Progressive dairy producers try to do the best jobs they can in all areas of management, yet while they know that it is best practice to measure colostrum quality before feeding it to their calves, for a number of reasons, they are just not actively doing it. Does this sound like a familiar theme for some of your clients? Practitioners help to reinforce colostrum monitoring best practices by making recommendations during regular visits and when dealing with calf-related issues on the farm. Often, our persistence (+/- a wreck or two) eventually gets them to take action. They get inspired to change, purchase a colostrometer, integrate its use into the colostrum harvesting process and we give ourselves a pat on the back for helping to optimize calf health. Then, when we walk through a month or so later, the colostrometer is either broken or sitting on a shelf collecting dust. What gives?
Obviously, there are a lot of factors that can cause protocol drift, but chief among them for measuring colostrum quality are the difficulties that we all know to be associated with colostrometers themselves – fragile equipment that has to be used under very specific temperature conditions. Recently, researchers have reported on an alternate method for estimating colostrum quality that will likely make monitoring colostrum quality much more practical for the average farm to do. This method utilizes a Brix refractometer to estimate total solids, which correlate with IgG content. Basically with one drop of colostrum on the instrument, at any temperature, the producer can make a decision whether to use that colostrum to feed neonates for optimal passive transfer, or use it for other purposes, such as feeding during the first few days of life.
Brix refractometers, also known as sugar refractometers, are commonly used in the food and wine industries to estimate sugar content. Several studies published in recent years have supported the validity of using Brix refractometers to measure total solids in colostrum, which is then correlated to IgG content. The latest research suggests a cutoff point of 21 percent solids for first calf heifer colostrum and 22 percent for higher lactation animals to correlate with a colostral IgG cutoff point of 50g/L. Brix refractometers come in both optical and digital models, with recent work showing good correlation in measurements between the two devices. They are cost effective for a farm to buy, with a price range of $50-$75 for simple optical models, to upward of $150 for some of the higher end digital models. Units are easy to use, calibrate, clean and maintain.
It is important to note that while the Brix refractometer significantly helps us measure colostrum quality, we are still lacking a reliable, easy, cowside test to measure the level of contamination in colostrum. High bacterial counts in colostrum may interfere with passive transfer of immunity, and pose a risk of making the calf sick directly from the colostrum, despite having high levels of IgG.
Colostrum that is clean but does not make the cut on IgG levels can be fed to older calves for the first few days of life, and calves will benefit both from the nutritional content of colostrum and the high IgG levels, which help to protect the gut locally. If not enough high quality colostrum is available for their calves’ needs, or if colostrum contamination is suspected, producers should consider using a colostrum supplement or colostrum replacement product as appropriate to the situation. Colostrum supplements contain less than 100g IgG and are designed for the calf that is getting at least some maternal colostrum already. Colostrum replacers are defined as containing over 100g of IgG and are designed to be used in place of maternal colostrum. They are also a great choice when cleanliness of colostrum is suspect.
An evaluation of Brix refractometry instruments for measurement of colostrum quality in dairy cattle. V. Bielmann ,*1 J. Gillan ,* N. R. Perkins ,* A. L. Skidmore ,† S. Godden ,‡ and K. E. Leslie * J. Dairy Sci. 93:3713–3721