Courtney Halbach provides valuable insights on cow housing at the 2022 Dairy Research Foundation Symposium

The majority, or 80 per cent, of Wisconsin's dairy farming systems are in free stall facilities, with only 5pc intensely grazing.

This shift is due to extreme weather conditions throughout the year, from frigid winters to hot summers.

Now, Australian dairy farmers are looking to farm intensification as weather extremes take a toll on herd health and milk production.

However, the barn's design must be correct to reap the benefits.

Ms Halbach and her team have extensively studied best practices regarding farm intensification.

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One of the issues free stall facilities pose is increased rates of lameness.

Worldwide, there is an average lameness occurrence of 23pc within these systems, with the ideal target being 5pc.

In Wisconsin, lameness occurrence remains at 13pc.

"We have improvements to make, whether that's free stall facility design, better resting space, or better treatment protocols," Ms Halbach said.

"Some factors that reduce lameness come down to how the housing is set up, flooring, how the pen is designed and lameness detection and management."

Factors that help reduce lameness:

Dairy farmers in Wisconsin who have the most success house their cows in deep, loose, bedded stalls, with the majority using sand.

"We have two-row stall layouts, which maximises space at the feed bunk. When you add more rows into a pen, you have limited feed bunk space, and not all cows can eat simultaneously," Ms Halbach said.

"I advocate for good stalls to encourage resting and not standing in the pen while making it easier for her to have a more comfortable area when she is out of the pen."

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When removing a cow from a pasture system into a free stall facility, her time budget changes.

"Instead of spending more time standing up grazing, she has more free time," Ms Halbach said.

"We try and target that new time towards lying time."

Ms Halbach says farmers should aim to have their cows lying down for 12 hours a day.

"When you consider the other times she is standing in her stall, feeding or socialising in the alleyway, we only have three hours a day when she can leave the pen," she said.

"When designing facilities, we want to ensure the cow group is small enough, so whether you're milking two or three times a day, she is not out of the pen for more than three hours because we want to protect that 12 hours of rest.

"Once we start going over three hours out of the pen, her daily time budget for lying down will reduce, and then we see a detrimental effect in milk production and hoof health."

Ms Halbach advocates for sand or deep loose bedding for the cows' resting area.

"We want a deep, sand bed or manure solids because it gives the cow nice traction as she is getting up and down in the stall; it covers her hoof nicely, and there is no risk of slipping," she said.

"Sand also promotes longer lying bouts, meaning she is lying down for longer and not having to get up and down as much."

Data collected in 2010 from 205 cows across 16 free stall barns revealed that, on average, cows on sand lay down for 1.3 hours more than those on mattresses.

A study performed in 2016 examined herds across Canada and compared the time cows lay down on various surfaces, including waterbeds, concrete, geotextile mattresses, mats and sand.

"Sand won out with basically 12 hours of lying time per day, then geotextile mattresses and normal mattresses fell short at about 10.5 hours per day," Ms Halbach said.

"We can't understand how concrete outperformed a waterbed; we guessed the concrete had some straw on top of it.

"Waterbeds have not arrived in Australia yet, and let's keep it that way because they're not good for lying time or lameness.

"When a cow is laying down on a waterbed, it's a nice even surface, but as she gets up and down, her hoof goes into the stall surface as the water dissipates around it, so she's hitting the concrete underneath."

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The study also revealed more cows to be lame on mattresses versus deep, loose bedding, in addition to a significant increase in hock and knee lesions.

"One way to overcome some of these lesions in a mattress facility would be to have more bedding on top of the mattress surface," Ms Halbach said.

"Although I'm a huge proponent of deep, loose bedding, there are mattress herds that have equivalent rates of lameness to farms that use deep, loose bedding - and it comes down to management."

Ms Halbach and her team have come across many issues when it comes to free stall design, including insufficient resting space, poorly designed stall dividers, cows lying diagonally, short stall length, restrictive divider loops, front lunge and bob obstructions, brisket locator obstructions, and incorrect neck rail location.

"When a cow gets up, she does a lunge, moving forward about 0.3 metres, then bobs, her head goes out, up and down, and then she comes forward and up," Ms Halbach said.

"In an ideal situation, we would be able to accommodate the cow's natural rising behaviour, but we're going to have to compromise when we move her inside to a free stall facility because we cannot allow her to move forward.

"We will have to keep her within that box, but we want to design the free stall so she can still lunge and bob up and down as she rises."

Ms Halbach says if making adjustments to the resting space's width, make them to the length, and recommends no more than 5.2 metres for a head-to-head layout.

"Some of the research has looked at stall design and found there are longer resting times in wider stalls and less lameness, so make sure when the cow is laying down, she has enough space without the risk of injury from the dividers," she said.

A significant issue with free stall barns is keeping cows lying down in extremely hot weather without animals bunching.

Cows seek out what they consider the coolest part of the barn, commonly the darker areas, instead of resting in their stalls.

Many barns in Wisconsin are moving to mechanical ventilation to displace heat, humidity and toxic gases.

"We recommend orienting barns east to west because less light comes in through the side walls in a naturally ventilated barn versus a barn oriented north to south where you would have direct sunlight coming into the resting area from 6am to 6pm," Ms Halbach said.

"Where I'm from, a lot of our winds come from the north and south, so having more side walls open to the prevailing winds helps with naturally ventilated facilities."

Ventilation design must address the resting stall micro-environment, provide a good air exchange rate, work year-round and be cost-effective.

Research out of Canada revealed that mechanical ventilation or installing fans over the stalls increases milk production by 2.6kg to 4.2kg of milk solids per cow per day, which supports the need for a ventilation system over the resting space.

There are various types of ventilation systems for free stall facilities:

"We're looking at ways to enclose the barn, not only to make it darker to avoid bunching behaviour but to ensure consistency year-round," Ms Halbach said.

"Naturally ventilated facilities are the cheapest option most of the time. They have low maintenance requirements and low running costs for the fans.

"Tunnel systems are the most expensive, with our cross facilities being more economical for larger herds.

"The biggest downfall of naturally ventilated barns is having wind shadows (or buildings) within 30 metres of the barn, which can be a limiting factor."

Research shows when a cow lays down, her core body temperature rises and then goes down as she stands up because she has more surface area to dissipate heat.

Cows gain 0.5 degrees when lying down for an hour but only dissipate 0.25 degrees when standing.

This research led Ms Halbach and her colleagues to ask; how can we keep cows lying down in the stall for longer?

They compared three groups; One relying on only natural ventilation, the other with low-speed fans and the third with high-speed fans.

One treatment had the stalls receive 1 metre per second air speed in the resting area; the other treatment received 2m/second airspeed.

They found that fans preserved the cows' resting time.

"Both the high and low-speed treatments kept cows lying down about the same or more than the temperature increased in the pen; the fans also kept core body temperature the same and protected milk yield," Ms Halbach said.

"With no treatment, the cow's body temperature increased as it warmed up."

However, when the fans operated at more than 2.4m/second, the running costs increased significantly, which left the team to recommend operating the fans at 1-2m/second in the resting space.