Variations in the body surface temperature of sows during the post weaning period and its relation to subsequent reproductive performance

Abstract

Objective: A study was made investigate factors affecting body surface temperature changes after weaning in sows, whether these can be used to aid detection of natural estrus and how they relate to subsequent reproductive performance.Methods: A total of 132 sows were selected during summer from a breeding farm, with mean parity of 3.6±2.3 and 28.5±0.9 days lactation length. Four daily measurements (6:00, 8:00, 16:00, and 18:00) of vulva (VST), udder (UST), ear base and central back skin temperatures for individual sows were taken by an infrared thermometer, continuing up to 8 days post weaning.Results: The VST obtained from sows showing estrus at 4 days post-weaning (4DPW), 5DPW, and 6DPW showed a peak at the fourth day post-weaning, but then started to decrease. The VST of sows not detected in standing heat (NDPW) remained at a lower level during the experiment, but UST was increased soon after weaning. The VST-UST temperature differences during daytime of sows that were showing behavioural standing heat on 4DPW, 5DPW, 6DPW, and 7DPW were 0.46°C±0.123°C, 0.71°C±0.124°C, 0.66°C ±0.171°C, and 0.58°C±0.223°C, respectively. The NDPW sows had the highest UST observed, but also the lowest VST so that a more negative value of temperature difference (–0.31°C) was seen during first few days post-weaning. A total of 119 sows were observed to show standing heat and were bred. The later the estrus, the smaller the litter size (p = 0.005).Conclusion: Sows which did not show behavior indicative of stable standing heat after weaning had a VST which remained at a lower level, but the UST increased soon after weaning. Therefore, for sow heat detection under field conditions, the changes of VST and UST and difference between the two should be considered together to increase the accuracy of detection.

Morphometric changes on the vulva from proestrus to oestrus of nulliparous and multiparous HYPERPROLIFIC sows

“…In recent years, a large number of methods to accurately predict the onset of oestrus under field conditions have been developed and thus, previous studies have used infrared thermography to detect changes in vulvar skin temperatures, devices to detect changes on electrical resistance of the vaginal mucus and the ultrasonography to detect or predict the occurrence of ovulation (Weng, 2020; Simoes et al, 2014; Hidalgo et al, 2014; Williams & Luzbel de la Sota et al, 2017).…”

“…Sexual behaviour of the sows during oestrus is affected by oestrogen concentration and is characterized by a variety of signals, such as vocalizations, riding of pen mates when group‐housed, changes in physical activity and/or feed intake decrease (Soede & Kemp, 1997). However, the most important signal is immobilization or ‘standing’ in response to back pressure from a teaser boar, another gilt or sow, or from a person (Soede & Kemp, 1997; Steverink et al, 1999; Simoes et al, 2014; Weng, 2020). Moreover, during oestrus the vulva appears hyperaemic, congested and swollen with a marked increase in its size (Soede & Kemp, 1997; Romoser et al, 2020).…”

Thermoregulation mechanisms and perspectives for validating thermal windows in pigs with hypothermia and hyperthermia: An overview

“…Finally, the vulvar region of sows has been studied due to the possibility that certain circulatory changes in those animals may indicate of their physiological condition; that is, IRT could help identify the estrus cycle and support assisted reproduction ( 175 ). Some authors suggest that a temperature increase of 2°C in this region can be indicative of estrus, which can be associated with the number of navicular cells ( 176 ). However, no reports have yet determined the sensitivity and specificity that would lead to validating this window in sows.…”

Infrared thermography as a possible technique for the estimation of parturition onset in sows

“…On the other hand, several studies have investigated the relationship between vulvar skin temperature and time of ovulation in swine, concluding that the technique could be an aid in predicting time of ovulation (Luño et al 2013 ; Scolari, 2010). Likewise, Weng ( 2020 ) concluded that infrared thermography could be used for mass screening aimed at the early diagnosis of heat, characterized by an increase of vulvar skin temperature. Still, due to many conflicting parameters as to whether body and/or vaginal temperature is related to the time of oestrus and if those parameters are accurate and reliable, the researchers also state that further studies are needed.…”