For Wairarapa-based farmer and farm consultant Aidan Bichan, cow flow should be top of the mind when designing and maintaining the tracks on your dairy farm.
He identified cross-slope or camber as a particularly crucial aspect.
“As soon as the cross-slope gets over 8% cows will stop walking on it.”
If cows are walking only along the edges or middle of a track, it is likely the camber is too steep.
Some cross-slope is necessary to stop water from settling on the track surface. Industry guidelines suggest a target slope of 3-5% or one-in-30 to one-in-20.
Bends also have the potential to impact on cow flow, particularly sharper angles.
“The issue is if a cow walks around a right-angle bend, the minute she is around that corner her peripheral vision is picking up movement behind her on the race. They have a tendency to look back and that will cause them to pause or to slow down.”
Although cows are hardly moving at Formula One pace along the track, there is still the speed differential from the inside cow to the outside cow to consider.
“If the inside one is nearly stopped it then stops the ones further back.”
Simply rounding off the bend by starting a more gradual angle 5m back either way from the angle intersection will improve cow flow. If that is not physically possible, Bichan recommended making the race width slightly wider at the corner and trying to avoid having the sharp bend too close to the yard entrance.
In the case of a T-intersection, consideration could be given to taking the corners out and linking the two tracks with a feeder race, leaving a triangular “round-about” in the centre of the intersection.
Even the location of the paddock gate can impact on cow flow. Bichan said the gateway should be the full width of the track.
“The minute they come out of the paddock they are effectively on the race width so you don’t get them milling around or spreading out.”
Angled gates or V gates are ideal as they immediately remove the right-angle turn at the paddock exit, improving cow flow.
Any obstacle impinging on the track – a post, a water trough – will create a bottleneck effect, potentially adding extra minutes to the walk to the dairy.
All tracks need a well-constructed base layer that is shaped to encourage water shedding, and a wear surface. Each layer should be well compacted – hoof traffic will not do the job. What material to use for constructing tracks largely depends on what is locally available – rock in Northland is different to rock in Canterbury so a little research goes a long way.
Turf and topsoil should be removed otherwise it will compact and settle over time, affecting track stability.
With the shape of the base layer so important to track longevity, choice of material and how it is constructed is important. DairyNZ guidelines recommend the base is made up of layers up to 150mm deep, with each layer compacted before the next is added. Moist sub-surface soils, pit metal and rotten rock all make good bases. Choice will ultimately come down to cost and availability.
Bichan said he had also seen base layers constructed from river run gravel with a cap layer to bind and hold it together. In that situation, he recommended that the base layer be at least twice as deep as the largest rock diameter to prevent rocks breaking up through the surface.
“The material you use for your base can be a wee bit ugly as long as you’ve got a good top-coat and maintain it.”
Material for the wear surface will depend on location but common examples would be pumice, shell rock, crushed rock and lime.
The transition from track to yard can be a problem for cow flow and if poorly designed can contribute to lameness.
A nib wall – ideally 75mm high by 300mm wide – prevents stones from the track being kicked on to the concrete and stops wash-down water over-shooting. Bichan said the surfaces either side of the nib wall would ideally be the same height. Stepping up is not too bad but stepping down on to the concrete yard should be avoided.
“Stepping down, if you get small stones over there, then they are actually transferring more weight forward which can lead to injury.”
Using a post and rail fence in the approach to the yard and keeping power away for the last 10m or so is another recommendation. He said cows will not walk within .5m of a wire carrying current, effectively narrowing the track.
If there is a steep slope to get up to the dairy, well-designed steps will encourage good cow flow.
“From a cow point of view, if you are going up and down a slope, 10% is okay; 18-20% is okay going up, but you will have real issues coming down – they start slipping.”
Steps with a 100-150mm riser and 800-1000mm length should cause minimal interruption to the cows’ gait. Like all hard surfaces, it’s crucial that they be kept free of stones.
Good track maintenance becomes as important as good design and construction execution. Bichan said it should be on the winter to-do list, but if an area starts to deteriorate during the season, get on to the repairs.
“Do not wait for weeks and months to do something about it. A, it will get worse, and B, that is where your lameness and cow flow problems come from.”
• For more information about track design, check out the DairyNZ Milksmart website.
