Dairy cow oestrus monitoring method and device

Abstract

The invention discloses a dairy cow oestrus monitoring method and device. The method comprises the following steps: A, acquiring a reflected light intensity value caused by the blood flow change of the nasal septum part of the dairy cow within a first time interval by using an infrared light sensor; b, preprocessing the intensity value of the reflected light in the first time interval; c, calculating a heart rate value by utilizing a preprocessing result; d, the average heart rate value is calculated within a second time interval, the second time interval comprises a plurality of first time intervals, and the average heart rate value is uploaded to the server; e, after a third time interval, collecting and calculating the average heart rate value of the next second time interval again. The dairy cow oestrus monitoring method and device have the advantages of being high in monitoring precision, timely and accurate.

Description

Technical Field

[0001] This invention relates to auxiliary equipment in animal husbandry, specifically to a method and device for monitoring the estrus cycle of dairy cows. Background Technology

[0002] With the continuous expansion of dairy farming and the rapid increase in the number of dairy cows, dairy farms are facing increasing pressure in estrus detection. Traditional methods for detecting estrus in dairy cows are time-consuming, labor-intensive, and lack timeliness, making them unsuitable for the needs of large-scale farming. Automated estrus detection technologies based on pedometers or smart collars monitoring cow activity have emerged and been widely adopted worldwide, but they have not overcome the bottleneck of detecting estrus in quiet conditions, hindering further improvements in mating efficiency. Although some studies have attempted to reflect estrus status through physiological parameters such as vaginal temperature and vaginal mucus resistance, these monitoring devices are highly invasive, causing significant harm to cattle, and cannot be worn stably for extended periods, thus limiting their widespread application. Therefore, exploring new physiological estrus markers and establishing novel, efficient automated estrus detection technologies to overcome existing technical problems and improve dairy cow reproductive efficiency is of great significance.

[0003] Heart rate, as a basic physiological indicator of dairy cows, reflects their health (inflammation, stress, etc.) and reproductive status (estrus, pregnancy, parturition, etc.). In recent years, researchers have monitored and analyzed changes in dairy cow heart rate under conditions such as heat stress (JO et al., 2024), mosquito and fly stimulation (Guo Hailan, 2010; Li Fusheng, 2010), disease diagnosis (MARTINEZ et al., 2014; KOVáCS et al., 2024), pregnancy (Wang Guangmeng et al., 2014), and parturition (KOVáCS et al., 2016; KOJIMA et al., 2024). However, there are very few reports on the patterns of heart rate changes during estrus. Schlünsen et al. (1987) reported that the average heart rate of dairy cows increases by 7% during estrus. Nordéus et al. (2012) found that the heart rate of heifers during estrus was significantly higher than that during estrus. Yuan Kaimin (2024) meticulously analyzed the heart rate changes of one dairy cow before and after the onset of estrus, finding that the cow's heart rate was around 70 beats / min before the onset of estrus, and increased significantly after the onset of estrus (P<0.05), reaching its highest value (93 beats / min) around the 3rd hour after the onset of estrus, and then returning to around 68 beats / min after the end of estrus. These studies indicate that changes in cow heart rate can reflect the estrus status of dairy cows and can be used as a basis for judging whether estrus has occurred. However, current technologies for monitoring cow heart rate are relatively backward, failing to achieve continuous and long-term monitoring, and there are no reports of using cow heart rate to indicate estrus. How to achieve continuous and long-term monitoring of cow heart rate? How to use heart rate changes to predict whether a dairy cow is in estrus? These technical problems have not been solved in the existing technology. Summary of the Invention

[0004] To address the shortcomings of existing technologies for monitoring bovine heart rate, which are outdated, fail to provide continuous and long-term monitoring, and lack reports on using bovine heart rate to indicate estrus, this invention proposes a method and device for monitoring the estrus cycle in dairy cows. This method can quickly and accurately monitor the estrus cycle of dairy cows, offering advantages such as high precision and a high degree of automation.

[0005] To achieve this goal, the present invention adopts the following technical solution.

[0006] This invention provides a method for monitoring the estrus cycle of dairy cows, which includes the following steps: A. During the first time interval, use an infrared light sensor to collect the intensity of reflected light caused by changes in blood flow in the nasal septum of the cow. B. Preprocess the reflected light intensity values ​​within the first time interval; C. Calculate the heart rate value using the preprocessing results; D. Calculate the average heart rate value within the second time interval, which includes multiple first time intervals, and upload the average heart rate value to the server. E. After the third time interval, the average heart rate value is collected and calculated again for the next second time interval.

[0007] A key feature of this invention is that it selects blood flow changes in the nasal septum of dairy cows, an area that is not covered by body hair and has a clearly visible blood vessel distribution, thus providing high monitoring accuracy.

[0008] In addition, in the method for monitoring the estrus period of dairy cows of the present invention, the preprocessing of the reflected light intensity value includes DC filtering, moving average filtering, eight-point average filtering and fast Fourier transform processing.

[0009] In addition, in the method for monitoring the estrus period of dairy cows of the present invention, the calculation of heart rate value in the preprocessing results includes using the frequency point with the largest amplitude after processing by fast Fourier transform as the peak frequency, obtaining the peak frequency index value, and using the formula: heart rate (beats / minute) = 60 × infrared light sensor sampling rate × peak frequency index value / number of fast Fourier transform points.

[0010] In addition, in the method for monitoring the estrus period of dairy cows of the present invention, the infrared light sensor includes an infrared light emitting source and a photosensitive receiver. The infrared light sensor is fixed to the nasal septum of the dairy cow and emits infrared light in the direction of the nasal septum. The infrared light emitted by the infrared light emitting source is absorbed by hemoglobin and is used to detect the change in hemoglobin absorption intensity caused by changes in blood flow due to heartbeat, which further causes a change in the intensity of reflected light received by the photosensitive receiver. The reflected light is collected by the photosensitive receiver as reflected light intensity data.

[0011] Furthermore, the method for monitoring the estrus period of dairy cows according to the present invention further includes: using a threshold for the change in the average heart rate value or a threshold for the percentage change as a basis for determining the estrus period of dairy cows.

[0012] The present invention also includes a dairy cow estrus monitoring device, which includes a main control unit, an infrared light sensor unit, a data preprocessing unit, a heart rate calculation unit, a heart rate average acquisition and transmission unit, and a server, wherein... The infrared light sensor unit is used to collect the intensity value of reflected light caused by changes in blood flow in the nasal septum of a cow during the first time interval using an infrared light sensor. The data preprocessing unit is used to preprocess the reflected light intensity values ​​within the first time interval; The heart rate calculation unit is used to calculate the heart rate value using the preprocessing results; The heart rate average acquisition and transmission unit calculates the average heart rate value within a second time interval, which includes multiple first time intervals, and uploads the average heart rate value to the server. The main control unit is connected to the infrared light sensor unit, the data preprocessing unit, the heart rate value calculation unit, and the heart rate value average acquisition and transmission unit. It is used to collect and calculate the heart rate value average for the next second time interval after the third time interval.

[0013] In addition, the server in the dairy cow estrus monitoring device of the present invention further includes an estrus determination unit, which is used to determine the estrus period of the cow based on the threshold of the average change in heart rate or the threshold of the percentage change.

[0014] The key point of this invention is that by developing an automatic acquisition device for physiological indicators such as bovine heart rate, it collects heart rate data during the estrus and interestrus periods of dairy cows, reveals the trend of heart rate changes before and after the onset and end of estrus, and statistically analyzes the difference in heart rate between the estrus and interestrus periods, or the percentage increase in heart rate during the estrus period compared to the interestrus period. Based on this, it infers the threshold of heart rate changes during estrus, and has originally developed a technology for identifying the estrus period of dairy cows, realizing automated monitoring of estrus in dairy cows. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating a method for monitoring the estrus period of dairy cows according to a specific embodiment of the present invention.

[0016] Figure 2 This is a schematic diagram of the control section of a method for monitoring the estrus period of dairy cows according to a specific embodiment of the present invention.

[0017] Figure 3 This is a schematic diagram showing the comparison of heart rates obtained using the estrus monitoring method for dairy cows according to a specific embodiment of the present invention.

[0018] Figure 4 This is a schematic diagram showing the comparison of heart rates obtained using the estrus monitoring method for dairy cows according to a specific embodiment of the present invention.

[0019] Figure 5 This is a schematic diagram showing the statistical results of the average heart rate during the intermediate estrus period and the estrus period, the difference between them, the percentage increase, and the duration of estrus, detected by the dairy cow estrus monitoring method according to a specific embodiment of the present invention.

[0020] Figure 6 To illustrate the method for monitoring the estrus period of dairy cows according to a specific embodiment of the present invention, the present invention provides a schematic diagram of detection results using the difference in heart rate between the estrus period and the estrus period or the percentage increase in heart rate during the estrus period compared to the estrus period as a threshold. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings.

[0022] The following detailed exemplary embodiments are disclosed. However, the specific structural and functional details disclosed herein are merely for the purpose of describing exemplary embodiments.

[0023] However, it should be understood that the present invention is not limited to the specific exemplary embodiments disclosed, but covers all modifications, equivalents, and substitutions falling within the scope of this disclosure. Throughout the description of the drawings, the same reference numerals denote the same elements.

[0024] Referring to the accompanying drawings, the structures, proportions, sizes, etc., depicted in the drawings are merely for illustrative purposes to aid those skilled in the art in understanding and reading the content disclosed herein. They are not intended to limit the conditions under which the invention can be implemented and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the positional limitations used in this specification are merely for clarity of description and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0025] It should also be understood that the term “and / or” as used herein includes any and all combinations of one or more of the related listed items. Furthermore, it should be understood that when a component or unit is referred to as “connected” or “coupled” to another component or unit, it may be directly connected or coupled to the other component or unit, or there may be intermediate components or units. In addition, other words used to describe the relationship between components or units should be understood in the same manner (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.).

[0026] Figure 1 This is a flowchart illustrating a method for monitoring the estrus cycle of dairy cows according to a specific embodiment of the present invention. As shown in the figure, the present invention provides a method for monitoring the estrus cycle of dairy cows, which includes the following steps: A. During the first time interval, use an infrared light sensor to collect the intensity of reflected light caused by changes in blood flow in the nasal septum of the cow. B. Preprocess the reflected light intensity values ​​within the first time interval; C. Calculate the heart rate value using the preprocessing results; D. Calculate the average heart rate value within the second time interval, which includes multiple first time intervals, and upload the average heart rate value to the server. E. After the third time interval, the average heart rate value is collected and calculated again for the next second time interval.

[0027] exist Figure 1 In a specific example, the first time interval is 10 seconds, the second time interval is 7 minutes, and the third time interval is 23 minutes. These time intervals can be adjusted according to actual needs. According to the dairy cow estrus monitoring method adopted in the specific embodiment of the present invention, the above specific time intervals have high accuracy and also avoid excessive data volume.

[0028] Furthermore, in the dairy cow estrus monitoring method of the present invention, the preprocessing of the reflected light intensity values ​​includes DC filtering, moving average filtering, eight-point average filtering, and fast Fourier transform processing. Therefore, the above data preprocessing methods can eliminate error values ​​or singular values ​​in the reflected light intensity data, avoiding misjudgments.

[0029] In addition, in the method for monitoring the estrus period of dairy cows of the present invention, the calculation of heart rate value in the preprocessing results includes using the frequency point with the largest amplitude after processing by fast Fourier transform as the peak frequency, obtaining the peak frequency index value, and using the formula: heart rate (beats / minute) = 60 × infrared light sensor sampling rate × peak frequency index value / number of fast Fourier transform points.

[0030] In addition, in the method for monitoring the estrus period of dairy cows of the present invention, the infrared light sensor includes an infrared light emitting source and a photosensitive receiver. The infrared light sensor is fixed to the nasal septum of the dairy cow and emits infrared light in the direction of the nasal septum. The infrared light emitted by the infrared light emitting source is absorbed by hemoglobin and is used to detect the change in hemoglobin absorption intensity caused by changes in blood flow due to heartbeat, which further causes a change in the intensity of reflected light received by the photosensitive receiver. The reflected light is collected by the photosensitive receiver as reflected light intensity data.

[0031] Furthermore, the method for monitoring the estrus period of dairy cows according to the present invention further includes: using a threshold for the change in the average heart rate value or a threshold for the percentage change as a basis for determining the estrus period of dairy cows.

[0032] The present invention also includes a dairy cow estrus monitoring device, which includes a main control unit, an infrared light sensor unit, a data preprocessing unit, a heart rate calculation unit, a heart rate average acquisition and transmission unit, and a server, wherein... The infrared light sensor unit is used to collect the intensity value of reflected light caused by changes in blood flow in the nasal septum of a cow during the first time interval using an infrared light sensor. The data preprocessing unit is used to preprocess the reflected light intensity values ​​within the first time interval; The heart rate calculation unit is used to calculate the heart rate value using the preprocessing results; The heart rate average acquisition and transmission unit calculates the average heart rate value within a second time interval, which includes multiple first time intervals, and uploads the average heart rate value to the server. The main control unit is connected to the infrared light sensor unit, the data preprocessing unit, the heart rate value calculation unit, and the heart rate value average acquisition and transmission unit. It is used to collect and calculate the heart rate value average for the next second time interval after the third time interval.

[0033] In addition, the server in the dairy cow estrus monitoring device of the present invention further includes an estrus determination unit, which is used to determine the estrus period of the cow based on the threshold of the average change in heart rate or the threshold of the percentage change.

[0034] The key point of this invention lies in the development of an automatic acquisition device for physiological indicators such as bovine heart rate. This device collects heart rate data during the estrus and interestrus periods, revealing the trend of heart rate changes before and after the onset and end of estrus. It also statistically analyzes the difference in heart rate between the estrus and interestrus periods, or the percentage increase in heart rate during the estrus period compared to the interestrus period, and infers the threshold for heart rate changes during estrus. This original invention provides a technology for identifying the estrus period in bovines, enabling automated monitoring of the estrus period.

[0035] There is a significant difference in heart rate between the estrus and dysestrus periods in dairy cows. Based on this characteristic, this invention sets a heart rate threshold, that is, the difference in heart rate between the estrus and dysestrus periods, or the percentage increase in heart rate during the estrus period relative to the heart rate during the dysestrus period, as the criterion for judging estrus. After careful analysis, it was found that when the heart rate difference is set to 7 beats / min or the heart rate increases by 10% relative to the heart rate during the dysestrus period, the estrus detection effect is the best, reaching 100%.

[0036] Figure 2This is a schematic diagram of the control section of a method for monitoring the estrus cycle of dairy cows according to a specific embodiment of the present invention. As shown in the figure, the control section includes a main control chip, a six-axis accelerometer, a heart rate sensor, an infrared temperature sensor, a communication module, a main circuit board, and a 3.7V / 3000mAh lithium battery, etc.

[0037] The main control chip is responsible for processing the data collected by each sensor and controlling the operation of the entire system. A six-axis accelerometer can detect changes in an object's posture from all directions. When worn on a cow's head, it can detect up-and-down, left-and-right, and back-and-forth swaying signals.

[0038] The communication module is mainly used to connect to the network and is responsible for remotely monitoring and analyzing the data collected by the sensors.

[0039] The heart rate sensor is responsible for collecting heart rate data, supports dynamic heart rate capture and real-time data updates, and its low power consumption and high waterproof performance are suitable for the sensitivity of nasal heart rate detection in cattle farms and the long-term working requirements of complex environments.

[0040] The main circuit board (PCB) is responsible for connecting all components together and providing the necessary power and data transmission paths; the 4.2V / 3000mAh lithium battery is responsible for providing power to the entire system and ensuring the normal operation of the equipment.

[0041] In addition, the lithium battery is equipped with a Type-C interface charging circuit board, which is connected to the battery by wires and powered by the main circuit board through contact pins. The main control chip, accelerometer, and 4G communication module are soldered on the main circuit board. To ensure the long-term stable operation of each sensor, main control chip, and 4G module, the voltage needs to be converted to the minimum operating voltage of each module, i.e., a selection circuit. At the same time, to save power, program-driven switches are designed to control the sleep and operation of the temperature sensor and 4G module. The sleep time and operation time are synchronized with the network time through networking.

[0042] The heart rate data acquisition process is as follows: First, the heart rate sensor is initialized, and its red and infrared light functions are enabled. The sampling rate is 100 Hz. Then, a heart rate data acquisition begins. If the register reads data for less than 10 seconds, the data is read repeatedly. If it reaches 10 seconds, various filtering and fast Fourier transform algorithms are applied to find the frequency point with the highest amplitude. Finally, the heart rate value is calculated using the formula: "Heart rate (beats / min) = 60 x sampling rate x peak frequency index / number of fast Fourier transform points". After 7 minutes of continuous acquisition, the data is automatically converted into an average value, uploaded, stored, and cleared. After a 23-minute sleep period, the data is reinitialized and the next 7-minute heart rate acquisition begins. This process is repeated continuously to collect cow heart rate data.

[0043] A method for monitoring estrus in dairy cows, as described in a specific embodiment of this invention, was used to randomly select 25 dairy cows with normal postpartum reproductive capacity for the experiment. The experimental cows were subjected to a synchronized estrus program. They were given an intramuscular injection of 100 μg of gonadorelin (a GnRH analogue), designated as day 0. Four days later, they were fitted with devices to collect real-time activity and heart rate data. On day 7, they were given an intramuscular injection of 2-3 ml of cloprostenol sodium (a PGF2α analogue). On day 8, they were manually observed for estrus. If estrus was observed, a rectal examination was performed to confirm follicle development. If follicle development was present, insemination was performed directly. Otherwise, gonadorelin was injected on day 9, and insemination was performed at regular intervals of 16 hours. The trends in heart rate changes before and after the onset and end of estrus were compared and analyzed. Simultaneously, the average heart rate for each cow during the period from the onset to the end of estrus, as well as the average heart rate on day 2 before estrus and corresponding to the estrus period, were statistically analyzed. The difference and percentage increase between the estrus and anteestrus periods were then calculated for each cow. By deeply analyzing this heart rate data, we can accurately understand the unique fluctuation pattern of heart rate during estrus in dairy cows, and thus set thresholds to determine whether a dairy cow is in estrus.

[0044] Figure 3 This is a schematic diagram comparing heart rates obtained using a dairy cow estrus monitoring method according to a specific embodiment of the present invention. As shown in the figure, the heart rates of 19 dairy cows in estrus were compared and analyzed at 0.5 hours (estrus period) from 4 hours before to 4 hours after the onset of estrus, with the heart rates at the same time point 2 days before estrus (diestrus period). The results are as follows... Figure 3 As shown, the heart rate of dairy cows during the interestrus period is relatively stable, ranging from 73 to 76 beats / min. After the onset of estrus, the heart rate gradually increases, reaching its peak at 2.5 hours (89.98 beats / min ± 5.63 beats / min), which is significantly higher than the heart rate at the same time point during the interestrus period (P < 0.01). In the figure, "✳" indicates a highly significant difference between the heart rate during estrus and the heart rate during the interestrus period at the same time point (P < 0.01).

[0045] Figure 4 This is a schematic diagram comparing heart rates obtained using a dairy cow estrus monitoring method according to a specific embodiment of the present invention. As shown in the figure, the heart rates of 19 dairy cows in estrus were compared and analyzed at 0.5 hours (estrus period) from 4 hours before the end of estrus to 4 hours after the end of estrus, with the heart rates at the same time point 2 days before estrus (interestrus period). The results are as follows... Figure 4 As shown, 4 hours after the end of estrus, the heart rate of dairy cows was basically the same as the heart rate at the same time on the second day before estrus, with no significant difference (P>0.05). However, 4 hours before the end of estrus, the heart rate of dairy cows was significantly higher than the heart rate at the same time on the second day before estrus (P<0.01). Meanwhile, Figure 4The study also showed that the heart rate of dairy cows during estrus gradually decreased from 2.5 hours before the end of estrus (88.41 beats / min ± 6.32 beats / min) to the level during estrus (77.16 beats / min ± 3.54 beats / min) 0.5 hours after the end of estrus. In the figure, “✳” indicates that the difference between the heart rate during estrus and the heart rate during estrus at the same time point is extremely significant (P < 0.01).

[0046] Figure 5 This diagram illustrates the statistical results of the average heart rate during the interestrus and estrus periods, their difference, percentage increase, and estrus duration detected using the dairy cow estrus monitoring method according to a specific embodiment of the present invention. As shown in the figure, the average heart rate during estrus was 86.65 beats / min (range 83.07 to 93.08 beats / min), generally higher than the average heart rate during the interestrus period (76.68 beats / min, range 72.81 to 81.59 beats / min), and increased by 9.98 beats / min (range 7.80 to 14.10 beats / min) compared to the average heart rate during the interestrus period, representing an increase of approximately 13.02% (range 10.28% to 18.77%). The average estrus duration in the experimental cows was 7.87 hours, with a maximum duration of 13.5 hours and a minimum duration of 5.5 hours. As can be seen from the figure, the estrus period is relatively limited and short; therefore, sensitive detection using the dairy cow estrus monitoring method of this invention is essential.

[0047] While a lower heart rate threshold can detect more cows in estrus, some may be falsely estrus. Conversely, a higher threshold may miss some truly estrus cows, leading to a lower detection rate. The challenge lies in setting a heart rate threshold that accurately detects estrus cows while avoiding unnecessary misjudgments. This invention uses the difference in heart rate between the estrus and anteestrus periods, or the percentage increase in heart rate during estrus compared to anteestrus, as the threshold. It was found that as the heart rate threshold increases, the number of detectable cows gradually decreases, and the estrus detection rate gradually declines. The highest estrus detection rate (100%) is achieved when the heart rate threshold increases by 7 beats / min or 10%. When the heart rate threshold exceeds 9 beats / min or increases by more than 11%, the estrus detection rate is below 78.95%, failing to meet production requirements. Therefore, a heart rate increase of 7 beats / min or 10% is considered the optimal estrus warning threshold. Figure 6To illustrate the method for monitoring estrus in dairy cows according to a specific embodiment of the present invention, this invention provides a schematic diagram of detection results using the difference in heart rate between the estrus and anteestrus periods, or the percentage increase in heart rate during estrus compared to anteestrus, as thresholds. As shown in the figure, the heart rate during estrus is significantly higher than during anteestrus (P < 0.01), approximately 9.98 beats / min higher, representing a relative increase of 13.02%, which can be used to indicate estrus. The highest estrus detection rate, 100%, is achieved when the heart rate increase is 7 beats / min or a relative increase of 10%. The results demonstrate that the method and device for monitoring estrus in dairy cows according to the specific embodiment of the present invention can monitor changes in heart rate in real time, accurately and effectively predict estrus in dairy cows, and has good application value.

[0048] The foregoing description illustrates and describes several preferred embodiments of the present invention. However, as mentioned above, it should be understood that the present invention is not limited to the forms disclosed in this specification and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described in this specification through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A method of dairy cow estrus detection, characterized in that, The method comprises the steps of: A. collecting the reflected light intensity value caused by the blood flow change of the cow's nasal septum part by using the infrared light sensor in the first time interval; B. preprocessing the reflected light intensity value in the first time interval; C. calculating the heart rate value by using the preprocessing result; D. calculating the average value of the heart rate value in the second time interval, the second time interval comprising a plurality of first time intervals, and uploading the average value of the heart rate value to the server; E. after the third time interval, re-performing the collection and calculation of the average value of the heart rate value in the next second time interval.

2. The method of estrus detection in dairy cattle according to claim 1, characterized in that, The preprocessing of the reflected light intensity value comprises direct current filtering, moving average filtering, eight-point average filtering, and fast Fourier transform processing.

3. The method of estrus detection in dairy cattle according to claim 2, characterized in that, The preprocessing result calculates the heart rate value, which comprises obtaining the peak frequency by using the frequency point with the largest amplitude after the fast Fourier transform processing, obtaining the peak frequency index value, and calculating the heart rate (times / minute) = 60 x infrared light sensor sampling rate x peak frequency index value / fast Fourier transform point number.

4. The method of estrus detection in dairy cattle as claimed in claim 1, wherein, The infrared light sensor comprises an infrared light emitting source and a photosensitive receiver, the infrared light sensor is fixed to the nasal septum part of the cow to emit infrared light to the nasal septum part, the infrared light emitting source emits infrared light which is absorbed by hemoglobin, which is used to detect the change of the absorption intensity of hemoglobin caused by the blood flow change caused by heartbeat, and further cause the change of the reflected light intensity received by the photosensitive receiver, and the reflected light is collected by the photosensitive receiver as the reflected light intensity data.

5. The method of estrus detection in dairy cattle as claimed in claim 1, wherein, Further comprising: According to the change amount threshold or the change percentage threshold of the average value of the heart rate value, as the basis for judging the estrus period of the cow.

6. A dairy cow estrus monitoring device characterized by, The device comprises a master control unit, an infrared light sensor unit, a data preprocessing unit, a heart rate value calculation unit, a heart rate value average value acquisition and transmission unit, and a server, wherein The infrared light sensor unit is used to collect the reflected light intensity value caused by the blood flow change of the cow's nasal septum part by using the infrared light sensor in the first time interval; The data preprocessing unit is used to preprocess the reflected light intensity value in the first time interval; The heart rate value calculation unit is used to calculate the heart rate value by using the preprocessing result; The heart rate value average value acquisition and transmission unit calculates the average value of the heart rate value in the second time interval, the second time interval comprising a plurality of first time intervals, and uploads the average value of the heart rate value to the server; The master control unit is connected to the infrared light sensor unit, the data preprocessing unit, the heart rate value calculation unit, and the heart rate value average value acquisition and transmission unit, and is used to re-perform the collection and calculation of the average value of the heart rate value in the next second time interval after the third time interval.

7. The dairy cow estrus monitoring device of claim 6, wherein, The server further comprises an estrus period judgment unit, which is used to take the change amount threshold or the change percentage threshold of the average value of the heart rate value as the basis for judging the estrus period of the cow.

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