All dairy farmers know the importance of the first meal of colostrum to ensuring a calf gets off to the best start in life. Feeding at least four litres of colostrum within six hours of birth is common practice on many farms. Following recommended practices for collecting and feeding colostrum will go a long way to ensuring calves are protected by maternal antibodies before they can develop their own immune systems. Having proof that your colostrum management is working can remind everyone why you feed colostrum the way you do. Having proof is now as easy as placing a drop of colostrum or blood serum on a simple testing device.
Brix refractometers have widely replaced traditional tests for colostrum quality and passive transfer status. Refractometers are able to offer immediate and accurate calf side result’s. Previously, passive transfer status would be tested by an expensive laboratory test that took up to 24 hours. Refractometers are very simple to use and become cost-effective after just a few uses.
Producers can purchase a refractometer from their local farm supply store or online. Optical refractometers are more subjective and can be misread. Digital refractometers are more expensive but extremely simple to use and don’t leave room for misreading results. Producers implementing a comprehensive colostrum testing protocol will see a return on investment on a digital refractometer quickly – calves fed good quality colostrum get sick less and require fewer treatments.
Colostrum management testing protocol
Test colostrum quality after collection and before feeding
1.Calibrate
- Follow manufacturer instructions for calibration
- Distilled water placed on the refractometer should produce a reading of zero
- Ensure the sample well is clean
2.Place a few drops of colostrum on the sample well
- Digital refractometers will read the sample
- Optical refractometers need to be held up to a light source and read manually
3.Clean the sample off the sample well
- Residue from previous samples can reduce accuracy
4.Feed colostrum if the reading is 22% or more
- Lower quality colostrum can be saved for later feedings, but should not be given at the first feeding
- Individual farms may wish to increase their cut-point for colostrum quality
Test colostrum quality every time. Only feed colostrum that is high-quality.
Test passive transfer status
1.Collect a blood sample from the jugular vein of a 1-6 day old calf
- Your veterinarian can provide training and supplies for blood collection
2.Allow a clot to form
- Handle the sample carefully – don’t shake it or drop it
- The clot will form over a few hours
- Avoid extreme temperatures (very cold or very hot)
- Place in a fridge if environmental temperature is higher or lower than room temperature
3.Take a serum sample
- Use a pipette or syringe and needle to draw up serum, avoiding the blood clot
4.Place the serum on the refractometer
- Digital refractometers will read the sample
- Optical refractometers need to be held up to a light source and read manually
5.Readings of 8.4% or more indicate successful passive transfer
Passive transfer status doesn’t need to be measured on every calf. Spot-checking will provide an indication of whether or not colostrum management is successful or needs to be re-evaluated. If a problem is found, work with your herd veterinarian to set up a more formal testing protocol and tweak colostrum management.
Calf Notes has a great conversion calculator that allows you to convert Brix readings from colostrum, serum, or whole milk into colostrum IgG (g/L), serum IgG (g/L), or whole milk percent solids. Work with your veterinarian to develop quality standards for your herd. Download the calculator here