In a grass based, rotational grazing system, good roadway infrastructure is essential to facilitate the efficient movement of the cows in a way that inflicts the least possible mechanical damage on their hooves. White line separation, white line penetration and sole bruising arise as a result of mechanical damage to the sole of the foot.
A recent Teagasc survey revealed significant infrastructure inadequacies. 55 farms were surveyed and 893 sections of roadway were examined. On average, roadways were 70% of the recommended width relative to herd size and only 4% were the optimal width (or greater) relative to herd size across all farms.
The researchers used an index-based scoring system to grade roadway surface condition, Index 1 being the poorest and Index 5 being the optimal surface condition. With regard to surface condition, the study found that just 14.2% of roadways were in optimal condition for animal movement.
Surface condition
- An Index based scoring system was created by Teagasc Moorepark researchers ranging from Index 1 (poorest) to 5 (optimal)
Index 1
Well-designed roadways with a good surface, that are maintained regularly, play a major part in the prevention and reduction of lameness in grazing dairy herds.
In these herds, most of the lameness problems seen are the result of mechanical damage or trauma to the part of the hoof that comes in contact with the ground surface. This mechanical damage can potentially result in white line damage and sole bruising.
- Roadways need to be sufficiently wide for the number of cows in the herd to allow them to move at their own pace, to avoid them being pressurised and stressed as they walk. Having the roadway sufficiently wide will allow the cows in the herd to move freely and unimpeded on the roadway. This helps to avoid the bumping and pushing which would otherwise occur. Such bumping and pushing, if it occurs, increases the risk of white line damage and sole bruising.
For a herd of 100 cows or less, the recommended width is 4 meters wide and add 0.5 metre extra for every 50 cows thereafter.
- A base layer 220-250mm deep of stone (50-100mm) overlaid with 60-80mm of 50mm down, with appropriate camber, and both layers rolled using a vibrating roller. As many roadways will also be subjected to tractor and trailer/slurry tanker traffic, a solid base is essential.
Ensure that the surface has a layer (c. 25 mm or 1 inch) of fine dressing material on top, is free of sharp stones and is in a good state of repair. This helps to reduce hoof trauma and white line damage associated with walking. Suitable material for top dressing can often be sourced locally and needs to be mechanically compacted.
The surface of the roadway needs to be higher than paddock. Otherwise, water will lodge on the roadway and erode the surface layer. Paddock gaps also need to be lower than the roadway to prevent water streaming from the paddock on to the roadway.
A camber slope from the middle of roadway to the edge is recommended. Allow for a 3% to 5% fall, but no greater than 8%. This slope will allow water on the roadway to get away and will be comfortable for cows to walk on. A slope steeper than 8% will be uncomfortable for cows to walk on and this will slow cow flow on the road.
Bends and junctions on the roadway need to be wider than the roadway. Cows tend to slow down at these points. Extra width will reduce this and facilitate good cow flow.
- Clear and trim trees and scrub along cow path allowing the roadway to stay as clean and dry as possible. Trees or high fences will prevent the roadway drying out.
- The electric fence should be placed such 0.5 metres form the roadway edge. The roadway verges need to be either removed or have drainage channels created at 5 metre intervals to enable water egress.
- Entrances to the paddocks should be wider than the roadway to reduce bottlenecks. It is also important to make sure there are no distractions on roadways like changes in the surface of the roadway, water troughs or other animals. These distractions will distract the cows and impede good cow flow.
- Keep the concrete yard free of stones by sweeping the areas where stones are most likely to be present such as the roadway-concrete junction. Where the concrete yard meets the cow roadway, build a nib wall to prevent stones being carried onto the concrete on the feet of the cows.
- Where there are steep slopes, e.g. entry/exit underpass, steps could be considered. Cows cope far better with steps than they do with slopes. Ideal rise is 100mm and a tread length of 1000mm works well. If space is limited, cows prefer shorter tread lengths rather than rises in excess of 100mm.
Use of Steps to Deal with Slopes
- To maintain and preserve roadways in good condition, avoid allowing heavy machinery traffic, such as silage trailers and slurry tankers to use the roadways. A tractor with a loaded slurry tanker could weigh in excess of 20 tonnes. If possible, drop the electric fence wires and direct this type of traffic through the paddocks. The use of an umbilical system to spread as much of farm slurry as possible will also reduce the potential for roadway damage.
- Prioritise the maintenance of the roadway that carries the most traffic, especially the roadways closest to the milking parlour.