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Milk: Liters to Pounds



Karen L. Jacobsen, BS, DVM, MS


Farm Animal Resources & Management (F.A.R.M.), LLC

706-340-0999 (mobile)

Colostrum management has a larger impact on calf health than any other management factor. Heifer calves leaving the dairy to be raised by a custom calf raiser should receive the same attention at birth as the heifers to be grown at home.

Amount & timing of colostrum feeding:

Some dairymen allow the calf to nurse the cow for the first 12-24 hours of its life before separating the calf form the cow.  Unfortunately, this is not a good practice on today's dairy farms because up to 2/3 of thses calves will not have adequate colostrum antibodies in their blood when tested.  Instead, the calf should be hand-fed "high-antibody" colostrum (see below) within the first 4 hours of life. Many cows have udders that are too pendulous and hang down too low for the calf to be able to nurse properly. Other cows may leak colostrum prior to calving, resulting in lesser quality (or no) colostrum available to the calf. Also, first and second calf heifers have lower quality colostrum than older cows. 

The newborn calf is born with almost no antibodies in the blood. Immediately after birth, the calf's intestine is able to absorb antibodies very well. As soon as anything enters the digestive tract (mucous, manure, dirt, straw, colostrum, etc.), the shape of the cells lining the calf's intestine starts to change from rectangular to square. The square cells are unable to absorb the antibodies. This decrease in absorptive capacity occurs rapidly. By 9 hours after stimulation, only about 50% of the available antibody is absorbed. By 12 hours, only 30% is absorbed.

The "4-4-4 RULE": Milk the cow within the first 4 hours after calving. Feed 4 quarts (~4 liters) of "green" or "high-antibody" colostrum within the first 4 hours after birth. (In very small calves & Jerseys, it may be possible to get only 3 liters in the calf). A second feeding of "green" or "good" colostrum should occur at 6-12 hours after birth. If possible, colostrum feeding should continue on days 2 and 3 of the calf’s life (using transition milk). Colostrum of lesser quality (yellow or red colostrometer reading) can be used for later feedings.

Each person administering colostrum needs to be taught the importance of colostrum and how to tube feed a calf that doesn't suckle with an esophageal feeder. Esophageal feeders with steel ball ends are preferred. Plastic or nylon ball ends can become sharp from the calf's teeth and cause damage to the calf's throat and esopagus.

Measuring Colostrum Quality via Colostrometer:

Because bovine colostrum has about 100 times the antibody content of milk, the quality and quantity of colostrum given are critical. The color and appearance of colostrum indicate only the amount of fat present, and are NOT indicative of the amount of antibodies present. Even an experienced dairyman cannot judge colostrum quality by simply looking at it.

The ColostrometerR is a handy commercial device which can be purchased online (about ) at This device measures the specific gravity of milk, which equates to the antibody level. It should be used on colostrum either fresh from the cow or at room temperature. Refrigeration thickens the colostrum, and readings will be falsely positive. The goal is to feed only "green" or "good" colostrum at the first feeding. Colostrum quality varies with age of dam (first and second calf heifers have lower quality) & other factors. Cows that leak milk prior to the calf nursing have lower antibody levels in the colostrum.

Colostrometer Readings:

Red = low antibody level

Yellow = medium antibody level

Green = high antibody level 



Colostrometers require at least 8 oz (250cc) of colostrum to test. Also, the glass colostrometer is breakable and is costs approximately $50 to replace.






Colostrum Qua

lity via Brix Refractometer:  


Refractometers are optical instruments that measure the amount of light refracted or bent as it passes through a liquid. The protein and sugar components of the liquid cause the light to bend.  

A “Brix” scale is commonly used for measuring the sugar content of syrup, honey and wine.  Also, the Brix scale can be used to measure the solids (nutrient) content of pasteurized milk fed to calves.

Because antibodies are the majority of the protein in colostrum, the level of antibodies in the sample is highly correlated to the amount of light bent or refracted.  

Refractometers are sufficiently accurate, affordable, durable and results are almost instantaneous. They can be used with colostrum of any temperature and require only a few drops.  

A Brix score of > 21 %  means high antibody levels in the colostrum. 

If the score is 18 - 20%, the milk can be used for second and third feedings. If the score is < 17 %, the antibody levels are low.

How to use an optical refractometer: Place a few drops of liquie (colostrum) on the glass plate and view the results through the optical eye-piece. A line of demarcation on the scale, the amount of light bent by the sample, will indicate a number ranging from zero to 32 percent. If the line is unclear, a midpoint in the cloudiness can be used as the value for the refractometer reading. Fat content of the colostrum may cause the cloudiness.

How to use a digital refractometer:  A few drops of colostrum are placed in the well on the device, and the Brix score is displayed on the digital readout. This option is more expensive, but there is no concern about cloudiness in the reading.


Storage and handling of colostrum:

Colostrum collection: The cow’s udder should be clean and dry at colostrum collection to minimize contamination with disease-causing bacteria. Colostrum & milk are wonderful culture media for bacterial growth. Colostrum can be refrigerated with these precautions:  1) Use only VERY CLEAN colostrum, 2) Use the freshest colostrum first,  3) Refrigerate for 24 hours maximum.  Refrigerating colostrum is risky due to the potential for bacterial growth. Often Salmonella outbreaks have been traced to poorly stored colostrum. Freezing is a better option for many farms. By using a colostrometer or Brix refractometer, the best colostrum can be saved and frozen in either nipple bottles or zip-type plastic bags for later use. Double bagging is helpful to prevent leakage if one bag breaks. Frozen colostrum can be thawed in lukewarm (not hot) water. Microwaving is not recommended because it is very easy to denature the antibodies.

If control programs for Mycoplasma, bovine leukemia virus, or Johnes are being implemented, then colostrum may be pasteurized using low-temperature long time (batch) pasteurizers. This reduces antibody content by up to 40%. It may be simpler to feed colostrum from cows that are tested negative for the above diseases. 



There are 4 reasons for failure of passive transfer in calves:

1 - Calf didn’t get any colostrum

2 - Calf didn’t get enough colostrum

4 - Calf didn’t absorb the colostrum

3 - Colostral quality was poor (leaking, first-calf heifers, etc.)

Blood samples can be collected for antibody testing in calves from 2 to 8 days old. On-farm estimations of antibody content can be made by measuring total serum protein by refractometer. NOTE: This requires a separate refractometer, with a urine/serum scale (not a Brix scale).  The blood must be centrifuged first to obtain the serum for testing.

Without colostrum absorption, the calf’s total serum protein level will be approximately 4.5 mg/dl.

Total serum protein  by refractometer:                        Grade:

< 4.5 = no colostrum                           F

4.5-4.9 = inadequate                          D

5.0-5.2 = poor                                    C

5.3-5.4 = borderline                            B

5.5-7.0 = acceptable                           A

> 7.0 = dehydration likely

Note that antibody absorption is reduced by 50% by 9 hours after birth.

Colostrum Absorption by the Newborn Calf

This information provided by:

Dr. Karen Jacobsen

Phone: 706-340-0999