Using a Brix Refractometer
- [Narrator] The concentration of IGG in colostrum varies widely from one cow to the next, from less than 20, to over 100 milligrams per mil.
Colostrum containing 50 milligrams per mil or more of IGG is considered to be a high-quality feed for newborn calves.
And most calves need to receive 150-200 grams of IGG to achieve successful transfer of passive immunity.
Measuring IGG concentrations in colostrum can be very useful in managing colostrum quality and monitoring colostrum feeding practices.
We can't tell by looking at colostrum how much IGG it contains, but we can use some simple on farm tools to separate high quality colostrum from low quality colostrum, and improve passive transfer rates.
In this video, Sonja Gelsinger will demonstrate how to use a Brix Refractometer to test colostrum quality.
- One of the tools that we can use for measuring colostrum quality is a refractometer.
This is an optical version of the refractometer.
It has an eyepiece at one end and then, at the other end, there's a surface on which we'll put the colostrum sample, the cover that you can flip down to spread out that sample, and then right above that, it has a screw that you will use to calibrate.
In order to calibrate the refractometer, you will use some clean, clear water that should come with your refractometer.
Very simply, you'll take the water and put just a few drops on the surface, flip the cover down to spread that out, and then look through the eyepiece at the scale at the bottom of the refractometer.
You'll want to do this in an area that is well-lit, so that you can clearly see.
What you're looking for is the interface between a blue region and a clear or white region.
And that line between those two colors should be right at zero.
If not, use a small screwdriver and turn the screw one way or the other to adjust that line to be at zero.
Similarly, for the digital refractometer, it has a surface here where we'll put our colostrum sample, or water to calibrate, and then it'll have some array of buttons.
The best way to know how to calibrate a digital refractometer is to look at the instructions.
Because each model is going to be slightly different.
To measure actual colostrum sample, first we'll wipe off the water from our calibration, then using a small pipette, we're going to put just a couple drops of the colostrum again, right on the surface of the refractometer just like we did with the water, and then again, flipping the cover down to spread it out so that it covers most of that surface.
And once again you're going to look through the eyepiece, look for the interface between the blue and the white, with the colostrum, it generally is not a very clear line, it'll be somewhat fuzzy, but what you're looking for is for that interface to be above 22.
And the units on a refractometer is going to be in percent Brix.
So you want it higher than 22%.
That is considered good quality colostrum.
If it's lower than that, it's fair or poor quality.
It's usually difficult to get an exact reading, especially on an optical refractometer, but as long as you're above 22, that's what you're going for.
Similarly on the digital refractometer, the same type of thing, it's just a little bit more precise.
You're going to put a couple drops on the surface of the refractometer, just so it's covered, it only takes one or two drops, and then you simply press the measure button, and it'll give you a reading.
This particular one is 15.9, which, as you notice, is not above 22%, so this is not a colostrum that we would want to use for calves.