It’s at about this time of year that we start to see many clients visiting us for advice on how to treat calves with diarrhoea, but did you know that most outbreaks of calf scours could be avoided altogether with good calf management practices?

For any animal to become “sick” there must be problems in each of the following 3 areas:

  • Host e.g a weak calf with a poor immune system
  • Agent e.g. the presence of a bacteria /virus /protozoa
  • Environment e.g. unhygienic, mucky calf sheds, dirty feeding equipment, poor ventilation


Most requests from farmers are for antibiotic treatments aimed at destroying the agent that has infected the calf. Not only are these ineffective against viruses and protozoa, the agent is not the only factor in the disease outbreak. If the other two factors (i.e. host and environment) are adequately managed then there becomes no need for expensive antibiotic therapy. Lets look at how we can manage these other factors.


Calves need a strong immune system to fight and destroy infectious agents it comes into contact with. Unfortunately, a calf is born without any immunity to the bugs in its environment until it develops its own immune system at around 30 days old.

To overcome this problem, it must receive immunity from its mother in the form of antibodies in colostrum. The calf can only absorb these antibodies in the first 12 - 24 hours of its life - after that it is too late!

Feed calves 2 x 2L feeds of good quality colostrum in the first 12hrs
A colostrum bank should be used for this purpose.

Only use first milking colostrum that has been measured with a Brix Refractometer as being good quality. Cows that are vaccinated (7in1, Salmonella,Scourshield) and are in good body condition score (BCS 4.5-5.5) produce better colostrum.

The calves are going to have a much better chance of fighting off infection if they are strong and growing well. Adequate nutrition will ensure the calf can grow and develop but also needs to target the developing rumen so that it can continue to do well after it is weaned.

Feed calves 4L of warm milk per day – or more
Provide pellets that are >20% protein and >12mJ ME from day 1
Straw and fresh water should always be available

Environment This is where the calf comes into contact with the agents.

The environment can be broken into two areas – calving and rearing. It is important that both these areas have as little contamination by the agent as possible to minimise the chance that the calf will become infected.

Calving Area

Cows should calve down in clean, dry areas. Prolonged calving/dystocia will reduce the calf’s chance of survival. Calves left in cold, muddy paddocks are more likely to not receive colostrum and are more likely to be exposed to infectious agents.

> Collect calves from calving areas a minium of TWICE daily
Rotate calving areas if they are becoming wet and muddy
Provide prompt assistance to cows with difficulty calving

Rearing Area

Both healthy and sick calves shed bacteria, viruses and protozoa that cause diarrhoea in their faeces. If there is heavy contamination of these infectious agents in the area where the calf is to be reared, it creates a much higher risk of succumbing to disease. Some agents can survive in the environment for over a year given the right conditions and provide a source of infection to calves entering the shed the following year. Likewise, during the rearing season, bedding will get contaminated. Deep litter bedding will make the ground very warm and actually kills most bacteria and viruses.

It is important to maintain strict levels of hygiene.

Disinfect the shed with good disinfectants e.g. Virkon® before introducing calves to the shed

Have deep litter bedding that drains well e.g. rice hulls Calves should be only allowed contact with other calves of a similar age/immune status. An “all-in all-out” system should be adopted in the calf shed to minimise contamination and exposure.

All-in All-out calf pens of similar age groups

Densely packed calf rearing sheds increases the amount and risk of contamination therefore there will be more exposure challenge.

Allow each calf 2-3m2 within its pen

If calves are kept warm and dry they will 10% faster. High levels of ammonia in the air can cause pneumonia in calves. If you can smell ammonia in the shed then ventilation is not adequate. There should be good ventilation high above the calf, ideally a gap between the walls and the shed roof on the side opposite the open face. Consider a north-facing shed to avoid weather extremes.

Have a warm, well-ventilated shed facing away from the extremes of weather

In summary, we can only eliminate certain infectious agents with antibiotics but can have much more success in controlling calf scours if we manage the host and environment well. Ensure calves are fed at least 4L of good quality colostrum in the first 12hrs of life, collected from a clean calving area and moved to a warm, ventilated and hygienic calf shed, where it is fed a nutritious diet.