Surface temperatures are influenced by handling stress independently of corticosterone levels in wild king penguins (Aptenodytes patagonicus)

Assessing the physiological stress responses of wild animals opens a window for understanding how organisms cope with environmental challenges. Since stress response is associated with changes in body temperature, the use of body surface temperature through thermal imaging could help to measure acute and chronic stress responses non-invasively. We used thermal imaging, acute handling-stress protocol and an experimental manipulation of corticosterone (the main glucocorticoid hormone in birds) levels in breeding king penguins (Aptenodytes patagonicus), to assess: 1. The potential contribution of the Hypothalamo-Pituitary-Adrenal (HPA) axis in mediating chronic and acute stress-induced changes in adult surface temperature, 2. The influence of HPA axis manipulation on parental investment through thermal imaging of eggs and brooded chicks, and 3. The impact of parental treatment on offspring thermal's response to acute handling. Maximum eye temperature (Teye) increased and minimum beak temperature (Tbeak) decreased in response to handling stress in adults, but neither basal nor stress-induced surface temperatures were significantly affected by corticosterone implant. While egg temperature was not significantly influenced by parental treatment, we found a surprising pattern for chicks: chicks brooded by the (non-implanted) partner of corticosterone-implanted individuals exhibited higher surface temperature (both Teye and Tbeak) than those brooded by glucocorticoid-implanted or control parents. Chick's response to handling in terms of surface temperature was characterized by a drop in both Teye and Tbeak independently of parental treatment. We conclude that the HPA axis seems unlikely to play a major role in determining chronic or acute changes in surface temperature in king penguins. Changes in surface temperature may primarily be mediated by the Sympathetic-Adrenal-Medullary (SAM) axis in response to stressful situations. Our experiment did not reveal a direct impact of parental HPA axis manipulation on parental investment (egg or chick temperature), but a potential influence on the partner's brooding behaviour.

Effects of grain-based pecking blocks on productivity and welfare indicators in commercial broiler chickens

OBJECTIVE

This experiment was conducted to investigate the effect of grain-based pecking blocks on productivity and welfare status at two commercial broiler welfare-certified farms.

METHODS

Production and welfare indicators were assessed at two farms (designated Farm A and B). Both farms had two windowless houses with forced tunnel-type ventilation and housed broilers at stocking densities of approximately 16.7 birds/m2 (Farm A) and 16.8 birds/m2 (Farm B). Each house was divided into two or three equal sections and was provided with or without pecking blocks. Grain-based pecking blocks, measuring 25 × 25 × 25 cm, were given to broilers in both farms at 1 block per 1,000 birds. Various parameters including productivity (body weight and flock uniformity), corticosterone levels (in fecal droppings and feathers), footpad dermatitis, hock burn, feather dirtiness, gait score, litter quality, body surface temperature, and volatile fatty acids in fecal samples were assessed at 26 days of age, whereas litter quality was analyzed at 13 and 26 days of age.

RESULTS

There were no significant effects of providing pecking blocks on productivity (body weight and uniformity), fecal and feather corticosterone, welfare indicators (i.e., footpad dermatitis, hock burn, feather cleanliness, and gait score), and litter quality (i.e., moisture, nitrogen, and pH). No differences in body surface temperature between the control and enrichment treatments were noted in Farm B, but body surface temperatures of the head (p = 0.029) and legs (p = 0.011) in the enrichment vs. control group were elevated in Farm A. Butyrate concentration in the enrichment vs control group was higher in Farm B (p = 0.023), but this effect was not detected in Farm A.

CONCLUSION

It is concluded that grain-based pecking blocks did not affect performance and welfare indicators. Further studies are warranted to elucidate the potential impact of grain-based pecking blocks on gut health indicators.

Gut microbiota intervention attenuates thermogenesis in broilers exposed to high temperature through modulation of the hypothalamic 5-HT pathway

BACKGROUND

Broilers have a robust metabolism and high body temperature, which make them less tolerant to high-temperature (HT) environments and more susceptible to challenges from elevated temperatures. Gut microbes, functioning as symbionts within the host, possess the capacity to significantly regulate the physiological functions and environmental adaptability of the host. This study aims to investigate the effects of gut microbial intervention on the body temperature and thermogenesis of broilers at different ambient temperatures, as well as the underlying mechanism involving the "gut-brain" axis.

METHODS

Broilers were subjected to gut microbiota interference with or without antibiotics (control or ABX) starting at 1 day of age. At 21 day of age, they were divided into 4 groups and exposed to different environments for 7 d: The control and ABX groups at room temperature (RT, 24 ± 1 °C, 60% relative humidity (RH), 24 h/d) and the control-HT and ABX-HT groups at high temperature (HT, 32 ± 1 °C, 60% RH, 24 h/d). RESULTS : The results demonstrated that the antibiotic-induced gut microbiota intervention increased body weight and improved feed conversion in broiler chickens (P < 0.05). Under HT conditions, the microbiota intervention reduced the rectal temperature of broiler chickens (P < 0.05), inhibited the expression of avUCP and thermogenesis-related genes in breast muscle and liver (P < 0.05), and thus decreased thermogenesis capacity. Furthermore, the gut microbiota intervention blunted the hypothalamic‒pituitary‒adrenal axis and hypothalamic-pituitary-thyroid axis activation induced by HT conditions. By analyzing the cecal microbiota composition of control and ABX chickens maintained under HT conditions, we found that Alistipes was enriched in control chickens. In contrast, antibiotic-induced gut microbiota intervention resulted in a decrease in the relative abundance of Alistipes (P < 0.05). Moreover, this difference was accompanied by increased hypothalamic 5-hydroxytryptamine (5-HT) content and TPH2 expression (P < 0.05).

CONCLUSIONS

These findings underscore the critical role of the gut microbiota in regulating broiler thermogenesis via the gut-brain axis and suggest that the hypothalamic 5-HT pathway may be a potential mechanism by which the gut microbiota affects thermoregulation in broilers.

Effect of standard and physiological cell culture temperatures on in vitro proliferation and differentiation of primary broiler chicken pectoralis major muscle satellite cells

Culture temperatures for broiler chicken cells are largely based on those optimized for mammalian species, although normal broiler body temperature is typically more than 3°C higher. The objective was to evaluate the effects of simulating broiler peripheral muscle temperature, 41°C, compared with standard temperature, 38°C, on the in vitro proliferation and differentiation of primary muscle-specific stem cells (satellite cells; SC) from the pectoralis major (PM) of broiler chickens. Primary SC cultures were isolated from the PM of 18-day-old Ross 708 × Yield Plus male broilers. SC were plated in triplicate, 1.8-cm2, gelatin-coated wells at 40,000 cells per well. Parallel plates were cultured at either 38°C or 41°C in separate incubators. At 48, 72, and 96 h post-plating, the culture wells were fixed and immunofluorescence-stained to determine the expression of the myogenic regulatory factors Pax7 and MyoD as well as evaluated for apoptosis using a TUNEL assay. After 168 h in culture, plates were immunofluorescence-stained to visualize myosin heavy chain and Pax7 expression and determine myotube characteristics and SC fusion. Population doubling times were not impacted by temperature (p ≥ 0.1148), but culturing broiler SC at 41°C for 96 h promoted a more rapid progression through myogenesis, while 38°C maintained primitive populations (p ≤ 0.0029). The proportion of apoptotic cells increased in primary SC cultured at 41°C (p ≤ 0.0273). Culturing at 41°C appeared to negatively impact fusion percentage (p < 0.0001) and tended to result in the formation of thinner myotubes (p = 0.061) without impacting the density of differentiated cells (p = 0.7551). These results indicate that culture temperature alters primary broiler PM SC myogenic kinetics and has important implications for future in vitro work as well as improving our understanding of how thermal manipulation can alter myogenesis patterns during broiler embryonic and post-hatch muscle growth.

Effects of feeding diets with zinc-l-selenomethionine on growth performance of broilers subjected to cyclic heat stress

Limited information exists on the use of zinc-l-selenomethionine (Zn-L-SeMet) in broiler diets and its effects on the growth performance, body temperature, mortality rates, blood profile, and gene expression, especially when animals are reared under cyclic heat stress conditions. This study aimed to investigate the impact of Zn-L-SeMet in broiler diets from 1 to 42 days of age reared under cyclic heat stress and its effects on growth performance, cloacal temperatures, mortality rate, blood parameters, and insulin-like growth factor 1 (IGF-1) and growth hormone receptor (GHR) gene expression in the breast muscle. A total of 1000 male Cobb 500® broiler chicks were randomly assigned to five treatments: 0, 0.15, 0.23, 0.47, and 1.30 mg/kg of Zn-L-SeMet. Each treatment consisted of 10 replicates with 20 birds each. No statistically significant differences in growth performance were observed from 1 to 21 days of age (P > 0.05). However, from 1 to 42 days, feed intake (FI) and feed conversion ratio (FCR) decreased linearly (P < 0.05). Cloacal temperatures showed no significant effects (P > 0.05), while overall mortality rate exhibited a quadratic response (P < 0.05), with the optimal inclusion level predicted to reduce broiler mortality at 0.71 mg/kg. Triglyceride (TRG) levels increased with 0.97 mg/kg (P < 0.05), and gama-glutamil transferase (GGT) levels decreased with the inclusion of 1.19 mg/kg (P < 0.05). No significant effects on IGF-1 and GHR gene expression were found (P > 0.05). In conclusion, the inclusion of 1.30 mg/kg of Zn-L-SeMet in diets of heat-stressed broilers improved growth performance from 1 to 42 days of age. An inclusion of 0.71 mg/kg reduced mortality rate, while 0.97 mg and 1.19 mg increased and reduced TRG and GGT levels, respectively.

It's cool to be stressed: body surface temperatures track sympathetic nervous system activation during acute stress

The acute stress response can be considered the primary evolutionary adaptation to maximise fitness in the face of unpredictable environmental challenges. However, the difficulties of assessing physiology in natural environments mean that comparatively little is known about how response variation influences fitness in free-living animals. Currently, determining acute stress physiology typically involves blood sampling or cardiac monitoring. Both require trapping and handling, interrupting natural behaviour, and potentially biasing our understanding toward trappable species/individuals. Importantly, limits on repeated sampling also restrict response phenotype characterisation, vital for linking stress with fitness. Surface temperature dynamics resulting from peripheral vasomotor activity during acute stress are increasingly promoted as alternative physiological stress indicators, which can be measured non-invasively using infrared thermal imaging, overcoming many limitations of current methods. Nonetheless, which aspects of stress physiology they represent remains unclear, as the underlying mechanisms are unknown. To date, validations have primarily targeted the hypothalamic-pituitary-adrenal axis, when the sympathetic-adrenal-medullary (SAM) system is likely the primary driver of vasomotor activity during acute stress. To address this deficit, we compared eye and bill region surface temperatures (measured using thermal imaging) with SAM system activity (measured as heart rate variability via electrocardiogram telemetry) in wild-caught captive house sparrows (Passer domesticus) during capture and handling. We found that lower body surface temperatures were associated with increased sympathetic nervous system activation. Consequently, our data confirm that body surface temperatures can act as a proxy for sympathetic activation during acute stress, providing potentially transformative opportunities for linking the acute stress response with fitness in the wild.

Effects of drinking water temperature in winter on growth performance, water consumption, surface temperature, and intestinal development of geese from 21 to 49 days of age

This research aimed to investigate the effects of drinking water temperatures on growth performance, water consumption, surface temperature, organ indices, blood parameters, and intestinal development of geese, and determine the optimal drinking water temperature for 21 to 49-d geese. A total of 192 twenty-one-day male Yuzhou white geese were allocated randomly to 4 groups with 8 replicate pens per group according to the drinking water temperature (drinking water temperature [7℃-12℃] at ambient temperature [T_C], 18℃ [T₁], 27℃ [T₂], and 36℃ [T₃], respectively). The results showed that increasing drinking water temperature did not significantly improve the BW, ADG, and ADFI of geese (P > 0.05), whereas drinking warm water of 36℃ for geese had a trend to increase FCR (0.05 < P < 0.1). Geese in group T₂ drank the most water per day on average, whereas geese in group T_C drank the least (P < 0.001). Geese in groups T₁, T₂, and T₃ had higher eyes temperatures than group T_C (P < 0.001). No significant differences were found on the organ indices and blood biochemical parameters (P > 0.05). Geese from group T₁ had higher crypt depth and muscularis thickness of duodenum (P < 0.05), and lower ratio of villus height to crypt depth than other groups (P < 0.001). Geese from group T₁ had higher activities of trypsin in duodenum and jejuna and amylase in jejuna at 49 d than other groups (P < 0.01). Overall, these data indicate drinking water at 18℃ can increase water consumption and eyes temperature, and improve the activity of digestive enzymes and promote intestinal development. Under our experimental conditions, we recommend that the optimal drinking water temperature for geese from 21 to 49 d of age is 18°C.

Maximum limit of sensible heat dissipation in Japanese quail

Surface temperature can be used as a tool for calculating sensible heat transfer. However, it needs to be associated with air temperature to identify the direction of heat flow (gain or loss). This study quantified sensible heat transfer in Japanese quail as a function of operative temperature. The meteorological variables were air temperature, relative humidity, and black globe temperature. Quail surface temperature was measured on 50 adult Coturnix coturnix japonica individuals 270 days old during 8 days by using a thermographic camera. The data were analyzed by the least-squares method to assess the effects of sex (male and female), period of the day (morning and afternoon), and body region (head, body, and feet). Quail surface temperature was strongly correlated with operative temperature. The total sensible heat flow was 64.02 W m^-2. The morning period had a mean operative temperature of 22.48 °C, providing a higher gradient between air and quail temperature and thereby producing a higher heat flow (82.19 W m^-2). In the afternoon, the heat transfer was lower (45.70 W m^-2) because the operative temperature was higher (30.84 °C). Comparison between sexes showed that heat transfer was higher in females (67.37 W m^-2) than in males (60.53 W m^-2). The head served as an important thermal window, with a heat transfer of 78.24 W m^-2, whereas the body and feet had a transfer of 56.80 W m^-2. Heat transfer by sensible mechanisms was quantified in Japanese quail. Heat transfer depended greatly on ambient temperature. When the operative temperature was below 28 °C, sensible mechanisms were efficient in dissipating heat to the environment. When the ambient temperature exceeded 29 °C, quail could not effectively dissipate heat to the environment through sensible mechanisms. At 30 °C and above, heat loss shifted to heat gain, causing thermal stress in Japanese quail.

Effect of L-serine on circadian variation of cloacal and body surface temperatures in broiler chickens subjected to feed restriction during the hot-dry season

The study aimed to evaluate the effects of L-serine on circadian variation of body temperatures in feed-restricted broiler chickens during the hot-dry season. Day-old broiler chicks of both sexes served as subjects; comprising four groups of 30 chicks each: Group A: water ad libitum + 20% feed restriction (FR); Group B: feed and water ad libitum (AL); Group C: water ad libitum + 20% feed restriction + L-serine (200 mg/kg) (FR + L-serine); Group D feed and water ad libitum + L-serine (200 mg/kg) (AL + L-serine). Feed restriction was performed on days 7-14 and L-serine was administered on days 1-14. Cloacal and body surface temperatures, recorded by digital clinical and infra-red thermometers, respectively, and temperature-humidity index were obtained over 26 h on days 21, 28 and 35. Temperature-humidity index (28.07-34.03) indicated broiler chickens were subjected to heat stress. L-serine decreased (P < 0.05) cloacal temperature in FR + L-serine (40.86 ± 0.07 °C), compared to FR (41.26 ± 0.05 °C) and AL (41.42 ± 0.08 °C) broiler chickens. Peak cloacal temperature occurred at 15:00 h in FR (41.74 ± 0.21 °C), FR + L-serine (41.30 ± 0.41 °C) and AL (41.87 ± 0.16 °C) broiler chickens. Fluctuations in thermal environmental parameters influenced circadian rhythmicity of cloacal temperature; especially the body surface temperatures, positively correlated with CT, and wing temperature recorded the closest mesor. In conclusion, L-serine and feed restriction decreased cloacal and body surface temperatures in broiler chickens during the hot-dry season.

Seasonal variations on semen quality attributes in turkey and egg type chicken male breeders

A biological experiment was carried out in twenty-four adult healthy breeder males each in turkey (Beltsville small white) and egg type chicken (White Leghorn Babcock) in order to assess the seasonal influence on semen production and quality. The birds were maintained in individual cages under uniform husbandry conditions throughout the year. The birds were fed with breeder ration and water ad libitum was offered with a constant photoperiod of 14 h/day. Physical and biochemical characteristics of semen, serum hormones (testosterone and thyroxine), and antioxidant activity (catalase and lipid peroxidation) were evaluated throughout the year (January-December). Based on the THI calculations, the observations were classified under three different seasons, namely, winter (November-February), spring (March, April, and October), and summer (May-September). Semen physical parameters, sperm concentration, motility, live sperm percentage, and sperm plasma membrane integrity were superior during the winter season. In seminal plasma, biochemical parameters (phosphorus, ALT, ALP, AST, and uric acid) had a significant (P < 0.05) difference between seasons. There was a significant difference (P < 0.05) among serum hormones (testosterone and thyroxine) that were higher during the winter season. Significant variation was observed in catalase and lipid peroxidation antioxidant enzyme activities (seminal and blood plasma) in winter than in the other two seasons. Both the turkey and egg type chicken breeders exhibited superior seminal characteristics, sex hormone profile, and antioxidant enzyme activity during winter seasons.

Thermal Conditioning Can Improve Thermoregulation of Young Chicks During Exposure to Low Temperatures

The risk of climate change is increasing year by year and changing environmental temperatures will increasingly have effects on productivity in the poultry industry. Thermal conditioning is a method of improving thermotolerance and productivity in chickens (Gallus gallus domesticus) that experience high ambient temperatures. Thermal conditioning involves exposure of chickens to high temperatures at an early age. This conditioning treatment can affect tolerance to other type of stress. However, the effect of thermal conditioning on tolerance of low temperatures has not been investigated. Therefore, in this study we investigated the effect of thermal conditioning in chickens on thermoregulation during exposure to low temperatures. Three day-old female broiler chicks were exposed to high ambient temperatures (40°C for 12 h) as a thermal conditioning treatment. A control group of chicks was kept at 30°C. At 7 days-old, both groups of chicks were exposed to low temperatures (16 ± 0.5°C) for 3 h. Thermal conditioning treatment reduced the decrease in rectal temperature during cold exposure that occurred in control chicks. In addition, hypothalamic mRNA expression of brain derived neurotrophic factor, thyrotropin-releasing hormone and arginine vasotocin genes was higher in thermal conditioning treated chicks than control chicks. The mRNA expression of avian uncoupling protein in the liver was also higher in thermal conditioning chicks. These results suggest that thermal conditioning treatment can improve thermoregulatory mechanisms of chicks under low temperature environments.

Glucocorticoids in a warming world: Do they help birds to cope with high environmental temperatures?

Climate change is threatening biodiversity world-wide. One of its most prominent manifestations are rising global temperatures and higher frequencies of heat waves. High environmental temperatures may be particularly challenging for endotherms, which expend considerable parts of their energy budget and water resources on thermoregulation. Thermoregulation involves phenotypic plasticity in behavioral and physiological traits. Information on causal mechanisms that support plastic thermoregulatory strategies is key to understand how environmental information is transmitted and whether they impose trade-offs or constraints that determine how endotherms cope with climate warming. In this review, we focus on glucocorticoids, metabolic hormones that orchestrate plastic responses to various environmental stimuli including temperature. To evaluate how they may mediate behavioral and physiological responses to high environmental temperatures, we 1) briefly review the major thermoregulatory strategies in birds; 2) summarize the functions of baseline and stress-induced glucocorticoid concentrations; 3) synthesize the current knowledge of the relationship between circulating glucocorticoids and high environmental temperatures in birds; 4) generate hypotheses for how glucocorticoids may support plastic thermoregulatory responses to high environmental temperatures that occur over different time-frames (i.e., acute, short- and longer-term); and 5) discuss open questions on how glucocorticoids, and their relationship with thermoregulation, may evolve. Throughout this review we highlight that our knowledge, particularly on free-living populations, is really limited and outline promising avenues for future research. As evolutionary endocrinologists we now need to step up and identify the costs, benefits, and evolution of glucocorticoid plasticity to elucidate how they may help birds cope with a warming world.

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.

Research Progress in the Early Warning of Chicken Diseases by Monitoring Clinical Symptoms

Global animal protein consumption has been steadily increasing as a result of population growth and the increasing demand for nutritious diets. The poultry industry provides a large portion of meat and eggs for human consumption. The early detection and warning of poultry infectious diseases play a critical role in the poultry breeding and production systems, improving animal welfare and reducing losses. However, inadequate methods for the early detection and prevention of infectious diseases in poultry farms sometimes fail to prevent decreased productivity and even widespread mortality. The health status of poultry is often reflected by its individual physiological, physical and behavioral clinical symptoms, such as higher body temperature resulting from fever, abnormal vocalization caused by respiratory disease and abnormal behaviors due to pathogenic infection. Therefore, the use of technologies for symptom detection can monitor the health status of broilers and laying hens in a continuous, noninvasive and automated way, and potentially assist in the early warning decision-making process. This review summarized recent literature on poultry disease detection and highlighted clinical symptom-monitoring technologies for sick poultry. The review concluded that current technologies are already showing their superiority to manual inspection, but the clinical symptom-based monitoring systems have not been fully utilized for on-farm early detection.

Characterization of differential gene expression of broiler chicken to thermal stress in discrete developmental stages

Prolonged exposure to high temperatures is linked to a range of physiological responses in broiler chickens including reduced disease resistance, low growth rate, and high mortality rate. In this study, we investigated the effect of heat stress on gene expression levels in 4-week-old and 6-week-old chickens each exposed to environments conditioned at thermoneutral (21 °C) and high (32 °C) temperatures. The analysis of differentially expressed genes (DEGs) using microarray revealed that genes underlying reactive oxygen species (ROS) production, cell nutrient intake, glucose metabolism, and circadian rhythm were differentially regulated in association with heat stress. We also found that the deviation in expression levels across the transcriptome in response to heat stress was significantly stronger (P< 2.2×10-16) in 6-week-olds compared to younger chickens. We finally observed a significant trend (r = 0.78, P< 2.2×10-16) that genes with a higher estimate of expression in the microarray were more likely to have a higher expression level in RNA-sequencing. Together, our findings provide comprehensive insights into the physiology involved in stress responses at varying developmental stages, which may facilitate chicken breeding to maximize their productivity under adverse conditions.

The influence on behavior and physiology of white-feathered end-of-cycle hens during simulated transport

Transportation is a stressful procedure that can alter end-of-cycle hen (EOCH) behavior and physiology. This study (5 × 3 × 2 factorial arrangement) aimed to assess the effects of temperature (T)/relative humidity (RH) (-10°C uncontrolled RH (-10), +21°C 30%RH (21/30), +21°C 80%RH (21/80), +30°C 30%RH (30/30), +30°C 80%RH (30/80)), duration (4, 8, 12 h), and feather cover [well (WF) and poorly-feathered (PF)] on white-feathered EOCH (65-70 wk) behavior and physiology. EOCH (n = 630) from 3 commercial farms were housed for adaptation (3-5 d), fasted (6 h), crated (53 kg/m2), and placed in a climate-controlled chamber. Data collected included chamber and crate conditions, feather condition score, mortality, core body temperature (CBT), behavior, and delta (∆) blood physiology. Analyses were conducted via ANOVA in a randomized complete block design (farm of origin) with significance declared at P ≤ 0.05. PF EOCH had higher mortality than WF hens during cold exposure (-10). EOCH ∆CBT demonstrated a greater (positive) change at 12 h for all T/RH compared to 4 h at 21/30, 21/80, and -10 (negative). Cold exposure (-10) resulted in a higher percentage of time spent shivering and motionless, while heat exposure resulted in a higher percentage of time spent panting for WF EOCH exposed to 30/30 and WF and PF hens exposed to 30/80. Hen ∆glucose had a greater (negative) change at 4 and 12 h for -10 compared to 4 h at 21/30, and all durations for 21/80, 30/30, and 30/80. PF hens exposed to -10 had a greater (positive) change in ∆sodium, ∆hemoglobin, and ∆hematocrit compared to WF birds (negative). The development of metabolic alkalosis was supported by the increase in ∆blood pH over time and the increase in ∆partial pressure of carbon dioxide, ∆bicarbonate, and ∆base excess extracellular fluid during cold exposure (-10). These results indicated that EOCH exposed to heat endured thermal stress while PF hens exposed to cold were unable to cope with cold stress.

Impacts of Air Velocity Treatments under Summer Condition: Part I—Heavy Broiler’s Surface Temperature Response

Simple Summary

The surface temperature variation of heavy broilers (42–61 d age) under heat stress is an important indicator of thermal comfort, but it is not well studied and reported yet. This study examined the variation of surface temperatures of broilers through two dynamic air velocity treatments under hot summer conditions. It was discovered that the surface temperatures varied over age, daytime, and environmental factors (air temperature, relative humidity, and temperature humidity index). A simple linear regression model to predict the surface temperature of heavy broilers was developed. The findings from this study will enhance knowledge to understand the broilers’ responses under heat stress, which will be helpful in providing necessary management decisions to create a comfortable thermal environment.

Abstract

Heavy broilers exposed to hot summer conditions experience fluctuations in surface temperatures due to heat stress, which leads to decreased performance. Maintaining a bird’s homeostasis depends on several environmental factors (temperature, relative humidity, and air velocity). It is important to understand the responses of birds to environmental factors and the amount of heat loss to the surrounding environment to create thermal comfort for the heavy broilers for improved performances and welfare. This study investigates the variation in surface temperatures of heavy broilers under high and low air velocity treatments. Daytime, age and bird location’s effect on the surface temperature variation was also examined. The experiment was carried out in the poultry engineering laboratory of North Carolina State University during summers of 2017, 2018, and 2019 as a part of a comprehensive study on the effectiveness of wind chill application to mitigate heat stress on heavy broilers. This live broiler heat stress experiment was conducted under two dynamic air velocity treatments (high and low) with three chambers per treatment and 44 birds per chamber. Surface temperatures of the birds were recorded periodically through the experimental treatment cycles (flocks, 35–61 d) with infrared thermography in the morning, noon, evening, and nighttime. The overall mean surface temperature of the broilers under two treatments was found to be 35.89 ± 2.37 °C. The variation in surface temperature happened due to air temperature, thermal index, air velocity, bird’s age, daytime, and position of birds inside the experimental chambers. The surface temperatures were found lower under high air velocity treatment and higher under low air velocity treatment. During the afternoon time, the broilers’ surface temperatures were higher than other times of the day. It was also found that the birds’ surface temperature increased with age and temperature humidity indices. Based upon the experimental data of five flocks, a simple linear regression model was developed to predict surface temperature from the birds’ age, thermal indices, and air velocity. It will help assess heavy broilers’ thermal comfort under heat stress, which is essential to provide a comfortable environment for them.

PglB function and glycosylation efficiency is temperature dependent when the pgl locus is integrated in the Escherichia coli chromosome

Background

Campylobacter is an animal and zoonotic pathogen of global importance, and a pressing need exists for effective vaccines, including those that make use of conserved polysaccharide antigens. To this end, we adapted Protein Glycan Coupling Technology (PGCT) to develop a versatile Escherichia coli strain capable of generating multiple glycoconjugate vaccine candidates against Campylobacter jejuni.

Results

We generated a glycoengineering E. coli strain containing the conserved C. jejuni heptasaccharide coding region integrated in its chromosome as a model glycan. This methodology confers three advantages: (i) reduction of plasmids and antibiotic markers used for PGCT, (ii) swift generation of many glycan-protein combinations and consequent rapid identification of the most antigenic proteins or peptides, and (iii) increased genetic stability of the polysaccharide coding-region. In this study, by using the model glycan expressing strain, we were able to test proteins from C. jejuni, Pseudomonas aeruginosa (both Gram-negative), and Clostridium perfringens (Gram-positive) as acceptors. Using this pgl integrant E. coli strain, four glycoconjugates were readily generated. Two glycoconjugates, where both protein and glycan are from C. jejuni (double-hit vaccines), and two glycoconjugates, where the glycan antigen is conjugated to a detoxified toxin from a different pathogen (single-hit vaccines). Because the downstream application of Live Attenuated Vaccine Strains (LAVS) against C. jejuni is to be used in poultry, which have a higher body temperature of 42 °C, we investigated the effect of temperature on protein expression and glycosylation in the E. coli pgl integrant strain.

Conclusions

We determined that glycosylation is temperature dependent and that for the combination of heptasaccharide and carriers used in this study, the level of PglB available for glycosylation is a step limiting factor in the glycosylation reaction. We also demonstrated that temperature affects the ability of PglB to glycosylate its substrates in an in vitro glycosylation assay independent of its transcriptional level.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12934-021-01728-7.

The Effect of Adding Herbal Extracts to Drinking Water on Body Temperature, Level of Thyroid Hormones and H:L Ratio in the Blood of Broiler Chickens Exposed to Elevated Ambient Temperature

The aim of the study was to determine the effect of supplementing drinking water with extracts from lemon balm, sage and nettle on body temperature, level of thyroid hormones and the heterophil to lymphocyte (H:L) ratio in the blood of broiler chickens exposed to elevated rearing temperature. One-day-old Ross 308 chicks were divided into four groups: group I (CON) and experimental groups II (LB), II (S) and IV (N), in which, from 22 to 42 days of rearing, drinkers were supplemented with lemon balm extract, sage extract or nettle extract (2 ml/l water), respectively. In addition, at 5 weeks of growth, all the groups were exposed to elevated ambient temperature (up to 30°C) for 5 days, after which the recommended thermal conditions were reinstated. During the study, mortality, rectal temperature and radiated temperature of the broilers were monitored. Blood was collected from 10 birds per group to determine the concentration of thyroid hormones (T3 and T4) and to make blood smears. The H:L ratio was determined based on the percentage of heterophils (H) and lymphocytes (L). The herbal extracts from lemon balm, sage and nettle, added to drinking water at 2 ml/l, reduced the blood level of the thyroid hormone (triiodothyronine) and rectal temperature in the experimental broilers during the initial period of thermal stress. Chickens receiving the nettle extract were also characterised by lower radiated temperature of the unfeathered body, a lower H:L ratio in the blood during the increase in ambient temperature, and the lowest mortality percentage. It can therefore be considered that the dietary supplementation of nettle, in the form and concentration used in this study, had the most favourable effect on the physiological status of the birds (body temperature, level of thyroid hormones and H:L ratio) exposed to elevated ambient temperatures (30°C), and thus on their welfare.

Effects of egg storage duration on egg quality, metabolic rate, hematological parameters during embryonic and post-hatch development of guinea fowl broilers

Considering the value of guinea fowl keets, successful incubation of eggs is particularly desirable in this poultry species. This study evaluated the effect of egg storage duration on egg quality, heat production, hematological parameters during embryonic development and post hatch performance of guinea fowl broilers. A total of 800 hatching eggs of guinea fowl were used for this study. Before incubation, 12 eggs per treatment were used to analyse egg quality. Then, eggs were numbered, weighed, and assigned to 2 treatment groups of 400 eggs each according to storage duration of 5, and 10 d at a temperature of 18°C. The eggs were set for incubation at 37.7°C and 55% relative humidity for 28 d in a forced-draft incubator. To determine heat production as a measure of metabolism, 60 eggs in each replicate were transferred to respiratory cages post hatch two 12 wk old guinea fowl were also used to determine heat production. CO₂ and O₂ were recorded to calculate heat production at internal pipping, hatch and at 12 wk of age. The hatched keets were reared for 12 wk and data were collected on feed intake, body weight and feed conversion ratio. Blood samples were collected at hatch and at 12 wk of age from 24 guinea fowls per treatment to analyze haematological parameters. The results showed that embryos and guinea fowls at 12 wks of age from eggs stored for 5 d had higher (P ˂ 0.05) heat production and body weights. However, a significant higher (P ˂ 0.05) level of basophile, eosinophils, and lymphocytes was observed in guinea fowls from 10 d storage egg. It was concluded that extended duration of egg storage negatively influenced the metabolic rate of embryos. It also impacted hematological parameters which may suggest influence on immune response during embryonic and post-hatch growth.

A Heuristic and Data Mining Model for Predicting Broiler House Environment Suitability

The proper combination of environment and flock-based variables plays a critical role in broiler production. However, the housing environment control is mainly focused on temperature monitoring during the broiler growth process. The present study developed a novel predictive model to predict the broiler (Gallus gallus domesticus) rearing conditions' suitability using a data-mining process centered on flock-based and environmental variables. Data were recorded inside four commercial controlled environment broiler houses. The data analysis was conducted in three steps. First, we performed an exploratory and descriptive analysis of the environmental data. In the second step, we labeled the target variable that led to a specific broiler-rearing scenario depending on the age of the birds, the environmental dry-bulb temperature and relative humidity, the ammonia concentration, and the ventilation rate. The output (final rearing condition) was discretized into four categories ('Excellent', 'Good', 'Moderate', and 'Inappropriate'). In the third step, we used the dataset to develop tree models using the data-mining process. The random-tree model only presented accuracy for predicting the 'Excellent' and 'Moderate' rearing conditions. The decision-tree model had high accuracy and indicated that broiler age, relative humidity, and ammonia concentration play a critical role in proper rearing conditions. Using a large amount of data allows the data-mining approach to building up 'if-then' rules that indicate suitable environmental control decision-making by broiler farmers.

Single nucleotide polymorphism in avian uncoupling protein gene is associated with thermoregulation in chicks

Avian uncoupling protein (av-UCP) is a key protein for thermoregulation in poultry. A single nucleotide polymorphism (SNP) in the av-UCP gene has been reported in chickens. The purpose of the current study was to clarify the association between this av-UCP gene mutation and thermoregulation in chickens. Wild and mutant type chicks for the av-UCP gene SNP (g. 1270 of the av-UCP gene exon 3 with C to T substitution and amino acid substitution) were exposed to high ambient temperature. Rectal temperature, radiation temperature on the body surface, and the expression of heat dissipation behavior (wing drooping and panting) during heat exposure were measured. In addition, oxygen consumption rate in the thermoneutral zone in wild and mutant type chicks was measured. Changes in wing temperature during heat exposure in wild-type chicks were lower than those in mutants. The latency of continuous wing drooping during heat exposure in wild-type chicks was shorter than in mutant chicks. It was also found that the SNP in the av-UCP gene caused reduced oxygen consumption. These results suggest that the av-UCP gene mutation affects thermoregulation, especially heat production, in chickens.

Infrared thermography is an effective, noninvasive measure of HPA activation

Infrared thermography (IRT) is increasingly applied as a noninvasive technique for measuring surface body temperature changes related to physiological stress. As a basis for validation of IRT as a tool for diagnostic use, we need to assess its potential to measure hypothalamic-pituitary-adrenal (HPA) axis reactivity. We used experimental manipulations of the HPA axis in house sparrows (Passer domesticus), i.e. adrenal tissue responsiveness to exogenous adrenocorticotropin (ACTH) and the efficacy of negative feedback using the synthetic glucocorticoid dexamethasone (DEX), to test whether IRT is an effective tool for measuring HPA reactivity. Experimental birds showed a pronounced decrease in skin temperatures after ACTH injection and an increase in temperature after DEX injection. However, individual variation in glucocorticoid levels were not related to skin temperatures except after ACTH injection in experimental birds. We show that IRT can be used to measure HPA reactivity but that skin-temperature is not a good index for glucocorticoid secretion at baseline levels. These results suggest that while IRT of skin temperatures is a useful, noninvasive measure of HPA axis reactivity under acute activation, this technique might not be suitable for measuring natural variation of circulating glucocorticoid levels.

Which factor is more important: Intensity or duration of episodic heat stress on broiler chickens?

With the current global warming, there is a predicted increase in frequency, intensity and duration of heat waves in future. Little is known of how this could affect the welfare of broiler chickens. Sixty-four broiler chickens were subjected to either high heat stress (HHS; 32 °C, 70% RH for 3 h), moderate heat stress (MHS; 30 °C, 70% RH for 6 h), or normal conditions (NC: 20 °C, 50% RH for 6 h) for two consecutive days. On both days, the temperature-ID chips on all chipped birds were scanned during pre-heat stress (PrHS), end of 3 h (3HS) and 6 h (6HS) of heat stress using a pocket reader. Half of the chip birds' CBT was measured at the end of each hour of heat stress (HS: 1^st -3^rd hour). Surface body temperatures (SBTs) from under the wing (WT), feet (FT), cloaca (CLT) and comb (CT) were measured. Blood samples, feed intake, daily weight gain and mortality was also monitored. Data was analysed using General Linear Model and simple linear regression. At 3HS, CBT/ΔCBT and all SBTs showed this trend: HHS>MHS>NC (P<0.001). The regression equations to predict ΔCBT in HHS and MHS are ΔCBT = 0.917 + 0.663 h, P<0.05 and ΔCBT = 0.371 + 0.338 h, P<0.05 respectively. Blood pH, pCO₂, iCa, HCO₃^- and TCO₂ showed same trend: HHS, MHS > NC (P<0.05). Comparing HHS for 3 h with MHS and NC for 6 h shows that CBT/ΔCBT, WT and CLT in HHS, MHS>control (P<0.001) while FT and CT showed a different trend (HHS > MHS > NC, P<0.001). pCO_2, feed intake and daily weight gain showed same trend (HHS, MHS > control). Temperature-ID chip (a less invasive technique) gave CBT/ΔCBT values that corresponded with the degree of heat stress experienced by the birds. Broilers were more tolerant to MHS than HHS after 3 h but MHS for 6 h and HHS for 3 h had similar impact.

Analysis of performance, bone characteristics, and expression of genes involved in the balance of ionic concentrations in broilers subjected to dietary electrolyte balance levels

1. Sodium bicarbonate (NaHCO₃), potassium carbonate (K₂CO₃), and ammonium chloride (NH₄Cl) are commonly used to correct dietary electrolyte balance (DEB) in birds. However, there are many gaps in the knowledge of their effects when used simultaneously. This study investigated the effect of DEB levels on performance, femur bone characteristics and the expression of genes related to the balance of ionic concentrations in broilers at 21 days of age.2. Male Cobb broiler chickens (n = 245), aged 1-21 d, were divided into groups based on a completely randomised design with five DEB levels (110 mEq/kg, 175 mEq/kg, 240 mEq/kg, 305 mEq/kg, and 370 mEq/kg).3. The performance characteristics measured included body weight (BW), body weight gain (BWG), feed intake (FI), feed conversion (FCR) and body weight birds slaughtered (BWS).4. The bone variables assessed in the femur were weight (WE), relative bone weight (RBWE), length (L), width (WI), maximum load supported (MLS), bone-breaking resistance (BR), and Seedor index (SI). In addition, the expression of CHP1, SLC9A1, and SLC24A3 in the livers, intestines and kidneys of birds was evaluated.5. The DEB level of 370 mEq/kg, at Na⁺ content of 0.48%, resulted in the highest averages for L, MLS, and BR of the femur. This DEB level increased the expression of SLC9A1 in the liver and SLC24A3 in the intestine. A 240 mEq/kg DEB level decreased the expression of CHP1 in the liver, while supplementation with 110 mEq/kg increased the expression of SLC24A3 in the kidney.6. In conclusion, 370 mEq/kg DEB improved FCR and increased the mean bone characteristics of the femur (L, MLS, and BR) and the expression of SLC9A1 and SLC24A3 in the liver and intestine, respectively. These findings should be considered in future assessments of the effects of DEB levels on broilers.

Spray-Dried Plasma Improves Body Weight, Intestinal Barrier Function, and Tibia Strength during Experimental Constant Heat Stress Conditions

Simple Summary

Broilers are especially heat sensitive because of the absence of sweat glands and their elevated metabolism. Under commercial conditions, extremely high temperatures (heat stress) reduce their performance. This research aimed to assess spray-dried feeding plasma (SDP) during constant heat stress (HS) on the performance, intestinal permeability, and bone strength in broilers. Chickens fed with a diet supplemented with SDP increased both their body weight and body weight gain compared to the HS control group. At the end of the study (d 42 of age), chickens fed with SDP significantly alleviated the increased gut leakage induced by HS and showed a significant increase in tibia strength compared with control HS chickens. The results in the present study suggest SDP mends gut integrity, hence reducing chronic systemic inflammation.

Abstract

The aim of this study was to see how spray-dried plasma (SDP) supplementation affected broiler chicken performance, intestinal permeability, and bone strength during persistent heat stress. One-day-old chicks (n = 480) were randomly assigned into twelve environmental corrals; four thermoneutral (TN-negative control, maintained at 24 °C from d 21–42); four heat stress (HS, exposed to 35 °C from d 21–42); and four heat stress treated with 2% SDP in the feed until d 28 followed by 1% SDP until d 42 (HS-SDP). The performance and serum levels of fluorescein isothiocyanate-dextran (FITC-d) were evaluated at d 21, 28, 35, and 42. The tibias strength was evaluated on d 21 and 42. The increment in chicken temperature (p < 0.05) was observed two h following the increase in environmental temperature in both HS groups and was associated with decreased performance parameters compared with the TN group. At d 42 of age, the chickens exposed to HS had an impaired gut permeability and decreased tibia strength compared to the TN group (p < 0.05). However, partially feeding SDP mitigated these adverse effects significantly. These findings imply that using SDP strategically during stressful times, such as prolonged heat stress, may help mitigate its negative consequences.

Betaine Alleviates Heat Stress-Induced Hepatic and Mitochondrial Oxidative Damage in Broilers

The aim of this study was to evaluate the effects of dietary betaine (BET) on growth performance, redox state, and related gene expression in broilers under heat stress (HS). A total of 144 21-day-old male broiler chickens with similar body weights were assigned randomly to three treatments with six replicates (eight chickens per replicate cage). Broilers in the control (CON) group were kept at thermoneutral (TN, 22±1°C) conditions and fed a basal diet until they were 42 days of age. Broilers in the other two groups (defined as HS and HS + BET) were exposed to HS (34±1°C, 8 h/day) and fed the basal diet without or with 1000 mg/kg BET, respectively. Rectal and cockscomb temperature of broilers was increased (P<0.05) in HS and HS + BET groups compared with the CON group, whereas there was no difference between HS and HS + BET groups. Dietary BET supplementation restored (P<0.05) average daily gain (ADG) and average daily feed intake (ADFI) of broilers and reversed (P<0.05) the increase in serum alanine transaminase (ALT) activity and malondialdehyde (MDA) content in the liver tissue of broilers under HS. The HS + BET group had higher (P<0.05) activities of superoxide dismutase (SOD) and glutathione peroxidase (GPX) in the liver tissue and mitochondria than the HS group, and the same pattern was observed for glutathione (GSH) and GSH/glutathione disulphide (GSSG) in the liver tissue. The decreased mRNA levels of GPX1 and uncoupling protein (UCP) in the liver induced by HS were restored by BET supplementation. In conclusion, dietary BET supplementation can alleviate HS-induced hepatic and mitochondrial oxidative damage of broilers by regulating mRNA expressions of GPX1 and UCP.

Effect of acute heat stress on cognitive performance of chickens in a feed-related discriminant task

Little is known about immediate and long-lasting effect of acute heat stress on chicken cognition. Thirty-five, 9-week-old birds were trained to differentiate two cone colours; white (rewarded, R; with feed underneath) and black (unrewarded, UR; empty). The sixteen birds that learnt the task were randomly assigned to three temperature regimens (TR: 22-24 °C (control), 30-32 and 36-38 °C for 3h/day) for three consecutive days during which rectal (RT), wing (WT) and eye (ET) temperatures were monitored. After the 3 h of exposure, birds were allowed to rest for 1 h before the commencement of the discriminant task. The latencies to open the cones (R and UR) and proportion of cones opened were recorded. A long-lasting effect was tested a week after exposure to TR. TR had a significant effect on RT, WT and ET. The motivation to turn over R cones was weaker in birds exposed to 36-38 °C than birds exposed to 22-24 °C. Also, the proportion of R cones opened were fewer in birds that experienced TR of 36-38 °C compared to birds exposed to 22-24 °C and 30-32 °C specifically on two out of the three cognitive test days (Days 1 and 3). Latency and proportion of UR cones opened was not affected by TR. RT, WT and ET were all negatively and significantly correlated with latency to open the UR cones. Previous exposure of birds to three TR had no effect on the latency to open both cones but the proportion of R cones opened was greater in birds exposed to 30-32 °C compared to the 22-24 °C birds. In conclusion, an immediate (36-38 °C) and long-lasting effect (30-32 °C) of acute heat stress was associated with a weak motivation to perform feed related discrimination task.

Impact of heat stress on broilers with varying body weights: Elucidating their interactive role through physiological signatures

Physiological determinants of different body weight (BW) broiler chickens under heat stressed conditions were investigated to compare the performance at market age considering medium body weight group as standard. At 5 weeks, broilers were categorized randomly into 3 treatments (N = 24 per group) as high (HBW) (>1050 g), medium (MBW) (900-1050 g) and low (LBW) (<900 g) followed by simultaneous exposure to normal and heat stress (HS) conditions at 40 ± 1 °C and 45 ± 5% RH for 4 h/day for a period of 7 days (D) and sample collection was employed at D0, D3 and D7. Physiological and stress responses, haematological and biochemical profile, intestinal gross and histological aspects were estimated using standard protocols. Heart rate and mean arterial blood pressure were significantly (P = 0.000) higher in HBW broilers followed by low and medium ones. Heat stress exposure indicated significant (P = 0.000) increase in heart rate, arterial blood pressure, respiration rate and comb temperature while cloacal temperature remained unaffected. Lymphocytes, eosinophils, total red blood cell count, haemoglobin, and haematocrit were reduced (P = 0.000) whereas mean corpuscular volume and mean corpuscular hemoglobin, heterophil count and heterophil to lymphocyte ratio were increased (P = 0.000) in response to HS. Circulating corticosterone and tri-iodothyronine concentrations showed inverse relationship with respect to BW variation and HS duration respectively with significant interaction (P = 0.000). Higher protein in LBW was observed on D3. Serum triglycerides remained unaffected till D3 exposure but significantly (P = 0.017) reduced on D7 with lowest content in HBW group. Serum alkaline phosphatase increased in LBW group with significant heat stress interaction (P = 0.000) on D3. HS reduced villi length and crypt depth; but their corresponding ratio increased. In conclusion, HBW broilers are more affected than MBW or LBW groups. This study established interactive roles of BW and HS on physiological responses in broilers.

Changes in facial surface temperature of laying hens under different thermal conditions

OBJECTIVE

The purpose of this study was to identify through infrared thermal imaging technology the facial surface temperature (FST) of laying hens in response to the variations in their thermal environment, and to identify the regional differences in FST to determine the most stable and reliable facial regions for monitoring of thermoregulatory status in chickens.

METHODS

Thirty Hy-Line Brown hens (25-week-old) were sequentially exposed to three different thermal conditions; optimal (OT, 22°C±2°C), low (LT, 10°C±4°C), and high temperature (HT, 30°C±2°C). The mean values of FST in five facial regions including around the eyes, earlobes, wattles, beak and nose, and comb were recorded through infrared thermography. The maximum FST (MFST) was also identified among the five face-selective regions, and its relationship with temperature-humidity index (THI) was established to identify the range of MFST in response to the variations in their thermal environment.

RESULTS

Hens exposed to OT condition at 15:00 displayed a higher temperature at wattles and around the eyes compared to other regions (p<0.001). However, under LT condition at 05:00 to 08:00, around the eyes surface temperature showed the highest value (p<0.01). In HT, wattles temperature tended to show the highest temperature over almost time intervals. Main distribution regions of MFST were wattles (63.3%) and around the eyes (16.7%) in OT, around the eyes (50%) in LT, and wattles (62.2%) and comb (18.3%) in HT. The regression equation between MFST and THI was estimated as MFST = 35.37+ 0.2383×THI (R2 = 0.44; p<0.001).

CONCLUSION

The FST and the frequency of MFST in each facial region of laying hens responded sensitively to the variations in the thermal environment. The findings of this experiment provide useful information about the effect of the thermal conditions on the specific facial regions, thus offering an opportunity to stress and welfare assessment in poultry research and industry.

Infrared thermography cannot be used to approximate core body temperature in wild primates

Understanding the physiological processes that underpin primate performance is key if we are to assess how a primate might respond when navigating new and changing environments. Given the connection between a mammal's ability to thermoregulate and the changing demands of its thermal environment, increasing attention is being devoted to the study of thermoregulatory processes as a means to assess primate performance. Infrared thermography can be used to record the body surface temperatures of free-ranging animals. However, some uncertainty remains as to how these measurements can be used to approximate core body temperature. Here, we use data collected from wild vervet monkeys (Chlorocebus pygerythrus) to examine the relationship between infrared body surface temperature, core body (intra-abdominal) temperature, and local climate, to determine to what extent surface temperatures reflect core body temperature. While we report a positive association between surface and core body temperature-a finding that has previously been used to justify the use of surface temperature measurements as a proxy for core temperature regulation-when we controlled for the effect of the local climate in our analyses, this relationship was no longer observed. That is, body surface temperatures were solely predicted by local climate, and not core body temperatures, suggesting that surface temperatures tell us more about the environment a primate is in, and less about the thermal status of its body core in that environment. Despite the advantages of a noninvasive means to detect and record animal temperatures, infrared thermography alone cannot be used to approximate core body temperature in wild primates.

Transforming the Adaptation Physiology of Farm Animals through Sensors

Despite recent scientific advancements, there is a gap in the use of technology to measure signals, behaviors, and processes of adaptation physiology of farm animals. Sensors present exciting opportunities for sustained, real-time, non-intrusive measurement of farm animal behavioral, mental, and physiological parameters with the integration of nanotechnology and instrumentation. This paper critically reviews the sensing technology and sensor data-based models used to explore biological systems such as animal behavior, energy metabolism, epidemiology, immunity, health, and animal reproduction. The use of sensor technology to assess physiological parameters can provide tremendous benefits and tools to overcome and minimize production losses while making positive contributions to animal welfare. Of course, sensor technology is not free from challenges; these devices are at times highly sensitive and prone to damage from dirt, dust, sunlight, color, fur, feathers, and environmental forces. Rural farmers unfamiliar with the technologies must be convinced and taught to use sensor-based technologies in farming and livestock management. While there is no doubt that demand will grow for non-invasive sensor-based technologies that require minimum contact with animals and can provide remote access to data, their true success lies in the acceptance of these technologies by the livestock industry.

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.

How Are Information Technologies Addressing Broiler Welfare? A Systematic Review Based on the Welfare Quality® Assessment

This systematic review aims to explore how information technologies (ITs) are currently used to monitor the welfare of broiler chickens. The question posed for the review was “which ITs are related to welfare and how do they monitor this for broilers?”. The Welfare Quality® (WQ) protocol for broiler assessment was utilized as a framework to analyse suitable articles. A total of 57 studies were reviewed wherein all principles of broiler welfare were addressed. The “good health” principle was the main criteria found to be addressed by ITs and IT-based studies (45.6% and 46.1%, respectively), whereas the least observed principle was “good feeding” (8.8%). This review also classified ITs and IT-based studies by their utilization (location, production system, variable measured, aspect of production, and experimental/practical use). The results show that the current focus of ITs is on problems with conventional production systems and that less attention has been given to free-range systems, slaughterhouses, and supply chain issues. Given the valuable results evidenced by the exploitation of ITs, their use in broiler production should continue to be encouraged with more attention given to farmer adoption strategies.

Thermal stress alters the basal value of serum proteins in laying hens

ABSTRACT This study aimed to evaluate the effect of thermal stress on the physiological and metabolic parameters in laying hens and the microbiological quality of eggs. The experiment was performed with 50 Rhode Island Red hens in the initial laying phase, under standard diet, lodged in 20 m² stalls under controlled temperature, for 30 days. The laying hens were randomly divided into two groups: G1 - the control group, which contained 10 hens exposed to the temperature of 17 ºC; G2 - the treatment group, which contained 40 hens exposed to the temperature of 30 ºC. The physiological parameters evaluated were: cloacal temperature, body surface temperature, heart rate, respiratory rate, and weight. Biochemical tests included total protein, albumin, globulin, and glucose. The group subjected to thermal stress showed lower body weight, increased heart rate, a slight increase in the respiratory rate, and increase in body surface temperature when compared with the control group (P < 0.05), although no significant differences were observed regarding cloacal temperature. As for the metabolic parameters, the treated group showed an increase in total proteins and globulins compared with the control group (P < 0.05), while albumin remained at basal levels. Additionally, hypoglycemia was observed in the treated group. Samples from egg shells and yolk were subjected to the analyses for the detection of Salmonella spp. These microorganisms were not detected amongst the egg samples.

Feather HSP70: a novel non-invasive molecular marker for monitoring stress induced by heat exposure in broilers

Poultry well-being and economic burden due to heat stress (HS) are of great importance to the poultry industry. Efficient design and effective evaluation of any strategies to alleviate the adverse effects of HS on poultry production require an accurate measurement of stress. However, current methods for monitoring stress in poultry are less than ideal, as they are invasive or subjective, and therefore variable. Here, we demonstrated that HSP70, the well-established intracellular stress chaperone, is expressed in chicken feather and is responsive to HS, and could therefore be used as a stress marker. Growing feathers were collected from the same bird (Cobb500, n = 9) in the morning (barn temperature 24°C) and afternoon (barn temperature 29.5°C) in the summer (2016 June 21) in Arkansas, USA. In the afternoon, the birds were panting and their core body temperatures were significantly higher compared to the morning time, as illustrated by iButton data thermo-loggers. Concomitantly, blood HSP70 mRNA and feather HSP70 expression (mRNA and protein) were significantly increased in the afternoon compared to the morning time. Similarly, HSP70 protein expression in the duodenum was also significantly higher in the afternoon compared to the morning period. Together, these finding identify feather HSP70 as a novel non-invasive molecular signature that mirrors the intracellular and systemic stress, which can be useful to monitor well-being of chickens and other avian species under different challenges.

An Automatic Head Surface Temperature Extraction Method for Top-View Thermal Image with Individual Broiler

Surface temperature variation in a broiler’s head can be used as an indicator of its health status. Surface temperatures in the existing thermograph based animal health assessment studies were mostly obtained manually. 2185 thermal images, each of which had an individual broiler, were captured from 20 broilers. Where 15 broilers served as the experimental group, they were injected with 0.1mL of pasteurella inoculum. The rest, 5 broilers, served as the control group. An algorithm was developed to extract head surface temperature automatically from the top-view broiler thermal image. Adaptive K-means clustering and ellipse fitting were applied to locate the broiler’s head region. The maximum temperature inside the head region was extracted as the head surface temperature. The developed algorithm was tested in Matlab^® (R2016a) and the testing results indicated that the head region in 92.77% of the broiler thermal images could be located correctly. The maximum error of the extracted head surface temperatures was not greater than 0.1 °C. Different trend features were observed in the smoothed head surface temperature time series of the broilers in experimental and control groups. Head surface temperature extracted by the presented algorithm lays a foundation for the development of an automatic system for febrile broiler identification.

Oral Administration of a Medium Containing L-Citrulline-producing Live Bacteria Reduces Body Temperature in Chicks

Recently, we showed that oral administration of crystallized L-citrulline (L-Cit) caused hypothermia under a control thermoneutral temperature (CT) and provided thermotolerance under high ambient temperature (HT) in chicks. The aim of this study was to clarify whether oral administration of a medium containing L-Cit-producing live bacteria can reduce body temperature in chicks under CT. In Experiment 1, 7-day-old chicks were orally administered either a medium (containing mainly L-Cit-producing live bacteria and 277 mM L-Cit) or an equimolar amount of L-Cit to determine their effects on body temperature (acute treatment). In Experiment 2, chicks were subjected to the same treatment from 7 to 13 days of age (chronic treatment). Rectal and surface body temperatures were recorded daily after 1 h of treatment. Both acute and chronic oral administration of the medium, but not of the equimolar amount of L-Cit, significantly reduced the rectal and surface body temperatures of the chicks. Chronic administration of the medium resulted in consistently low rectal and surface body temperatures during the entire experimental period. In conclusion, acute or chronic administration of the medium containing L-Cit-producing live bacteria, but not of the equimolar amount of L-Cit, reduced the rectal and surface body temperatures of the chicks. Our results suggest that medium containing L-Cit-producing live bacteria can be used as a new feed supplement for lowering the body temperature of chicks.

Supplementation of Bacillus subtilis-based probiotic reduces heat stress-related behaviors and inflammatory response in broiler chickens

Probiotics reduce stress-related inflammation and abnormal behaviors in humans and rodents via regulation of the microbiota-gut-brain axis. The objective of this study was to determine if probiotic, Bacillus subtilis, has similar functions in broiler chickens under heat stress (HS). Two hundred forty 1-d-old broiler chicks were assigned to 48 pens with 4 treatments: Thermoneutral (TN)-RD (regular diet), TN-PD (the regular diet mixed with 1 × 106 CFU/g feed probiotic), HS-RD and HS-PD. Probiotic (Sporulin) was fed from day 1; and HS at 32°C for 10 h daily was initiated at day 15. The data showed that final BW, average daily gain , and feed conversion efficiency were improved in PD groups as compared to RD groups regardless of the ambient temperature (P < 0.01). Heterophil to lymphocyte ratio was affected by treatment and its value was in the order of HS-RD > HS-PD > TN-RD > TN-PD birds (P < 0.01). Compared to TN birds, HS birds spent more time in wing spreading, panting, squatting close to the ground, drinking, sleeping, dozing, and sitting but spent less time in eating, standing, and walking (P < 0.05 or 0.01). In addition, HS birds had greater levels of hepatic IL-6, IL-10, heat shock protein (HSP)70, and HSP70 mRNA expression (P < 0.01) and greater levels of cecal IgA and IgY (P < 0.01) compared to TN birds. Within TN groups, TN-PD birds had greater concentrations of hepatic IL-10 (P < 0.05) and cecal IgA (P < 0.01) than TN-RD birds. Within HS groups, HS-PD birds spent less time in wing spreading, panting, squatting close to the ground, drinking, sleeping, dozing, and sitting but spent more time in eating, foraging, standing, and walking than HS-RD birds (P < 0.05 or 0.01). The HS-PD birds also had lower concentrations of hepatic IL-6 and HSP70 (P < 0.01), whereas greater levels of IL-10 (P < 0.05) and lower concentrations of cecal IgA and IgY (P < 0.01). These results indicate that broilers fed the probiotic, B. subtilis, are able to cope with HS more effectively by ameliorating heat-induced behavioral and inflammatory reactions through regulation of microbiota-modulated immunity.

Monitoring foot surface temperature using infrared thermal imaging for assessment of hoof health status in cattle: A review

Detection of lameness early in cows is important from the animal welfare point of view and for reducing economic losses. Currently, many studies are being conducted for assessment of hoof health status by measuring the surface temperature of skin in cattle and other animal species in different parts of the world. Infrared Thermography (IRT) is able to detect lesions of hooves associated with lameness by measuring the changes in coronary band and hoof skin surface temperature. The surface temperature of a lame limb will be increased when the hoof has lesion(s). IRT has been used as a non-invasive diagnostic tool for early detection of hoof lesions based on the temperature difference between affected and non-affected hoof and maximum foot temperature on the regions of interest. In spite of having many potential applications in cattle production, factors affecting the temperature readings in thermograms must also are considered while taking images. Standard operating procedures must be established before taking thermographs under different circumstances, by considering all the factors that affect its normal function. IRT may help in minimising the cost of veterinary services, low yield, compromised fertility and culling expenses, where lameness cannot be resolved in early stages.

Thermoregulatory postures limit antipredator responses in peafowl

Many animals inhabit environments where they experience temperature fluctuations. One way in which animals can adjust to these temperature changes is through behavioral thermoregulation. However, we know little about the thermal benefits of postural changes and the costs they may incur. In this study, we examined the thermoregulatory role of two postures, the head-tuck and leg-tuck posture, in peafowl (Pavo cristatus) and evaluated whether the head-tuck posture imposes a predation cost. The heads and legs of peafowl are significantly warmer when the birds exhibit these postures, demonstrating that these postures serve an important thermoregulatory role. In addition, the birds are slower to respond to an approaching threat when they display the head-tuck posture, suggesting that a thermoregulatory posture can limit antipredator behavior.

Summary: The head-tuck and leg-tuck postures of peafowl help conserve heat but can impair antipredator responses.

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.

Brood size constrains the development of endothermy in blue tits

Altricial birds are unable to maintain body temperature when exposed to low ambient temperatures during the first days after hatching. Thermoregulatory capacity begins to form as postnatal development progresses, and eventually nestlings become homeothermic. Several factors may influence this development at both the level of the individual and the level of the whole brood, but to our knowledge no studies have focused on the effect of brood size per se on the development of endothermy in individual nestlings. We performed cooling experiments on blue tit (Cyanistes caeruleus) nestlings in the field, to study how different experimental brood sizes affected the development of endothermy in individual nestlings and the thermal environment experienced by the whole brood in the nest. Nestlings from all experimental brood sizes showed a decrease in cooling rate as they grew older, but birds from reduced broods showed an earlier onset of endothermy compared with nestlings from enlarged and control broods. This difference manifested during early development and gradually disappeared as nestlings grew older. The thermal environment in the nests differed between treatments during nestling development, such that nest temperature in reduced broods was lower than that in enlarged broods during all days and during nights at the end of the experimental period. We suggest that the development of endothermy in blue tit nestlings is not ontogenetically fixed, but instead may vary according to differences in developmental, nutritional and thermal conditions as determined by brood size.