Posted on 2016-11-14 11:17:00
A sample of “fresh colostrum” - 3,600,000 cfu/ml!
If this colostrum is left for just 2 hours at room temperature, the bacterial count could be as high as 230 million cfu/ml!
A human baby is born with some antibodies passed on through the placenta, but the calf is not so lucky. It arrives totally naïve and relies entirely on colostrum to receive its antibodies. Flooding a new born calf with dirty colostrum could damage it for life. Harmful bacteria prevent antibodies being absorbed, and make the calf particularly susceptible to disease. Any calves with a bacterial scour in the first few days of life should give you a clue about your colostrum hygiene.
‘Hygienic colostrum’ is easier said than done! On dairy farms we work in an environment full of bacteria and during the harvesting, collection, storage and feeding of colostrum there are plenty of opportunities for bacteria to invade and cause problems. Most importantly we have to recognise that colostrum and milk products are the ideal medium for bacteria to live and multiply. It’s also an ideal warm temperature as it comes out of the cow, just right to promote multiplication. In a recent trial some colostrum was harvested containing 3,600,000 bacteria cfu/ml– a bacterial soup! The target level is less than 100,000 cfu/ml bacteria but be aware these can double every 20 minutes at room temperature.
So in essence, everything we do from the point of milking the cow, to the point when it goes into the calf’s mouth has to be done quickly and efficiently, taking care to keep it clean and reduce the time bacteria have to breed.
Forward planning will help: Prepare!
Wash and sanitise the cow’s teats then dry. Strip to remove teat sealant. Wear clean gloves and keep them clean.
Make sure the collection bucket has been thoroughly washed with dairy circulation cleaner and scrubbed if necessary. Hypochlorite alone won’t work, colostrum is very fatty, so a detergent/steriliser works best, then rinse with water.
Make sure the oral calf feeder is dedicated to new born calves, use a separate one for sick calves. Clean with hot water and circulation cleaner. The same applies to any calf feeding bottles and teats. Make sure any colostrum storage bags or vessels are clean and ready to fill with a clean funnel. Milk the cow and test the colostrum with a colostrometer or refractometer.
If the colostrum is good enough (green), or 20 + on the Brix scale, feed immediately, but any remaining colostrum should be cooled rapidly and stored.
A jerrycan full of ice can be dropped into the bucket of warm colostrum. The ratio is 4:1. i.e. 20L of colostrum cooled by a 5L block of ice. Once cooled to 4 °C, a preservative such as potassium sorbate, or ‘MilkMate’ will drop the pH and prevent bacterial build up for a few days. These products don’t kill bacteria, simply restrict their growth. So if you start with dirty colostrum, it won’t make it clean. Put a lid on the bucket to keep dirt out. Keep in a fridge for up to a week.
If you want to keep good colostrum for future use, then bag off small quantities into Store & Thaw colostrum bags and freeze flat to create a thin sheet of ice, so it thaws quickly.
2L of colostrum takes 15 mins from -20 °C to + 40 °C in 15 mins, 4L takes 25 mins. Pop bottles and ice cream containers with just 2L of colostrum can take up to 100 minutes.
A long thawing time in a 2L pop bottle means the bacteria in colostrum get a chance to incubate for a couple of hours. This means you could be drenching the calf with freshly brewed E Coli! The key is to thaw quickly and feed quickly to limit the bugs breeding.
The type of bag can make a big difference too. If the bag is thick in the centre it will take much longer to thaw. The graph shows 3.5L colostrum from the same cow, thawing in the same bath, at the same time. The thin one took 32 minutes to reach 40 °C and the thicker one took 65 minutes.
What about pasteurisation?
Pasteurisation is not sterilisation. Heat treating colostrum at 60°C for 60 mins will kill off many pathogens but not the ones which enjoy a high temperature! So some will remain and could potentially cause problems later. Johne’s bacteria need much higher temperatures to be killed off. There is evidence that calves fed pasteurised colostrum absorb antibodies more efficiently, but it has to be clean to start with!
Colostrum sample Pre and post Pasteurisation using a Store & Thaw bath and circulator. 1,000,000 cfu/ml, down to 3,000 cfu/ml.
What about defrosted colostrum?
Frozen colostrum will keep for up to a year. Defrosting must take place below 50 °C to avoid cooking the antibodies. It must be defrosted quickly in warm water, or slowly overnight in a fridge. A thin sheet of ice in a Store & Thaw bag is ideal. Frozen colostrum will float in water, if you can keep the colostrum submerged, it will thaw more quickly. e.g. in a specially designed tank.
Only harvest healthy colostrum from healthy cows. Feed the calf quickly, or cool and freeze the excess quickly. Pasteurise if you wish to create a cleaner product for better passive transfer, but don’t rely on pasteurisation to clean up a dirty sample. Defrost frozen colostrum quickly before the bugs get a chance to multiply.
Then - feed ‘on time’ in the first 6 hours after birth - Job done!
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If you want to check the level of contamination in your colostrum and the immune status of your calves, ask your vet to blood sample the calves, and send some colostrum away for bacteriology.