Cloacal Temperature Research Articles

Microscopic alterations and adaptation in the lungs of the Japanese quail exposed to acute or chronic heat stress

BackgroundGlobal warming causes heat stress, a significant bioclimatic factor affecting poultry welfare. The effects of heat stress on the morphology of the Japanese quail lungs were investigated in this study. A total of 16 adult Japanese quail were randomly distributed into four groups: a control group (CT), acute heat stress (AH), chronic heat stress with 7 days (CH1) and chronic heat stress with 28 days exposure (CH2). The CT group were maintained at 25 °C temperature, the AH group were exposed to 38 °C temperature for 24 h, and the CH groups were exposed to 35 °C for seven and 28 days. At the end of exposure, the birds were euthanised, and lung tissues were collected and processed for microscopy. Tissue sections were stained using H&E stain, Gomori’s stain and immunofluorescence labelling.ResultsThis study showed no significant difference in body weight, cloacal temperature, respiratory rate and lung parameters in heat-stressed groups compared with the control group. However, microscopic analyses revealed blood congestion, leakage of blood into the airway, inflammatory response and tissue breakage in the heat-stressed groups.ConclusionsHeat stress harmed the lungs of the Japanese quail based on duration and intensity. The negative impact could cause instant mortality, but if the quail survives the initial impact, it can adapt to the heat stress with long-term consequences on its performance.

Select Venous Analytes and Fibrinogen Determination Using Two Methods in Brown Pelicans.

The brown pelican (Pelecanus occidentalis) is a species often affected by natural and man-made disasters such as hurricanes and oil spills, as well as general human activities; that subsequently receives medical care and rehabilitation. During rehabilitation, blood may be collected for various tests to help with diagnosis, treatment, and monitoring. Reference intervals for this species are limited, dated, and typically from small sample sizes. Seventy-one presumed healthy brown pelicans were sampled as part of their pre-release examination from rehabilitation at the Wildlife Center of Texas after a large volume stranding from December 2014 to January 2015, and various venous analytes were measured to establish updated reference intervals for brown pelicans. Fibrinogen was measured via heat precipitation and the Abaxis VSPro equine fibrinogen cartridge to determine reference intervals and in an attempt to validate the VSPro for use in avian species. Abaxis VS2 Avian/Reptile Chemistry panel, iSTAT CG4+, and iSTAT Chem8+ results, in addition to body condition score, spun PCV, cloacal temperature, and fibrinogen were measured. Proposed reference intervals for brown pelicans are presented. Fibrinogen results were not comparable between the gold standard method and the VSPro, indicating that the VSPro is not appropriate for use in brown pelicans.

Impact of increased pre-start diet density on broiler chick behavior, corticosterone levels, and performance responses under cold stress during early life

This study assessed the effects of increased pre-start diet density on the metabolism, crop filling, and overall performance of broilers under cold stress during their initial 14 days of life. Using 576 one-day-old Cobb500 male chicks from 27-week-old breeders, the experiment employed a 2 × 2 arrangement, varying thermal conditions (thermoneutrality or cold stress at 18 °C for 8 h) and pre-start diet composition (21.5% crude protein, 2970 kcal/kg or 22.5%, 3050 kcal/kg). The cold stress group exhibited lower cloacal temperature and decreased crop filling rate during the first two days (P < 0.05). Chick behavior was significantly affected at 1 and 5 days (P < 0.05), and corticosterone levels in serum were higher for the cold stress group at 7 days (P < 0.05). Feed intake at 7 days was lower in the high-density feed group (P < 0.05). No significant interactions were observed for feed intake, body weight gain, or feed conversion ratio at 7 and 35 days (P > 0.05). Cold stress resulted in performance losses, impacting feed conversion and the Productive Efficiency Index. The dense diet influenced performance only within the first week, with subsequent diets showing no effect, suggesting dietary manipulation alone was insufficient to mitigate cold stress-induced losses.

Comparison of Manual Restraint With and Without Sedation on Outcomes for Wild Birds Undergoing Decontamination.

The decontamination process for plumage-contaminated wild birds, such as those affected by oil spills, is lengthy and involves manual restraint and manipulation of all body parts. Birds commonly react to this in ways that suggest they are extremely stressed (eg, struggling, vocalizing). We proposed to reduce stress during the wash process using sedation and hypothesized that the use of sedation would not negatively impact survival. Contaminated birds in need of washing were randomly selected to be either sedated (butorphanol 2 mg/kg IM + midazolam 1 mg/kg IM and flumazenil 0.1 mg/kg IM for reversal) or not sedated at 3 US rehabilitation centers over the course of 1 year. Response to sedation was rated on a scale of 0-4 with 0 as no effect to 4 as excessively sedate. Data such as cloacal temperatures at various time points, lengths of various portions of the wash process, preening behavior in the drying pen, and disposition were collected. No statistical differences were found between sedated and nonsedated birds for any of the data points collected, including survival. There was a significant association between birds with higher cloacal temperatures in the drying pen and with birds held longer in the drying pen with improved survival; however, these findings were unrelated to whether the birds were sedated. Our findings show that sedation with butorphanol 2 mg/ kg IM and midazolam 1 mg/kg IM reversed with flumazenil 0.1 mg/kg IM can be used during the wash process for wild birds without adverse effects. Careful attention must be given to heat support for all birds while drying to prevent hypothermia.

Is the Pyrenean newt (&lt;em&gt;Calotriton asper&lt;/em&gt;) a thermoconformer? Cloacal and water temperature in two different thermal periods in a Pre-Pyrenean stream population

In ectothermic animals, heat seems to be a determining factor because it influences many vital activities such as locomotion, the ability to escape, feeding, and reproduction, among others. In aquatic environments, physical characteristics of water prevent small ectotherms from thermoregulating and therefore it is expected that their body temperature remains similar to water temperature. Throughout its distribution and annual cycle, the Pyrenean newt (Calotriton asper) is exposed to a wide range of water temperatures that affect its biological and ecological traits like the standard metabolic rate, oxygen consumption, activity period and growth pattern. This study analyses the relationship between the cloacal and water temperatures in a Pre-Pyrenean population of C. asper in two periods with well differentiated water temperatures (July and September). The aims are to establish if there are differences between sexes in cloacal temperature, whether reproductive activity modifies cloacal temperature, and to analyse the degree of thermoconformity of the species. The results indicate that cloacal temperature depends on the water temperature, corroborating the idea that C. asper is mainly a thermoconformer, as it corresponds to an aquatic ectotherm. However, the cloacal temperature of newts was slightly higher than water temperature. In individuals in amplexus, cloacal temperature was significantly higher than in specimens that are not in this mating position, and in July, females showed much greater dispersion in cloacal temperature than males, which is probably related to spawning behaviour.

Effect of platelet-activating factor on food intake, cloacal temperature, voluntary activity and crop emptying rate in chicks

Platelet-activating factor (PAF) plays a significant role in several leucocyte functions, including platelet aggregation and inflammation. Additionally, PAF has a role in the behavioral and physiological changes in mammals. However, the effect of PAF has not been well studied in birds. Therefore, the study aimed to determine if PAF affects feeding behavior, voluntary activity, cloacal temperature, and feed passage through the digestive tract in chicks (Gallus gallus). We also studied the involvement of PAF in the innate immune system induced by lipopolysaccharide (LPS), a cell wall component of gram-negative bacteria. Both intraperitoneal (IP) and intracerebroventricular (ICV) injections of PAF significantly decreased food intake. IP injection of PAF significantly decreased voluntary activity and slowed the feed passage from the crop, whereas ICV injection had no effect. Conversely, ICV injection of PAF significantly increased the cloacal temperature, but IP injection had no effect. The IP injection of LPS significantly reduced the mRNA expression of lysophosphatidylcholine acyltransferase 2, an enzyme responsible for PAF production in the heart and pancreas. On the other hand, LPS significantly increased the mRNA expression of the PAF receptor in the peripheral organs. The present study shows that PAF influences behavioral and physiological responses and is related to the response against bacterial infections in chicks.

Fluxo de calor sensível e latente de codornas japonesas mantidas em diferentes ambientes térmicos

ABSTRACT This study aimed to estimate the heat flux through sensitive mechanisms and respiratory evaporation of Japanese quails kept in thermoneutral and warm environments, using simple environmental and physiological measures. 192 nine-week-old quails were used, distributed in a completely randomized design at two temperatures (T1 = 24°C and T2 = 32°C), with 12 replicates of eight birds each, with an experimental period of 63 days, divided into three 21-day periods. Physiological measurements of respiratory rate (RR), cloacal temperature (TC), and body surface temperature (TS) were measured twice a week. The behavior of the energy balance in the climatic chambers was obtained using the total thermal energy exchanges per unit surface area of the birds, derived from the sum of sensible (radiation and convection) and latent heat exchanges. Respiratory rate (P&lt;.0001), surface temperature (P&lt;.0001), and cloacal temperature (P=0.0047) were higher in the 32°C environment. The expired air temperature (P&lt;.0001) and heat loss by respiratory evaporation (P&lt;.0001) showed higher values when the quails were in an environment of 32°C, while the heat losses by convection (P&lt;.0001) and radiation (P&lt;.0001) were higher in a thermal comfort environment. In Japanese quails kept in a controlled environment, sensible heat dissipation by convection is the main way to eliminate excess thermal energy, when the air temperature is up to 32ºC.

Anesthetic effects of the ketamine and midazolam association by intranasal or intramuscular route in domestic chickens: prospective, blinded, randomized and crossover study.

This prospective, blinded, randomized crossover study aimed to assess the anesthetic effects of the combination of 30 mg/kg ketamine and 2 mg/kg midazolam via intranasal (IN) or intramuscular (IM) routes in twelve domestic chickens. Physiological parameters (respiratory rate - RR, heart rate - HR, and cloacal temperature -Tºcloacal) were monitored throughout the experiment, along with recovery time and sedation level (S0: awake, no recumbency, responsive to stimuli; S1: blinking eyes, recumbency, relaxed, response to stimulus, mild movement; S2: open eyes, recumbency, relaxed, mild response to stimuli; S3: closed eyes, recumbency, relaxed, no movement). In the IM group, all birds reached S3, while in IN 5/12 reached S3, 4/12 reached at most S1, and 1/12 at most S2. IM administration showed higher sedation at 5, 10, 15, 20, 30, 35, 40, and 45 minutes (p<0.05). IN administration exhibited a shorter total recovery time (26.3±21.4 min vs. 92.9±33.4 min; p<0.001). No time, group, or time-group interaction effects were observed in HR and cloacal Tº, with a trend to a decrease in RR both groups (p<0.001). Increased incidences of vocalization and agitation was observed via IM (4/12 vs. 0/12; p=0.028), with no difference in salivation. Despite faster recovery with less agitation and vocalization, the ketamine and midazolam combination via IN provided less consistent sedation compared to the IM route in chickens.

Comparison between a Tail Clamp and Electrical Stimulation for Sevoflurane Minimum Anesthetic Concentration Determination in Green Iguanas (Iguana iguana).

This study aimed to compare the minimum anesthetic concentration (MAC) of sevoflurane in green iguanas using elec- trical stimulation and tail clamping as noxious stimuli. Seven adult green iguanas (Iguana iguana) weighing 580 to 1,300 g were enrolled. Each iguana was anesthetized twice after a 1-week washout period, with MAC being determined using a tail clamp (MACt) or electrical stimulation (MACe ) techniques. After sevoflurane mask induction and endotracheal intubation, the fraction of expired sevoflurane (Fe 'Sevo) was maintained at 3.1% for 15 min before noxious stimulation. In a bracketing design, the subsequent Fe'Sevo values were increased or decreased by 10% after positive or negative responses, respectively. Each targeted Fe 'Sevo was kept constant for 15 min before stimulation. In MACt, the noxious stimulus involved closing a Kelly hemostatic curved forceps to the first ratchet at the base of the tail. At the same site, in MACe, 2 30 × 0.8-mm hypodermic needles inserted 1 cm apart were connected to an electrical stimulator set to deliver 30 mA at 50 Hz at a 6.5-ms interval. The hemostat and the needles were repositioned 2 cm distally and on alternate tail sides at each stimulation round. Individual MAC was obtained when 2 consecutive crossover events occurred (a positive response preceding a negative response or vice versa), with the MAC of each group represented by the average of the individual MAC values. Median (interquartile range) values for the sevoflurane MAC did not differ significantly between groups (2.2 [2.2 to 2.8%] in MACe and 2.2 [1.8 to 3.5%] in MACt ; P = 0.812). Time to anesthesia induction, time to MAC measurement, heart rate (HR), end-tidal carbon dioxide (ET'CO2), and cloacal temperature were not different between groups. Both the tail-clamping and the electrical stimulation techniques yielded resembling sevoflurane MAC values in green iguanas, which makes the tail clamp a reliable alternative to electrical stimulation-based MAC research in this species.

Alga marinha calcária na dieta de poedeiras semipesadas nas fases de recria e pré-postura

Abstract Calcareous seaweed (Lithothamnium calcareum) is a source of organic minerals and has been used as an alternative food in poultry nutrition. The objective is to evaluate the levels of calcareous algae in the diet of chickens during the rearing and pre-laying phases, as also on the performance and thermoregulation variables. One hundred and forty-four semi-heavy Hisex Brown hens, aged 12 to 18 weeks, were used in the rearing and pre-laying stages. They were fed with four levels of calcareous algae (0%, 10%, 20%, 30%), which were used in place of the calcitic limestone. Six replications and six birds were used per experimental unit, distributed in a completely randomized design. Feed intake, weight gain, feed conversion, body weight, viability, and thermoregulation through cloacal temperature (°C), mean body temperature (°C), and mean skin temperature (°C) were evaluated. There was no significant difference (P &gt; 0.05) in the thermoregulation of the birds. There was a difference (P &lt; 0.05) in the feed intake during the pre-laying phase, however, the other parameters showed no difference (P &gt; 0.05). The inclusion of up to 30% calcareous algae in the diet of semi-heavy laying hens in the rearing and pre-laying phases did not affect the performance or thermoregulation of the birds. Therefore, it is possible to substitute calcitic limestone with up to 30% of the calcareous algae in the diet of semi-heavy laying hens.

Effects of cold stress on physiologic metabolism in the initial phase and performance of broiler rearing

This study aimed to investigate the effects of 8 h of cold stress (18 °C) every day in broiler chicks during the first 7 days of rearing on crop filling analysis, yolk sac consumption, digestive and immune organs weights, and physiological metabolism at seven days and performance between 1 and 35 days. Cobb500 male broiler chickens (n = 274) were randomly assigned to two treatments. The treatments consisted of varying environmental temperatures during the first week post-housing. Chicks were reared at a thermoneutral temperature (32 °C) or under cold stress (18 °C) for 8 h/day during the first week, and both groups were subsequently reared at a thermoneutral temperature for 8–35 days. The thermoneutral group reached 90% full crop after 48 h of housing (P < 0.05), while the cold-stressed group had more empty crops at 2 h and 48 h after housing (P < 0.05). The chick cloacal temperature was not affected by the treatments (P > 0.05). Additionally, the treatment did not affect serum amylase and corticosterone levels, feed intake, body weight gain, or feed conversion ratio (P > 0.05, while the cold-stressed group had elevated heterophil/lymphocyte count at day 7 (P < 0.05). The thermoneutral group showed higher viability (%) at 7 and 35 days and a higher production factor at 35 days (P < 0.05). Broiler chickens under cyclic cold stress experienced decreased yolk sac absorption during the first week and increased feed intake and feed conversion ratio after 35 days of rearing. Viability was also lower in the cold-stressed group. An appropriate strategy to minimize these adverse effects is to rear the chicks in a thermoneutral environment during the first week.

Physiological Responses in Broiler Chickens Administered Lycopene During the Hot-Dry Season

Abstract This study evaluates the effects of lycopene administration on body weight, mortality, cloacal temperature, and haematological responses, in broiler chickens exposed to heat stress. 40 day-old broiler chicks were divided into control and lycopene groups, 20 chickens each. Each bird in the control group received olive oil (1 ml.kg−1), and lycopene at 10 mg.kg−1 mixed with olive oil was given to each bird in the lycopene group by oral gavage once daily for 28 days. The dry- and wet-bulb temperature of the broiler chickens’ pen was recorded three times daily from days 8 to 28. The body weights were measured weekly. The incidence of mortality was recorded. The cloacal temperatures were measured on days 14, 21 and 28. The blood samples were collected for haematological analyses, on day 28. The results indicated a high overall temperature-humidity index (31.24 ± 0.43 oC) of the thermal micro-environment of the broiler chickens. There was no significant difference (P &gt; 0.05) in body weight. The percentage mortality in the control group was relatively higher compared to the lycopene group. Lycopene reduced the cloacal temperature responses and the daily fluctuations in broiler chickens. The decreased (P &lt; 0.05) heterophil:lymphocyte ratio and percentage erythrocytes haemolysis were recorded in the lycopene group. In conclusion, lycopene administration reduced mortality and improved cloacal temperature and haematological responses without exerting any significant beneficial or negative effects on the body weight in broiler chickens exposed to heat stress.

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 42days 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 1.30mg/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 21days of age (P > 0.05). However, from 1 to 42days, 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 0.71mg/kg. Triglyceride (TRG) levels increased with 0.97mg/kg (P < 0.05), and gama-glutamil transferase (GGT) levels decreased with the inclusion of 1.19mg/kg (P < 0.05). No significant effects on IGF-1 and GHR gene expression were found (P > 0.05). In conclusion, the inclusion of 1.30mg/kg of Zn-L-SeMet in diets of heat-stressed broilers improved growth performance from 1 to 42days of age. An inclusion of 0.71mg/kg reduced mortality rate, while 0.97mg and 1.19mg increased and reduced TRG and GGT levels, respectively.

Possible role of corticosterone on behavioral, physiological, and immune responses in chicks

Glucocorticoids are one of steroid hormone and have a variety of functions including stress response, carbohydrate metabolism, and modulation of immune system in vertebrates. Corticosterone is the main glucocorticoid in birds, although the precise role of the glucocorticoid during immune challenge is not fully understood. Therefore, the purpose of the present study was to determine if a single subcutaneous injection of corticosterone could affect inflammation-related gene expressions in the spleen and liver of chicks (Gallus gallus). In addition, the effects of corticosterone injection on the food intake, cloacal temperature, formation of conditioned visual aversion, and plasma constituents were also measured. Corticosterone did not affect the food intake or cloacal temperature and did not cause conditioned visual aversion in chicks. The corticosterone injection was associated with a significant decrease in gene expression of several pro-inflammatory cytokines including inducible nitric oxide synthase and cyclooxygenase-2 in the spleen and liver at 1 and 3 h post-injection. Corticosterone increased the plasma glucose and uric acid concentrations and the antioxidant capacity. In summary, the present study suggests that corticosterone is likely not associated with food intake, cloacal temperature or the development of aversive sensation, but suppresses the synthesis of inflammation-associated bioactive molecules and increases the antioxidant capacity in chicks.

Effect of chronic heat stress on the carbonylation of glycolytic enzymes in breast muscle and its correlation with the growth performance of broilers

Chronic heat stress has detrimental effects on the growth performance of broilers, and the potential mechanism is under exploration. In this study, the protein carbonyl modification was introduced to glycolytic enzymes to evaluate its relationship with the growth performance of heat-stressed (HS) broilers. A total of 144 male 28-day-old broilers were assigned to 3 treatments: the normal control group (NC, raised at 22°C with free access to feed and water), the HS group (raised at 32°C with free access to feed and water), and the pair-fed group (PF, raised at 22°C with an amount of feed equal to that consumed by the HS group on a previous day). Results showed that heat stress decreased the average daily growth, increased the feed-to-gain ratio (F/G), decreased breast muscle rate, and increased abdominal fat rate compared with the NC and PF groups (P < 0.05). Higher cloacal temperature and serum creatine kinase activity were found in the HS group than those of the NC and PF groups (P < 0.05). Heat stress increased the contents of carbonyl, advanced glycation end-products, malonaldehyde, and the activities of catalase, glutathione peroxidase, and total antioxidant capacity compared with the NC and PF groups (P < 0.05). Heat stress increased the contents of glucose and lactate, declined the glycogen content, and lowered the relative protein expressions of pyruvate kinase muscle type, lactate dehydrogenase A type (LDHA), and citrate synthase compared to those of the NC group (P < 0.05). In contrast to the NC and PF groups, heat stress intensified the carbonylation levels of phosphoglucomutase 1, triosephosphate isomerase 1, β-enolase, and LDHA, which were positively correlated with the F/G (P < 0.05). These findings demonstrate that heat stress depresses growth performance on account of oxidative stress and glycolysis disorders. It further increases the carbonylation of glycolytic enzymes, which potentially correlates with the F/G by disturbing the mode of energy supply of broilers.

A diminutive snake species can maintain regional heterothermy in both homogeneous and heterogeneous thermal environments.

Regional heterothermy is a pattern whereby different body regions are maintained at different temperatures, often to prioritize the function of certain body parts over others, or to maximize the function of organs and tissues that vary in thermal sensitivity. Regional heterothermy is relatively well understood in endotherms, where physiological mechanisms maintain heterogeneity. However, less is known about regional heterothermy in ectotherms, where behavioral mechanisms are more important for generating thermal variation. In particular, whether small and elongate ectotherms with high surface area to volume ratios such as diminutive snakes can maintain regional heterothermy, despite rapid thermal equilibration, is not yet known. We measured regional variation in body temperature and tested whether environmental heterogeneity is used to generate regional heterothermy in the ring-necked snake (Diadophis punctatus) using both field and laboratory studies. We found that ring-necked snakes have robust regional heterothermy in a variety of contexts, despite their small body size and elongate body shape. Temperature variation along the length of their bodies was not detectable when measured externally. However, snakes had higher mouth than cloacal temperatures both in the field and in laboratory thermal gradients. Further, this regional heterothermy was maintained even in ambient laboratory conditions, where the thermal environment was relatively homogeneous. Our results indicate that regional heterothermy in ring-necked snakes is not solely driven by environmental variation but is instead linked to physiological or morphological mechanisms that maintain regional variation in body temperature irrespective of environmental context.

Feed withdrawal influences egg production, egg quality and antioxidant variables in White Leghorn layers reared during the tropical summer season

ABSTRACT 1. An experiment was conducted with White Leghorn layers (Babcock BV 300) to optimise the feed withdrawal schedule for egg-laying hens (67 to 80 weeks) reared in open-sided poultry houses during the tropical summer season. 2. Four feeding schedules (1. ad libitum access to the layer feed, 2. feed withdrawal from 9 AM-5 PM, 3. 11 AM-5 PM, and 4. 1 PM-5 PM followed by free access to the layer feed) were examined. Each feeding schedule was offered to 12 replicates consisting of 12 layers housed in four adjacent cages (45.7 × 35.6 × 43.2 cm). 3. Fasting the layers from 1-5 pm reduced egg production compared to layers fasting from 9 or 11 am. The FI/egg or unit egg mass was highest in layers fasted from 1-5 pm. In the 9 am-5 pm fasted group, the cloacal temperature (CT) increased significantly at 11 am and gradually reduced at 3 pm. In the 1-5 pm fasted group, the CT remained higher at 3 pm and 5 pm. 4. The cell-mediated immune response in layers fasted from 9 am or 11 am was higher than those fed ad libitum or 1-5 pm fasted group. Lipid peroxidation was higher in layers 1-5 pm fasted group, and significantly lower LP was found in groups that fasted from 9 am or 11 am. In general, the activities of serum antioxidant enzymes (glutathione peroxidase, glutathione reductase, superoxide dismutase) were higher in layers that fasted from 9 am or 11 am compared to those that had ad libitum feed or fasted from 1-5 pm. 5. It was concluded that the feed withdrawal should be initiated during the forenoon (9 AM/11 am-5 pm) for optimum production and to reduce oxidative stress in egg-laying hens reared during summer in the tropical region.

Thermal exchanges, physiological responses and productive performance of Guinea Fowl (Numidia meleagris) subjected to different air temperatures.

The objective of this research was to evaluate the thermal exchanges, physiological responses, productive performance and carcass yield of Guinea Fowl confined under thermoneutral conditions and under thermal stress. For the experiment, 96 animals were confined in 8 experimental boxes of 1 m2 of area, each, divided in equal numbers and placed inside two distinct climatic chambers, where the birds were distributed in a completely randomized design, with two treatments (air temperatures of 26 and 32°C, respectively). For the collection of physiological responses and carcass yield 16 birds were evaluated and for the collection of data on feed and water consumption and productive responses, 48 birds per treatment were evaluated. The environmental variables (air temperature (AT), air relative humidity and wind speed), temperature and humidity index (THI), heat exchanges, physiological responses (respiratory rate, surface temperature, cloacal temperature and eyeball temperature), feed (FC) and water (WC) consumption and production responses (weight gain, feed conversion index and carcass yield) of the birds were evaluated. With the elevation of the AT, it could be noticed that the THI went from a thermal comfort condition to an emergency condition, where the birds lost part of their feathers, increased all physiological responses evaluated, and consequently, reduced by 53.5% the amount of heat dissipated in the sensible form and increased by 82.7% the heat losses in the latent form, increasing also the WC. ATs of up to 32°C did not significantly affect the productive performance and carcass yield of the guinea fowl.

Transcriptome analysis of the uterovaginal junction containing sperm storage tubules in heat-stressed breeder hens

Sperm storage tubules (SSTs) in the uterovaginal junction (UVJ) of the oviduct are major sites of sperm storage after artificial insemination or mating. Female birds may regulate sperm motility in the UVJ. Heat stress can decrease the reproductive ability of broiler breeder hens. However, its effects on UVJ remain unclear. Changes in gene expression aid in understanding heat stress-affected molecular mechanisms. Herein, we wanted to conduct a comparative transcriptomic analysis to identify the differentially expressed genes (DEGs) in the UVJ of breeder hens under thermoneutral (23°C) and heat stress (36°C for 6 h) conditions. The results indicated that cloacal temperatures and respiratory rates were significantly increased in heat-stressed breeder hens (P < 0.05). Total RNA was extracted from the hen UVJ tissues containing SSTs after heat exposure. Transcriptome analysis identified 561 DEGs, including 181 upregulated DEGs containing heat shock protein (HSP) transcripts and 380 downregulated DEGs containing immune-related genes, such as interleukin 4-induced 1, radical S-adenosyl methionine domain containing 2, and 2'-5'-oligoadenylate synthetase like, in heat-stressed hens. Gene Ontology analysis revealed the significantly enriched terms involving HSPs. Kyoto Encyclopedia of Genes and Genomes analysis identified 9 significant pathways, including the protein processing in endoplasmic reticulum (11 genes including HSPs), neuroactive ligand-receptor interaction (13 genes including luteinizing hormone/choriogonadotropin receptor), biosynthesis of amino acids (4 genes including tyrosine aminotransferase), ferroptosis (3 genes including heme oxygenase 1), and nitrogen metabolism (carbonic anhydrase [CA]-12 and CA6) pathways. Protein-protein interaction network analysis of DEGs revealed 2 large networks, one containing upregulated HSPs and the other containing downregulated interferon-stimulating genes. Overall, heat stress inhibits innate immunity in the UVJ tissues of broiler chickens, and heat-stressed chickens protect their cells by increasing the expression levels of HSPs. The identified genes are potential candidates for further exploration of the UVJ in heat-stressed hens. The identified molecular pathways and networks increase our understanding of the sperm storage reservoirs (UVJ containing SSTs) within the reproductive tract and may be used to prevent heat stress-induced fertility loss in breeder hens.

Thermal Manipulation During Incubation: Effects on Embryo Development, Production Performance, Meat Quality, and Thermal Tolerance of Broiler Chickens

Thermal manipulations during the embryonic period have positive effects on thermotolerance and the productive performance of broilers subjected to acute heat stress. This study aimed to investigate the potential effects of Thermal manipulation during incubation (TMI) on productive performances and thermotolerance of broiler chickens growing in tropical climates. A total of 900 Cobb 500 broiler chicken eggs from a 35-week-old breeder flock were incubated in standard incubation conditions (37.8°C, 60% relative humidity) until day 7, when they were divided into 3 groups (300 eggs per group). The control group (C) was incubated at standard incubation conditions while T6 and T12 groups were subjected to, respectively, 6 hours/day and 12 hours/day of TMI (T° = 39.5°C, relative humidity = 65%, Embryonic day = 7-16). The relative embryo and albumen weight were determined from 10 to 18 days of incubation. The hatching event was checked between 450 and 504 hours of incubation, and egg hatchability, chick quality, and cloacal temperature were also determined. One hundred and twenty-five chicks from each incubation group were transferred to the farm and raised for 6 weeks. During this period, their post-hatch performances were determined. At week 6, blood samples were collected to measure T3, T4, and corticosterone hormone levels. Then, the 6-week-old broilers were slaughtered to determine meat yield and quality. Results showed that the chick’s rectal temperature was significantly reduced in T6 and T12 groups compared to the C group, while hatchability and one-day-old chick weight were not affected. Final body weight and feed conversion ratio were significantly improved in the T12 group, compared to other groups. Thermal manipulation during incubation for 6 and 12 hours significantly reduced mortality rate and pectoralis major muscle drip loss while it increased muscle pH at 24 hours post-mortem (pH24). Corticosterone, T3, and T4 plasma hormone levels at week 6 were also significantly reduced by TMI. Therefore, exposing hatching eggs to 39.5°C and 65% of relative humidity from days 7 to 16 of incubation for 12 hours/day is recommended for the poultry industry in tropical climates. Keywords: Chronic heat stress, Fast-growing broilers, Hatching and post-hatch performances, Thermal manipulation, Thermotolerance, Meat quality