Colostrum and Transition milk – Frequently Asked Questions


What is colostrum?

Colostrum is the first milking, and only the first milking post-calving. It contains high levels of solids with high amounts of energy, antibodies, hormones, vitamins, minerals and more. The focus of colostrum is the antibodies it contains. Five weeks pre-calving a cow begins producing antibodies called Immunoglobulin G (IgG). As the calf is born with virtually no immunity, colostrum has the important job of transferring immunity to the calf.

How does a calf get its immunity from colostrum?

This is done when colostrum is consumed and IgG is absorbed through specific sites along the intestinal tract. IgG is a protein and it recognises the sites to which it must pass through to the blood. This is called passive immunity and the calf uses this to fend off any challenges it meets along the way. Failure to achieve this is called failure of passive transfer.

How soon must I collect colostrum post-calving?

It is important to collect this colostrum from the cow as soon as possible after calving. Within 1-4 hours at the earliest. The concentration of IgG begins to decline once the cow has calved. Additionally, every cow has different levels of IgG in their colostrum and so maximise the chance of having a high concentration of IgG, it should be collected as early as possible.

How soon should a calf get colostrum?

This can play a major role in saving a calf through illness. Not only must we race to get the cows colostrum before the concentration of IgG is too dilute, we also must race to get it into the calf. The sites begin to close when the calf is born and so to ensure the calf has adequate absorption capacity, it is vital that the calf receives colostrum withing the first 1-2 hours. Within six hours of birth, the capacity for the calf to absorb IgG through the intestinal wall has decreased by 50%. The gut has completely closed to absorption of IgG by 24 hours of life. Another crucial element is allowing the calf to get a little bit from the cow before feeding them manually. Once colostrum hits the intestinal wall it increases the speed at which the sites close. Hence, if a calf drinks 0.5L within 30 minutes after calving and we manually feed them 4 litres three hours later, it may not absorb sufficient amounts of colostrum and so experience what we call failure of passive transfer. However, if the calf receives 4 litres of colostrum within 1 hour of birth and nothing for another 12 hours, they will most likely have adequate passive transfer of IgG, aka. sufficient immunity.

Is it okay to use any cows colostrum for my calf?

It is okay to use any healthy cows colostrum for your calf. Having sufficient antibodies/IgG in the colostrum being fed is most important. One thing to think about is the spreading of infectious disease. Diseases such as Johne’s disease and Mycoplasma can be transmitted via colostrum and milk and so, feeding colostrum from the calf’s own Dam will minimise the potential spread of such diseases. If this is not possible, feeding colostrum from individual cows, rather than pooling it, can also help reduce the risk of spreading disease.

How do I know that my colostrum has sufficient antibodies/IgG?

The only way to have any idea of this is to test the colostrum. It is possible to test it quickly and easily on farms with reusable tools such as the brix refactometer, colostrometer. Follow this link to see how you can use either of these tools which are quick and easy to use as well as being affordable. Many people think that if the colostrum is thick then it is good colostrum for the calf. While this may have a lot of energy due to high fat content it does not tell us anything about the concentration of IgG. The only way is through testing.

Is it ok to move calves straight on to milk replacer after colostrum?

It is high risk moving the calves directly from their colostrum feed onto regular milk replacer. Even though the intestinal tract is closed off to IgG within 24 hours of birth, it remains highly porous for up to two weeks of life. Therefore, it is very important that calves receive transition milk or transition milk replacer prior to regular milk replacer. This feed has properties to encourage intestinal development and protecting it in the process. We are often told that calves must go onto milk replacer within two days of birth due to the high throughput of calves.

What is transition milk?

The surface of the intestinal tract remains porous for up to two weeks after birth. This leaves it highly exposed and vulnerable to bacteria, viruses and other pathogens that it will meet along the way. Transition Milk increases the closing of the intestines with its ingredients such as oligosaccharides. These are carbohydrates that encourage cell binding and hence the binding of the intestines. Furthermore, the cells of the small intestine are replaced by new cells within a few days of birth and at this stage, the surface antibody from colostrum is rapidly depleting leaving these new cells vulnerable to attack. Although transition milk is significantly lower in IgG compared to colostrum and calves cannot absorb this antibody from the small intestine through to the blood, transition milk contains many immune properties at a much greater level than whole milk, which helps calves to fight disease. These antibodies line the surface of the intestine acting as a physical barrier to the external bugs which a calf encounters during this vulnerable period.

In addition to an extremely vulnerable digestive system, the young calf needs extra energy to adjust to life outside the womb. Nutritionally, transition milk is greater in solids than whole milk or regular milk replacer, providing the calf with more energy to fight infection and other external challenges it may face such as changing temperatures.

How long should you feed transition milk for?

A calf should get transition milk for a minimum of five days. This is to give some time to help the development of the digestive tract before moving away from the added protection it provides. If you have vaccinated the cows for rotavirus, you need to feed the calves transition milk from these vaccinated cows for a minimum of 10 days for any level of protection. Calves can be benefit from this vaccinated milk for up to three weeks post-calving. The more intense the infection is on the farm, the longer the calves should be fed transition milk, to provide them with greater protection.

For how long does a cow produce Transition milk

Transition milk is usually considered to be 2nd milking post-calving to 8th milking. It is called transition milk as its ingredients are moving from colostrum to the whole milk that goes into our bulk tanks. Therefore, the point at which it becomes whole milk can vary slightly from cow to cow.

What do I need to look for in a transition milk replacer?

There is only one transition milk replacer on the market. To be sufficient in replacing milk replacer a specific focus has to be placed on what makes transition milk special. Rather than placing all the focus on solids – fat and protein. It is essential the entire package. Transformula does this, more can be learned about it on our transformula page;

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