Abstract

A slatted concrete floor is commonly used as a draining floor in the passageways of cattle cubicle barns in Sweden as well as in many other countries. A high-performing slatted concrete floor will usually be dryer than a solid floor with the same surface structure. When using a slatted floor the width of the gap between slats, i.e. the slot, is always a compromise between the demand for good draining capacity for manure and urine, and the requirement that the animals should not be harmed by treading through or getting jammed in the slots. The slats should have a certain width to give sufficient support for the claw, reducing the contact pressure. Narrower slats and an increased void ratio will on the other hand, improve the drainage. In Sweden, the allowed dimensions of slatted floors are stated in the Animal Protection Regulation of the Animal Welfare Act. The aim of the investigation was to provide facts to be used in a review of the recommendations and regulations concerning slatted floors for cattle. In the investigation the effect of varying the dimensions of slats and slots on the contact pressure between claw and slatted floor was to be studied. The hypothesis was that the support for the claw could be increased and maximum pressures at sensitive points under the claw reduced for a given void ratio, by reducing the width of both slats and slots. The contact pressure between claw and floor was measured using a thin (0.1 mm) sensor unit (I-Scan®) connected to an analysing computer system (Nilsson, et.al., 2002). The sensor unit consisted of a matrix of individual pressure sensing locations also referred to as “sensels”. Two different measuring units were used, one with 3.2 sensels/cm2 and another with 15.4 sensels/cm2. The result of a measurement could be printed or displayed as a pressure distribution map on a monitor. After some initial field measurements on a dairy cow, a laboratory set up simulating a standing cow by use of a cadaver foot (length 105 mm, width 112 mm) was developed. Using this equipment, pressure maps for eight different claw positions on each of the following floor dimensions: 125/40, 125/30 (also representing 90/30), and 75/25 (slat width in mm / slot width in mm) and applying 1800 N vertical load were recorded and compared with a solid floor. For each claw position a comparison was made between the different floor designs, using the parameters mean contact pressure and maximum local contact pressure. The contact area of the claw was divided into four anatomically separate zones: the rear part of the sole, the abaxial wall bulb junction, the wall zone and the bulb. For each of the zones, the maximum local contact pressure was determined. Due to the high vulnerability of the rear part of the sole and the abaxial wall bulb junction, the recorded pressures for these two zones were considered most important in the subsequent evaluation of the result. The maximum local contact pressure of the sole and wall zone was recorded to be 2-3 times higher on a slatted concrete floor than on a solid concrete floor. For example the maximum contact pressure of the claw sole zone was 0.9 MPa on a solid floor and 2.4 MPa on a slatted (125/30) floor. The maximum local contact pressure measured under the wall zone reached 1.9 MPa on a solid concrete floor and 4.2 MPa on a slatted (75/25) concrete floor. When both slat and slot widths were reduced from 125/40 to 90/30 the support for the claw was improved (i.e. a lower mean contact pressure was recorded). The maximum local contact pressures on the rear part of the sole and the abaxial wall bulb junction were also lowered. When the widths of slats and slots were further reduced, this tendency was not so clear as an improved support and reduced maximum local contact pressure was only found in 50% of the claw positions applied in the test. The results of this investigation supported the assumption that previously prescribed dimensions of the slatted floor could not be regarded as an optimal compromise but allowed too wide slots and required unnecessarily wide slats. After a review the Swedish Animal Protection Regulation was changed to instead of prescribing slat and slot widths, today the void ratio constituted by slots and maximum slot width are stated to max. 28% and max. 35 mm respectively regarding grown-up dairy cows. In this way the manufacturers of these floorings have also been given more freedom in designing the floors

Published in

Book title: Proceedings of XVI CIGR World Congress
Publisher: VDI Verlag, Düsseldorf

Conference

XVI CIGR World Congress

SLU Authors

• Nilsson, Christer

  • Department of Agricultural Biosystems and Technology, Swedish University of Agricultural Sciences
    

• Ventorp, Michael

  • Department of Agricultural Biosystems and Technology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Animal and Dairy Science
Veterinary Science


Permanent link to this page (URI)

https://res.slu.se/id/publ/9107