Sheryl Haitana

One lesson farmers can take from Covid-19 is the importance of self isolation and hygiene when it comes to calf rearing this season, says Fonterra senior veterinary manager Mike Shallcrass.
Coronavirus strains are common in calves and can cause deadly scours. As with many of the infectious diseases in calves, isolating sick calves from the rest of the calves is vital, he says.
“Put them in the hospital pen away from the other calves and keep them there until they go out on pasture. Don’t put them back with the other calves when you think they look better.”
The other important task is cleaning calf equipment thoroughly with hot soapy water to kill any bacteria.
“Feed your sick mob last and clean the equipment to get the milk fat layer off because the bugs can live in it.”
Mike presented a webinar for Dairy Women’s Network Calf Rearing series in June on calf diseases.
His key take home messages are for farmers to make the time to prioritise the best start for their calves because it will save them time and money long term.
“The most limited resource on farm is time. There are some simple rules around calf rearing and most people know them, but when you are pushed for time the temptation is to cut corners.”
Mike is passionate about the growth of NZ’s young stock from birth to heifers calving in the herd.
“As a country, we do have problems with heifer reproductive performance. An empty heifer is a cost in terms of time, money, and GreenHouse Gas emissions and reduces the efficiency of the farming system.”
Taking the job in Fonterra’s On-farm Excellence – Animals Team was an opportunity for the dairy vet to advise Fonterra farmers and help cows throughout NZ.
“What was exciting about this job was the opportunity to help millions of cows. For a vet, part of the satisfaction of your job is helping animals. That’s why we do it.”


The health of the national herd starts on day one – getting enough quality
colostrum into a newborn calf, he says.
“Calves who receive enough good quality colostrum early enough can be bomb proof.”
Calves are born without any immunity to disease and must acquire it through colostrum. If they don’t get enough colostrum within the first 24 hours their immune system can be compromised.
This is called Failure of Passive Transfer of immunity (FPT).
An Australian study has shown calves that don’t get enough colostrum are twice as likely to die before weaning than calves who get enough. They are 1.5 times more likely to get scours and 1.7 times more likely to get a respiratory disease.
NZ research into calves left on their mothers for the first 24 hours shows only half of the calves are getting enough colostrum, Mike says.
“It’s common to collect cows and calves once a day (OAD) but for some calves it’s too late.
“Ideally you would be picking up your calves at least twice a day (TAD), milking your freshly calved cows twice a day, and making sure that only the best colostrum goes to those newborn calves.”
The practicality of picking up calves twice a day comes down to time pressure again and is not practical on all farms. If farmers can’t collect calves then bottle feeding colostrum in the paddock is a compromise solution, he says. Other research has shown Kiwi farmers are reasonably good at feeding calves colostrum early and feeding them the right volume. The biggest issue on NZ farms, however, is colostrum storage because of the sheer volume farmers are dealing with.
“In NZ we deal with a flood of colostrum and deal with bulk storage. Bacterial contamination anywhere along that chain will affect the quality of all of that colostrum milk.”
The importance of hygiene through this process is vital. Storing colostrum in plastic containers, for example, is not ideal because micro scratches are hard to clean and bacteria can hide in them.
The quality of colostrum drops significantly after the first milking so a good solution is to separate that gold colostrum milk, store it well, and keep it aside for newborn calves.


Decisions around calf feeding frequency and whether to use milk replacer must take into consideration both financial costs and time restraints.
Farmers who feed calves on a high milk volume will need to be feeding calves TAD. These calves will experience fast growth, but the calves’ rumen will develop more slowly and they may have a growth check when they are weaned, Mike says.
Calves reared on a low milk volume system can be fed OAD, as long as they have access to enough other feed all day to meet their nutritional needs. These calves may have slower growth rates but their rumens will develop faster and they will have a smaller growth check when weaned off milk.
When it comes to calf milk replacer, farmers need to consider the ingredients closely, he says.
From an animal health point of view, calves should be fed whole milk for the first four weeks.
“For a younger calf the closer their feed is to whole milk the better – that’s all they’re designed to digest.”
If farmers want to use a milk replacement then they should opt for a whole milk based one in those first four weeks.
“Milk replacement should be a whole milk replacement. Once a calf is four weeks old you can be more relaxed with what they can eat.”
Whey-based milk replacement is missing the fats and proteins that form a curd in a calf’s stomach and in the first four weeks there will be a real risk of nutritional scours.

• To find out more watch Mike’s webinar at
• Key resources can be found at www. and in the DairyNZ Calf Tool Kit.