Efficient and accurate estrus detection is the most important
factor limiting reproduction in most dairy animals/herds. Efficiency
defines the proportion of dairy animals seen in estrus of all
animals eligible for showing estrus. Accuracy gives the percentages
that were correctly identified as being in estrus. In a well-managed
herd, the maximal estrus detection rate was found to be 60% of
ovulations when dairy animals were observed two or three times
daily. With continuous observations, the detection rate may increase
to 95% in the second and later postpartum ovulations. Failure to
observe animals in estrus delays first service, lengthens oestrus
intervals, and is one of the primary factors lengthening projected
average minimum calving to conception interval by increasing the
number of days open. It contributes more to lengthy calving
intervals than conception failure. In addition, inaccurate estrus
detection lowers conception rate. Many animals are inseminated when
not in estrus.
Efficient reproductive management depends on the ability to detect
estrus. There should be a systematic program for estrus detection.
Criteria of such a program:
Frequency of observation
(three times a day minimum)
Time allotted for
observations (10 minutes per time for a herd of 50 animals)
Assignment of employees
to estrus detection (no other duties at estrus detection times)
Employees should be trained in proper methods for estrus detection,
semen handling and artificial insemination. If there is
shortage of labour, investment in oestrus detection aids should be
Estrus Detection Aids
increase the efficiency of the estrus detection; although best
method is visual examination but it is difficult in herd.
are usually males that have been altered so that cannot mate but
usually have sexual desire. These may be:
These are surgically altered male, usually sterile. The most common
method is vasectomy, removing the section of vas deferens. This
prevents the sperm passage but still allowing the transmission of
sexually transmitted diseases.
There is surgically or non surgically alteration in direction of
penis. When penis is erected, its direction is not straight. So when
it mounts the cow, copulation does not occur. These bulls should not
be large in size and weight.
Androgenized Cow or
These cows are treated with male hormones.
Electronic Heat Detection Device:
They can measure the pressure applied to the female back, the
activity level of female or the changes in hormone level.
Chin Ball Marker:
placed under the chin of the bull. It causes the paint to rub on the
back of the cow on which it is mounted.
Ka Mar Heat Detector:
device contains red dye and is glued on the tail. If the cow is
mounted, the pressure on the device causes the dyes to mix, creating
a visible colour change.
are motion sensors attached on the neck or fore leg. This sensor
indicates the increased activity level associated with estrus by
measuring the changes in amount of walking.
Blood or Milk Progesterone Kit:
used to measure the progesterone level. Normally it is less than 1
ng. During diestrus it is 8-11n g/ml.
Heat Expectancy Table or Record:
beginning of breeding season it can be used to generate a list of
animals that should be cycle during a given time. Both primary and
secondary signs should be recorded. It is also useful when animal
will return to the next estrus specially in animal with silent heat.
Computerized Estrus Detection Aid:
equipped with transmitters are glued to the tail head. When the
mounting activity begins, the transmitter depresses and signals are
sent to the receiver. Mounting data includes transmitter number,
date, time and duration of mount. These are sent to the receiver and
downloaded to computer.
also use dogs smelling or video camera.