There are many tools of the trade when it comes to taking care of calves. One of those tools that often gets overlooked is the refractometer. This is an essential tool in your toolbox, it gets used every day. There are several different refractometers on the market and they are used in a variety of settings, but on the dairy farm, you are looking for a refractometer that uses the Brix scale for measurements.
What is a Refractometer?
Refractometers are based on Snell’s Law, meaning a beam of light changes angle when passed through one medium to another. In our case, it measures the amount of light refraction in a sample of colostrum to determine the concentration of IgG antibodies. As the increase of the concentration, so does the degree to which the light is bent.
Did you know that the temperature of a sample can affect the angle of the light refraction? It is true, a sample should be at room temperature for the most accurate result. A higher temperature substance will result in lower, lesser quality readings.
Types of Refractometers:
There are 2 main types of refractometers that farmers use. They are optical refractometers and digital refractometers. Both of which provide accurate results when used correctly. Both will last a long time if they are handled and stored properly.
Optical Refractometers:
- They do not use batteries, they use ambient light.
- Hold up to the light to get the reading from the scale in the eyepiece.
- The high-fat content in colostrum can cause the line of the scale to be blurred, which can be difficult to read
- Must be calibrated with distilled water every time you use it.
- Sample cannot have any bubbles between the colostrum, the prism, and the cover piece or it will give a false reading.
- Do not immerse in water.
- Use a clean soft rag to wipe clean the prism.
- Need to use the screwdriver that comes with it to adjust for calibration.
- Relatively inexpensive
- The cover can break off if not handled properly
Digital Refractometers:
- The light comes from a LED light within the refractometer.
- Has a digital display for the readings.
- Easier to use and read the results
- Must be calibrated with distilled water every time you use it.
- Do not immerse in water.
- Use a clean soft rag to wipe clean the prism.
- Different styles available-dip style and handheld versions.
- More expensive
- Uses batteries
Why do you need to use a refractometer?
Since one cannot determine the quality of a bucket of colostrum just by looking at it, a refractometer is used to help determine the actual quality. The quality of colostrum can vary greatly and is dependent on many factors, including the age of dam, bred, the season of the year, and the history of disease. Determining the concentration of IgG in a bucket of colostrum can mean the difference in whether you have a successful or failure of passive transfer of immunity to the newborn calf. When you are using a Brix refractometer to measure the quality of each bucket of colostrum, will help you to separate the high quality from the lesser quality and ensure your colostrum management program is successful. This way you can use the high-quality colostrum meals for the first and second feedings while reserving the lesser quality colostrum for mixing with transitional milk after 2 days of age.
Care and Storage tips:
- Keep the prism surface clean. Use a damp, clean, soft cloth for wiping the surface clean after each use.
- Use only a few drops of each sample for the readings.
- Do not hold the refractometer under running water.
- Do not leave the refractometer in direct sunlight.
- Do not store refractometers in a humid area.
- If you are using a digital model, remove the batteries if you are storing them for a prolonged period of time.
- Be careful not to drop or bump the refractometer, as the prism is very fragile, and if it is broken it is unable to be repaired.
No matter what type of refractometer your dairy uses, it is one of the most essential tools in your toolbox in the maternity ward and should be a key component in your colostrum management program. When used correctly, you will be able to label and store your colostrum according to its quality and ensure that each calf born has the best chance for a successful passive transfer of immunity.