Tail chalking is the heat detection system of choice in today’s
large dairy operations. This is due mainly to the high percent of
heats that can be detected through this system, as it provides an
efficient means to accurately identify cows that have stood to be
mounted since the last heat detection period. It is also a rather low-cost means of heat detection.
Tail chalking involves placing a mark on the cow’s tail head, so
that when she stands to be mounted, this mark will be erased, or
at least changed. Therefore estrus can be diagnosed based on the
absence or change to the mark, in combination with secondary signs
of heat and farm records.
Herds that have adopted this system after using visual
observation generally have experienced a significant increase in
their heat detection rate. Tail chalking also allows detection of cows
that are not very active during estrus, because of the “tell-tale”
signs left behind after being involved in estrus related activities.
REQUIREMENTS
There are five basic requirements for the tail chalking system to
work efficiently:
1. Every cow must be observed and the paint or chalk touched-up
every day as needed to ensure uniformity in brightness of the
marks.
2. There should be consistency in the way the mark is applied.
Estrus diagnosis is based on the absence or change of the
mark. As herd mates mount the mark will begin to be rubbed
off. This is important because over 30 percent of cows do not
express high levels of activity during estrus, and therefore do
not stand to be mounted enough times for the mark to be
totally erased. Changes to the mark induced by only a few
mounts can be detected if these marks are being applied and
checked in the same manner every day.
3. There should be a good record keeping system. Accurate
records are one of the most valuable tools in any heat
detection program. More often than not, the records will
provide you with the necessary information to decide if a
questionable cow should be bred or not, or to confirm your
decision to breed a cow. There are many herds that use their
records to anticipate potential return to estrus after a cow has
been bred. When detecting estrus, technicians should walk the
pens with a report on the reproductive status of the herd to be
used as a quick reference, or if possible, a hand-held computer
loaded with the herd’s reproductive information. This report, or
hand-held, should contain at least the following information on
each cow:
a. Pen or group assigned to each cow
b. Ear tag or identification number of each cow
c. Reproductive status of each cow (BRED, NOT BRED,
OK/OPEN, PREG)
d. Days in milk for each cow
e. Times that each cow has been bred
f. Days since last heat or breeding for each cow
g. Breeding code for each cow’s last breeding
h. Sire to be used for each cow
4. Technicians should have a profound understanding and ability
to detect secondary signs of heat. Heat detection in the
tail chalking system uses secondary signs of heat to make the
decision to breed approximately 20 percent of the time. It is
imperative to provide training in this topic. Some secondary
signs of heat most used by technicians are:
a. Rub marks on the pins that are produced when a cow is
dismounting a cow in heat
b. The presence of mucus or discharge which is produced by
the cervix mainly to serve as a lubricant for natural service
c. Swelling and/or coloration of the vulva is another
secondary sign. Blood irrigation is increased in the
reproductive tract during estrus.
d. The presence of saliva and lick marks on the back and/or
rump area are the result of chin resting by other cows
e. Uterine tone is an excellent indicator. Rectal palpation can
provide information on both uterine tone and mucus
discharge.
5. Headlocks: Even though there are many herds that successfully
use the tail chalking system without headlocks, heat detection and breeding can be accomplished quicker and more efficiently
if cows are in headlocks. Overcrowding poses interesting
challenges to the tail chalking system, therefore, whenever
possible overcrowding should be avoided in breeding pens.
INTERPRETATION
A mark that has been completely erased is considered the
PRIMARY sign of heat in the Tail Chalking system. If chalk or paint
has been completely rubbed off within a normal heat or breeding
interval, or within two to six days after a Prostaglandin injection,
there should be no doubt in the technician’s mind that the cow
should be bred.
Because not every cow is highly active during estrus, there will
be marks that are only partially rubbed off. In this instance good
reproductive records and knowledge of secondary signs of heat
become useful. A proper interpretation of secondary signs of heat is
critical to breeding the right cows. In many herds there will be cows
that are clean as from being mounted but it is due to licking (as
shown in the picture to the right); the technician must be able to tell
the difference. Some markers contain an agent to produce a bitter
flavor designed to deter licking of the marks.
Be aware that many secondary signs of heat can be caused by
reasons other than estrus-related activities. Therefore you must
observe more than one secondary sign of heat to confirm estrus.
MARKERS
There are many markers available on the market: oil-based
paints, water-based paints, chalks, and aerosols, each with a wide
variety of colors and unique characteristics. It is important to take
care not to over-apply any of these markers. Heavy application of a
marker will make removal through common mounting and rubbing
activity difficult, especially on cows that aren’t very active when in
estrus.
Once you have chosen which marker to use, it is important to
promptly learn to apply marks in a consistent manner, and to
accurately interpret changes to those marks.
Most large dairies use a combination of colors to quickly identify
reproduction status. For example, blue may be used to identify fresh
cows and cows still below the voluntary waiting period. Orange is
often applied at the end of the voluntary waiting period or at first
breeding to indicate cows eligible to be bred. A third color (green) is
usually reserved for cows that have been confirmed pregnant.
RECOMMENDATIONS
When applying the marks with chalk, it is recommended to apply
with both forward and backward strokes, to evenly coat the hair. The
last stroke should be made against the direction of the hair to keep
a high percentage of hair in an upright position.
There must be someone responsible for heat detection on every
farm, and this person should be properly trained and retrained to
perform this task. In an ideal situation, several people on the farm
would be properly trained and qualified to detect estrus. However,
consistency is important, every employee must be on the same page
when identifying cows to breed when using the tail chalking method.
When in doubt, never try to convince yourself that a cow is in heat. If
a cow does not give enough reasons to breed her, move on to the next
cow. Accuracy of heat detection should always be a major concern.
Most experienced technicians draw a line on the back of the leg of
the cows in heat making the cow easy to locate when returning with
loaded guns. After breeding a cow, the date should be written on her
rump.
Do not abuse rectal palpation in search for uterine tone and/or
mucus discharge. This is only justified in less than ten percent of
questionable cows.
Do not hesitate to re-breed cows. Under the tail chalking system,
some cows will be bred too early and will be showing good signs of
heat the next day. If the day after being bred a cow’s mark is erased
and the date on rump is at least somewhat disturbed, this cow
should be re-bred.
SUMMARY
It is highly recommended that employees who are assigned to
detect estrus utilizing a tail chalking system be properly trained to
maximize efficiency and accuracy.
Heat detection is one of the most important chores on a dairy,
when done correctly it allows for higher whole-herd reproductive
performance.
Re-breeding will usually increase conception rate. It is a good
idea for herds to have a re-breeding policy in place.
Rectal palpation in search of uterine tone and mucus discharge
is a very useful tool, but it should not be abused. Palpation
abuse is time-consuming and will therefore keep cows locked up
unnecessarily for longer periods of time.
It is very easy to detect cows that are obviously in heat. Special
efforts need to be made to accurately detect questionable heats. The
accurate detection of these questionable heats will have a positive
impact on the herd’s pregnancy rate.
PDF IN ENGLISH
PDF IN SPANISH