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0706 PD: Review of colostrum in calves

Mark Alley Published on 07 August 2006

It is well-known that acquiring and absorbing adequate amounts of colostral immunoglobulins are essential to the health of the neonate, since calves are born almost void of any circulating antibodies. Colostrum is defined as the first milk harvested from the cow immediately after calving.

Colostrum is composed of high levels of immunoglobulins (IgG, IgM and IgA), vitamins, minerals, fat, protein and other cellular components. All of these pieces are essential for the successful development of the calf. Cows begin transporting immunoglobulins into the mammary gland from the circulatory system several weeks prior to calving. However, this process ends abruptly at calving. This colostrum declines rapidly in regard to immunoglobulin concentration and overall nutritional content shortly after calving. Therefore, it is mandatory that colostrum be harvested as soon as possible after calving and given to the calf.

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Harvesting
Colostrum donors on most farms are defined as any cow or heifer that has recently calved. However, there should probably be more selection criteria placed on these donors. Cows that have leaked milk, are sick, have evidence of mastitis or bloody milk or have been milked prior to calving should not have their colostrum used as the primary source of immunoglobulins. However, colostrum from heifers can produce adequate levels of immunoglobulins and should be considered as colostrum donors.

Since these calves are babies, colostrum should be harvested in as clean a manner as possible. Proper udder hygiene of these colostrum donors is mandatory to insure that large numbers of bacteria are not inoculated into these immunologically naïve calves. Also, proper attention to cleanliness in milking and storage equipment is necessary.

One clinical study revealed a negative association between bacteria counts in colostrum and IgG absorption. A recent study on a dairy in Minnesota revealed the majority of colostrum samples taken directly from the cow contain minimal bacterial contamination. However, there was also shown a drastic increase in total coliform count and total plate count after harvesting the colostrum into a milking bucket.

Therefore, storage after harvesting may be a more critical point in colostrum management than collection technique.

Determining colostrum quality
The most commonly described method of measuring colostrum quality on the farm is with the use of a colostrometer. Fleenor and Stott determined a statistical correlation between globulin concentration and specific gravity. However, some research states there may be some potential problems with the use of a colostrometer for predicting IgG concentration. First, it has been shown cold temperatures may adversely affect the reading of colostrum, causing poor-quality colostrum to appear to have adequate immunoglobulin concentration. Second, as milk composition changes, especially among breeds, there may be some significant variation in readings of colostrometers.

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Another commonly used method to determine colostrum quality is based on volume of colostrum produced at the first milking. As milk yield increases above 17.8 pounds, colostral IgG concentration decrease, and these animals should not typically be used as donors.

The most recent instrument used for screening for IgG concentration in colostrum is the Colostrum Bovine IgG Midland Quick Test Kit®. This cow-side test detects IgG concentration either as less than 50 or greater than 50 grams per liter. Chigerwe and others have determined this kit to be a useful tool in screening colostrum without the concerns regarding ambient temperature fluctuations seen with the use of the colostrometer. The cost of the test is between $3.75 and $4 per colostrum sample.

Timing
Rajala reported a 2 gram per liter decline in IgG concentration for every 30-minute delay in feeding colostrum. Therefore, calves should be fed enough volume of colostrum to receive 100 to 200 grams of immunoglobulins as soon as possible after birth. In most situations, this equates to 3 or 4 liters to insure adequate IgG concentration in the calf. Multiple studies have shown colostrum intake through suckling alone is inadequate for sufficient IgG concentrations. Ideally, all calves should be removed from the dam within two hours of birth and force-fed the appropriate volume if they will not nurse the full volume.

Storage of colostrums
Many times, there is a significant delay between harvesting of colostrum and actually feeding the calves. If bacteria are accidentally introduced into this colostrum at harvest, bacterial numbers will quickly multiply. If colostrum is not going to be fed within two hours after collection, it should be stored at 47°F to minimize bacterial growth. Colostrum should be stored in refrigerators in containers that are small enough to cool quickly.

If colostrum is going to be stored for longer periods of time, it should be stored in 1-gallon freezer bags (double-bagged) in a frost-free freezer. These bags can be easily stacked in the freezer to minimize storage space. They should be labeled with date of collection, cow identification and colostrometer reading. Colostrum can be stored in this method for up to 18 months without any deterioration in IgG concentration. However, the cellular components present in fresh colostrum will be destroyed. Therefore, fresh colostrum is preferred to frozen colostrum, if available.

Colostrum alternative
Although fresh colostrum is definitely the preferred source of immunoglobulins for calves, occasionally there are instances when colostrum is unavailable. Until recently, the only alternative was the use of colostrum supplements. These supplements contain minimal IgG concentration (less than 90 grams of IgG per dose) and have been shown to be poorly absorbed when used solely as a colostrum substitute.

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Fairly new to the market are products defined as colostrum replacers. In these, the higher quality products contain at least 100 grams of bovine immunoglobulin per dose. A study performed by Dr. Geof Smith and Dr. Derek Foster at NCSU College of Veterinary Medicine revealed that a colostrum replacer product was superior to a colostrum supplement in providing adequate passive transfer in a group of 80 Holstein bull calves on a farm in North Carolina.

Testing strategies for colostrum

Delivery
Typically, testing for successful colostrum delivery is based on history of problems and is not performed as a routine monitoring program. However, as dairies begin to increase in size, herd owners begin to rely on employees to get colostrum to these valuable assets. One relatively inexpensive method to monitor success in colostrum delivery is the use of a small sample of blood to check total protein levels. The test can be accurately used on healthy calves from 12 hours old to 7 days old. The goal is to have 80 percent of calves tested with total protein levels greater than 5.5. However, if colostrum replacers or supplements are being used, total protein may not be an accurate measure of total IgG absorption. PD

References omitted due to space but are available upon request.

—From 2006 North Carolina Dairy Conference Proceedings

Mark Alley, DVM, Clinical Instructor, North Carolina State University

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