Animal health: Calf sheds play key role in producing healthy calves

“We learned a lot on that trip. All the sheds were insulated to cope with the extremes in temperatures and they had a lot of mechanical ventilation.”

However, he decided that for his situation he wanted a shed which had natural ventilation and calves were not all sharing the same air space.

After seeing a more suitable example of a calf shed in Holland, viewed on YouTube, he designed an open-fronted shed, with 10 pens, which could each accommodate 10 calves.

The pens were fitted with gates and locking calf yokes at the front for ease of cleaning and feeding, and measure 6.7 metres by 4.6m.

The yokes meant Mr Williams was able to keep an eye on whether or not individual calves were drinking, so that problems were picked up quickly.

The shed has a pitched roof, 95cm at the back and 3.2m at the front, and staggered panels at the back mean air enters at the rear and exits through the front.

The walls were clad with insulation boards and, importantly for Mr Williams, there was no nose-to-nose contact between the pens.

Mr Williams said: “We put a lot of thought into the shed and although it is not perfect, it is a vast improvement. We wanted to make things easier and more efficient, but also cut pneumonia incidence.”

He explained antibiotic use had been reduced significantly, and he was only needing to treat about 15 20 per cent of calves now, with most problems arising in the first two weeks the calves are on-farm.

“We have little control of where the calves are coming from and, for the first fortnight, we still get some pneumonia, but after that period they do settle down.”

VET VIEW

VET Sean Hughes, of Shropshire Farm Vets, said the biggest problem when designing a calf shed was that the calves were constantly changing during the rearing process and the shed needed to be adequate for all stages.

He added ventilation, moisture and humidity were some of the main considerations when assessing the suitability of calf housing.

“You need clean air to get rid of moisture, dust, ammonia and bacteria,” he said.

He added that smoke bombs were a good way of tracking the movement of air flow in a shed.

“An adequately ventilated building should clear of smoke in a few minutes.”

He also said humidity levels should be below 75 per cent, as above that bugs were able to survive for longer in the environment.

“Humidity is all about how much moisture is in the air at any one time. If there is lots of moisture, the calf will have to use a lot of its own energy to keep itself warm.”

RISK FACTORS

IN data collected and analysed by AHDB, the biggest risk factor for pneumonia was the season in which the calves arrived on-farm.

Sarah Pick, of AHDB, explained this research involved a group of calf rearers in Herefordshire and involved more than 3,000 calf records collected in 2017 and 2018.

She said: “There was a peak in pneumonia incidence between November and April, and we saw higher growth rates of 1.05kg/day in spring and summer, compared to 0.95kg/day in autumn and winter.”

She said this increase in pneumonia could be down to higher stocking rates during winter months, as well as the range of health issues that come with housing at this time.

Pneumonia was also higher among calves fed once-a-day, but Ms Pick said it was difficult to decide whether this difference was just down to feeding policy or was also linked to housing with the two often inextricably linked.

Sourcing

Breed and sourcing of calves also played a role, with the percentage of calves being treated for pneumonia rising to almost 70 per cent when batches were sourced from more than 10 sources.

When arriving from fewer than three sources, pneumonia incidence was about 20 per cent.

Almost 60 per cent of dairy bull calves were treated for pneumonia, which was higher than any other breed category, she said.

Ms Pick said: “This could be due to a lack of hybrid vigour, but also could be because of their perceived lower market value, which means they might not be getting the same initial treatment as dairy heifer calves.”