When a calf is born, its immune system isn't developed and it must absorb antibodies from colostrum until its own immune system becomes functional. The immune compounds in colostrum are essential to prime that non-developed immune system and to protect calves against disease in their first few weeks of life.
"When a calf gets enough good-quality colostrum we call that successful transfer of immunity," says Farm Source Senior Veterinary Manager, Michael Shallcrass. "The reverse is called a failure of passive transfer. Calves that don't get enough good quality colostrum are at greater risk of disease and twice the risk of dying compared to calves that get enough colostrum."
Once they hit the ground after calving the timer starts and there is a 24-hour window to get that good-quality colostrum into them. This is for two reasons - the calf's ability to absorb antibodies declines over 24 hours, while at the same time the levels of antibodies in the cow's colostrum start to decline as she begins making transition milk.
This is why it is important to milk freshly calved cows and feed newborn calves good quality colostrum as soon as possible. The 24-hour window is key to a quality start to life for your calves. "The ability of the calves' guts to absorb antibodies diminishes over time, so the sooner you can get good quality colostrum into them, the more they're going to absorb and the more benefit they're going to get out of it," Michael says.
"There isn't enough absorption after 24 hours. That's why the industry stresses the three Qs of colostrum, which are quickly, quality and quantity."
Michael Shallcrass, Senior Veterinary Manager
The recommendation is to feed calves four to six litres of colostrum within their first 24 hours of life. But because a calf can only hold about 1.5 to two litres in its abomasum (fourth stomach), two feeds within the first 12 hours is the target.
"We see the best results when calves are given the opportunity to suckle from their dams and also given supplementary colostrum within 24 hours of birth," Michael says. "And since there is so much natural variation among cows, by bringing in the freshly calved cows twice a day we can get the best-quality colostrum out of them."
Gold colostrum is the first milking after a cow has calved.
"It's called gold in part because of the yellow colour in the milk but also because it's the most precious thing that a calf can be given," says Michael.
Dr Ajmal Khan, Senior Scientist Animal Nutrition and Physiology, AgResearch explains why it is so important calves get gold colostrum.
"There is no alternative to gold colostrum, it's energy-dense and contains defence molecules that provide immunity to the calves. It contains a lot of bioactive molecules that are important to the development of their organs and promotes growth. It provides calves with protection against diseases in their first four to six weeks of life."
When newborn calves are given the correct amount of high-quality colostrum it helps ensure they experience less scours and disease, reduces death rates, encourages growth rates and improves the productivity and fertility of those animals.
But not all colostrum is the same and determining the best quality is important. This can be done by a simple, inexpensive measure with a Brix refractometer.
"It's common practice in New Zealand for farmers to pool their colostrum and store it in the same container," Michael says. "Which is good practice as it provides a broader range of antibodies for calves to ingest. But there is a risk of mixing high-quality colostrum with colostrum that isn't quite as good because that dilutes the best-quality stuff, so if you're going to pool your gold colostrum, make sure it's going in with a Brix reading of at least 22%."
Brix refractometers are simple to use and they provide assurance that calves are receiving the best-quality colostrum possible.
"Calves are the future of herds and there is a good opportunity to ensure they get the best start possible when they hit the ground, using a Brix refractometer can make a big difference to that start," Michael says.
Many farmers will have an opportunity to improve their colostrum management practices and therefore improve the health of their calves. And no matter what your system is, it's important to keep it simple and ensure everyone in your team follows it consistently.