Colostrum’s Importance in Newborn Dairy Calves
By Sydney Goldstein
Introduction
Colostrum is the first milk secreted from a mammary gland directly after
parturition (giving birth) that is rich in nutrients and antibodies. Synthesized by the
mother right before giving birth, this milk is essential to newborn animals for protection
against pathogens. Newborn calves must drink colostrum in adequate amounts in order
to gain passive immunity from his or her mother because they are born without
antibodies in their blood to protect them from disease.
This paper is going to address the significance of feeding colostrum to newborn
calves, as well as the constituents that make up high quality first milk. The golden
standard for testing the quality of the milk will be introduced. Lastly, the paper will
discuss how colostrum is digested and absorbed by the calf.
Timed Feeding
It is critical that colostrum be fed to the newborn as soon as possible after a calf
is born since the calf will not be able to survive without the antibodies it contains. It is
preferred practice to feed the milk to the calf within the first hour of life. Only during the
first 24 hours of a calf’s life can he or she absorb the antibodies contained in this milk
directly through the lining of the small intestine. The direct absorption allows the
colostrum’s immune-boosting properties to gain entry into the bloodstream and circulate
throughout the body.
First Meal: A newborn calf nursing colostrum from a bottle1.
Milk Constituents
Immunoglobulin G (IgG) is a specific type of antibody found abundantly in
colostrum. Many of colostrum’s extraordinary properties can be attributed to the amount
of IgGs in this milk. IgGs are only effective in calves when an adequate amount is
consumed, based on body weight, by the newborn, usually approximately three quarts.
In addition to IgG, lactoferrin is a critical component of colostrum. It is an iron
binding protein that has antibacterial properties. Bacteria are kept from growing due to
lactoferrin withholding free iron from the bacterial cells in the small intestine. Therefore,
the bacteria cannot use it as a nutrient or energy-yielding agent.
Components and Factors Affecting the Quality of Colostrum
Colostrum needs to be very energy dense to give a newly born animal the strong
start it needs in life. Therefore it contains high amounts of fat, protein, minerals and
antibodies compared to subsequent milkings. These components may be affected in the
mother based on events leading up to parturition.
Interestingly, the level of IgGs present in colostrum can vary depending on
several factors such as the volume of milk produced by the mother, age and disease
status of the mother, and nutritional status of the mother. Higher volumes of milk tend to
dilute the amount of immunoglobulins present, meaning the milk is of lower quality than
desired to assure the calf will gain all the benefits of drinking the immune system
protecting fluid.
Therefore, in theory, a calf would need to drink more of this milk to reap the same
advantages as that of a calf whose mother produced a more immunoglobulin dense
milk. As far as age of the mother is concerned, older mothers tend to produce milk with
more immunoglobulins since they have been exposed to more environmental
pathogens and built up a resistance.
Being able to pass their strong immune function on to their offspring is known as
passive immunity. Healthy disease status of the mother, or a disease-free status, also
plays an important role in passing healthy immunity on to the calf. When the dam has
been immunized against many diseases her body carries antibodies against those
pathogens that can be given to her baby.
Mothers who were fed a well-balanced diet and are therefore in a strong
nutritional state can usually give a more desirable energy profile in their colostrum,
since they had the energy available in their bodies to create milk rich in fat, protein, and
minerals. Dams who are in a state of poor nutrition may produce colostrum that is
somewhat deficient in vitamins A, D, and E, or in fat and protein levels, since she needs
to assure her own body gets those nutrients before partitioning them to her milk.
Lastly, it was stated that colostrum must be fed within 24 hours in order for the
calf drinking it to absorb the antibodies in the small intestine after digesting the milk.
However, it has been proven that the earlier a calf gets the colostrum into his or her
system, the more advantageous it is to his or her immune function.
Quality Assurance
Since it is so essential for calves to ingest colostrum that is of high quality, some
processes of testing it have become regularly practiced in the dairy industry. The most
commonly used instrument that tests colostrum is called a colostrometer. It is a glass
tube that measures the density of the colostrum (and proportionately the density of
IgGs) in the milk when kept at a constant control temperature of 72 degrees Fahrenheit.
The reason for the specific temperature is that, just like with other liquids, the density of
the fluid can be affected at temperatures that are too low or too high.
Left: Colostrometer illustration2. Right: Colostrometer in excellent quality milk sample3.
As seen in the right-hand visual, the different colors on the arm of the
colostrometer indicate the levels of IgGs contained in the colostrum based on specific
gravity. Red would indicate a low amount; that milk should not be fed, but rather
discarded because it will not give a calf the immune protection it needs. Yellow is an
adequate amount of IgGs, but not optimal to feed. If the milk ranges there, the person
responsible for feeding the calf must make a judgment call. Since relatively lower levels
of IgGs in milk can be overcome by feeding larger quantities, that person would need to
calculate if it is probable that the calf would drink enough of the milk to ensure it gained
passive immunity. Finally, if the result on the colostrometer reads green, it is of excellent
quality and should be fed in the proper amount to the calf based on his or her body
weight.
How Colostrum is Absorbed
A calf’s digestive system is not yet fully developed until after the first 24 hours of
life. Nutrients are digested in the stomach. Then, all the lifesaving ingredients of
colostrum can be directly absorbed by the small intestine in the same form they are
found in feed. Antibodies are not watered down or broken into smaller subunit parts.
The calf first ingests colostrum. After the solution moves down the esophagus it
is directed into the abomasum, also known as the true stomach, by a flap called the
esophageal groove. Here digestive enzymes break down high-energy nutrients such as
proteins, fats, and carbohydrates. Next, the broken down subunits of those molecules,
along with wholly intact IgGs and lactoferrin move along to the small intestine. Once
here, the nutrients are absorbed across the small intestinal wall. IgGs diffuse passively
across the intestinal wall to be incorporated into the bloodstream. Lactoferrin lingers in
the villi of the gastrointestinal tract to bind freely floating iron, making it unavailable for
pathogenic bacteria, such as Escherichia coli (E. coli), to use as a food source. Keeping
iron away from pathogenic bacteria means that microbes will be unable to multiply and
colonize in the calf, thereby preventing disease.
Colostrum flowing into the stomach of a calf. Some of the parts of this diagram will not
be discussed. The key parts are the esophageal groove and abomasum4.
Conclusion
Colostrum is extremely important milk that is secreted by the mother the first time
the newborn nurses, or shortly after birth. It contains energy dense nutrients as well as
antibodies that give the newborn the passive immunity it needs to survive. If given within
the first 24 hours of life, it aids the calf in immune function and nourishment. Without
colostrum, calves are not able to survive, or they may be weak and more infectionprone than their herd mates for the entirety of their lives. Therefore, this milk should be
given as soon as possible after birth, in as high amounts as the calf is willing to drink.
References
1 http://myculturedpalate.com/blog/2012/05/21/buttercups-lbc-little-brown-calf/
2 http://www.valleyvet.com/ct_library_info.html?product=30e07989-7b6a-11d5-a19200b0d0204ae5&showText=1.
3 http://calfcare.ca/colostrum-management/using-a-colostrometer/
4 http://calfcare.ca/calf-feeding/the-calf’s-digestive-system/