Relationship among eye and muzzle temperatures measured using digital infrared thermal imaging and vaginal and rectal temperatures in hair sheep and cattle

Facial and ocular thermal mapping in black-and-gold howler monkey (Alouatta caraya) by infrared thermography: An ex situ study

BACKGROUND

This study used infrared thermography (IRT) for mapping the facial and ocular temperatures of howler monkeys, to determine parameters for the diagnosis of febrile processes. There are no published IRT study in this species.

METHODS

Were evaluated images of a group of monkeys kept under human care at Sorocaba Zoo (São Paulo, Brazil). The images were recorded during 1 year, in all seasons. Face and eye temperatures were evaluated.

RESULTS

There are statistically significant differences in face and eye temperatures. Mean values and standard deviations for facial and ocular temperature were respectively: 33.0°C (2.1) and 36.5°C (1.9) in the summer; 31.5°C (4.5) and 35.3°C (3.6) in the autumn; 30.0°C (4.3) and 35.6°C (3.9) in the winter; 30.8°C (2.9) and 35.5°C (2.1) in the spring.

CONCLUSIONS

The IRT was effective to establish a parameter for facial and ocular temperatures of black-and-gold howler monkeys kept under human care.

Relationships of infrared thermography temperature with core temperature in goat

Rectal temperature is widely used as an indicator of animal health. However, rectal temperature is conventionally measured by an invasive method, which may reduce animal welfare. So, this study aimed to determine the relationships between the deep-body (core) temperature and body surface temperatures in goats and develop a linear regression equation to establish the core temperature based on body surface temperatures. Body surface temperatures (head, eye, muzzle, horn, back, scrotum and groin) of goats were measured by infrared thermography (IRT). Ambient temperatures were measured by digital thermometer. Core temperatures were measured by a digital vet thermometer. Pearson correlation analysis was used to analyze the relationship between body surface temperatures, ambient temperature, and core temperature. Simple linear regression analysis was used to develop core temperature assessment equations. Correlation analysis showed that groin temperature was highly correlated with core temperature, and low correlated with ambient temperature. The body surface temperature of other region was low correlated with core temperature, and highly correlated with ambient temperature. Regression analysis showed that the determination coefficient of core temperature assessment equation based on groin temperature was the highest (P < 0.0001, R2 = 0.55), and those based on surface temperature of other regions were low (P < 0.01, R2 ≤ 0.16). We concluded that body surface temperatures obtained by IRT could be used for the assessment of goat core temperature. The core temperature assessment equations developed by the temperature of the body surface, which is less affected by ambient temperature, was found to have a higher determination coefficient than the equations developed using body surface temperature that is more affected by ambient temperature.

Animal Welfare Assessment and Meat Quality through Assessment of Stress Biomarkers in Fattening Pigs with and without Visible Damage during Slaughter

The study aimed to investigate the physiological and meat quality differences between Non-Ambulatory, Non-Injured (NANI), and without apparent abnormalities (non-NANI) pigs in a commercial slaughterhouse setting, focusing on the impact of stress and health conditions on the overall well-being and meat quality of the animals. A total of 241 surgically castrated crossbred male pigs from Southern Brazil were analyzed, with 131 non-NANI pigs and 110 NANI pigs. Infrared orbital temperature, rectal temperature, hematological parameters, and meat quality measurements were collected. Statistical analysis included ANOVA tests and principal component analysis (PCA). NANI pigs exhibited significantly higher infrared orbital temperatures and rectal temperature (p < 0.01). Hematological analysis revealed higher levels of hemoglobin, hematocrit, and red blood cells in NANI pigs (p < 0.05). White blood cell count and lactate dehydrogenase were significantly elevated in NANI pigs (p < 0.01), indicating potential infections or inflammatory responses. Meat quality parameters showed that NANI pigs had lower pH values, higher luminosity, and increased drip loss (p < 0.01), reflecting poorer water retention and potential muscle glycogen depletion. The study highlights the physiological and meat quality differences between NANI and non-NANI pigs, emphasizing the impact of stress, health conditions, and handling procedures on the animals. Blood biomarkers proved valuable in assessing physiological stress, immune response, and potential health issues in pigs, correlating with meat quality abnormalities. Utilizing these biomarkers as predictive tools can enhance animal welfare practices and contribute to improving meat quality in the swine industry.

Evaluation of Non-Contact Device to Measure Body Temperature in Sheep

Non-contact devices have been used in the measurement of body temperature in livestock production as a tool for testing disease in different species. However, there are few studies about the variation and correlations in body temperature between rectal temperature (RT) and non-contact devices such as non-contact infrared thermometers (NCIT) and thermal imaging/infrared thermography (IRT). The objective of this work was to evaluate the accuracy of non-contact devices to measure the body temperature in sheep, considering six body regions and the possibility of implementing these systems in herd management. The experiment was carried out at the experimental farm of the Catholic University of Valencia, located in the municipality of Massanassa in July of 2021, with 72 dry manchega ewes, and we compared the rectal temperature with two types of non-contact infrared devices for the assessment of body temperature in healthy sheep. Except for the temperature taken by NCIT at the muzzle, the correlation between RT vs. NCIT or IRT showed a low significance or was difficult to use for practical flock management purposes. In addition, the variability between devices was high, which implies that measurements should be interpreted with caution in warm climates and open pens, such as most sheep farms in the Spanish Mediterranean area. The use of infrared cameras devices to assess body temperature may have a promising future, but in order to be widely applied as a routine management method on farms, the system needs to become cheaper, simpler in terms of measurements and quicker in terms of analyzing results.

Longitudinal genomic analyses of automatically-recorded vaginal temperature in lactating sows under heat stress conditions based on random regression models

BACKGROUND

Automatic and continuous recording of vaginal temperature (TV) using wearable sensors causes minimal disruptions to animal behavior and can generate data that enable the evaluation of temporal body temperature variation under heat stress (HS) conditions. However, the genetic basis of TV in lactating sows from a longitudinal perspective is still unknown. The objectives of this study were to define statistical models and estimate genetic parameters for TV in lactating sows using random regression models, and identify genomic regions and candidate genes associated with HS indicators derived from automatically-recorded TV.

RESULTS

Heritability estimates for TV ranged from 0.14 to 0.20 over time (throughout the day and measurement period) and from 0.09 to 0.18 along environmental gradients (EG, - 3.5 to 2.2, which correspond to dew point values from 14.87 to 28.19 ˚C). Repeatability estimates of TV over time and along EG ranged from 0.57 to 0.66 and from 0.54 to 0.77, respectively. TV measured from 12h00 to 16h00 had moderately high estimates of heritability (0.20) and repeatability (0.64), indicating that this period might be the most suitable for recording TV for genetic selection purposes. Significant genotype-by-environment interactions (GxE) were observed and the moderately high estimates of genetic correlations between pairs of extreme EG indicate potential re-ranking of selection candidates across EG. Two important genomic regions on chromosomes 10 (59.370-59.998 Mb) and16 (21.548-21.966 Mb) were identified. These regions harbor the genes CDC123, CAMK1d, SEC61A2, and NUDT5 that are associated with immunity, protein transport, and energy metabolism. Across the four time-periods, respectively 12, 13, 16, and 10 associated genomic regions across 14 chromosomes were identified for TV. For the three EG classes, respectively 18, 15, and 14 associated genomic windows were identified for TV, respectively. Each time-period and EG class had uniquely enriched genes with identified specific biological functions, including regulation of the nervous system, metabolism and hormone production.

CONCLUSIONS

TV is a heritable trait with substantial additive genetic variation and represents a promising indicator trait to select pigs for improved heat tolerance. Moderate GxE for TV exist, indicating potential re-ranking of selection candidates across EG. TV is a highly polygenic trait regulated by a complex interplay of physiological, cellular and behavioral mechanisms.

Non-invasive, real-time stress measurement: Vocalization compared with thermal imaging in kittens of the domestic cat in response to social separation

Finding tools to assess the stress response which can be easily applied, are non-invasive, reliable and measured in real time is still a relevant topic in many areas of biology. Vocal characteristics and temperature of certain body areas have been suggested to reflect HPA axis and ANS activation. We hypothesized that changes in vocalizations and peripheral body temperature will show the magnitude of the stress response, and that the change in these will covary. Our aim was to measure the change in vocal characteristics and eye and nasal temperature of kittens (n = 43 from nine litters of seven mixed-breed mothers) during a potentially stressful event and to test how these correlated. We found change in several vocal and thermal parameters during a short social separation. Our findings indicate that arousal due to ANS activation in kittens of the domestic cat resulted in an increasing number of vocalisations of longer duration and higher intensity, and in lower and a wider range in fundamental frequency. Calls also became less tonal with more jitter. Change in temperature was generally negative in the lacrimal caruncle as well as in the rhinarium, but with great variance across individuals. Change in eye temperature positively correlated with the intensity of the calls and the change in nose temperature positively correlated with the change in call length. The results suggest the continued difficulty in interpreting both physiological and behavioural data to assess an individual´s stress response.

Dairy Cow Mastitis Detection by Thermal Infrared Images Based on CLE-UNet

Thermal infrared technology is utilized for detecting mastitis in cows owing to its non-invasive and efficient characteristics. However, the presence of surrounding regions and obstacles can impede accurate temperature measurement, thereby compromising the effectiveness of dairy mastitis detection. To address these problems, we proposed the CLE-UNet (Centroid Loss Ellipticization UNet) semantic segmentation algorithm. The algorithm consists of three main parts. Firstly, we introduced the efficient channel attention (ECA) mechanism in the feature extraction layer of UNet to improve the segmentation accuracy by focusing on more useful channel features. Secondly, we proposed a new centroid loss function to facilitate the network's output to be closer to the position of the real label during the training process. Finally, we used a cow's eye ellipse fitting operation based on the similarity between the shape of the cow's eye and the ellipse. The results indicated that the CLE-UNet model obtained a mean intersection over union (MIoU) of 89.32% and an average segmentation speed of 0.049 s per frame. Compared to somatic cell count (SCC), this method achieved an accuracy, sensitivity, and F1 value of 86.67%, 82.35%, and 87.5%, respectively, for detecting mastitis in dairy cows. In conclusion, the innovative use of the CLE-UNet algorithm has significantly improved the segmentation accuracy and has proven to be an effective tool for accurately detecting cow mastitis.

The use of body surface temperatures in assessing thermal status of hutch-reared dairy calves in shaded and unshaded conditions

The study was carried out in a Hungarian large-scale dairy farm during a 5-day period in hot August weather. Altogether 16 preweaning calves were chosen for the study. An agricultural mesh with 80% shielding was stretched over eight calf cages at 2 m from the ground to shield the cages in their entirety, while eight others were left unshaded. Ambient temperature and relative humidity were measured in 10 min intervals inside and outside one of the hutches in the shaded and unshaded groups during the total length of the study. The rectal temperature of the calves was measured by a digital thermometer every 4 h. Surface temperatures were measured on body parts, in the same intervals as rectal temperature with an infrared thermometer. Measuring sites included: the leg (metacarpus), muzzle, eye bulb, scapula, and ear. Statistical analyses were performed to assess the effects of shading on environmental and body temperatures and to also assess the strength of the association between core, skin and ambient temperatures; to estimate the temperature gradient between body shell and core; to compare the changes in heat dissipation capacity of the different body regions (as represented by temperatures of various sites) with increasing ambient temperature controlling for shaded or unshaded conditions; and to predict the risk of hyperthermia (rectal temperature not lower than 39.5°C) with the CART classification method. The average rectal temperatures suggest that the temperature conditions both in shaded and unshaded groups imposed a severe heat load on the calves. The temperature of the body shell, as represented by skin temperatures, shows a much more significant variation, similar to ambient temperature. As expected, areas that are closer to the core of the body (ear and eye) show less difference from rectal temperature and show a narrower range (lower variance), as more distal regions (leg, scapula) have a wider range. Body surface temperatures are more related to ambient temperature in calves than rectal temperature. The predictive value of infrared body surface temperatures for predicting heat stress or rectal temperature is low.

Body surface temperature of rats reveals both magnitude and sex differences in the acute stress response

Understanding how biological markers of stress relate to stressor magnitude is much needed and can be used in welfare assessment. Changes in body surface temperature can be measured using infrared thermography (IRT) as a marker of a physiological response to acute stress. While an avian study has shown that changes in body surface temperature can reflect the intensity of acute stress, little is known about surface temperature responses to stressors of different magnitudes and its sex-specificity in mammals, and how they correlate with hormonal and behavioural responses. We used IRT to collect continuous surface temperature measurements of tail and eye of adult male and female rats (Rattus norvegicus), for 30 minutes after exposure to one of three stressors (small cage, encircling handling or rodent restraint cone) for one minute, and cross-validated the thermal response with plasma corticosterone (CORT) and behavioural assessment. To obtain individual baseline temperatures and thermal responses to stress, rats were imaged in a test arena (to which they were habituated) for 30 seconds before and 30 minutes after being exposed to the stressor. In response to the three stressors, tail temperature initially decreased and then recovered to, or overshot the baseline temperature. Tail temperature dynamics differed between stressors; being restrained in the small cage was associated with the smallest drop in temperature, in male rats, and the fastest thermal recovery, in both sexes. Increases in eye temperature only distinguished between stressors early in the response and only in females. The post stressor increase in eye temperature was greater in the right eye of males and the left eye of females. In both sexes encircling may have been associated with the fastest increase in CORT. These results were in line with observed behavioural changes, with greater movement in rats exposed to the small cage and higher immobility after encircling. The female tail and eye temperature, as well as the CORT concentrations did not return to pre-stressor levels in the observation period, in conjunction with the greater occurrence of escape-related behaviours in female rats. These results suggest that female rats are more vulnerable to acute restraint stress compared to male rats and emphasise the importance of using both sexes in future investigations of stressor magnitude. This study demonstrates that acute stress induced changes in mammalian surface temperature measured with IRT relate to the magnitude of restraint stress, indicate sex differences and correlate with hormonal and behavioural responses. Thus, IRT has the potential to become a non-invasive method of continuous welfare assessment in unrestrained mammals.

Infrared Thermography as a Potential Non-Invasive Tool for Estrus Detection in Cattle and Buffaloes

The productivity of dairy animals has significantly increased over the past few decades due to intense genetic selection. However, the enhanced yield performance of milk animals caused a proportional increase in stress and compromised reproductive efficiency. Optimal reproductive performance is mandatory for the sustainable production of dairy animals. Reproductive efficiency is marked by proper estrus detection and precise breeding to achieve maximum pregnancies. The existing conventional methods of estrus detection are somewhat labor intensive and less efficient. Similarly, the modern automated methods that rely on detecting physical activity are expensive, and their efficiency is affected by factors such as type of housing (tie stall), flooring, and environment. Infrared thermography has recently emerged as a technique that does not depend on monitoring physical activity. Furthermore, infrared thermography is a non-invasive, user-friendly, and stress-free option that aids in the detection of estrus in dairy animals. Infrared thermography has the potential to be considered a useful non-invasive tool for detecting temperature fluctuations to generate estrus alerts without physical contact in cattle and buffaloes. This manuscript highlights the potential use of infrared thermography to understand reproductive physiology and practical implementation of this technique through discussing its advantages, limitations, and possible precautions.

Evaluation of the Thermal Response of the Horns in Dairy Cattle

Dairy cattle are typically disbudded or dehorned. Little is known, however, about the biological function and role of horns during thermoregulatory processes in cattle, and thus about the potential physiological consequences of horn removal. Anecdotal evidence suggests that dairy cow horns increase in temperature during rumination, and few studies on other bovid species indicate that horns aid thermoregulation. The objective of this study was, therefore, to elucidate a possible thermoregulatory function of the horns in dairy cattle. Using non-invasive infrared thermography, we measured the superficial temperature of the horns, eyes, and ears of 18 focal cows on three different farms in a temperate climate zone under various environmental circumstances. Observations of social and non-social behaviours were conducted as well. Based on environmental temperature, humidity, and wind speed, the heat load index (HLI) was calculated as a measure of the heat load experienced by a cow. The temperature of the horns increased by 0.18 °C per unit HLI, indicating that horns serve the dissipation of heat. Dehorned cows had higher eye temperatures than horned cows, though this result should be interpreted with caution as the low sample size and experimental setup prevent casual conclusions. We did not, however, find changes in horn temperature during rumination, nor with any other behaviours. Our study thus supports a role of horns in thermoregulation, but not related to rumination. These results should be considered when assessing the potential consequences of horn removal, a painful procedure.

The use of infrared thermography to noninvasively measure the surface temperature of polar bears during bouts of social play

Infrared thermography or thermal imagery is a noninvasive tool that can be used to measure the temperature of surfaces. Typically, thermal imagery is used for construction or military purposes but is increasingly used as a noninvasive tool in wildlife studies. We investigated the use of thermal imagery to measure surface temperature changes as a proxy for energetic expenditure. We measured the surface temperature of polar bear (Ursus maritimus) eyes, while immobilized, to determine whether the eye is a thermal window that can accurately indicate internal temperature. We found a significant difference (2.68 ± 0.41°C) between the surface temperature of the eye measured with thermal imagery and the internal rectal temperature. Additionally, we measured surface temperature changes in polar bears after bouts of social play as a proxy for energy expenditure. Mean temperature of the eye increased by 1.34 ± 0.43°C after social play, indicating that this activity increased energy expenditure. During the fasting season, polar bears rely on fat stores, and any energy expenditure beyond what is required to travel may be costly to their survival, particularly in years of low resource availability. We conclude that thermal imagery is a useful tool to noninvasively investigate the energetics of social play.

Effect of Thermal Stress on Thermoregulation, Hematological and Hormonal Characteristics of Caracu Beef Cattle

This study evaluated the influence of environmental temperature on thermoregulation, hormonal, and hematological characteristics in Caracu cattle. Blood samples, hair length, coat and muzzle colors, rectal (RT), and surface temperatures were collected from 48 males and 43 females before (morning) and after sun exposure for eight hours (afternoon). Infrared thermography (IRT) was used to identify superficial temperature that exhibits a high correlation with RT. Hematological parameters, hormone concentrations, RT, and the superficial temperature obtained by IRT that exhibited the highest correlation with RT were evaluated by variance analysis. Regarding IRT, the lower left side of the body (LS) showed the highest correlation with the RT. Interaction between period and sex was observed for LS, cortisol, and eosinophils. Cortisone, progesterone, and RT were influenced by period and sex. Neutrophils and segmented neutrophils were influenced by the period, which showed the highest concentrations after sun exposure. Platelets, leukocytes, lymphocytes, and monocytes were influenced by sex. Heat stress changes several physiological characteristics where males and females exhibited differences in their responses to heat stress. Furthermore, most characteristics evaluated remained within the regular values observed for taurine Creole breeds, showing that Caracu is adapted to tropical climates.

Eye surface infrared thermography usefulness as a noninvasive method of measuring stress response in sheep during shearing: Correlations with serum cortisol and rectal temperature values

During shearing, animals' welfare is adversely affected and acute stress occurs. Once animal perceives a threat, it develops behavioral, autonomic, endocrine or immune responses to maintain homeostasis. This study aimed to investigate the usefulness of eye temperature assessment by infrared thermography (IRT) to evaluate acute stress response in sheep undergoing a shearing procedure. From each animal, blood sampling, rectal and eye temperature assessment were performed before shearing (T_PRE), 5 (T_POST5) and 60 (T_POST60) minutes after the end of shearing procedure. On blood samples the serum cortisol concentrations were evaluated. Rectal temperature (T_RECTAL) was measured using a digital thermometer. Thermographic acquisitions of eye temperature were performed from the eye total area (T_EYE) and from three regions of interest (lateral canthus, T_ROI-1; central cornea, T_ROI-2; medial canthus, T_ROI-3). One-way analysis of variance showed a significant increase of serum cortisol concentration, T_RECTAL, T_EYE and T_ROI-3 (p < 0.001). Serum cortisol was positively correlated with T_RECTAL and T_ROI-3 at T_POST5 and T_POST60. T_RECTAL resulted positively correlated with T_ROI-3 at T_PRE, T_POST5 and T_POST60. Agreement between T_RECTAL and each eye temperature considered (T_EYE, T_ROI-1, T_ROI-2, T_ROI-3) has been shown by Bland-Altman plots at each time point of monitoring period. The findings obtained in the current survey suggest that the medial canthus is the most suitable region for eye temperature measurement to asses stress response in animals. Moreover, this study highlighted the usefulness of IRT as an immediate and non-invasive physiological measure to assess stress response in sheep.

Evaluation of the Best Region for Measuring Eye Temperature in Dairy Cows Exposed to Heat Stress

Eye temperature (ET) has long been used for predicting or indicating heat stress in dairy cows. However, the region of interest (ROI) and temperature parameter of the eye have not been standardized and various options were adopted by previous studies. The aim of this study was to determine the best ROI for measuring ET as the predictor of heat stress in dairy cows in consideration of repeatability and validity. The ET of 40 lactating Holstein dairy cows was measured using infrared thermography. The mean and maximum temperature of five ROIs—medial canthus (MC), lateral canthus, eyeball, whole eye (WE), and lacrimal sac (LS)—were manually captured. The results show that the ET of left eyes was slightly higher than that of right eyes. The ET taken in MC, WE, and LS within 2 min had a moderate to substantial repeatability. The maximum temperature obtained at the LS had the highest correlation coefficients with respiration rate and core body temperature (all p < 0.001). Therefore, the maximum temperature of LS should be considered by future studies that want to use ET as the predictor or indicator of heat stress in dairy cows.

Progress on Infrared Imaging Technology in Animal Production: A Review

Infrared thermography (IRT) imaging technology, as a convenient, efficient, and contactless temperature measurement technology, has been widely applied to animal production. In this review, we systematically summarized the principles and influencing parameters of IRT imaging technology. In addition, we also summed up recent advances of IRT imaging technology in monitoring the temperature of animal surfaces and core anatomical areas, diagnosing early disease and inflammation, monitoring animal stress levels, identifying estrus and ovulation, and diagnosing pregnancy and animal welfare. Finally, we made prospective forecast for future research directions, offering more theoretical references for related research in this field.

Daily variation of the cortisol and insulin concentration, glycemia, surface temperature, and behavior patterns due the administration of equine Chorionic Gonadotropin in rams

Sex steroids can modulate the circadian rhythmicity of some physiological and behavioral functions of sheep. During the non-breeding season, Corriedale rams have a low testosterone concentration, but the administration of equine Chorionic Gonadotropin (eCG) stimulates its secretion. Therefore, the daily variation of cortisol and insulin concentrations, glycemia, behavioral pattern (eating, ruminating, standing, lying, and sleeping), and rostral and eye surface temperatures were compared in rams treated or not treated with eCG during the non-breeding season [between August (late winter) and September (early spring)]. Twenty Corriedale adult rams (BW 63.4 ± 7.3 kg; BCS: 3.5 ± 0.5; mean ± SD; age: 2-3 years old) were randomly assigned to 1 of 2 treatments: a) Treated: administration of 1000 IU of eCG intramuscularly and b) Control: control, without application of eCG. All the rams were managed under the same feeding and environmental conditions (individual pens outdoors). All variables were measured each hour for 26 h, except testosterone and insulin that were measured at 09:00, 10:00, 12:00, 15:00, 18:00, 21:00, 22:00, 24:00, 03:00, 06:00, 09:00 and 11:00 h. Testosterone and cortisol concentration were greater in Treated than Control rams (testosterone: 32.7 ± 0.7 nmol/L vs 5.8 ± 0.7 nmol/L; P <0.0001; cortisol: 11.3 ± 0.6 nmol/L vs 9.9 ± 0.6 nmol/L; P =0.02). The eye surface temperature was 0.9°C lower in the Treated than in the Control rams (P =0.004). The characteristics of the daily variation pattern of cortisol, glycemia, glycemia:insulin ratio, and surface temperature were not affected by the treatment, the acrophases being at ∼06:00 h, ∼18:00 h, ∼08:00 h, and ∼11:00 h, respectively. The acrophase of insulin concentration was observed earlier in Treated than in Control rams (13:02 ± 0:56 vs 15:47 ± 0:53; P =0.04). Additionally, the acrophase of the time spent eating was advanced in Treated rams (09:48 ± 00:16 vs 10:20 ± 00:16; P =0.04) and sleeping (21:39 ± 00:57 vs 02:02 ± 01:06; P <0.0001). Treated rams slept less time than Control rams (P =0.04). In conclusion, the administration of eCG modulated the daily variation pattern of insulin concentration and the behavioral pattern (period in which rams were observed eating and sleeping). Nevertheless, although there was a greater cortisol concentration and reduced eye surface temperature, the administration of eCG did not modify their daily variation pattern, suggesting that this is robust, limiting the effect of testosterone on their basal pattern.

Effects of Reduced Space Allowance and Heat Stress on Behavior and Eye Temperature in Unweaned Lambs: A Pilot Study

Simple Summary

In Europe, young lambs can be transported long distances for slaughter. While transport is regulated by E.U. law, there is a lack of research investigating the optimal transport conditions specifically for young lambs. For example, while the regulations set a minimum space allowance for lambs above 26 kg, no minimum is specified for young lambs meaning they can be transported in overcrowded conditions. Further, while the temperature within the vehicle must be maintained between 5–30 °C, this is well above the 21 °C said to be the upper end of the comfortable range for lambs. This study aimed to investigate how variation in space allowance and temperature can affect the welfare of young lambs. Three groups of lambs were created where either the density of individuals (0.27 vs. 0.20 m² per head) or the temperature range (12–18 °C vs. 19–30 °C) varied. Lambs housed in the higher density and heat stress groups showed more discomfort and higher body temperatures. In addition, lambs kept in the heat stress group lost weight over the course of the study, and showed signs of heat stress when the temperature exceeded 25 °C. These results indicate that the regulations for the transport of young lambs need to be refined.

Abstract

Current European animal transportation law contains only a few and vague indications concerning how to move lambs of less than 26 kg. Moreover, little information is available in the literature about factors affecting these lambs’ welfare. We investigated the effect of space allowance and ambient temperature on the welfare of unweaned Lacaune lambs during a simulation of long-distance transportation (19 h). Three groups of lambs (N = 130) were housed in equally sized pens for 19 h, Control (C; n = 39; 0.27 m² per head), Low Space Allowance (LSA; n = 52; 0.20 m² per head), and Heat Stress (HS; n = 39; 0.27 m² per head) groups. LSA lambs had lower space allowance than C but were tested at the same temperature, within their Thermoneutral zone (range = 12–18 °C). The HS lambs were, instead, subjected to higher temperatures (range = 19–30 °C). Scan sampling of behavior was conducted, eye temperature and body weight were also recorded. LSA and HS lambs showed more discomfort behaviors (p < 0.05) and higher eye temperatures (p < 0.001) compared to C lambs, while HS lambs additionally showed a decrease in body weight over the experimental period (p < 0.001). This study indicates that lower space allowances and higher temperatures impact negatively the welfare of lambs transported for slaughter suggesting that the regulation should be implemented taking these factors into account.

Biometric Physiological Responses from Dairy Cows Measured by Visible Remote Sensing Are Good Predictors of Milk Productivity and Quality through Artificial Intelligence

New and emerging technologies, especially those based on non-invasive video and thermal infrared cameras, can be readily tested on robotic milking facilities. In this research, implemented non-invasive computer vision methods to estimate cow's heart rate, respiration rate, and abrupt movements captured using RGB cameras and machine learning modelling to predict eye temperature, milk production and quality are presented. RGB and infrared thermal videos (IRTV) were acquired from cows using a robotic milking facility. Results from 102 different cows with replicates (n = 150) showed that an artificial neural network (ANN) model using only inputs from RGB cameras presented high accuracy (R = 0.96) in predicting eye temperature (°C), using IRTV as ground truth, daily milk productivity (kg-milk-day^-1), cow milk productivity (kg-milk-cow^-1), milk fat (%) and milk protein (%) with no signs of overfitting. The ANN model developed was deployed using an independent 132 cow samples obtained on different days, which also rendered high accuracy and was similar to the model development (R = 0.93). This model can be easily applied using affordable RGB camera systems to obtain all the proposed targets, including eye temperature, which can also be used to model animal welfare and biotic/abiotic stress. Furthermore, these models can be readily deployed in conventional dairy farms.

Sustained heat stress elevated corneal and body surface temperatures and altered circulating leukocytes and metabolic indicators in wether lambs supplemented with ractopamine or zilpaterol

Understanding how β adrenergic agonists influence the physiology of heat stress could lead to mitigation options. We sought to investigate body surface temperatures in feedlot wethers supplemented with ractopamine or zilpaterol and exposed to heat stress for 18 d. Corneal and skin temperatures were assessed via infrared thermography at 1- and 2-m distances. Rectal temperatures and circulating leukocytes, metabolites, and electrolytes were also measured. Heat stress increased (P < 0.05) rectal temperatures in unsupplemented and zilpaterol-supplemented lambs but not in ractopamine-supplemented lambs. Heat stress also increased (P < 0.05) surface temperatures of the cornea, nose, ear, and back, regardless of supplement. Observations were comparable between thermography performed at 1 and 2 m, and higher emissivity settings generally produced less variation. Heat stress tended to increase (P = 0.08) blood monocytes in unsupplemented but not ractopamine- or zilpaterol-supplemented lambs. Granulocytes were increased (P < 0.05) by heat stress in ractopamine-supplemented lambs but decreased (P < 0.05) in zilpaterol-supplemented lambs. Blood glucose, triglycerides, and cholesterol did not differ among groups, and blood lactate was reduced (P < 0.05) by heat stress in zilpaterol-supplemented lambs only. Blood Na+ was reduced (P < 0.05) and Ca2+ increased (P < 0.05) by heat stress, regardless of supplement. These findings indicate that β1- and β2-adrenergic agonists differentially relieve some but not all heat stress-induced changes in stress indicators. Moreover, corneal and skin surface temperatures measured by infrared thermography reasonably identified body temperature changes at a distance of 2 m.

Lipopolysaccharide endotoxin injections elevated salivary TNFα and corneal temperatures and induced dynamic changes in circulating leukocytes, inflammatory cytokines, and metabolic indicators in wether lambs

Pathogenic infections increase morbidity and reduce performance in livestock, and thus understanding the comprehensive physiological changes associated with infections can benefit production sustainability. In this study, we sought to investigate such physiological responses to an acute immune challenge in lambs. Polypay wethers received single IV injections of 1.5 µg/kg lipopolysaccharide endotoxin (LPS-injected; n = 6) or saline (controls; n = 6). Corneal temperatures (via infrared thermography), rectal temperatures, blood, plasma, and saliva were assessed every 2 hr for 10 hr after injections. Blood was also assessed at 24 hr. LPS-injected lambs exhibited elevated (P < 0.05) corneal and rectal temperatures that peaked at 4 hr but were still slightly greater (P < 0.05) than controls at 10 hr. Circulating total white blood cells, monocytes, and granulocytes were reduced (P < 0.05) in LPS-injected lambs within the first 4 hr but were subsequently greater (P < 0.05) than in controls. Lymphocytes were reduced (P < 0.05) in LPS-injected lambs over the first 8 hr and did not differ from controls thereafter. Red blood cells, hematocrit, and hemoglobin were increased (P < 0.05) in LPS-injected lambs over the first 6 hr, indicating mild dehydration. Blood glucose briefly increased (P < 0.05) in LPS-injected lambs at 2 hr but was less (P < 0.05) than in controls thereafter. Blood lactate was greater (P < 0.05) in LPS-injected lambs between 6 and 10 hr after injections, which together with reduced (P < 0.05) CO2 partial pressure indicated a metabolic shift toward glycolysis. LPS-injected lambs exhibited a transient increase (P < 0.05) in plasma TNFα at 2 and 4 hr only and sustained increases (P < 0.05) in CXCL9 and CXCL10 beginning at 6 and 4 hr, respectively. They also exhibited a mild, paradoxical increase (P < 0.05) in the anti-inflammatory sFRP3. Salivary TNFα was increased (P < 0.05) in LPS-injected lambs at 2 hr only. Regression analyses indicated that rectal temperatures were a generally poor predictor of the other inflammatory components in this study, with the exception of circulating leukocyte populations. Likewise, correlations among the 10 cytokines measured in this study were generally weak, with notable exceptions between CXCL9 and CXCL10 and between IL-21 and IFNγ. These findings demonstrate that physiological changes to even short-lived immune challenges are dynamic in nature and persist beyond the time frame of febrile responses and other common assessments.

Recent Advances on Early Detection of Heat Strain in Dairy Cows Using Animal-Based Indicators: A Review

In pursuit of precision livestock farming, the real-time measurement for heat strain-related data has been more and more valued. Efforts have been made recently to use more sensitive physiological indicators with the hope to better inform decision-making in heat abatement in dairy farms. To get an insight into the early detection of heat strain in dairy cows, the present review focuses on the recent efforts developing early detection methods of heat strain in dairy cows based on body temperatures and respiratory dynamics. For every candidate animal-based indicator, state-of-the-art measurement methods and existing thresholds were summarized. Body surface temperature and respiration rate were concluded to be the best early indicators of heat strain due to their high feasibility of measurement and sensitivity to heat stress. Future studies should customize heat strain thresholds according to different internal and external factors that have an impact on the sensitivity to heat stress. Wearable devices are most promising to achieve real-time measurement in practical dairy farms. Combined with internet of things technologies, a comprehensive strategy based on both animal- and environment-based indicators is expected to increase the precision of early detection of heat strain in dairy cows.

Non-Invasive Physiological Indicators of Heat Stress in Cattle

Cattle are susceptible to heat stress, especially those kept on high levels of nutrition for the purpose of maximising growth rates, which leads to a significant heat increment in their bodies. Consequences include compromised health and productivity and mortalities during extreme events, as well as serious economic loss. Some measures of heat stress, such as plasma cortisol and temperature in the rectum, vagina, or rumen, are invasive and therefore unlikely to be used on farms. These may cause additional stress to the animal due to handling, and that stress in itself can confound the measure. Consequently, it is desirable to find non-invasive alternatives. Panting score (PS), cortisol metabolites in faeces, milk, or hair, and the infrared temperature of external body surfaces are all potentially useful. Respiratory indicators are difficult and time consuming to record accurately, and cortisol metabolites are expensive and technically difficult to analyse. Infrared temperature appears to offer the best solution but requires further research to determine the thresholds that define when corrective actions are required to ensure optimal health and productivity. Research in this area has the potential to ultimately improve the welfare and profitability of cattle farming.

The Influence of Predictability and Controllability on Stress Responses to the Aversive Component of a Virtual Fence

To ensure animal welfare is not compromised, virtual fencing must be predictable and controllable, and this is achieved through associative learning. To assess the influence of predictability and controllability on physiological and behavioral responses to the aversive component of a virtual fence, two methods of training animals were compared. In the first method, positive punishment training involved sheep learning that after an audio stimulus, an electrical stimulus would follow only when they did not respond by stopping or turning at the virtual fence (predictable controllability). In the second method, classical conditioning was used to associate an audio stimulus with an electrical stimulus on all occasions (predictable uncontrollability). Eighty Merino ewes received one of the following treatments: control (no training and no stimuli in testing); positive punishment training with an audio stimulus in testing (PP); classical conditioning training with only an audio stimulus in testing (CC1); and classical conditioning training with an audio stimulus followed by electrical stimulus in testing (CC2). The stimuli were applied manually with an electronic collar. Training occurred on 4 consecutive days with one session per sheep per day. Sheep were then assessed for stress responses to the cues by measuring plasma cortisol, body temperature and behaviors. Predictable controllability (PP) sheep showed no differences in behavioral and physiological responses compared with the control treatment (P < 0.05). Predictable uncontrollability of receiving the aversive stimulus (CC2) induced a higher cortisol and body temperature response compared to the control but was not different to CC1 and PP treatments. CC2 treatment sheep showed a higher number of turning behaviors (P < 0.001), and more time spent running (P < 0.001) than the control and PP treatment groups, indicating that predictability without controllability was stressful. The behavior results also indicate that predicting the event without receiving it (CC1) was less stressful than predicting the event then receiving it (CC2), suggesting that there is a cost to confirmation of uncontrollability. These results demonstrate that a situation of predictability and controllability such as experienced when an animal successfully learns to avoid the aversive component of a virtual fence, induces a comparatively minimal stress response and does not compromise animal welfare.

Assessing response to dry-off in dairy cows kept outdoors using spontaneous behaviours and infrared thermography-a pilot study

We used spontaneous behaviours to assess response to dry-off involving abrupt dietary and milking frequency changes, followed by regrouping, after the last milking in 15 clinically healthy Holstein-Frisian cows kept outdoors. Moreover, we explored the potential of infrared thermography to detect eye temperature variations possibly induced by dry-off. On days - 1, 0, 1 and 2 relative to dry-off, we recorded whether cows vocalised during feed delivery; ate fresh feed within 5 min; and mean maximum eye temperature at approximately 1 h after feed delivery. On days 1 and 2, cows were more likely to eat fresh feed compared to days - 1 and 0. No difference in likelihood of vocalising was found. Compared to day - 1, eye temperature was substantially higher on days 0 and 2. Collectively, the results suggest that cows responded, both behaviourally and physiologically, to the abrupt dry-off management. The interpretation of the current findings deserves further investigation using larger sample sizes, more controlled environments and further behavioural, physiological, cognitive and clinical measures.

Methods to quantify heat stress in ruminants: Current status and future prospects

The physiology of hyperthermia or heat stress in mammals is complex. It is a totally systemic condition that in varying degrees involves all organs, tissues and body fluid compartments. The nature and magnitude of the response is influenced by animal specific characteristics (e.g. age, diet, body condition, gender, reproductive stage), environment and animal management. Given the multifaceted nature of heat stress, and the varied ruminant production systems based in varied geoclimatic zones, it has been difficult to find appropriate measures of heat stress for production ruminants. This has become an urgent challenge as production systems intensify globally in a warming climate. Bioclimatic indices such as the Temperature-Humidity Index (THI) have evolved to incorporate some measure of animal physiology. However, these indices do not have strong relationships with core temperature trajectories and altered respiratory dynamics of animals with excessive heat load. In recent decades, the careful physiology studies of the 1950-80s, have given way to numerous studies trialling a plethora of new technologies and computational approached to measure heat stress. Infrared thermography of body surface temperatures, automated measures of respiration rate and radiotelemetry of internal body temperatures are the most intensively researched. The common goal has been to find the 'holy grail' decision-making threshold or timepoint as to the animal's wellbeing. Are we making any progress?

A sampling strategy for the determination of infrared temperature of relevant external body surfaces of dairy cows

Infrared thermography is a tool to investigate the welfare of cattle. This study aimed to identify a sampling strategy for recording infrared thermograms in dairy cows, in order to most efficiently determine biologically relevant changes in the maximum infrared temperature (IRT) of the eyes and coronary band of forelimbs. Thirty-one dairy cows were used for the study. They were assessed with four replicates of thermograms for each of the head and lower forelimb per cow for 6 mostly consecutive days (sessions). The data obtained were subjected to random effects Analysis of Variance which was used to estimate the variance components for this sampling model, using maximum IRT of both eyes; (left + right eye)/2 and both limbs; (left + right coronary band of forelimb)/2 as dependant variables. The variance components were used to calculate least significant differences (LSD) between two theoretical treatment groups under different sampling scenarios. Analysis showed that there was minimal improvement in precision beyond 2 thermograms within a session but there was improvement with increasing the number of sessions from 2 to 3. The LSD of both eyes and both limbs reached a biologically relevant difference (0.4 and 0.9 °C, respectively) at a minimum number of 14 - 16 cows monitored for 2 consecutive thermography sessions, or 10 - 12 cows for 3 sessions. We conclude that no more than 2 replicate IRT measures are required per session but that measuring on 3 consecutive days should be considered, depending on whether time or number of cows used is the primary limitation.

Infrared thermography reveals surface body temperature changes during proestrus and estrus reproductive phases in Gyr heifers (Bos taurus indicus)

Our aim was to evaluate the application of infrared thermography (IRT) to detect body surface temperature variation of body regions during the proestrus and estrus phases of the reproductive cycle of Gyr heifers and investigate environmental factors that could affect these measurements. Fifty-seven heifers were submitted to an ovulation synchronization protocol. This was followed by monitoring the heifers every 12 h over 60 h. Heifers were monitored for rectal and vaginal temperature using a digital thermometer. The surface temperature of the eye, vulva, and muzzle regions were monitored by IRT. Meteorological data was recorded for temperature and humidity. Observation of sexual behavior was performed to monitor estrus onset. Transrectal ultrasonography was used to identify the dominant follicle and confirm ovulation of all heifers. We observed a decrease in temperature of the rectum and vagina, as well as in the eye and vulva regions within the first 12 h after the completion of the synchronization. This period coincides with the expected proestrus phase of the estrous cycle. A progressive increase in all temperatures was noticed in the following 36 h, which coincides with the estrus phase of the reproductive cycle. The regions evaluated around the vulva and eye exhibited the highest temperature and experienced less environmental distortion than the muzzle area thermographs. Environmental factors, such as rainfall and temperature-humidity index, influenced the IRT readings altering the radiation patterns detected. In conclusion, IRT is an effective method to detect temperature variation during the proestrus and estrus phases in Gyr heifers. Furthermore, biological and environmental effects should be considered when collecting and interpreting IRT data in livestock.

Comparison of thermal imaging and rectal temperature in the diagnosis of pyrexia in pre-weaned calves using on farm conditions

Measuring core body temperature is used as part of the diagnostic process in assessing the health of animals. Typically in calves, this is carried out using a rectal thermometer which can be time consuming, stressful to the calf and is invasive by nature. A non-invasive technique that is gaining recognition is thermal imaging. This study investigated the use of thermal imaging as a technique to assess core body temperature in pre-weaned artificially reared calves. A total of 125 male and female calves had rectal temperatures measured daily from day 7 until day 40 of life, and at the same time had a thermal image taken of the area around the medial canthus of the eye. A weak correlation (r = 0.28) was found between calf rectal temperature and thermal image temperature. A multivariable predictive model for core body temperature increased the correlation (r = 0.32) when including the environmental parameters of air temperature (p < .001) and wind speed (p < .001) as well as reconstituted milk replacer consumption (p < .01). The effectiveness of a predictive model including these parameters for the detection of calves with a core body temperature ≥ 39.5 °C was examined and found to have a sensitivity of 0% and a specificity of 100%. The results of this study demonstrate the need to take thermal environmental parameters into consideration when using thermal imaging to assess body temperature. However, the results suggest that accurate measures of core body temperature using thermal imaging cannot be achieved under commercial farm conditions. Further research is needed to determine what other factors could be measured to increase predictive ability.

Using infrared thermography on farm of origin to predict meat quality and physiological response in cattle (Bos Taurus) exposed to transport and marketing

Temperature is used as an indicator of animals' response to external stimuli and thus it could potentially be used as an indicator or poor animal welfare and meat quality. Remote monitoring of temperature can be achieved using infrared thermography (IRT) at the farm of origin before animals are sent to slaughter. Relationships between temperatures of cattle measured using IRT on-farm and potential indicators of stress and meat quality were investigated in 481 cattle in 2 experiments, one with sea transport and another with land transport. On-farm measurements included IRT and behavioural assessment of temperament along with measurement of physiological indicators of stress and carcass traits post-mortem. Significant correlations were found between IRT and meat pH, meat colour, creatine kinase, glucose, non-esterified fatty acids, magnesium, and temperament (P < .05). That said, these correlations did not persist across both experiments. Current findings suggest that on-farm IRT could have the potential to assist with the detection of compromised animal welfare and predict meat quality.

Core and peripheral site measurement of body temperature in short wool sheep

Understanding circadian rhythms of body temperature is important for the interpretation of single body temperature measurements and the assessment of the physiological state of an animal. The ability to measure body temperature at peripheral locations may also be important in the development of minimally invasive tools for remote temperature measurement in livestock. This study aimed to investigate how well body temperature measured at peripheral sites reflected a commonly used core measurement (vaginal temperature) and the circadian rhythmicity of the body temperature of sheep with a view to practical application in extensive sheep production systems. Eleven crossbred ewes were implanted with peripheral temperature sensing microchips (LifeChip®) which were positioned transversely in the sternocleidomastoid (neck) muscle and subcutaneously under the tail. iButton® temperature loggers were placed intravaginally to record core body temperature measurements (Tv). The body temperature measurements observed at the peripheral sites in the neck (Tn) and tail (Tt) differed significantly to those measured at the core site, Tv (P < 0.05), with Tn lower than Tv and Tt lower than both Tv and Tn. Similarities in circadian rhythm patterns were observed across the day between Tv, Tn and Tt in repeated measures analysis, with a short period of difference between Tv and Tn (from 1400 to 1600 h) and a long period of difference between Tv and Tt (from 1000 to 2100 h) (P < 0.05). These results suggest that neck muscle temperature measurements may have utility in detecting circadian rhythm patterns in core temperature in sheep, but may not accurately reflect absolute core temperatures. Peripheral measures may require adjustment or correction to more accurately reflect absolute core temperature with respect to determining accurate clinical thresholds relative to the expected normal temperature for the time of day observed. Further investigation into the utility and application of peripheral measurement of body temperature is warranted.

Effects of heat stress on pullet cloacal and body temperature

One measure of the thermal status of poultry is cloacal temperature measured with a cloacal thermometer; however, this method requires handling the bird, is invasive, and can be stressful. Infrared thermography is an alternative means for assessing bird thermal status. The objective of this study was to investigate the body temperature response of pullets subjected to different environmental air temperatures during the growing phase and to evaluate the relationship between the cloacal temperature and the body parts surface temperature. A total of 648 chicks (Lohmann LSL Lite) were used in 2 different phases, phase I (day 1 through 6 wk of age) and phase II (week 7 through 17). During phase I, chicks were reared at 1 of 3 different thermal environments: thermal comfort (35°C–19°C), mild heat stress (38°C–22°C), or mild cold stress (28°C–17°C). In phase II, pullets were randomly redistributed to 1 of 4 daytime temperature treatments: 20°C; 25°C; 30°C; and 35°C, all with night time temperature of 20°C. Cloacal temperature and body surface temperature for 8 parts (head, eye, comb, chest, back, wing, leg, head area, and body area) were obtained weekly from 4 to 2 birds per treatment, respectively, during phase II. There were no effects for the interactions between the 2 experimental phases for cloacal and body parts surface temperature. There was a strong correlation (P < 0.001) between cloacal temperature and each body part temperature; cloacal temperature followed a quadratic response to environmental air temperature treatments. Pullets subjected to 35°C/20°C and 30°C/20°C had the highest body parts temperatures compared with the other 2 treatments (P < 0.05). The leg surface temperature was greatest in all treatments, and the chest the lowest. Regression between cloacal and body parts temperature had a 95% predictive accuracy of better than 0.4°C, suggesting a useful alternative to direct cloacal temperature measurement.

Modelling and Validation of Computer Vision Techniques to Assess Heart Rate, Eye Temperature, Ear-Base Temperature and Respiration Rate in Cattle

Simple Summary

Animal monitoring normally requires procedures that are time- and labour-consuming. The implementation of novel non-invasive technologies could be a good approach to monitor animal health and welfare. This study aimed to evaluate the use of images and computer-based methods to track specific features of the face and to assess temperature; respiration rate and heart rate in cattle. The measurements were compared with measures obtained with conventional methods during the same time period. The data were collected from ten dairy cows that were recorded during six handling procedures across two consecutive days. The results from this study show over 92% of accuracy from the computer algorithm that was developed to track the areas selected on the videos collected. In addition, acceptable correlation was observed between the temperature calculated from thermal infrared images and temperature collected using intravaginal loggers. Moreover, there was acceptable correlation between the respiration rate calculated from infrared videos and from visual observation. Furthermore, a low to high relationship was found between the heart rate obtained from videos and from attached monitors. The study also showed that both the position of the cameras and the area analysed on the images are very important, as both had large impact on the accuracy of the methods. The positive outcomes and the limitations observed in this study suggest the need for further research

Abstract

Precision livestock farming has emerged with the aim of providing detailed information to detect and reduce problems related to animal management. This study aimed to develop and validate computer vision techniques to track required features of cattle face and to remotely assess eye temperature, ear-base temperature, respiration rate, and heart rate in cattle. Ten dairy cows were recorded during six handling procedures across two consecutive days using thermal infrared cameras and RGB (red, green, blue) video cameras. Simultaneously, core body temperature, respiration rate and heart rate were measured using more conventional ‘invasive’ methods to be compared with the data obtained with the proposed algorithms. The feature tracking algorithm, developed to improve image processing, showed an accuracy between 92% and 95% when tracking different areas of the face of cows. The results of this study also show correlation coefficients up to 0.99 between temperature measures obtained invasively and those obtained remotely, with the highest values achieved when the analysis was performed within individual cows. In the case of respiration rate, a positive correlation (r = 0.87) was found between visual observations and the analysis of non-radiometric infrared videos. Low to high correlation coefficients were found between the heart rates (0.09–0.99) obtained from attached monitors and from the proposed method. Furthermore, camera location and the area analysed appear to have a relevant impact on the performance of the proposed techniques. This study shows positive outcomes from the proposed computer vision techniques when measuring physiological parameters. Further research is needed to automate and improve these techniques to measure physiological changes in farm animals considering their individual characteristics.

Effects of physiological stage and season on infrared thermograms of different body areas of dairy cows raised under tropical conditions

The objective of this study was to investigate the influence of season and pregnancy stage on the temperature of various body areas of Holstein cows using digital infrared thermography, an effective and non-invasive technique. The temperature was recorded at several areas of the body surface to determine the most reliable body area for measurement of rectal temperature in pregnant and non-pregnant animals. Holstein cows (n = 24) were divided into groups according to their physiological stage. The experimental period was 365 days, containing a dry (April-September) and rainy (October-March) season, with parameters measured every 28 days. Thermographic data for different body areas, rectal thermometry, ultrasonography, and climatic data were collected between 7:00 and 9:00. Thermogram-recorded temperatures significantly differed (P < 0.05) between seasons and reproductive phases. Moreover, significant differences were noted between the temperatures of the flank, lateral udder, and perineal areas across seasons (P < 0.05). The udder, perineal, and rectal temperatures differed according to the reproductive phase (P < 0.05). Significant correlations (P < 0.01) were observed between reproductive phases and rectal, ocular globe, snout, flank, and perineum temperature. The body areas examined by thermographic imaging presented different temperatures, exhibiting physiological variation. Season and physiological stage influenced the temperature of body areas of milk cows.

Establishment of validated models for non-invasive prediction of rectal temperature of sows using infrared thermography and chemometrics

Rectal temperature is an important physiological indicator used to characterize the reproductive and health status of sows. Infrared thermography, a surface temperature measurement technology, was investigated in this study to explore its feasibility in non-invasive detection of rectal temperature in sows. A total of 124 records of rectal temperature and surface temperature in various body regions of 99 Landrace × Yorkshire crossbred sows were collected. These surface temperatures together with ambient temperature, ambient humidity, and wind speed in pig pens were correlated with the real rectal temperature of sows to establish rectal temperature prediction models by introducing chemometrics algorithms. Two types of models, i.e., full feature models and selected feature models, were established by applying the partial least squares regression (PLSR) method. The optimal model was attained when 7 important features were selected by LARS-Lasso, where correlation coefficients and root mean squared errors of calibration were 0.80 and 0.30 °C, respectively. Particularly, the validity and stability of established simplified models were further evaluated by applying the model to an independent prediction set, where correlation coefficients and root mean squared errors for prediction were 0.80 and 0.35 °C, respectively. The validation of established models is scarce in previous similar studies. Above all, this study demonstrated that introduction of chemometrics methodologies would lead to more reliable and accurate model for predicting sow rectal temperature, thus the potential for ensuring animal welfare in a broader view if extended to more applications.

Computer vision and remote sensing to assess physiological responses of cattle to pre-slaughter stress, and its impact on beef quality: A review

Pre-slaughter stress is well-known to affect meat quality of beef carcasses and methods have been developed to assess this stress. However, development of more practical and less invasive methods are required in order to assess the response of cattle to pre-slaughter stressors, which will potentially also assist with the prediction of beef quality. This review outlines the importance of pre-slaughter stress as well as existing and emerging technologies for quantification of the pre-slaughter stress. The review includes; i) indicators of meat quality and how they are affected by pre-slaughter stress in cattle, ii) contact techniques that have been commonly used to measure stress indicators in animals, iii) remotely sensed imagery techniques recently used as non-invasive methods to monitor physiological and behavioural parameters and iv) potential implementation of remotely sensed imagery data to perform contactless assessment of physiological measurements, which could be related to the pre-slaughter stress, as well as to the indicators of beef quality. Relevance to industry, conclusions and recommendations for research are included.

Measurements of peripheral and deep body temperature in cattle - A review

Automation of the measurement of the physiological and behavioural parameters of livestock has become an important goal for both scientists and farmers. Accurate data and knowledge about farmed animals, especially in cattle breeding, are needed. Proper early diagnosis of a cow's health status in real time allows for preventing the development of infection, oestrus detection and leads to reduced environmental stress. Thus, it contributes to more effective herd management. Among the physiological parameters, body temperature and its fluctuations are key indicators of health and well-being in animals. Currently, along with the development of technical solutions and their implementation, increasingly more attention is being paid to the continuously measurement of body core and peripheral temperature in animals. Recently there has been an increased number of publications devoted to this subject. However, there is a need to systematise this knowledge as these studies have had different purposes, have been performed in various environmental conditions, and the measurements were taken using different methods and equipment. As such, the results obtained by the different authors often may not be comparable. For this reason, this paper has two main purposes: to present the most widely used continuous methods of peripheral and body core temperature measurement, and to show its references values which characterise the individual locations of the cattle body in thermoneutral ambient. An analysis of the professional publications regarding measurements of peripheral and deep body temperature led to the conclusion that these methods have high research and diagnostic potential. However, it is necessary to standardised research to enable better and more comparable results, including among others; different cattle groups, animal age, health and environmental conditions.

Use of thermal imaging in dairy calves: exploring the repeatability and accuracy of measures taken from different anatomical regions

Three experiments were undertaken to 1) quantify the repeatability and reproducibility of thermal imaging across day and operator experience and 2) assess the correlation between descriptive infrared (IR) temperature parameters from different anatomical areas and core body temperature in dairy calves under 12 wk of age. In experiment 1, a single operator captured 30 replicate images of both the left and right eyes (defined as the whole eye + 1 cm margin) and the rectal area (defined as the anus +1.5 cm margin) from each of 16 calves. In experiment 2, three operators of varying experience captured images from both the left and right eyes and the rectal area of each of 12 calves. In experiment 3, a single operator captured images of the right eye and rectal area for a period of 5 consecutive days for each of 205 calves. All images were captured between 0900 and 1300 h. Core body temperature, obtained via rectal thermometer, was recorded every day for each of the 205 calves following completion of IR image capture. Ambient temperature and relative humidity were adjusted for each thermal image prior to manual extraction of maximum, minimum, and average temperature parameters. In experiment 1, lowest error variance was found within the maximum temperature parameter and the right eye was determined as the most repeatable anatomical area, with 80.48% of the total proportion of variance attributed to the calf. Results indicated that capturing at least three replicate images would provide the precision required to identify ill-health in calves. In experiment 2, operator variance was low across anatomical areas, with values of ≤0.01°C² for the right and left eyes and ≤0.04°C² for the rectal area. In experiment 3, day to day variation of thermal image measurements and core body temperature were minimal across anatomical areas with values of ≤0.008°C². Correlations ranging from 0.16 to 0.32, and from 0.31 to 0.47 were found between maximum eye and core body temperature and maximum rectal area and core body temperature, respectively. Results of the present study indicate a low level of variability and high level of repeatability within IR temperature measurements in calves under 12 wk of age, particularly within maximum temperature parameters. Providing operators of varying abilities with a basic standardized protocol is sufficient to limit between-operator variation. Further research is required to investigate whether correlation between IR and core body temperature can be improved.

Relationship of weight gain with infrared temperatures in Nelore and F1 (Nelore × Angus) heifers reared in two forage production systems1

Intensive production systems require high-yield genetics as obtained in Bos taurus × Bos indicus crossbreeding. Generally, high-producing taurine cattle are more susceptible to parasites and heat stress. This study evaluated animal performance, heat-stress measurement (infrared temperatures), and internal parasite infection with daily weight gain in heifers from 2 genetic groups (Nelore and F1-Nelore × Angus) reared in 2 forage production systems (with or without crop-livestock system) during 1 yr. The main objectives were to determine the relationship between infrared measures and animal performance and whether it differs between genetic groups and environments. Thirty-six heifers were randomly assigned to 2 forage production systems, one considered as high-input system with crop-livestock system and other exclusive livestock system considered as low input. At each 28 d, infrared thermography (IR) temperatures, weight, and internal parasite infection (fecal egg count) were measured. The temperatures of the eye, snout, forehead, dewlap, body, ground and squeeze chute were determined. F1 heifers had higher weight gain than Nelore (P < 0.05) and both did not differ in internal parasite infection (P > 0.05). F1 heifers had higher IR than Nelore (P < 0.05). The main body points that differentiate between genetic groups were dewlap, forehead, and eye. Higher dewlap IR temperature (DW) was associated with higher average daily gain (ADG) during dry season (independently of genetic groups) (ADG = -0.755 + 0.032 × DW; R2 = 0.44). Otherwise, the IR temperatures had a negative relationship with ADG during rainy season and low forehead IR temperature was related to higher average daily gain (ADG = 1.81 - 0.033 × forehead; R2 = 0.12 for F1 animals and ADG = 1.46 - 0.025 × forehead; R2 = 0.07 for Nelore). The infrared temperatures were more related to animal performance during the dry season, which had high temperature and low humidity. The infrared temperatures were able to identify the animal response to the environment challenge. Animals with higher temperatures (dewlap and forehead) had higher daily gain during the dry season.

Short communication: using infrared thermography as an in situ measure of core body temperature in lot-fed Angus steers

Thirty-six Black Angus steers were used in a replicated study; three replicates of 12 steers/replicate. Steers had an initial non-fasted BW of 392.3 ± 5.1, 427.5 ± 6.3, and 392.7 ± 3.7 kg for each replicate, respectively. Steers were housed outside in individual animal pens (10 m × 3.4 m). Each replicate was conducted over a 6-day period where infrared thermography (IRT) images were collected at 3-h intervals, commencing at 0600 h on day 1 and concluding at 0600 h on day 6. Rumen temperatures (T _RUM) were measured at 10-min intervals for the duration of each replicate using a radio-frequency identification (RFID) rumen bolus. These data were used to determine the relationship with surface temperature of the cattle, which was determined using IRT. Individual T _RUM were converted to an hourly average. The relationship between T _RUM and surface temperature was determined using Pearson's correlation coefficient. There were no linear trends between mean hourly T _RUM and mean surface temperature. Pearson's correlation coefficient indicated that there were weak associations (r ≤ 0.1; P < 0.003) between T _RUM and body surface temperature. These data suggest that there was little relationship between the surface temperature and T _RUM.

Evaluating the impact of breed, pregnancy, and hair coat on body temperature and sweating rate of hair sheep ewes in the tropics

The objective of this study was to evaluate the effect of pregnancy, breed, and hair coat on body temperature and sweating rate (SR) of hair sheep. St. Croix White (STX; = 9) and Dorper × STX (DRPX; = 9) ewes (3.6 yr of age) were evaluated over 4 d at 126 d of gestation (PREG) and over 4 d at 46 d postpartum (OPEN) in the shade and sun and in the morning (AM; 0900 to 1200 h) and afternoon (PM; 1300 to 1600 h) after a 20 min acclimation to each condition on each day. Data loggers recorded vaginal temperature (VT) at 10-min intervals for 96 h. Rectal temperature (RT) was measured using a digital veterinary thermometer, and respiration rate (RR) was measured as breaths per minute (bpm). Sweating rate was calculated from measured air properties passing over a shaved (300 cm) and unshaved area of the ewes' body using a portable calorimeter. Data were analyzed using GLM procedures of SAS (SAS Inst. Inc., Cary, NC) with breed, pregnancy status, sun exposure, and time of day as main effects. Mean temperature, relative humidity, temperature-humidity index, wind speed, and solar radiation on the days of data collection were 28.2°C, 82.8%, 80.3, 4.2 km/h, and 237.5 W/m, respectively. There was no difference ( > 0.10) in RT, RR, and SR between DRPX and STX ewes. The PREG ewes had lower RT ( < 0.007) and SR ( < 0.0001) and higher RR ( < 0.007) than OPEN ewes (38.5 ± 0.2 vs. 39.1 ± 0.2°C, 70.2 ± 3.1 vs. 88.3 ± 3.1 g⋅m⋅h, and 79.5 ± 2.2 vs. 72.1 ± 2.2 bpm, respectively). During the PM, RR, RT ( < 0.05), and SR ( < 0.006) were higher than in the AM. In the sun, RR ( < 0.001) and SR ( < 0.0001) were higher than in the shade, but there was no difference ( > 0.10) in RT. There was no difference in SR ( > 0.10) between the shaved and unshaved area of the ewe. The DRPX ewes had higher ( < 0.0001) VT than STX ewes. The PREG ewes had higher ( < 0.001) VT than OPEN ewes during the night time and lower VT than the OPEN ewes during the day time ( < 0.0001). The OPEN ewes had a greater ( < 0.009) daily range of VT than PREG ewes did (2.5 ± 0.4 vs. 1.1 ± 0.4°C, respectively), but there was no breed difference ( > 0.10). Hair coat did not have an influence on the SR of the ewes, and PREG ewes appeared to use increased respiration as opposed to sweating to help control RT. The narrower range of body temperature, measured as VT, of PREG compared to OPEN ewes may be a protective mechanism for the developing fetus.

Hair coat characteristics and thermophysiological stress response of Nguni and Boran cows raised under hot environmental conditions

Breed, age, coat colour, month and temperature humidity index (THI) influence on body weight (W), body condition score (BCS), thermophysiological variables (rectal temperature (Tr), skin temperature (Tsk)) and hair length was studied in Nguni (n = 19) and Boran (n = 16). As a result of this study, breed influenced W, BCS and Tsk on the neck and belly (P < 0.05). The BCS and W of Nguni cows were higher than the Boran cows. Hair length of both breeds increased from February to August. The THI influenced thermophysiological variables (P < 0.05). Increased Tr for both breeds was recorded in February and April, respectively (P < 0.05). Month influenced Tsk and June recorded lower values (P < 0.05). Younger cows (3-8 years) had lower weight and high Tr and Tsk (P < 0.05). Nguni cows had high neck and thurl temperatures in June while Boran cows had the highest in August (P < 0.05). Red, dun and white-black Boran cows had increased BCS. Nguni cows with red, fawn and white cows had high BCS. Fawn-coloured Nguni cows and white-brown Boran cows had the more weight than cows with other colours compared in the study. White-red Nguni and Boran cows recorded the highest Tr. For Nguni cows, neck and belly temperatures were significantly (P < 0.001) correlated to thurl temperature. Boran cows had significant (P < 0.001) correlations for THI and neck, belly and thurl temperatures. The current study found that Nguni cows were more adapted to the prevailing bioclimatic changes. However, Boran cows have the potential of performing well under heat stress conditions over time.

High systemic and testicular thermolytic efficiency during heat tolerance test reflects better semen quality in rams of tropical breeds

This study aimed to assess the capacity of Morada Nova (MN) and Santa Inês (SIN) rams to maintain body and testicular homeothermy under thermal challenge. For 5 days in the summer, 16 males (SIN = 7 and MN = 9) underwent a heat tolerance test, i.e., period 1-animals maintained in the shade (11 to 12 h); period 2-animals exposed to sunlight (12 to 13 h); and period 3-animals returned to the shade (13 to 14 h). The respiratory rate, heart rate, rectal temperature, and infrared surface temperatures (IRT) of the trunk, back, eyeball, and testicles were assessed in each period. The index of capacity of tolerance to insolation (ICTI), which indicates the animals' level of adaptability, was calculated for each animal. Semen quality and testicular parenchyma integrity were assessed before and after the thermal challenge. Statistical analyses were performed at 5% significance. In period 1, the variables had baseline values for both genotypes. In period 2, the variables involved in thermolysis significantly increased (P < 0.05), which matches a thermal discomfort situation. In period 3, the variables returned to baseline values and some values were lower than those in period 1. Semen quality and testicular parenchyma integrity suffered no negative effects with the thermal challenge. IRT ocular and IRT testicular were positively correlated (P < 0.05). It is concluded that MN and SIN rams had efficient thermolytic mechanisms that favor preserving gonadal functionality. The animals were considered resilient to a thermal challenge. In addition, infrared thermography was an efficient tool to verify body and testicular thermoregulation.

Vulvar thermal pattern following synchronization of estrus is linked to fertility after timed artificial insemination in goat

Aim of this study was to study the vulvar thermal pattern variation during the timed artificial insemination protocol in Angora goat and identify the relationship with the successful rate. Does (36 adult healthy females) were synchronized using PGF2α at the day 0, 11 days of progesterone impregnated sponges intra-vaginally, PMSG 48 h before sponges withdraw (day 11) and the intra-cervical inseminations were carried out 48 h later (Timed Artificial Insemination: TAI) with chilled semen. Vulvar (VST) and perivulvar (PST) areas were considered to evaluate the thermal pattern during the protocol at the day 0 and at the TAI using a thermo camera (E60, FLIR System). Differences of temperature (ΔT) between the surfaces were calculated for each time. The does were monitored for pregnancy, delivery time and prolificacy. Pregnant (P) and non-pregnant (NP) does were compared in terms of VST, PST and ΔT using two ways ANOVA considering time and pregnancy as sources of variability. VST was lower than PST in all the monitored does (P < 0.05) (34.79 ± 0.14 vs 36.58 ± 0.14 °C) and without differences between P and NP at day 0 (35 ± 0.18 vs 36.39 ± 0.22 °C). Significant difference (P < 0.05) between P and NP does was recorded at TAI in terms of VST (33.89 ± 0.31 vs 35.40 ± 0.24 °C) and ΔT (-3.16 ± 0.34 vs -1.62 ± 0.26 °C). In conclusion thermal emission by glabrous surfaces in goat may be used to identify the right response induced by hormonal treatments and to optimize the application of assisted reproductive techniques at the field level.