Research Article

Heat Detection of Gilts Using Digital Infrared Thermal Imaging Camera

Veasna Chem1 †, Hong-Seok Mun1,2 †, Keiven Mark B. Ampode1, Shad Mahfuz1, Il-Byung Chung1, Muhammad Ammar Dilawar1,3, Chul-Ju Yang1,3,*

1Department of Animal Science and Technology, Sunchon National University, Suncheon 57922, Korea; 2Department of Multimedia Engineering, Sunchon National University, Suncheon 57922, Korea; 3Interdisciplinary Program in IT-Bio Convergence System (BK21 Plus), Sunchon National University, 255 Jungangno, Suncheon 57922, Korea.

† These authors contributed equally to this work.

Received | May 24, 2022; Accepted | April 30, 2022; Published | September 15, 2022

*Correspondence | Chul-Ju Yang, Department of Animal Science and Technology, Sunchon National University, Suncheon 57922, Korea; Email: yangcj@scnu.ac.kr

Citation | Chem V, Mun HS, Ampode KMB, Mahfuz S, Chung IB, Dilawar MA, Yang CJ (2022). Heat detection of gilts using digital infrared thermal imaging camera. Adv. Anim. Vet. Sci. 10(10): 2142-2147.

DOI | http://dx.doi.org/10.17582/journal.aavs/2022/10.10.2142.2147

ISSN (Online) | 2307-8316

Copyright: 2022 by the authors. Licensee ResearchersLinks Ltd, England, UK.

This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

Introduction

The sound health of livestock animals is essential for high productivity and good economic returns. The body temperature of farm animals is a very important parameter for ensuring their physiological health and well-being. For example, various physiological changes such as proestrus, estrus, pregnancy, breastfeeding, parturition, etc., can affect the body temperature (Neethirajan, 2017). The skin’s surface works as a heat-radiating cooling system, allowing thermal imaging to quantify temperature gradients accurately. Changes in blood flow and tissue angiogenesis can affect the skin’s surface temperature under physiological circumstances. Moreover, body temperature is an important parameter when assessing animal health (Süli et al., 2017). Information on body temperature is very useful in diagnosing and treating diseases in animals. It enables the early detection of infected animals and the investigation of the disease’s scope and severity. With the correct recognition and rational use of physiological indicators of changes in body temperature in pigs, early detection, diagnosis, and treatment of several pig diseases are possible. (Zhang et al., 2019).

In recent years, the control of estrus and ovulation has become the main topic for a batch of flow management, which requires a pool of females service-ready for Artificial Insemination at set times. Additionally, the swine industry needs to develop new technologies that can maintain estrus and ovulation. Failure to detect estrus accurately has the greatest impact on labor rate and little size (De Rensis and Kirkwood, 2016; Kraeling and Webel, 2015). By measuring body temperature, it can accurately identify the sow’s estrus, so that it can be fertilized in timely breeding to improve the reproductive rate of sows. Temperature changes in pregnant sows are monitored in real-time, which serves to determine their health. Depending on body temperature, it is possible to increase the birth rate of sows by organizing appropriate breeding tasks (Polit, 2018).

Infrared thermography (IRT) is a non-destructive examination method for determining an object’s symmetric and asymmetric surface temperatures. Infrared cameras collect infrared radiation produced from the surface and convert it to electrical impulses, resulting in thermal pictures that depict the body’s surface temperature distribution (Irenilza et al., 2020). Furthermore, infrared thermometry (IRTM) is a non-contact temperature measuring technique with various benefits over other temperature monitoring techniques used in veterinary medicine. Even though handling the patient is unnecessary, with infrared (IR) temperature monitoring, the danger of infection is greatly reduced. This is helpful in animals since handling and constraint cause stress, which affects core and surface temperatures. (Soerensen and Pedersen, 2015). Infrared thermography (IRT) can be used for rapid screening of foot lesions in sheep (Talukder et al., 2015). In Veterinary medicine, IRT has been successfully used in many applications such as foot and mouth disease (Rainwater-Lovett et al., 2008), clinical mastitis (Hovinen et al., 2008, Polat et al., 2010, Martins et al., 2013), bovine respiratory disease (Schaefer et al., 2007; Schaefer et al., 2012), and to test for detection of oestrus in dairy cows (Talukder et al., 2014b). Changes in the surface thermal image of a normal horse can be used to detect claudication or inflammation. Thermal imaging has been used to diagnose inflammation as well as to evaluate several other clinical syndromes (Figueiredo et al., 2013). Therefore, DITI can easily recognize and detect temperature changes and can be used as a means to detect and monitor normal and abnormal physiological phenomena (Sykes et al., 2012). In livestock, DITI has been used for assessing fertility in rams and bulls, monitoring heat in dairy cattle, diagnosing leg and foot problems in horses and cattle, characterizing the responses of cattle to freeze branding and hot-iron, and evaluating thermal comfort in poultry (Bowers et al., 2009).

The pig anus temperature can be said to be the temperature measurement area that best represents the pig body temperature. And pig body temperature is mainly measured by inserting a thermometer directly into the anus. However, traditional temperature monitoring methods based on core organs (heart, intestine, and brain) and rectal tubes, on the other hand, have a number of drawbacks, including a wide range of temperature measurement variations and the risk of disease transmission via equipment or device, all of which cause discomfort and waste consumables (Neethirajan, 2017; Lin et al., 2019). Therefore, recently, attempts have been made to easily measure the body temperature of pigs through a non-contact method. Pig body temperature can also determine a pig’s physiological condition. Recently, an attempt has been made to measure the temperature using a non-contact digital infrared thermal imaging camera (DITI) and to detect the physiological condition of pigs through the temperature measurement results. Therefore, the goal of this study was to investigate the possibility of replacing a contact thermometer with a non-contact thermometer and digital infrared thermal imaging camera (DITI), and the detection of estrus using a DITI camera in gilts.

Material and methods

Animal and housing

The experiments on the heat detection of gilt using digital infrared thermal imaging cameras were performed for 30 days in winter from 20 December 2021 to 19 January 2022 at the Sunchon National University Experimental Farm, South Korea. The experimental group comprised a total of 7 gilts of around 8 months of age (129.21±2.51kg). The females were crossbred [(Landrace White x Yorkshire) x (Duroc)], Individually housed in 2 x 0.60 meter stalls with temperature and humidity control. The diet used in the study was designed to match NRC’s nutritional recommendations (1998) (Table 1). Throughout the study, the pigs had unlimited access to feed and water. The gilts were orally administered with synthetic progesterone daily for 18 days for estrus synchronization. After 24 hours, each

Table 1: Composition (%) of the experimental diet

Table 3: Temperature (°C) of Anus and Vulva taken by FLIR camera during first 18 days

Table 4: Vulva Temperature (°C) of gilts taken by FLIR camera during the proestrus and estrus period

The anus temperature of gilts measured using a thermometer, non-contact infrared thermometer, and FLIR E76 is presented in Table 2. As shown in Table 2, the anus temperature of gilts using FLIR had no differences with the thermometer, non-contact infrared thermometer, and a digital infrared thermal camera (FLIR E76). No significant differences were observed in the temperature measurements with DITI camera FLIR E76 with an ordinary thermometer. Therefore, we considered DITI camera (FLIR E76) as the smart tool for the rest of the trail. In the study by Petry et al. (2017), infrared imaging (IR) technology can be used as precise. Swine and other animals, including wildlife, can monitor their core body temperature with a non-contact alternative.

The temperature of the anus and vulva measured by using FLIR is presented in Table 3. As shown in Table 3, the temperature of the anus and vulva taken by FLIR camera has no significant different (p>0.05). This study enabled us to assess differentiated gilts’ thermal imaging during the proestrus and estrus period. Blood flow to the vulva via the internal pudendal artery increases during estrus due to increased circulating estradiol from growing follicles. This increase in blood flow also raises the vulva’s surface temperature. Anatomically, the vulva of the gilt is more conspicuous than that of other livestock species, and it is not blocked by the tail, making changes in surface area temperature gradients easy to detect. (Frandson et al., 2003).

Table 4 shows the vulva temperature taken by the FLIR camera during the proestrus and estrus period. The MIN and MAX temperature of gilts during the proestrus period is significantly lower (p < 0.05) than during estrus. The AVG temperature of vulva is not significantly different (p > 0.05).

Studies using infrared technology for estrus detection and estimating ovulation time in dairy cows have shown mixed results. In 2012, a study conducted by Talukder et al. (2014) showed whether infrared thermography temperature monitoring could be used to identify estrus and estimate ovulation time in dairy cows. In that study, the results revealed that out of 20 cows, only 12 cows were ovulated, seven cows weren’t ovulated, and one cow developed cystic ovarian disease based on the temperature prediction detected by infrared thermography. In another study, 12 sows of two parities were considered in the winter season while the temperature was the indicator for ovulation (Jeong et al., 2016). The vulva and rectum temperature measurement was conducted after the pig got 5 ml regumate (estrus synchronization agent) for 15 days. At the same time, vulva and rectal temperatures were higher than on other days. The mean vulva and rectal temperature of heated sows was 38.8 °C, while that of unheated sows was 38.7 °C.

The vulva and rectum thermal temperature detection differences might have been caused by the house’s ambient temperature and environment. Environment conditions such as airflow and temperature can affect the accuracy of thermal images. The suggested ideal temperature for obtaining thermal images of the skin surface is approximately 20-30°C (Love et al., 1976; Turner et al., 1986). Regardless of the fact that ambient temperature remained in the acceptable range (less than 25.8 °C), there was a greater difference between estrus and diestrus at an ambient temperature below 20 °C. At 21.4 °C, changes in vulva thermal temperature between estrus and diestrus were identified, but not at an ambient temperature of 12.1 °C, according to Jones et al. (2005). The reason for the failure to distinguish estrus from diestrus at this temperature range is unknown; possibly, the quantity of heat generated by the body is reduced at this temperature range. At ambient temperatures below 10 °C, the greatest variations in vulva thermal gradients were detected. These findings conclude that the most significant barrier to reliable thermal gradient measurements in the environment. Thermal gradients are affected by various factors, including ambient temperature, air movement, moisture, and debris (Cravello et al., 2008). Another study on estrus detection in Chinchilla lanigera using FLIR C2 thermal imaging camera showed a clear difference with and without a confirmed estrus of Chinchilla lanigera. The temperature of the external genital region rises dramatically during estrus, obviously due to genital congestion. This finding may be utilized to non-invasively diagnose estrus, which is crucial because this species lacks conventional estrous behavior (Polit et al., 2018).

Conclusion

In light of the findings, the anus of gilts can be the temperature measurement area that best represents the pig body temperature. There was no difference in the temperature measurement using a thermal imaging camera from the temperature measured directly with a thermometer. Moreover, when a sow exhibits estrus, the vulva temperature rises compared to the non-estrus state. A significant difference was observed in the vulva temperature of gilts during proestrus and estrus using the thermal imaging camera, with a difference of temperature rises by 0.8°C in estrus compared to proestrus. The temperature range and the value differences between proestrus and estrus suggested that the DITI camera could be a new technology for heat detection in gilts. It is recommended to use digital infrared thermal imaging technology in the swine industry to detect heat with its effectiveness.

Acknowledgment

The authors would like to acknowledge the Korea Institute of Planning and Evaluation for Technology in Food, Agriculture, and Forestry (IPET) and Korea Smart Farm R&D Foundation through the Smart Farm Innovation Technology Development Program, funded by the Ministry of Agriculture, Food, and Rural Affairs (MAFRA) and Ministry of Science and ICT (MSIT) and Rural Development Administration (RDA) (421047-03).

Conflict of interest

The authors declare that there is no conflict of interest regarding the publication of this article.

novelty statement

Previous research has never been done on using digital infrared thermal camera FLIR E76 for heat dection on gilts. This study found a possible way of using this technology in the swine smart farming.

authors contribution

The authors contributed equally to the manuscript.

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