Posted by Milk Spectialties Global Calf Technical Team on Jun 26, 2020 2:49:27 PM
A refractometer with a brix scale is a very useful device for monitoring the nutrition and health of dairy calves. It is a durable piece of equipment that will last many years if cared for properly.
WHAT IS A REFRACTOMETER?
A refractometer is a device that can be used to measure the sugar or solids content of various
solutions. There are manual (figure 1) and digital (figure 2) versions, both of which work very well on the farm. The manual type is usually available for less than $100. Refractometers are available with different types of scales to measure specific gravity, total solids, and Brix. Uses for a Brix refractometer are discussed below. Your herd veterinarian can help you select the most appropriate model for your farm.
LEFT: Figure 1
RIGHT: Figure 2
WHAT IS THE BRIX SCALE?
Brix is an approximate measure of the sugar content (or other dissolved solids) of a water-
based solution. Brix has traditionally been used in the food industry, such as wine and fruit juice making. The Brix scale has been adapted for the dairy industry to measure the quality of colostrum, percent solids of milk, and blood total protein of newborn calves.
Figure 3 shows what a Brix reading looks like on a manual refractometer, reading approximately 23% Brix.
The first time you use your refractometer and every so often, you should calibrate it using
distilled water. This will ensure that your Brix readings are always accurate. Distilled water is
readily avail-able in gallon jugs from most supermarkets. Distilled water can also be used to clean the refractom-eter between readings since tap water can cause a build-up of solids on the glass. For calibration, be sure to follow the specific instructions for your refractometer, but in general a drop of distilled water is applied to the glass (the same way you would apply a sample for testing) and the scale is adjusted using the knob or screw on the top. When viewed through the eyepiece, the blue line should line up with zero when correctly calibrated as shown in the following pictures.
HOW TO CALIBRATE A MANUAL REFRACTOMETER
USES FOR A BRIX REFRACTOMETER ON THE FARM
COLOSTRUM QUALITY—Fresh colostrum can be tested using a refractometer for adequate levels of immunoglobulins to ensure that your calves will get off the right start. Colostrum measuring 22% or higher is generally considered high quality.
PASSIVE TRANSFER OF IMMUNITY—Calves can be checked for adequate passive transfer of immunity at 1-3 days of age. Blood collected from the jugular vein can be spun down in a centrifuge or allowed to sit upright overnight in the refrigerator. A drop of serum (the part of the blood without the red or white blood cells) can then be applied to the refractometer. A Brix reading of at least 7.8-8.4% indicates effective passive transfer of immunity. Use caution if readings are too high as this can indicate that calves are dehydrated.
NUTRITION—A Brix refractometer can be used to evaluate the percent solids of liquid nutrition. The natural percent solids of normal whole milk is generally 12-13%. The Brix reading of the milk plus two is a close approximation of the percent total solids. For example, waste milk with a Brix reading of 10% would be 12% solids. Brix readings of milk replacer are not directly comparable to whole milk. It is possible to establish a standard curve for a specific milk replacer and use that to approximate percent solids. A formula (below) can also be used to calculate percent solids using the weight of the powder and water. Note that water is 8.27 pounds per gallon at 100F.
Reach out to the technical experts at Milk Specialties Animal Nutrition for more information or to ask a question.