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Calf rearing strategies | Agvance Nutrition New Zealand


Calf rearing good practice ensures healthy, happy calves!

Approximately 1.5 million calves are reared in New Zealand each year – 1 million being dairy heifers that will become the future herd replacements. How these calves are raised will affect how they grow and at what weight they enter the herd. It is essential to give such calves a great start to life so as to ensure a long productive, healthy milking life. Heifers that reach target weights make successful milking cows and raising them well starts from the day they are born.


Within the first 24 hours of being born, all calves, including bobbies must receive adequate fresh colostrum or a colostrum substitute and this should continue for at least the first 4 days of life because it will protect against disease by fighting infections within the gut. The calf should drink at least 2 litres of fresh gold colostrum during the first 6 hours of life, and then again at 12 hours to get protective antibodies known as immunoglobulins as they are born with poorly developed immune systems. This process is most effective in the first 24 hours after birth and is known as ‘passive transfer.’ Failure to do this, known as Failure of Passive Transfer (FPT) to absorb enough immunoglobulins in these first critical 24 hours, can make a calf susceptible to disease, death and long term reductions in animal productivity. Past studies have found that 10 – 40% of calves are deficient in colostrum which can result in higher morbidity rates and slower growth rates through to 14 weeks of age.


FPT is fairly common with NZ studies indicating a 33% prevalence at various intervals during the spring calving period. A number of reasons why calves get FPT are the following: a) the colostrum has inadequate immunoglobulin levels, b) feeding insufficient volumes of colostrum, c) feeding takes place too late after birth and d) bacteria especially Coliforms contaminate the colostrum at harvest, during storage or at feeding.


To combat FPT, it is imperative that you test your calves to make sure that they are getting enough high quality colostrum within the first 24 hours of life. There are a number of ways to measure and prevent FPT:

  1. Testing your calves for FPT between 24 hours and 7 days of age through blood sampling to check total protein levels
  2. Test quality of Colostrum’s level of antibodies using a Brix refractometer available from your vet or farm store. Brix readings over 22% indicate high quality immunoglobulin colostrum. Test pooled Colostrum as well and if this is of poor quality, then individual cows will need to be tested as results vary considerably. It should be noted that immunoglobulin concentrations and colostrum volumes are extremely variable in dairy cattle.
  3. Feeding Colostrum beyond 24 hours may be an advantage as the calf gut closes and the immunoglobulin has time to bind to infectious agents in the gut thereby limiting disease prevalence and severity.
  4. Store colostrum in multiple drums, in a cool place, out of sunlight and stir twice a day.
  5. Use valuable fresh Gold colostrum, but may be used if frozen for up to 6 months.
  6. Ensure good routine hygiene and health practices are employed by scrubbing all feeding equipment, disinfecting pens, promptly removing sick calves, vaccinate, provide clean shelters and make regular health checks.

Calf rearing good practice ensures healthy and happy calves. Along with the above best practice, always handle calves gently and with care. Provide calves with warm, dry shelters if they are not with their mothers. Calf pens must also be well maintained. Minimise stress by feeding calves at the same times each day and always ensure that they have adequate fresh water. Feeding good quality feed / meals will achieve weaning weight with a well- developed rumen. The key to successful calf rearing is allowing the calf to gradually adapt to a pasture based diet that will in turn allow for the critical development of the rumen and optimum growth rates to be attained.


The use of a vet only product such as Optiguard, a Biogro certified organic input, helps bind toxins and will prevent scours and optimises the growth of your young livestock. Optiguard is a very fine milled down form of Zeolite which helps calves transition from Colostrum to grass / meal. It helps the rumen grow and aids in the digestion processes. Being easy to dispense into feed troughs or onto calf meal, calves love the taste while gaining all the benefits that it provides. Try Optiguard by contacting your local vet or chat to one of our Agvance field agents directly.

In conclusion, if calves are well looked after, treated with some tenderness and given the correct nourishment from when they are born, the effort of such input will pay dividends throughout their milking / productive life.