Heat detection in dairy cows: the key to success

Cow herd fertility is crucial to the financial success of a farm. The time of insemination is of essential importance, but it is more and more difficult to detect cows in heat. In the following article you will learn more about the different phases and signs of estrus. In addition, we look at the advantages of heat detection with smaXtec and show a sample curve.

Female cattle become sexually mature at about 7 to 10 months of age, but they should be inseminated at a later point. The first time a cow is covered is at about 18 to 20 months. If a cow is in heat, she is ready to mate and can become pregnant. The heat cycle is about three weeks long, which means that at regular intervals of 21 days, a cow is in heat all year round. A heat lasts up to 1 ½ days. [1]

If the animals are covered too early, often their own development and, in the worst case, also the development of the unborn calf suffer. The optimal time of insemination depends on the age, the breed and the body condition of the heifers. Studies have shown that heifers with a live weight of 520 kg when calving show an 800 kg higher milk yield in the first lactation than heifers with a live weight of only about 420 kg at the time of calving. If the first insemination takes place too late, for example, at around 27-28 months this, in turn, results in lower pregnancy rates as possible fatty degeneration of the ovaries may occur.[3]

Heat detection and timely insemination are therefore essential for the profitability/economic success of the farm.

The different stages and signs of heat

In order to be able to determine the correct insemination time, it is important to recognize the onset of estrus as quickly as possible. Depending on the heat phase, one can observe typical estrus symptoms. In the different phases of a heat, the signs and behavior of the cows change. The four phases are defined as follows.

  1. Proestrus

This is the period in which estrus-related behavioral changes occur for the first time. Increased sniffing and mounting of other animals, first mucus forms (viscous). The cow retains milk. This phase lasts about six to ten hours.

  1. Estrus

The proestrus is followed by the main estrus. The heat symptoms are intensified. The animal “stands” and allows itself to be mounted by other cows. It also leads to increased restlessness and may cause increased bellowing. The animal eats less. A clear, thin mucus discharge can be seen on the underside of the tail.

This section lasts about 18 hours and at the end of this phase is the best time for insemination. Ovulation occurs in most cattle at the end of the main heat, where most of the heat symptoms are already less apparent. Thus, the optimal insemination time lays in the last third of the estrus, about 10-12 hours after the onset.

  1. Metoestrus

In the metoestrus, the readiness to mate begins to fade away and external and internal symptoms disappear. The mucus is now strong and very viscous.

  1. Anestrus

The anestrus is the longest phase of the estrus and lasts about 14 days. There are no symptoms of estrus in this phase. [1] [2]

Heat detection with the smaXtec system

Visual animal observation is the simplest form of heat detection, but many farmers know how problematic this can be: the more animals, the less time remains for observation and the worse heat detection gets. However, the financial success of a farm depends heavily on the fertility of the herd. The timing of insemination is crucial, yet it is becoming increasingly difficult to detect heats. There are several reasons for this: High-performing cows show fewer and fewer signs of estrus and these are often not recognized by visual observation. In addition, the heat often takes place at night. More than 70% of the animals show a heat during the night and therefore regular monitoring of the animals is essential in order to be able to determine the onset of heat and subsequently calculate the optimal insemination time. [3]  Also, with increasing herd sizes difficulties arise in heat detection due to the large number of cows and the limited time available for heat detection.

This is where smaXtec can help. The automatic and reliable heat detection provided by activity measurement is based on the recognition of characteristic changes in behavioral or movement patterns during heat. Continuous measurement provides the system with round-the-clock heat detection, which has many advantages.

Reduced time required

Visual estrus detection requires many factors to be considered and is very time-consuming. The herd should be observed four times daily for at least 15 minutes in the resting phase to achieve the best results. Farmers need a lot of time for this process. With the smaXtec system, visual observation by the farmer is no longer necessary as the smaXtec Messenger sends a notification as soon as cows show increased activity at the right stage of the cycle.

Financial advantage

Using smaXtec, you receive animal-specific information around the clock and bears fruit: users confirm that thanks to the system, a higher fertility rate and a reduced intermediate calving time are ensured. smaXtec calculates an optimal insemination window to achieve a better conception rate and less days open.

The certainty of never missing a heat

If farmers observe their cows visually, it can often lead to undetected heats as due to genetics and feeding cows show only brief heat symptoms. In addition, the animals often show signs at night. Especially in the summer months, significant signs of estrus can often be observed only at night. During the day the cows are usually too hot to move very much. smaXtec provides you with the certainty of never missing a heat and thus ensured your animals can be inseminated at just the right moment.

The ideal insemination window thanks to smaXtec

The smaXtec system not only detects the heat conditions of your animals but also determines the optimal insemination time. Once a heat notification is sent, the system provides you with information regarding the right time for insemination.

The insemination time window consists of several phases, whereby in the beginning no exact time is yet displayed. An exact time window is only displayed in the Messenger once the system has correctly calculated the time frame. The insemination window opens eight hours after main estrus has been reached.

Heat detection – smaXtec example curve

The smaXtec system detects estrus based on the typical change in cows’ activity. In the example given, the movement activity (red curve = movement activity) increased significantly on June 5, so a heat detection notification was sent. After reaching the main heat, the insemination window with the best insemination time is shown to the user. The optimal insemination time for the animal was on June 6 between 5:16 and 11:16 a.m. This time span is marked in green in the notification. After reaching the red dot, smaXtec recommends refraining from insemination.

Screenshot of an example curve with a heat notification.

Screenshot of the smaXtec Messenger indicating a heat notification.

Are you interested in using the smaXtec system on your farm to benefit from heat detection and all other functions of the system? Contact us today!



[1] https://www.bauernhof.net/enzyklopaedie/brunst-bruenstige-kuh/

[2] https://www.raumberg- gumpenstein.at/cm4/de/forschung/publikationen/downloadsveranstaltungen/finish/2750-2415-tempsens/26820-methoden-der-brunsterkennung-beim-rind.html

[3] Weiß, J.; Pabst, W.; Strack, K.-E. und Granz, S. (2005): Tierproduktion. 13., überarbeitete Auflage. Stuttgart: Parey Verlag.

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