Advice on minimising disease risks in market-bought calves

Calf rearers buying stock from the mart should accept that the disease risk will be high and plan with their vet to create a farm-specific approach to calf health.

There are no blanket recommendations for managing bought-in calves.

But rather than waiting for sickness to occur, it is more cost-effective to work out a strategy for treatment and prevention, says vet Graeme Fowlie of Meadows Vets in Aberdeenshire.

See also: Mycoplasma bovis bigger issue than thought, research shows

Simply giving calves a week to settle on-farm to reduce their stress levels before beginning a pneumonia vaccination programme will not work, Graeme points out.

Success depends on the farm’s pathogens, what the calves might bring, and the vaccine products available, he says.

Infection pressure

In addition, the high level of infection pressure – created by a lot of calves from multiple farms mixing together – combined with high stress levels and poor immunity will mitigate any protection.

Handling, travelling distances and changes in feed all adding up to make these calves more susceptible to infection and disease, at this time of year, is almost inevitable, he explains.

Working with a calf-rearing client last winter, Graeme discovered eight common pneumonia pathogens in nasal swabs taken from poorly calves that had been sourced from market.

“We found four viruses and four bacteria, and all eight pathogens were identified in a pooled sample from just five calves.

“No wonder calves were getting ill with so much disease challenge,” he says. (See “Vaccination plan for 150-calf enterprise”.)

While the farmer’s stockmanship skills helped his calves to survive, he was struggling to get them fully better.

Once they reached six months of age, animals were “growing respectably, but not reaching their potential”, says Graeme.

“Cattle [that have recovered from pneumonia] eat the same, but feed efficiency is poor, and weight gain slow,” he adds.

Nasal swabs

Apart from the financial impact from lost performance and the effects on calf welfare, he says that treating sick calves affects everyone’s morale.

On this farm, meticulous treatment records and the results from nasal swabs for each successive group allowed Graeme to adjust the farm’s initial vaccination protocol as a new group of calves arrived.

“We started vaccinating for IBR [infectious bovine rhinotracheitis] but this was found at very low levels infrequently, so we replaced this with vaccination for M bovis.

“This can only be given to calves from four weeks of age, a week after arrival. We got on slightly better with this.

“In the second group, we found coronavirus in all calves and fortunately were able to use a new vaccine – it is licensed to use from birth – for calves on arrival in the third group,” he says.

The result was that the vaccination strategy for groups two and three reduced total treatments, and the third group of calves saw the biggest health improvements and lowest injection rate.

“Ultimately, this saved time in catching and injecting a calf, and money on treatment drugs. Feed conversion and growth rates improved in this group.”  

Sourcing calves

Alongside a farm health plan, ideally calves would be sourced from one trusted farm with a known colostrum protocol and vaccination policy.

When this is not practical, Graeme suggests anyone buying at market should try to select and group calves of a similar age.

He explains this is because disease tends to be related to age rather than size.

Scours are common in the first seven to 14 days of life, for example, whereas pneumonia appears from four to six weeks and especially immediately post-weaning.

Older calves may look stronger but can arrive with more problems.

For instance, they may have recovered from cryptosporidium and be shedding or could arrive on-farm carrying pneumonia.

Mixing older calves with younger ones simply transfers more disease, he says.

While impossible to avoid stress in market-bought calves, the effects can be reduced by focusing on the highest standards in feeding and hygiene – and a good setup.

The biggest problems Graeme sees are overstocking, wet floors and a cold air space.

Draughts and poor ventilation all encourage disease and further impact the calf’s poor immune system, he says.

“A wet bed means a calf gets wet and cold, and this magnifies if housing is overstocked.

“It isn’t too difficult to improve ventilation, and adding loads of straw will allow calves to snuggle down in the dry.

“Also, make a plan with your calf nutritionist, because milk changes and weaning rations have a massive effect on calves.”