lame (score 1; arched back walking) animals.

Moderately lame cows also had a larger negative overlap than non-lame cows. Cows with mild lameness had a positive overlap in contrast to non-lame and moderately lame cows, but did not differ significantly from non-lame cows in speed or stride and step length. Thus, slatted concrete resulted in the greatest impairment of gait of slightly lame cows, but there was only a very small, nonsignificant difference between lame and non-lame cows on sand and rubber flooring.

In a second experiment, the floor’s slipping resistance was judged by the same trackway analysis. Slatted concrete and five solid floors (smooth concrete, diamond grooved concrete, hexagon stamped concrete, mastic asphalt and solid rubber mat) of different material and friction were tested after three weeks of accommodation. The results showed that all the solid floors had a better locomotion result than the slatted concrete flooring. Steps were also less asymmetrical on solid floors.

The mastic asphalt surface demonstrated significantly higher static and dynamic friction than concrete floors, and elastic rubber mats revealed the highest friction properties. The rubber mats resulted in the longest stride and step length. Strides and steps on smooth and grooved concrete were shorter and closer to that of slatted concrete floor than those obtained on the other floors.

Step asymmetry was expressed most on the smooth concrete floor and least on the rubber mats. There was no evidence of flooring influencing step abduction.

Long-term influence of different flooring systems
In a three-year project, 150 heifers were studied from approximately 12 months of age throughout their first lactation in a commercial dairy herd. Claw conformation, locomotion and claw and leg lesions were regularly studied at trimming when housed and at pasture. During the winter housing period before calving, heifers were allocated to either concrete freestalls (hard) or deep straw bedding (soft), both with a scraped concrete alley.

Heifers on hard flooring had higher growth and wear rate of claws and a higher prevalence of sole hemorrhages and dermatitis than heifers on deep straw bedding. Heifers on hard flooring thereby developed more overgrown claws and heel horn erosion. Leg lesions in the heifers were only observed in the freestall system.

All heifers were grazed for four months from May, and at trimming in September no differences between groups regarding any observed traits were seen. Before their first calving in autumn they were all housed in a freestall system with soft mattresses. Half the animals from each group from the previous heifer housing period were allocated to either concrete slats or rubber slatted flooring in the alleys. After a four-month lactation period during the winter housing season, the most prominent finding was 3.6 times higher risk for lameness, 2.2 times higher risk for sole hemorrhage and sole ulcer and 2.8 times higher risk for white line hemorrhage in animals on concrete slats compared to those on rubber slats.

Although not significant, animals coming from deep straw bedding had a higher prevalence of sole hemorrhages and sole ulcers than those from the freestalls, especially when moved to the concrete slats compared to rubber slats. Soft floors are beneficial for cows’ claw and leg health, but heifers changing from a soft to a hard flooring system need a longer acclimatization period and trimming of overgrown claws.

What is the cow’s opinion on flooring?
The preference for hard (concrete) and soft (rubber) flooring was tested group-wise in a 300-cow commercial organic dairy herd. Firstly, the preference for soft, extra soft or solid concrete flooring was tested when cows were standing in the holding pen before milking. Secondly, the walkway from the parlor to the cubicles was alternatively equipped with slatted or solid rubber mats or with slatted concrete flooring.

The holding pen and walkway were divided lengthwise in two equal parts and each floor type was tested during four days on the left, following by four days on the right side of the holding pen and the walkway, respectively. Control treatments were made with concrete flooring on both sides. All behavior was recorded by video. In the holding pen, the number of cows on each floor was assessed every seventh minute. On the walkway to the cubicles after milking, the number of cows walking on respective floor type or changing between them was assessed continuously from the video.

Dairy cows preferred to stand and walk on rubber flooring compared to concrete flooring. A slightly higher preference for extra soft rubber compared to soft rubber when standing and for solid rubber compared to slatted rubber flooring when walking was observed. When the space per cow increased in the holding pen during milking, the proportion of cows choosing rubber mats versus concrete floor increased.

With more than 75.35 square feet (7 square meters) per cow, the preference for soft and very soft rubber mats versus concrete flooring was similar and over 70 percent in comparison to the concrete control. The number of animals choosing soft flooring versus concrete on the walkway increased gradually over time, and on the fourth test day it reached almost 80 percent preference for solid and slatted rubber mats.

Disadvantages of rubber flooring
Certainly, rubber flooring is a more expensive solution, but the question is if there is a return of investment in reduced lameness, decreased treatment cost, better fertility and increased feeding activity; this not including animal well-being. From our experiments we could see that claw wear was much less on rubber than on a more abrasive flooring like new casted concrete or mastic asphalt.

However, claws seem to adapt to different floors such that less wear is compensated by less growth, and more wear from an abrasive flooring results in more growth. Thus there may be no dramatic differences between old concrete flooring with low abrasiveness and rubber flooring.

It is probable that the higher incidence of heel horn erosion on deep straw bedding only is an effect of lower turnover rate of claw horn growth compared to freestalls because the occurrence of dermatitis of the claws was higher in the freestall system. The higher occurrence of heel horn erosion on slatted rubber mats was associated with less draining area compared to the concrete slatted flooring. This problem can be solved by scraping of the floors.

General reflections
Cow behavior can influence lameness indirectly. Foot lesions are related to prolonged standing and walking connected with higher activity due to social interactions and these themselves are related to overcrowding and poor cubicle comfort. Claw injuries are influenced by over-exposure to hard, abrasive and unhygienic floors, while leg injuries, such as hock and carpus injuries, are related to difficulty in lying and rising and prolonged uncomfortable lying on hard, abrasive and unhygienic floors in the stalls. PD

References omitted due to space but are available upon request by sending an email to editor@progressivedairy.com .

— Excerpts from 2010 WCDS Advances in Dairy Technology proceedings

Christer Bergsten