Reduced Heat Production Research Articles

Hypothermia: Beyond the Narrative Review-The Point of View of Emergency Physicians and Medico-Legal Considerations.

Hypothermia is a widespread condition all over the world, with a high risk of mortality in pre-hospital and in-hospital settings when it is not promptly and adequately treated. In this review, we aim to describe the main specificities of the diagnosis and treatment of hypothermia through consideration of the physiological changes that occur in hypothermic patients. Hypothermia can occur due to unfavorable environmental conditions as well as internal causes, such as pathological states that result in reduced heat production, increased heat loss or ineffectiveness of the thermal regulation system. The consequences of hypothermia affect several systems in the body-the cardiovascular system, the central and peripheral nervous systems, the respiratory system, the endocrine system and the gastrointestinal system-but also kidney function, electrolyte balance and coagulation. Once hypothermia is recognized, prompt treatment, focused on restoring body temperature and supporting vital functions, is fundamental in order to avert preventable death. It is important to also denote the fact that CPR has specificities related to the unique profile of hypothermic patients.

Modern Smart Street Light Monitoring Systems

Abstract: This study highlights the importance of Modern Street light control systems over traditional ones, with LED lamps emerging as the most suitable choice due to their advantagessuch as reduced heat production, lower electricity consumption, and extended lifespan. The main goal is to enhance system efficiency by minimizing unnecessary electricity loss during daylight and when lighting is not required. Automating street lights using LDR and PIR sensorsin conjunction with Arduino Uno offers a costeffective and secure solution, eliminating the drawbacks of manual switching and simplifying cost reduction and maintenance. Additionally,applying a ZnO coating to the street light casings provides effective protection against dust and moisture, resulting in efficient lighting. The process involves sol-gel deposition of ZnO nanoparticles on silica glass substrates, followed by preannealing and repeated dip coating. Annealing at temperatures between 450°C and 600°C further improves the results. The uniformand defect-free coatings are confirmed by SEM images, while transmission spectra reveal over80% penetration of visible light (400 nm to 900 nm). Lower precursor concentrations lead to better penetration of light below 300 nm wavelength.

181 Effect of Temperature and Humidity on Daily Feeding Behavior in Swine

Abstract Heat stress has negative impacts on pork production, particularly during the grow-finish phase. During heat stress events, swine alter feeding behavior to reduce heat production, which can negatively affect performance. Recent technology advancements in feed management systems allow for individualized data recording of feeding behavior for group housed pigs during the finishing phase. The objective of this study was to utilize an RFID-based feed management system to determine feeding behavior patterns of finishing pigs during heat stress conditions and identify changes in behavior due to heat stress events. Data included one pen of 29 Duroc boars reared in a mechanically ventilated facility in north central North Carolina. Feed Intake Recording Equipment (FIRE) pig feeders (n = 3; Osborne Technologies) fed individual pigs in the group housed setting using RFID technology and recorded the number of visits, feed intake of each visit, visit duration, and body weight of each pig during each visit. Feeders were calibrated once per week to ensure accuracy of feed intake and body weight measurements. On day 1 of the study, pigs were placed in the experimental pen and body weights were recorded (37.4 kg ± 4.9 kg) using the FIRE feeders. Air temperature, humidity, and dew point data were collected continuously every 5 minutes from day 13 until the end of the finishing period. Pigs exited finishing (134.5 ± 8.6 kg) on day 83. Feeding behavior traits (number of visits and feed intake) were summarized by day. Temperature, humidity, and heat index were summarized by a maximum, minimum, and mean value for each day. Average temperature, humidity, feeder visits a day, and average daily feed intake across the trial was 26.3 ± 1.6 º C, 75.8 ± 6.7%, 6.1 ± 1.0 visits, 2.66 ± 0.39 kg. Models were used to associate feeding behavior traits with the quadratic effects of day and the linear effects of average temperature and humidity and the interaction of temperature and humidity. Temperature and humidity were associated (P < 0.01) number of feeder visits and average daily intake per day. Further, there was an interaction (P < 0.01) between temperature and humidity in relation to number of feeder visits and average daily feed intake. Results suggest substantial variation in feeding behaviors can be explained by temperature and humidity.

Sol-gel dip-coated TiO2 nanofilms reduce heat production in titanium alloy implants produced by microwave diathermy

Objective: To verify that the TiO2 nanofilm dip-coated by sol-gel can reduce titanium alloy implants (TAI)’s heat production after microwave diathermy (MD). Methods: The effect of 40 W and 60 W MD on the titanium alloy substrate coated with TiO2 nanofilm (Experimental Group) and the titanium alloy substrate without film (Control Group) were analyzed in vitro and in vivo. Changes in the skeletal muscle around the implant were evaluated in ex vivo by histology. Results: After 20 min of MD, in vitro the temperature rise of the titanium substrate was less in the Experimental Group than in the Control Group (40 W: 1.4 °C vs. 2.6 °C, p < .01, 60 W: 2.5 °C vs. 3.7 °C, p < .01) and in vivo, the temperature rise of the muscle tissue adjacent to TAI was lower in the Experimental Group than in the Control Group (40 W: 3.29 °C vs. 4.8 °C, p < .01, 60 W: 4.16 °C vs. 6.52 °C, p < .01). Skeletal muscle thermal injury can be found in the Control Group but not in the Experimental Group. Conclusion: Sol-gel dip-coated TiO2 nanofilm can reduce the heat production of TAIs under single 40～60 W and continuous 40 W MD and protect the muscle tissue adjacent to the implants against thermal injury caused by irradiation.

Pure silica fiber Raman gain enabled high-power low-quantum defect fiber laser

Reducing the quantum defect (QD) is a promising solution to mitigate the thermal load and lower system noise. Besides, owing to many advantages such as wavelength agility and non-photon darkening, Raman fiber laser (RFL) has attracted much attention in recent years. However, to date, there is no report in RFL on QD reduction by silica fiber, which is the most common gain medium with mature fabrication technology of high-power RFL. In this paper, we propose and experimentally demonstrate a ten-watt-level low-QD RFL gained by a piece of commercial silica fiber. The QD can be reduced to 0.56 %, corresponding to a laser power of 6.2 W. After system optimization, the output power can be scaled up to 17.7 W, with a QD of 1.48 % and a slope efficiency of 72.0 %. To the best of our knowledge, this is the lowest QD ever reported in fiber laser based on pure silica gain. This work can offer an effective and low-cost solution for fiber laser system with reduced heat production.

LncRNA and mRNA expression profiles in brown adipose tissue of obesity-prone and obesity-resistant mice

SummaryObesity-prone or obesity-resistant phenotypes can exist in individuals who consume the same diet type. Brown adipose tissue functions to dissipate energy in response to cold exposure or overfeeding. Long noncoding RNAs play important roles in a wide range of biological processes. However, systematic examination of lncRNAs in phenotypically divergent mice has not yet been reported. Here, the lncRNA expression profiles in BAT of HFD-induced C57BL/6J mice were investigated by high-throughput RNA sequencing. Genes that play roles in thermogenesis and related pathways were identified. We found lncRNA (Gm44502) may play a thermogenic role in obesity resistance by interacting with six mRNAs. Our results also indicated that seven differentially expressed lncRNAs (4930528G23Rik, Gm39490, Gm5627, Gm15551, Gm16083, Gm36860, Gm42002) may play roles in reducing heat production in obesity susceptibility by interacting with seven differentially expressed mRNAs. The screened lncRNAs may participate in the pathogenesis of weight regulation and provide insight into obesity therapy.

Numerical simulation and experimental investigation on tribological performance of SiC surface with squamous groove micro texture

AbstractTo improve the tribological characteristics of the face seal, the squamous groove micro textures with different area proportion and the circular dimple micro texture were designed and manufactured. The disc‐disc friction and wear experiments and numerical simulation were carried out in oil lubrication. The pressure distribution, friction coefficient, fluid temperature and wear morphology are investigated. The study show that the friction coefficients of the micro textured and untextured samples decline with the increase of load, but first increase and then decrease with the rise of rotational speed. Micro textured samples could decline the friction coefficient effectively, and the asymmetric structure in the lubricant inflow and outflow region of the squamous groove micro texture makes it have better tribological performance. In addition, the micro texture can increase heat dissipation area, reduce heat production and collect wear debris, which could modify the lubricant temperature and wear morphology effectively.

Prenatal acoustic programming of mitochondrial function for high temperatures in an arid-adapted bird.

Sound is an essential source of information in many taxa and can notably be used by embryos to programme their phenotypes for postnatal environments. While underlying mechanisms are mostly unknown, there is growing evidence for the involvement of mitochondria—main source of cellular energy (i.e. ATP)—in developmental programming processes. Here, we tested whether prenatal sound programmes mitochondrial metabolism. In the arid-adapted zebra finch, prenatal exposure to ‘heat-calls’—produced by parents incubating at high temperatures—adaptively alters nestling growth in the heat. We measured red blood cell mitochondrial function, in nestlings exposed prenatally to heat- or control-calls, and reared in contrasting thermal environments. Exposure to high temperatures always reduced mitochondrial ATP production efficiency. However, as expected to reduce heat production, prenatal exposure to heat-calls improved mitochondrial efficiency under mild heat conditions. In addition, when exposed to an acute heat-challenge, LEAK respiration was higher in heat-call nestlings, and mitochondrial efficiency low across temperatures. Consistent with its role in reducing oxidative damage, LEAK under extreme heat was also higher in fast growing nestlings. Our study therefore provides the first demonstration of mitochondrial acoustic sensitivity, and brings us closer to understanding the underpinning of acoustic developmental programming and avian strategies for heat adaptation.

Tolerance capability of desert sheep and goats to exercise heat stress under hot dry conditions, and its correlation with their production performance

The study aims to investigate tolerance capability of desert Barki sheep and goats to exercise heat stress (EHS) under the hot-dry conditions of Coastal Zone of Western Desert, in Egypt. Over the period from 2009 to 2014, mature ewes and does were exposed to exercise heat stress (EHS); walking for 7 km in July and August from 12 noon to 3 pm (simulating summer grazing on poor pasture). Physiological parameters: rectal temperature (RT), skin temperature (ST), respiratory rate (RR) and gas volume (GV) were measured at rest, by 7am, and directly after exposure. Tidal volume (TV) and metabolic rate (MR) were further calculated.Exposing desert Barki sheep and goats to EHS, raised significantly (P ≤ 0.01) their physiological parameters (RT, ST, RR, and GV), and decreasing their MR and TV. The main thermoregulatory mechanism of desert Barki sheep to tolerate EHS, was to increase their respiratory heat loss (increase RR and GV). While, Barki desert goats relied mainly on rapid shallow painting, besides reducing heat production. Barki goats showed better tolerance to physical stress under hot dry conditions than Barki sheep. Individual variation, were the main cause of variability in changes the studied parameters with EHS, followed by year and species variation.Changes in the physiological parameters with EHS were positively (P ≤ 0.05) correlated with body weight at exposure, insignificantly for yearling and weaning weights. Light weight desert lambs and kids at weaning are less tolerant to physical heat stress. While heavy animals at yearling, especially goats, have difficulty in walking for long distance under heat stress. Medium size desert goats, and relatively sheep, seems to be more compatible with hot dry conditions, than either light or heavy performed animals. For breeding purpose, there is room for selection in desert sheep and goat for tolerance to environmental stress, together with selection for production traits.

Influence of heat stress on the quality of sperm production of boars-producers of different breeds and its fertilizing ability

The primary purpose of this work is to study the heat stress on the quality of sperm production in boars of different breeds (Large White, Landrace, Duroc, Maxgro). The authors found that heat stress affects the activity of pigs. The desire to reduce heat production leads to sedentary, passive animals, accompanied by decreased appetite, shortness of breath and inhibition of sexual reflexes in individuals. Against this background, the disturbances arising in the body, reinforced by a local increase in scrotal temperature, harm semen quality. The authors observed a tendency for decreased ejaculate volume and a decrease (statistically significant in most breeds) in the sperm concentration in the ejaculate by 11.47-34.96%. But at the same time, the organoleptic values (colour, consistency, smell) did not change. Heat stress hurts the fertility of pigs, reducing the probability of successful embryo implantation. The fertility of sow inseminated with semen from boars during heat stress decreased by 10.3-23.7%. And also, the fertility of the sow did not reach pre-stress levels until the end of the observation. Based on the study results, the authors found that, depending on the breed, pigs can tolerate heat stress in a more severe or milder form. The species Large White and Maxgro are less sensitive to increased ambient temperature (they had fewer changes in general condition, semen and fertility) than Duroc and Landrace pigs.

Effects of heat stress on performance and thermoregulatory responses of Piau purebred growing pigs.

The study of how different breeds adapt to heat stress and the further understanding of mechanisms underlying pigs thermotolerance is of utmost importance to attenuate the negative effects of heat stress on pigs welfare, physiology, and performance. Therefore, this study aimed at evaluating the effects of ambient temperature on performance and thermoregulatory responses of Piau purebred pigs. The Brazilian native pig breed Piau is a fat-type breed characterized by adaptability and resistance to diseases. To achieve our goal, Piau purebred pigs (65kg initial BW) were allocated to one of the two constant ambient temperature conditions: thermoneutral (22°C; n=11) and heat stress (30°C; n=11). The experimental period lasted 15 days (days 1 to 15). Pigs were individually weighed at the beginning and end of the experimental period. Body and rectal temperatures, respiratory rate and blood indicators of stress and metabolism were measured throughout the experiment. Piau purebred pigs exposed to 30°C had lower (p<0.05) feed intake, body weight gain and final body weight than pigs at 22°C. Feed conversion rate was not affected (p>0.05) by ambient temperature. Irrespective of ambient temperature, pigs had similar (p>0.05) backfat thickness and loin eye area. Piau pigs at 30°C had increased (p<0.05) nape, dorsal, flank, and rectal temperatures and increased respiratory rate than their counterparts reared at 22°C. In summary, our results show that Piau purebred pigs acclimation to 30°C of ambient temperature is characterized by increased body skin temperature to optimize sensible heat loss to the environment; increased respiratory rate to promote latent heat loss; and by a concomitant reduced voluntary feed intake to reduce heat production associated with digestion and metabolic processes with negative effects on body weight gain.

Novel adipokine asprosin modulates browning and adipogenesis in white adipose tissue.

Obesity is an increasingly serious epidemic worldwide characterized by an increase in the number and size of adipocytes. Adipose tissue maintains the balance between lipid storage and energy utilization. Therefore, adipose metabolism is of great significance for the prevention, treatment and intervention of obesity. Asprosin, a novel adipokine, is a circulating hormone mainly secreted by white adipose tissue. Previous studies have shown that asprosin plays a role in fasting-induced homeostasis, insulin resistance, and glucose tolerance. However, whether it can regulate the metabolism of adipose tissue itself has not been studied. This study intended to examine the roles and potential mechanisms of asprosin in adipose regulation. We first demonstrated that the expression level of asprosin was significantly downregulated in subcutaneous white adipose tissue (scWAT) of high-fat diet (HFD)-fed or cold-stimulated mice. Overexpression of asprosin in scWAT reduced heat production, decreased expression of the browning marker uncoupling protein 1 (UCP1) and other browning-related genes, along with upregulation of adipogenic gene expression. Mechanistically, we found that Nrf2 was activated upon cold exposure, but this activation was suppressed after asprosin overexpression. In primary cultured adipocytes, adenovirusmediated asprosin overexpression inhibited adipose browning and aggravated lipid deposition, while Nrf2 agonist oltipraz could reverse these changes. Our findings suggest that novel adipokine asprosin negatively regulated browning and elevate lipid deposition in adipose tissue via a Nrf2-mediated mechanism. Asprosin may be a promising target for the prevention and treatment of obesity and other metabolic diseases.

Effects of Thermal Conditioning on Changes in Hepatic and Muscular Tissue Associated With Reduced Heat Production and Body Temperature in Young Chickens.

Effects of increased summer temperatures on poultry production are becoming more pronounced due to global warming, so it is important to consider approaches that might reduce heat stress in chickens. Thermal conditioning in chickens in the neonatal period can improve thermotolerance and reduce body temperature increases when birds are exposed to high ambient temperature later in life. The objective of this study was to investigate physiological and molecular changes associated with heat production and hence body temperature regulation under high ambient temperatures in thermally conditioned chicks. Three-day-old broiler chicks (Chunky) were thermally conditioned by exposure to a high ambient temperature (40°C) for 12 h while control chicks were kept at 30°C. Four days after the treatment, both groups were exposed to 40°C for 15 or 90 min. The increase in rectal temperature during 90 min of exposure to a high ambient temperature was less in thermally conditioned than control chicks. At 15-min of re-exposure treatment, gene expression for uncoupling protein and carnitine palmitoyletransferase 1, key molecules in thermogenesis and fatty acid oxidation, were significantly higher in pectoral muscle of control chicks but not conditioned chicks. Hepatic argininosuccinate synthase (ASS) decreased and hepatic argininosuccinate lyase (ASL) increased after reexposure to a high temperature. The concentrations of hepatic arginosuccinic acid, and ASS and ASL expression, were upregulated in conditioned chicks compared with the control chicks, indicating activity of the urea cycle could be enhanced to trap more energy to reduce heat production in conditioned chicks. These results suggest thermal conditioning can reduce the increase in heat production in muscles of chickens that occurs in high ambient temperatures to promote sensible heat loss. Conditioning may also promote energy trapping process in the liver by altering the heat production system, resulting in an alleviation of the excessive rise of body temperature.

A Theoretical Argument for Extended Interpulse Delays in Therapeutic High-Frequency Irreversible Electroporation Treatments.

We sought to determine whether modifications to the delays within H-FIRE bursts could yield a more desirable clinical outcome in terms of ablation volume versus extent of tissue excitation. We used a modified spatially extended nonlinear node (SENN) nerve fiber model to evaluate excitation thresholds for H-FIRE bursts with varying delays. We then calculated non-thermal tissue ablation, thermal damage, and excitation in a clinically relevant numerical model. Excitation thresholds were maximized by shortening d1, and extension of d2 up to 1,000 μs increased excitation thresholds by at least 60% versus symmetric bursts. In the ablation model, long interpulse delays lowered the effective frequency of burst waveforms, modulating field redistribution and reducing heat production. Finally, we demonstrate mathematically that variable delays allow for increased voltages and larger ablations with similar extents of excitation as symmetric waveforms. Interphase and interpulse delays play a significant role in outcomes resulting from H-FIRE treatment. Waveforms with short interphase delays (d1) and extended interpulse delays (d2) may improve therapeutic efficacy of H-FIRE as it emerges as a clinical tissue ablation modality.

Saccharomyces Cerevisiae var. Boulardii CNCM I-1079 during late gestation and lactation improves voluntary feed intake, milk production and litter performance of mixed-parity sows in a tropical humid climate

Under heat stress, sows reduce voluntary feed intake to reduce heat production. To improve the health and performance of sows, live yeasts have been used, and may have potential to reduce heat stress. Therefore, the present study aimed to evaluate the impact of supplementation of two levels of the live yeast Saccharomyces cerevisiae var. boulardii CNCM I-1079 (SB) on productive and reproductive performance of sows in tropical humid climatic conditions. A total of 300 mixed-parity sows divided into 3 treatments of 100 sows each. Sows were fed the live yeast Saccharomyces cerevisiae var. boulardii with a minimum concentration of 2 × 1010 colony forming units (CFU)/g viable yeast cells (LB) on top at the following levels of inclusion: CON - 10 g of sugar on gestation (d 90 –110) and 10 g of sugar on lactation (d110 to weaning); SB1 – 10 g of sugar +150 mg of LSB on gestation (d 90–110) and 10 g of sugar +285 mg of LSB on lactation (d110 to weaning) and SB2−10 g of sugar +300 mg of LSB on gestation (d 90–110) and 10 g of sugar +570 mg of LSB on lactation (d110 to weaning). SB improved voluntary feed intake (P < 0.001), milk production (P = 0.041) and piglet average weight at weaning (P < 0.05). In addition, SB2 tended to improve milk fatty acids content (P = 0.095) when compared to SB1 and CON. Our findings lead us to believe that the strategic use of Saccharomyces cerevisiae var. boulardii CNCM I-1079 during gestation and lactation has the potential to enhance sow milk production and piglet performance and weaning weight.

Communication—Prediction of Thermal Issues for Larger Format 4680 Cylindrical Cells and Their Mitigation with Enhanced Current Collection

The paper numerically explores the electrochemical and thermal behaviour of a larger format 4680 cylindrical cell recently proposed by Tesla and explains the need to go “tabless.” An idealized spiral geometry is used for 2D simulations with the traditional tab-based current collection method and a new continuous current collection method compared. The new design is found to mitigate the ohmic losses experienced around the “jelly-roll” current collectors which are significant for the traditional tabbed case, thus leading to higher efficiency and capacity and reduced heat production.

ENERGY BALANCE UNDER RESTRICTED FEEDING IN RUMINANTS

Forty-eight adult local desert non-pregnant and non-lactating females, age 4-5 yrs.; Barki sheep (n= 16 and average body weight 34.53 ±1.56 kg), Balady goats (n= 16 and average body weight 31.11 ± 1.63 kg), and Shami goats (n=16 and average body weight 28.08±0.92 kg) were used to study effects of long-term restricted feeding regime on body weight changes and balance of energy and protein. Animals of each species were allocated to two levels of feed intake; control feeding treatment (CON) where animals fed a diet at a level of feeding to meet approximately the metabolizable energy for maintenance requirement (MEm), while those on the other dietary treatment was fed almost 50% of these quantities on a BW basis, termed as the restricted treatment (restricted; RES). Alfalfa hay and concentrate feed mixture (50:50% as DM basis) were given based on requirement recommendations. The results could be summarized as follows: 1-Comparison between Balady goats (BG) and Sheep (SH): The ADG was not affected (P<0.05) by animal species (BG vs. SH), however, it was affected (P<0.01) by feed intake level where the RES animal group showed a negative ADG (-65.6 g/d) compared with the CON group that achieved positive ADG (36.4 g/d). Both of SH and BG had similar negative energy balance (EB) values (67.0 vs. 61.4 KJ/ kg0.75/d, for BG and SH respectively). Nitrogen balance (NB) was greater (P<0.01) for SH (107.64 mg/kg0.75/d ) vs. BG (89.47 mg/kg0.75/d) and was greater (P<0.01) for animals fed on CON intake (251.47 vs. 208.55 mg/kg0.75/d, respectively) than those fed on RES intake (-36.18 vs. -29.62 mg/kg0.75/d, respectively), which gave a negative NB. 2.Comparison between Balady goats (BG)and Shami goats (SG): The ADG was not affected (P< 0.05) by animal species (BG vs. SG) being corresponding values 45.1 and 40.6 g/d respectively. However, ADG was affected (P< 0.001) by feed intake level where the RES animal group showed a negative ADG (-55.6 g/d) compared with the CON group that achieved positive ADG (30.1 g/d). Under CON intake, EB was an insignificant decrease in SG compared to BG. However, under RES intake both BG and SG had a negative energy balance (kJ/kg0.75/day) and it was lower (P<0.01) in SG than that in BG. Animals fed on the CON intake level had a greater (P<0.01) value for EB compared to those fed on RES intake and the latter gave a negative balance. Nitrogen balance (NB, mg/kg0.75/day) was a trend to be greater (P<0.10) for SG vs. BG. Also, animals under the CON intake level captured more nitrogen than their counterparts, which lost a large amount of nitrogen. Also, the retention N was increased (P<0.01) in SG than BG under the CON intake level, however, all breeds were lost N under the RES intake level especially in SG (-76.37) followed by BG (-29.62). It could be concluded that with hot conditions, sheep may have an advantage in a decreased Metabolizable energy for maintenance (MEm) requirement and reduction in heat production of a magnitude adequate to maintain body weight. There is a similar rate of using the energy between sheep and goats with moderate or limited nutrition planes. It is clear that Balady goats are better than Shami goats in their ability to reduce the energy expenditure via reducing the rate of metabolism when they were fed on restricted intake.

Feeding behavior of grow-finish swine and the impacts of heat stress.

Heat stress has negative impacts on pork production, particularly in the grow-finish phase. During heat stress events, the feeding behavior of pigs is altered to reduce heat production. Several different systems have been developed to study feeding behavior. Most systems are not accurate representations of grow-finish commercial production as feed intake is monitored for only one pig at a time. The objective of this study was to utilize a feed monitoring system, representative of commercial conditions, to determine feeding behavior patterns of grow-finish pigs throughout the year and to identify changes that occurred during heat stress events. Feeder visit data were collected on barrows and gilts (n = 932) from three different sire breeds, Landrace, Yorkshire, and Duroc, between May 2014 and April 2016. Days in the study were partitioned into groups based on their maximum temperature-humidity index (THI), where a THI less than 23.33 °C was classified as "Normal", a THI between 23.33 and 26.11 °C was classified as "Alert", a THI between 26.11 and 28.88 °C was classified as "Danger", and a THI greater than 28.88 °C was classified as "Emergency". Feeding behavioral differences among breeds and sex were observed across all THI categories. Landrace-sired pigs had fewer feeder visits compared to Duroc- and Yorkshire-sired pigs. Gilts had fewer feeder visits than barrows in all THI categories. Differences in feeding behavior patterns between THI categories demonstrated that heat stress reduced the feeding duration of Landrace-sired pigs without any dramatic effects on the other pigs in the study. During elevated temperatures, all pigs tended to increase feeding events during the early (03:00-05:59) and late (18:00-20:59) periods of the day. Utilizing a feed monitoring system that is a more accurate representation of commercial conditions will lead to a greater understanding of feeding behavior among breed types and sexes during heat stress, allowing producers to enhance their ability to properly care for their pigs during both normal and heat stress events.

PSIII-39 Gene expression in adipose tissue at 8 months could explain adult overweight status in Beagle dogs

Abstract Individuals are more or less prone to excessive fat deposits and body weight. This could result from differences in the expression of gene involved in adipose tissue metabolism in early life. This study aimed to identify such possible differences in puppy dogs. Twenty-four 4-wk old females Beagle puppies were raised in the same environment, and fed with the same diet, ad libitum but for 3.5 h. Dogs were allotted in 3 groups according to their fat-free mass, fat mass, and pelvic circumference at 24 months of age: IW (n = 9; ideal body condition, OW1 (n = 6; moderately overfat) and OW2 (n = 9; overfat/obese). Subcutaneous and visceral adipose tissue (VAT) samples were collected at the time when animals were neutered (8 months). The mRNA level of genes involved in the regulation of lipolysis (perilipin, HSL), lipogenesis (ACC, ADRP, CPT1, FAS, FABP), adipogenesis (PPARg, SREBP-1c), thermogenesis (UCP1, UCP2), glucose uptake (GLUT4), insulin signaling (IRS2), and adiponectin production was assessed by real time RT-PCR. Gene expression levels in the three groups were compared by a Wilcoxon test. Ethics approval was granted by the French Ministry of Research and Royal Canin’s Ethical Committee. Compared to IW, OW2 dogs had a lower expression of UCP1 in the VAT (P = 0.049). This could result in reduced heat production by non-shivering thermogenesis. Moreover, a low UCP1 expression has been linked to obesity. Compared to IW, OW1 dogs had a higher transcription level of ACC and ADRP genes (P &amp;lt; 0.05). ACC is a point of regulation of the FA synthesis whereas ADRP is involved in the differentiation of the pre-adipocytes, and fat storage. These results suggest that the overweight/obesity phenotype could be associated with a lower heat loss, and the moderately overweight phenotype with a higher ability to fat synthesis compared to the lean phenotype.

84 Improving dietary amino acid balance reduces heat production in lactating sows exposed to heat stress

Abstract We hypothesized that lactating sows fed a reduced CP (RCP) diet with supplemental AA to improve AA balance produce less metabolic heat (HP) compared with feeding a conventional diet (control). The objective was to measure HP of sows (n = 24) fed control (19.6% CP) or RCP (14.2% CP) under thermoneutral (TN, 21 ± 1.5°C) or cycling heat stress (HS, 32 ± 1.5°C daytime and 24 ± 1.5°C nighttime). Diets contained 0.90% SID Lys and 2,580 kcal/kg. Positive pressure indirect calorimeters were used to measure gas exchange in individual sows with litters (sow + litter), and individual piglets on lactation d 4, 8, 14 and 18, and HP determined overnight (1900–0700) and during daytime (0700–1900). Sow and litter weights were recorded on d 1, 10 and 21. Sow HP was calculated by subtracting litter HP from sow + litter HP based on BW0.75. Model included the fixed effect of diet, random effects of block and sow, sow feed intake as a regression variable and day as the repeated measurement. Compared to control, HP (kcal/h·kg0.75) of RCP was lower (P &lt; 0.01) overnight (5.25 vs. 5.96 ± 0.38), during daytime (6.33 vs. 6.94 ± 0.23), and over 24-h (5.78 vs. 6.46 ± 0.24) under HS. Under TN, HP of RCP tended to differ (P = 0.107) overnight (5.20 vs. 5.90 ±0.57) and over 24-h (5.93 vs. 6.48 ± 0.50) and did not differ (P = 0.190) during daytime (6.66 vs. 7.06 ± 0.52). Under HS, lactation day affected HP (P &lt; 0.05) overnight and over 24-h, with HP increasing from d 1 to 14 and decreasing from d 14 to 18. Under TN, day of lactation did not affect sow HP. Feeding RCP diet to lactating sows decreased HP, and this effect was more pronounced in sows housed under HS.