A Bit About Colostrum

Published on Thu, 03/17/2022 - 6:05pm

A Bit About Colostrum.

 By Jaclyn Krymowski.

 The dairy industry has invested heavily in calf health with countless hours of meticulous research and detailed study. It’s safe to say its producers are well aware of how important colostrum is to that effort.

But building rigorous protocols and quality requirements starts with a foundational understanding of how colostrum works, what it provides the calf and what exactly influences its quality. This not only ensures that employees are getting calves off to the best possible start, but it can also help you establish a backup plan for cows that have little or poor-quality colostrum.

Colostrum components
The first milk produced following parturition contains more than antibodies (or immunoglobulins) for immunity. Colostrum also has increased concentrations of proteins, as well as fat, minerals, and vitamins A and C compared to regular milk. The higher concentration of protein is due to the transfer of antibodies to the calf.

Building a solid defense system is essential for a newborn’s growth and development. Replacement heifers especially need the maximum benefit of immunity as diseases caught early in life can have a negative impact on production later in life.

The absorption of colostrum and its antibodies happens in the intestine. From there, the macromolecules (such as antibodies and nutrients) are then absorbed into the bloodstream. In an event called “gut closure” that happens as the intestine matures, the calf can no longer absorb immunoglobulins.

In dairy calves, this happens at about 24 hours of life making it the absolute cut off that an animal must receive an adequate colostrum dose. However, studies have shown that gut closure is a gradual process, meaning that as the hours go by less antibodies will be absorbed making it imperative to offer colostrum in the correct amount as soon as possible after birth.

Research has also found that a large supply of different globulins, or components, in colostrum offer the calf a quick source of other additional nutrients (such as proteins) that might not have been fully provided during gestation.

All about the quality
As time goes on, the quality of colostrum produced by the cow also goes down. A cow will transition from colostrum to milk in the first three to four days postpartum. However, after the first milking the colostrum after tends to have a lower concentration of immunoglobulin G (IgG).

According to the University of Maryland Extension, a positive, high-quality IgG score over 50 g/L is considered high quality.  A Brix refractometer is the ideal tool of choice for dairy producers to measure IgG scores as it will give the best measure of total solids. However, a colostrometer also works well and is more affordable. This device measures the colostrum’s density based on gravity.

Natural colostrum is always the best choice, though in a pinch there are commercial substitutes on the market. And, because colostrum composition depends on the environment and pathogens the cow was exposed to, obtaining it from within the herd is preferable. That said, a calf doesn’t need to drink colostrum from its dam specifically.

How colostrum is stored and thawed is extremely important to preserve quality. If fresh colostrum cannot be fed within an hour of milking, it can be refrigerated (<35°F) for up to 24 hours. You can warm it up to feeding temperature in a warm water bath – the same method is recommended for thawing frozen colostrum.

Colostrum can be frozen for up to a full year without impacting its quality, but it should be warmed up slowly and kept from overheating. (The University of Maryland Extension recommends never thawing in water over >120°F to avoid destroying any antibodies.)  It’s also important that the freezer you keep it in is reliable without risk of any thawing.

Remember, certain animals tend to producer poorer quality of colostrum than others. As a rule of thumb, you can expect first calf heifers to produce smaller amounts of colostrum and at a lower quality compared to a mature cow who has been exposed to more. It’s always recommended to run a quality test on each batch of fresh colostrum before deciding to feed, store or dump it.

The impact of feeding
No matter the quality of your colostrum, it won’t do any good if it is fed too little and too late. Ideally, a calf’s first serving of colostrum happens within a couple hours of birth. A longstanding rule of thumb is to give calves 10 to 12% of their bodyweight’s worth of colostrum within the first eight hours. However,  Iowa State University experts recommend that a calf should have four quarts of high-quality colostrum within the first four hours, followed by at least two more quarts between six and eight hours. Specifically, that should allow the calf to have anywhere from 100 to 150g of IgG as quickly as possible.

It should be noted that smaller calves shouldn’t necessarily receive significantly less colostrum. Research has shown that small breeds like Jerseys still have high nutrient requirements and need at least a full gallon to gallon and a half of colostrum.

The transitional colostrum that a cow produces between calving and regular milk can still be fed to calves. While the antibodies won’t be able to be fully absorbed, this milk is still high nutrient dense and full of nutrients the calf can benefit from.

In any case where colostrum replacements or supplements are needed, thorough research and professional consultation should be done on any product prior to purchase. Poor quality or improperly fed products can have disastrous effects on young animals; always consult with your veterinarian and nutritionist.