Colostral Management

At birth the calf is very susceptible to disease and has little nutritional reserves. The dam's colostrum provides elements that boost the calf's immune system and fulfills many nutritional needs.
Colostrum is viewed as the single most important nutritional factor available to the calf and management practices that enhance delivery of colostrum to the newborn calf are critical for increasing calf survival.

Immunity and other benefits of colostrum
In contrast to older animals, the newborn calf has not encountered disease causing organisms previously; although fully functional, the calf's immune system has not had the "experience" of recognizing specific disease agents. Further, the bovine placenta does not allow the passive transfer of protective immunoglobulins to the calf. As a result the calf relies on colostral consumption to prime the immune system with elements made by the more experienced dam.
It is important to remember that immunoglobulin acquisition does not guarantee a disease free future for the calf. Whether a calf remains disease free or not depends on a balance between exposure to disease verses disease defenses.

Factors besides immunoglobulin are also secreted into the colostrum. These include immune-acting cells and a variety of non-immunoglobulin proteins. The more standard nutritional elements are also present in far greater abundance in colostrum than in normal cows' milk. The total solids in colostrum are approximately double those found in milk. Fat percentage is approximately 50% increased, while protein content is more than quadrupled. The bulk of the increased protein is of course immunoglobulin but casein content is also double that found in milk. Lactose is the only major constituent of colostrum that is lower (approximately 50%) than the level in normal milk. Thus, while the newborn calf's body reserves are not extravagant, the feeding of colostrum provides the calf with an abundance of protein and energy.

Associated with the high levels of fat in colostrum, the fat soluble vitamins A, D and E are also present at four to eight times normal milk levels. Vitamin B12 is available at an 8-fold higher concentration. The macrominerals (calcium, phosphorus and magnesium) are at double to quadruple normal milk levels, while the micronutrients (e.g. copper, iron, zinc, cobalt) are present at 5 to 20 times normal milk levels. Aside from its value as a source of immune enhancement, colostrum provides the calf with critically important nutrients.

Evaluation of Colostrum
The two most important factors in passive transfer of immunoglobulins are the total amount ingested and the time after birth when colostrum is received.

Concentration of immunoglobulins varies between cows. The concentration of immunoglobulins can be estimated by measuring its specific gravity. A colostrometer can measure the specific gravity and can be helpful in selecting the cows from which colostrum is fed to the newborn calf. The specific gravity should be measured at a set temperature (preferably 72 degrees Fahrenheit). It should measure in the green area on the colostrometer (equivalent to 50mg/ml)

A recommendation for the minimum immunoglobulin mass that a newborn should receive is about 100 grams. A more appropriate aim is to provide 200-300 grams, thus 4 liters of colostrum at 50mg/ml would provide 200 grams.

Timing of Colostrum Consumption
The time at which colostrum is fed to the newborn calf is also very important. The earlier the calf receives an appropriate amount of immunoglobulin, the better the absorption will be. The recommendation must be that colostrum is fed as soon as possible after birth and preferably within the first two hours of life. Delaying the first colostral feeding beyond six hours of life has been shown to decrease the efficiency of immunoglobulin absorption and increase the calf's susceptibility to disease.

Feeding Colostrum
The method of feeding colostrum to calves has also been investigated. These studies suggest that suckled colostrum provides better passive transfer to the calf. In many cases, however, this is impractical and it is frequently better to ensure colostral ingestion than to wait until the calf consumes the colostrum by nipple feeder. Feeding colostrum via nipple feeder is a good practice but it may require inordinate amounts of time for calves with weak suckle reflex. Administration of colostrum by an esophageal feeder will introduce the colostrum into the rumen rather than the abomasum. When sufficient volume is provided, however, the majority will pass rapidly into the abomasum and allow adequate absorption, even though the efficiency of absorption may be slightly impaired.

Heat treating the colostrum
The colostrum can be heat treated to get rid of most disease causing organisms. This can be done at 145 degrees F for 30 minutes. This will not kill the agent that causes Johne's and may have a reduction of immunoglobulin levels up to 10 - 15%