Friday, March 29, 2024

Doing the good yards

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Rectangular or round – it’s a debate that’s being raging for years and, for the design committee of the new Southern Dairy Hub, one that has caused hours of discussion.
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Southern Dairy Hub director and design committee member Kevin Ferris, who has eight dairies including those he sharemilks, is a believer in round yards. All of his dairies have them, even the three herringbones. However, the scientists on the design committee favoured a rectangular yard for the farm’s rotary, believing it was more efficient.

“The hub is going to have a round yard,” Ferris said. 

“That was our final decision. After looking at research farm dairies in the North Island and dairies on commercial farms throughout the country, we’ve decided on a round yard.

“There are pluses and minuses for both but at the end of the day round yards are more cow-friendly and more farmer-friendly and that really is the bottom line. We look after the cows and we look after the people.”

The hub will have up to four herds for research purposes and multiple backing gates to keep the herds separate were easier to work and cheaper to install in a round yard than in a rectangular yard.

Washdown was also simpler because the lowest point in a circular yard was the centre whereas in a rectangular yard it was usually at the end furthest away from the dairy.

“It’s a lot further to wash all the muck. With a circular yard you just have to wash it to the centre,” Ferris said.

Multiple entry points and entry points far enough back from the bridge would aid cow flow.

“If you have the entry point too close to the bridge in a circular yard, most of the cows walk into the yard and face the wrong way and then have to be turned around compared to a rectangular yard where they walk in from the end and walk up towards the yard.

“Also in a circular yard the cows on the edge of the yard are moving at a different rate to the cows at the centre so that can cause problems.

“But if you have staff that know how to work the backing gates properly and the entry points at the right places then none of this is a problem.”

Ferris said it was important to get dairies designed as best as they could be, even down to the gate latches.

“If you get the little things wrong, even little things like gate latches and people have to struggle each day to open and shut that gate, then other things can go south very quickly.”

Yard size can be decided by working out the maximum number of cows the yard will have to hold, adjusting it for the number that will be in the dairy, then multiplying it by 1.2m2 for Jersey cows and 1.5m2 for large Friesians. For example, a 400-cow crossbred herd to be milked in a 40-bail rotary would require a 432m2 yard (1.2m2 x (400 – 40).

Yard surfaces should be non-slip for both cows and people but excessive abrasiveness could cause lameness.

Wet concrete can be stamped, trowelled, rolled or brushed with a heavy broom as it dries to create a non-slip surface. Hardened concrete can be scabbed or cut.

A yard too rough for cows’ feet can be smoothed by dragging a heavy concrete block across it several times and then washing it.

The strength of the concrete should be between 25 MPa (megapascals) and 32 MPa. Weaker concrete (25 MPa) wears because of the action of the cows feet and remains rough but stronger concrete can become slippery as the cows wear away the surface layer, creating a smooth, polished finish that will then have to be scrabbled to stop it becoming dangerous.

In circular yards the slope is usually towards the drain in the centre of the yard but in rectangular yards, the slope can be used to coax cows to walk forward into the dairy.

Cows are more comfortable standing forward on an upward slope and a 3% to 4% (1:30 to 1:25) slope towards the dairy encourages them to face the dairy and not to turn around while waiting to be milked. 

However, slopes greater than 4% increase concrete wear and cause too much weight to be transferred to the cows’ back legs, which can cause injury. For entrances that are greater than 5% (1:20) steps should be built.

The yard slope should fall towards the drainage points and rectangular yards for large herds sometimes have these in the centre so effluent doesn’t have to be washed to the far end.

Although this can work well for cleaning, cows can be reluctant to step on or over the grating of the drain or an area where water is lying and cow flow into the dairy can then become a problem. 

Lameness can also happen as cows are pushed by those behind them to step over the drain.

The edges of all yards need a kerb at a minimum height of 150mm to stop effluent washing on to undrained areas. Kerbs should be protected by pipe rails so cows don’t get pushed on to them.

In some areas during summer it might be necessary to suspend shade cloth over a yard to provide shade for cows waiting to be milked, to prevent heat stress.

For more information go to: www.dairynz.co.nz/milking/dairy-design/yard-and-handling-facilities/yard-design/

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