Insights into the cornerstone of calf rearing

Insights into the cornerstone of calf rearing

Dairy
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New research shows the importance of ensuring calves receive high-quality colostrum.

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Is your mortality rate for calves less than 3 per cent?

Do you treat less than 10pc of unweaned calves for illness?

If you answered no, you're not alone, and you may be wondering how some dairy farmers meet these industry targets.

Despite variable calf management practices, one of the most important factors is proper colostrum management.

Revisiting past work and opportunities that exist for improvement in calf rearing

A 2017 study by the Graham Centre for Agricultural Innovation (J. Dairy Sci. 102: 8352-8366) surveyed 106 farms across Australia on calf management.

They found that the average mortality rate of pre-weaned calves was 5.6pc, which is higher than the Dairy Australia industry achievable target of 3pc.

Average calf morbidity, a figure which shows the proportion of calves treated for illness, was 23.8pc.

Only a quarter of farms in the study met the industry target of less than 10pc pre-weaning morbidity.

It was clear there was a high variation in colostrum management.

For example, only half of the farms surveyed tested colostrum, and only half of the colostrum samples met the target IgG concentration (a measure of the quality of colostrum).

Failure of transfer of passive immunity occurred in 41.9pc of calves sampled.

The colostrum goal: achieve passive immunity transfer

'Passive' immunity refers to the transfer of antibodies, also called immunoglobulins or IgG, from the dam to the calf via colostrum.

This differs from 'active' immunity, where a calf is exposed to an infection and mounts its own immune response.

Colostrum, when managed correctly, provides the calf with protection, via passive immunity, during the first four to six weeks of life.

A serum total protein, measured by collecting a blood sample from the calf, of greater than 5 grams per decilitre ( 5g/dl) indicates adequate passive immunity.

US trial suggests moving total protein targets

At a July 2020 Dairy NSW Young Dairy Farmer Network event, Dr Matthew Petersen from Zoetis Australia, presented recent research from the US.

The study involved 39,619 calves across 15 dairy farms and assessed the effect of serum total protein on early-life health and growth.

"Based on this data, the goalposts have moved," he said.

"Typically, serum total protein at greater than 5g/dl translated to adequate passive immunity.

"This research shows that health outcomes are optimised when serum total protein is 6.0-8.5 g/dl."

Importantly, only 2.1pc of trial calves failed to achieve passive immunity transfer.

The large difference between US and Australian results highlights the significant opportunity to improve colostrum management in Australia.

Consensus on new total protein targets for farmers

Coincidentally, at the same time that this research was released, a group of 18 researchers from Northern America formed a consensus on passive immunity recommendations. These findings align with the study mentioned above and set more specific targets for serum total protein across a calf population, rather than just a 'pass or fail' cut point.

How do we apply these serum total protein targets on-farm?

Consult with your veterinarian on blood sampling and checking total protein serum with a Brix meter.

Testing should ideally occur at 36-72 hours post-birth and will give your calf rearing team a lead performance indicator.

This allows for proactive management to correct any colostrum issues rather than reacting to an outbreak of calf illness.

Identifying individual animals with reduced immunity can also allow for closer monitoring of higher risk cases.}

The four Qs of colostrum management still apply

The fundamentals of colostrum management have not changed.

The four Q's still apply:

Quality: Determine colostrum quality on-farm with a Brix meter.

High-quality colostrum correlates to a Brix score of 22pc.

Quickly: Target the first feed within six hours of birth - after this, the intestine's ability to absorb IgG has decreased by 30-50pc.

A second feed is required within 24 hours of birth, and a third feed is possible.

Between 24 to 36 hours after birth, no more IgG can be absorbed.

Quantity: 10pc of birth weight of high-quality colostrum for the first three feeds.

Squeaky clean: Remove the calf from the dam as soon as possible.

Clean, disinfect and dry teats before milking.

Collection, storage and feeding equipment must be spotlessly clean and disinfected before use.

Consider adding potassium sorbate to colostrum set aside for feeds two and three; this will inhibit bacterial growth

For further colostrum information refer to Dairy Australia's 'Rearing Healthy Calves' manual.

No time for testing: overcoming this perceived barrier

If we fail to manage colostrum quality and achieve the transfer of passive immunity, there are costs for the farm due to:

  • increased morbidity and treatments, including possible reliance on antibiotics
  • lower lifetime milk production and feed conversion efficiency; and
  • increased mortality rates

The average amount of labour time required to bring a sick calf to recovery typically ranges from 30 minutes to more than an hour.

It takes less than 10 minutes to test, store or thaw colostrum for each calf.

Add a few more minutes to take and test a blood sample.

The alternative is an extended time requirement and additional costs to treat a sick calf.

Prevention is better than cure.

Standard operating procedures, the way forward for calf management

NSW DPI is currently working with industry stakeholders including Dairy Australia, service providers and farmers to develop new calf standard operating procedures.

These will include best practice guidelines aligning with the latest advances in dairy research.

For more information on calf rearing, visit the Dairy Australia website, contact your local Dairy Australia regional development program or email Peter Havrlant peter.havrlant@dpi.nsw.gov.au or call 0418 540 073.

Follow @NSWDPIDairy on Facebook.

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