Moderate Ambient Temperatures Research Articles

Microclimate and thermal refuge influences on sage-grouse brood habitat selection

Wildlife space use is driven by three primary mechanisms, predator avoidance, foraging, and thermoregulation. The latter has largely been overlooked in wildlife research. Understanding how habitat use is influenced by thermoregulatory properties is a critical component to depicting species' ecology. Galliformes’ (i.e., ground nesting birds with precocial young) ecology is predisposed to thermal extremes, where newly hatched chicks are unable to thermoregulate <14 d post-hatch, and have limited capabilities until >21 d post-hatch. We examined greater sage-grouse (Centrocercus urophasianus) brood rearing habitats and provide the first evaluation as to how microscale thermal environments influenced habitat selection. We monitored 24 broods, collected 82,929 black bulb temperature measurements from thermal arrays (n = 256) comprised of stainless steel black bulbs (i.e., surrogate for operative temperature) to compare brood morning (i.e., foraging, n = 78), afternoon (i.e., loafing, n = 82) and associated random locations (n = 96) between early (≤21 d post-hatch) and late (>21 d post-hatch) brood-rearing. We measured vegetation at all locations to disentangle relationships between cover and thermoregulatory metrics. We found that microclimates at all foraging locations heated more rapidly than either their loafing or random locations. Alternatively, loafing locations moderated ambient temperature more effectively than foraging locations but were similar to random locations. Broods were using loafing sites that both increased their ability to avoid predators (i.e., increased shrub structure) and buffered ambient temperature better than their foraging locations. Interestingly, random afternoon locations tended to lack concealment from predators, despite these locations showing improved thermal buffering compared to foraging locations. However, early brood-rearing habitats appeared to moderate ambient temperatures more effectively than late. Our results suggested that managing vegetation for structural heterogeneity will afford a diversity of thermal refuge for greater sage-grouse broods during this critical life history stage.

The effectiveness of vapor-injection for an inverter air-source heat pump compared with vapor-return

The vapor-injection assisted with air-source heat pump (ASHP) has become one of the focuses in the last decade. It can improve the heating performance of the ASHP system in low ambient temperatures by experiments. However, the vapor-injection is ineffective in moderate ambient temperatures owing to the high pressure of the compressor intermediate chamber. On the other side, the effectiveness of vapor-injection is rarely discussed. Based on experiments and the thermodynamic analysis method, this paper proposes an inverter air-source heat pump (IASHP) with vapor-injection and vapor-return. With the scope from −20 °C to7.0 °C for ambient temperature, it focuses on the heating performance of the prototype with different compressor frequencies for both vapor-injection and vapor-return modes. Moreover, the effectiveness of vapor-injection is discussed. The results show that the vapor-injection is superior to vapor-return for improving the heating performance of the prototype. Not only does the vapor-injection significantly affect refrigerant mass flow rate, but it also makes the relative entropy reduction (RER) of the compressor outlet decrease by 0.025–0.03 kJ/(kg·K). In the case of ambient temperature at −4.0 °C, the vapor-injection improves by 6.6 % and 3.4 % for heating capacity and COP of the prototype. Besides, the effectiveness of vapor-injection lies in the RER of the compressor outlet, which is suitable for vapor-injection using different refrigerants.

The “Naked neck” gene and the adaptability of the native chicken to heat stress on station in Cameroon

The rational use of the native chicken genetic resource is seen a viable option for sustainably improving poultry meat production in Cameroon. This study aimed at assessing the potential of the Na gene for resilience under acute heat stress. The study was done in two trials. Firstly, a total of 180 young roosters reared in similar management conditions from the 1st to the 8th week of age were randomly distributed per genotype according to a 3 x 2 factorial design including two treatments (acute and moderate ambient temperatures) of 90 birds each and three genotypes (Na*Na, na*na and Na*na) of 30 birds per treatment. Treatments consisted of moderate and acute ambient temperatures of 25-27°C and 39 - 42°C respectively for 5 hours/day from 8 to 12 weeks of age. The genotypes within and between the treatments were compared for body weight (BW), average daily weight gain (ADG), water consumption (WC), feed consumption (FC), and feed conversion ratio (FCR). Results showed that the na*na and Na*na were statistically comparable but superior to the Na*Na genotype under moderate temperature. The three genotypes were significantly affected (P&lt;0.05) by the heat stress. However, the Na*na was less affected and maintained the highest ADG and lowest FCR. For the second trial, 90 birds including 30 birds randomly sampled per genotype were compared for the feathering intensity and five carcass characteristics and giblets at 24-week-old. The results revealed an association of the “Na” gene with 21 to 50 % feather reduction in heterozygote and homozygote respectively whereas heterozygote naked neck had greater body and carcass weight as well as giblet and head weights (P&lt;0.05). The animal model equation could clearly quantify the genotype effect. The phenotypic advantage evidenced for the Na gene is confirmed as an adaptation to heat stress whereas the significant superiority of heterozygote Na*na for most of the traits opens a window for the valorisation of potential overdominance effects for poultry breeding in hot climates.

Influence of a cubic wood particle orientation in space on the characteristics and conditions of its ignition

The article presents the results of the experimental and theoretical studies of the ignition processes of dry particles of woody biomass with a wide variation in heating conditions. A detailed analysis of the typical frames of the videogram has shown that the temperature of the oxidizing agent affects the nature of the ignition process of a wood particle. Under conditions of moderate ambient temperatures (Tg ≤ 873K), ignition, as a rule, occurs in the gas region under the particle. At the same time, the ignition of wood particles under conditions of high-temperature heating (at Tg > 1073K) proceeds in the gas phase in a small (very thin) neighborhood around the wood particle along its entire perimeter.A model is formulated that describes the ignition under the considered rather typical conditions and differs from the known description of the processes of convection of gaseous pyrolysis products during the induction period. Based on the results of the experiments, the influence of the type of woody biomass on the characteristics and conditions of ignition of fuel particles has been analyzed. It has been established that dry particles of woody biomass made of pine under relatively low ambient temperatures (at Tg≤873 K) ignite much faster compared to particles of similar size from birch, aspen and cedar. Differences in ignition delay times reach 90%. At high ambient temperatures (Tg≥1273K), the ignition delay times of all four investigated fairly typical types of woody biomass differ insignificantly (the deviation of the ignition delay times does not exceed 5%).The analysis of the influence of the orientation of wood fibers in space relative to the direction of the heat flow vector on the characteristics and conditions of ignition has also been carried out. It is shown that the orientation of the wood particle in space does not significantly affect the characteristics and conditions of ignition. This trend has been registered for all four types of wood studied.

Dietary supplementation of Ocimum gratissimum improves growth performance and immune response in broilers under high ambient temperature.

Ocimum gratissimum (OG) was found to have immunity boosting effect on Taiwan country chickens and broiler chickens raised in moderate ambient temperature in previous studies, and the current study investigates its potential on the growth performance, blood traits, intestinal traits, and immune responses in Ross 308 broilers raised in high ambient temperature which can induce mild heat-stress (26 to 33 ˚C, average 30 ˚C). Two hundred 1-d-old male/female chicks were randomly assigned to a control group, three OG (1 g/kg, 3 g/kg, and 5 g/kg)/basal diet groups, and one Amoxicillin group. Data collected during the experiment indicated that the weight gain increase of 1742 g/bird to 1815 g/bird comparing control to 5 g/kg OG supplementation was statistically significant. In addition, the production efficiency factor was also noticeably increased by OG, particularly in the 5 g/kg group, and the uric acid levels were decreased in the 3 and 5 g/kg OG groups (from 4.26 to 2.91 and 2.90 mg/dL, respectively), indicating heat-stress alleviation was observed. Several areas of the carcass saw desirable growth changes, including the increase of breast muscle ratio observed in the 5 g/kg OG group, an overall decrease in abdominal fat in all OG groups, as well as dimensional changes in several areas of the digestive system. Lastly, the hemaglutination, hemaglutination inhibition, and phytohemaglutinin tests indicated elevated immuno-response in all OG groups. In conclusion, OG has exhibited the ability to alleviate symptoms of mild heat-stress, leading to improvement of the digestive organ development and increase of carcass mass and mean weight gain for birds, and we find OG to be a potentially beneficial feed supplement for poultry raising in high ambient temperature conditions.

Nestling Altricial Rodents and Lagomorphs Are Not Ectotherms.

AbstractBased on the synthesis of data on metabolic rates of 15 species investigated at moderate ambient temperatures, nestlings of most studied species of altricial rodents and lagomorphs exhibit thermoregulatory control of thermogenesis within 3 d after birth, signifying that they express physiological thermoregulation for 86%-100% of their time as nestlings. Classifying nestlings as ectotherms (or poikilotherms) is thus inappropriate and fosters misconceptions regarding their body temperatures (Tb's), control of Tb-sensitive functions (e.g., cardiac output), and energetics of development. The fact that nestlings live as litters in nests means that their thermoregulatory capacities in their actual, natural lives often far exceed the capacities they exhibit as isolated individuals-pointing to a pressing need for improved understanding of the physiology of litters. Litters in nests are already known in two cases to exhibit true homeothermy at ages when individuals studied in isolation express only modest thermoregulatory abilities. Golden (Syrian) hamster nestlings are exceptional, requiring 2 wk to develop thermoregulatory thermogenesis. They are properly considered ectotherms at up to 2 wk of age, helping to clarify that most species-being dramatically different-are not.

Prehospital Use of Ultrathin Reflective Foils.

Ultrathin reflective foils (URFs) are widely used to protect patients from heat loss, but there is no clear evidence that they are effective. We review the physics of thermal insulation by URFs and discuss their clinical applications. A conventional view is that the high reflectivity of the metallic side of the URF is responsible for thermal protection. In most circumstances, the heat radiated from a well-clothed body is minimal and the reflecting properties of a URF are relatively insignificant. The reflection of radiant heat can be impaired by condensation and freezing of the moisture on the inner surface and by a tight fit of the URF against the outermost layer of insulation. The protection by thermal insulating materials depends mostly on the ability to trap air and increases with the number of covering layers. A URF as a single layer may be useful in low wind conditions and moderate ambient temperature, but in cold and windy conditions a URF probably best serves as a waterproof outer covering. When a URF is used to protect against hypothermia in a wilderness emergency, it does not matter whether the gold or silver side is facing outward.

Assessing the environmental ruggedness of paper spray ionization (PSI) coupled to a portable mass spectrometer operated under field conditions

Significant efforts have went towards coupling portable mass spectrometric systems and ambient ionization methods, with a culminating goal of field-based, point-of-need screening of harmful chemicals. While fieldable, ambient MS methods are an intriguing combination, ruggedness of these ionization methods in regard to naturally-occurring environmental conditions while operating in-situ, such as ambient temperature, relative humidity (RH) and wind, bears further investigation, as such reports are limited. In this work, a systematic characterization of paper spray ionization-mass spectrometry (PSI-MS) performance under variable environmental conditions was undertaken on a field-deployable MS system. Of all conditions, the presence of wind speeds greater than 3 m/s (∼7 MPH) was shown to have the most substantial effect on the spectral attributes of signal intensity and duration of the PSI-MS spraying event. Generally, moderate ambient temperature and %RH produced the best spectral performance for PSI-MS. Heat maps were generated from field-collected data across variable temperature and %RH in an effort to inform general PSI-MS performance trends and guide on-site operation by potential users.

A comparative analysis of the characteristics of the water removal processes in preparation for incineration of typical wood waste and forest combustible materials

The article presents the results of the experimental studies of the processes of removing moisture from fairly typical and widespread forest combustible materials, and woodworking waste under conditions of their thermal preparation for combustion. Based on the results of the experiments, the main regularities of the drying processes of woody biomass under conditions of radiation-convective heating have been established. The integral characteristics (characteristic times) of the drying process of forest biomass under typical (for this technology) heating conditions have been determined. The experiments were carried out on equipment that provides a low level of error (less than 3.3%) for determining the main characteristics of the biomass dehydration process. The values of the mass rates of moisture removal (Weva) of four promising (for modern and future power engineering) and fairly common types of biomass have been established in the ambient temperature range from 333 to 393 K, which corresponds to the operating modes of the drying equipment of power plants. According to the results of the experiments, it was shown that at relatively moderate ambient temperatures (333≤ Tg ≤ 353 K), the type of wood has a rather significant effect on the characteristics and conditions of the dehumidification process. At the same time, the process of drying wood chips is much faster compared to other types of biomass. As the ambient temperature rises (at 373≤Tg ≤ 393 K), the influence of the type of biomass decreases. As a result of the experiments, a physical model of the process of removing moisture from the bulk layer of biomass was formulated. According to the results of the experiments, it was found that before burning forest biomass in boilers of thermal power plants, it is most advantageous to carry out drying in conditions of relatively moderate (at 333≤Tg ≤ 353 K) ambient temperatures. The studies carried out provide grounds for justifying the use of forest combustible material as fuel (or one of the components of the fuel mixture) at thermal power plants currently operating on coal.

High-Level Inactivity Despite Favorable Environmental Conditions in the Rock-Dwelling Dwarf Tortoise Chersobius boulengeri

In arid regions with summer rainfall, herbivorous reptiles are able to acquire water and fresh food in the presence of high environmental temperatures that can promote ectotherm activity. However, extremely high temperatures and below average rainfall may also limit foraging opportunities due to risks of overheating and predation while gathering scarce food. Karoo Dwarf Tortoises (Chersobius boulengeri) inhabit an arid region in South Africa where most rains fall around austral summer (October–May). We used focal-animal observations and instantaneous recording to assess their behavioral patterns. Despite relatively high rainfall and available plant growth, Karoo Dwarf Tortoises spent approximately 80–90% of their time in retreats. Whereas activity (behavior outside retreats) in the spring was unrelated to time of the day, possibly due to moderate ambient temperatures, activity in the summer was restricted to the afternoon and evening, when tortoises walked and scanned for food and retreats, and fed only 11 min/d on average. In summer, body temperature of tortoises within retreats was positively associated with retreat temperatures, but tortoises appeared to thermoregulate using bodily postures and possibly other means. We suggest that Karoo Dwarf Tortoises mitigate predation risks by maintaining a low level of activity and thermoregulating within retreats. The short feeding time of Karoo Dwarf Tortoises compared to other tortoise taxa may result in slow growth and reproductive rates, which might in turn affect population resilience and conservation needs of this endangered species.

All-positional flux cored wire with lower trace element contents and improved ambient temperature toughness for welding P91 steels

The productivity benefits of utilizing flux cored wire for welding P91 steels have been recognized for many years. However, due to the moderate ambient temperature impact toughness and relatively high level of the Bruscato factor (X-factor) of the weld metal from the flux cored wire consumables, the application range of the FCAW in welding P91 steels has been limited when compared with other processes, e.g., GTAW, SMAW, and SAW. Consequently, the development for continuous improvement of the P91 flux cored wire has been an active area. Efforts have been focused on optimizing weld chemical composition to control the levels of trace elements and improve the impact toughness. The present paper introduces the latest advances achieved in the improvement of a rutile-based all-position flux cored wire for P91 steels. The progress has resulted in an optimized weld metal chemical composition with a substantially lower X-factor, better mechanical properties with significantly improved impact toughness at ambient temperature, and further enhanced out of position welding performance.

Investigation of PM10, PM2.5, PM1 in an unoccupied airflow-controlled room: How reliable to neglect resuspension and assume unreactive particles?

It is now well recognized that Particulate Matter (PM) is one of the main air pollutants affecting both ambient and indoor air quality. While ambient PM mass concentration measurements are often performed by air quality monitoring networks, current regulations do not address their indoor concentrations. The latter can be estimated nonetheless from a mass balance analysis accounting for (i) the transfer of particles from outdoor and (ii) their typical indoor sources (emissions, resuspension) and sinks (deposition, removal by air exchange). Inherently, the mass balance analysis is valid with inert atmospheric species, i.e. mass is conserved and described by sources and sinks, thus assuming no physicochemical transformations. To check that the relative imbalance (RI) is not significant over different size fractions, a series of careful measurements were conducted in an unoccupied room within a building incorporating an energy-efficient design (minimal heat losses, negligible air leaks, etc.). We show that by carefully characterizing the room properties, i.e. the air exchange rate, penetration factors and deposition rates for sized-resolved particles, the PM10 and PM2.5 fractions, which are typically regulated outdoors, as well as PM1, can be well estimated indoors (with RI between measured and expected values < 19%) under moderate ambient temperatures (<22 °C in this study). However, RI increases significantly, especially for submicron particles, at higher temperatures, indicating possible transformations in the particulate phase, which are not accounted for by the mass balance model. Therefore caution is recommended regarding the mass balance analysis to estimate PM fractions indoors, especially for PM1.

Ionosilica-based anion exchangers for low-temperature thermochemical storage of energy under mild conditions of adsorbent regeneration and saturation

Three ionosilica materials have been tested for low-temperature thermochemical storage of energy under mild conditions of adsorbent regeneration and saturation. The previous synthesis procedures were adapted to prepare materials possessing an organosilica framework with silylated cationic blocs and Cl-, HSO4-, SO42- anions in various proportions as extra-framework compensating counter-ions. Transmission and Scanning Electron Microscopy, Wavelength Dispersive X-Ray Fluorescence, Energy Dispersive X-ray Spectroscopy, Thermogravimetric analysis, adsorption of gaseous nitrogen at 77 K, 29Si Solid-State Nuclear Magnetic Resonance spectroscopy were employed to establish the key characteristics of the three ionosilica samples in terms of elemental composition, particle morphology and textural properties, thermal stability and regenerability, or variability of surface activity during repeated hydration-dehydration cycles. Their capacity to adsorb water vapor at cool and moderate ambient temperatures after incomplete surface drying was demonstrated by means of the scanning microscopy operating in low-vacuum mode at 275 K, or more precisely by measuring the water adsorption isotherms at 313 K and the related differential heats under static conditions. Finally, flow calorimetry operating in the moist-gas flow mode was used to measure the integral heat accompanying the adsorption of water vapor at its partial pressure of 2.8 kPa and 296 K as well as the kinetics of heat release in three drying-saturation cycles. After a drying procedure carried out under helium flow at 353 K, the thermal performance of two ionosilica samples containing both HSO4- and SO42- counter-ions was sufficient enough to consider them as potential adsorbents for auxiliary space heating in homes, small businesses, or public buildings.

Foraging Ecology and Diurnal Activity Patterns of Klipspringer (Oreotragus oreotragus) in Yetefet Woyenat Forest, East Gojjam, Ethiopia

The foraging ecology and diurnal activity patterns of the klipspringer (Oreotragus oreotragus) were studied in Yetefet Woyenat Forest from September 2017 to August 2018 during the dry and wet seasons. Data were collected by visual observation using focal and scan sampling methods. The result indicated that klipspringers were observed feeding on grasses, herbs, trees, and shrubs, but were primarily browsers during both wet and dry seasons. Carissa edulis was the most consumed plant species in the study area, followed by Rosa abyssinica and Maytenus arbutifolia. Despite moderate ambient temperatures, klipspringers were mostly active during early morning and late afternoon, feeding 45.56% of the daylight hours during the dry season and 43.75% during the wet season. Klipspringers were facing threats due to human activities in the study area. Thus, appropriate conservation measures should be taken to reduce disturbance of their ecology.

Laying performance, immune response and antioxidant properties of hens segregating for naked neck and frizzle genes under low ambient temperature

Major genes could be introgressed into laying hens to attenuate heat stress. However, under cold and/or moderate ambient temperature, these genes might possess different behaviour. The main objective of this study was to evaluate laying performance, immune response, and antioxidant status of native laying hens segregating for naked neck (Na) and frizzle (F) genes under low ambient temperature. Five genotypes were studied: homozygous naked neck (NaNaff), heterozygous naked neck (Nanaff), homozygous frizzle (nanaFF), heterozygous frizzle (nanaFf), and normally feathered (nanaff). The hens were raised under temperature range 22.2–16.7°C. No adverse effect due to ambient temperature was detected in laying performance for naked neck genotypes. Significant decrease in egg weight was recorded in nanaFF genotype compared to the other genotypes leading to significant decrease in egg mass. Significant improvement in shell thickness was associated with Na and F genes. NaNaff genotype had a significantly higher eggshell strength compared to nanaff. Furthermore, Na and F genes improved cellular mediated immune responsiveness, whereas this improvement did not extend to humoral immunity. Birds carrying F gene in homozygous state had a higher total antioxidant activity compared to the remaining genotypes. It could be concluded that the presence of Na and F genes in laying hens raised under low ambient temperature significantly increased shell thickness and, in turn, improved shell strength. Moreover, they greatly enhanced cellular immunity, particularly in heterozygous naked neck status.

Temperature-Induced Chemical Changes in Soundless Chemical Demolition Agents

AbstractThis paper explored the relationship between ambient temperature, calcium oxide (CaO) hydration, and calcium carbonate (CaCO3) generation in cold and moderate ambient temperatures (2°C–19°C...

Role of temperature on the development of hypoxia in blackwater from grass

In eastern Australia the development of hypoxic blackwater/floodwater and its detrimental consequences are more common in summer than winter. This study examined the effect of temperature on the development of hypoxic conditions which was determined as biochemical oxygen demand (BOD) in floodwater when pasture grass (a source containing labile organic carbon) was inundated. Labile dissolved organic carbon (DOC) in blackwater is one of the main factors that contribute to the development of hypoxic conditions. Temperature plays a key role on the microbial mineralization of labile DOC and hence the development of hypoxic conditions. Prolonged flooding at different seasons (having different temperatures) was simulated in the laboratory by incubating fresh pasture grass cuttings with river water and soil at three different temperatures (20 °C, 27.5 °C and 35 °C) for 20 days. Although this study shows that elevated ambient temperatures can result in more rapid development of hypoxic conditions during the first week of flood peak, it is evident that blackwater formed at relatively moderate ambient temperatures (e.g. 20 °C) has a similar potential to deoxygenate the receiving water bodies, especially after one week's duration of flood peak.

Evaluating performance of hybrid PCM-fan and hybrid PCM-desiccant vests in moderate and hot climates

Personal cooling vests containing phase change material (PCM) are commonly used for outdoor workers. They cool the human torso and provide a better rating of overall thermal comfort in hot environments. However, PCM cooling vests become less effective at conditions where a high sweat secretion is present, and at very humid or very dry ambient conditions. Therefore, design variations have been used to justify the use of the PCM cooling vest in such conditions. These mainly include the hybrid PCM-Desiccant cooling vest, containing thin solid desiccant packets attached to the PCM packets, and the hybrid PCM-Fan vest, formed of PCM packets and ventilation fans.The aim of this study is to develop criteria for comparing the performance of the three vests at different ambient conditions and human metabolic rates. The comparison used predicted values of torso skin temperature and overall thermal comfort using validated simulation models for heat and mass transfer in each of the vest layers, integrated with a validated bio-heat model. Steady state results were obtained at metabolic rates of 3 and 6 MET at ambient temperatures of 35, 40 and 45 °C with varying relative humidity (RH). Based on developed criteria, it was found that the use of the PCM-only vest is recommended at activity level of 3 MET in moderate ambient temperature of 35 °C and at ambient RH of 17% and 27%. At the higher ambient temperatures of 40 °C and 45 °C and low ambient RH, the use of the hybrid PCM-Fan vest is recommended. However, at moderate RH both hybrid vest types can be used while at higher ambient RHs, the use of hybrid PCM-Desiccant vest is justified. Similarly, it was shown that at higher metabolic rate of 6 MET, both hybrid vests can be used at moderate RH. However, at high RH, the hybrid PCM- Desiccant vest is recommended.

Effect of relative humidity at either acute or chronic moderate temperature on growth performance and droppings' corticosterone metabolites of broilers

The present study aimed to investigate the effect of relative humidity (RH) at either acute or chronic moderate ambient temperature (Ta) on growth performance and droppings' corticosterone metabolites of broilers. Two experiments were conducted: effect of RH (35, 60 or 85%) on average daily feed intake (ADFI) and droppings' corticosterone metabolites at acute (1 d: 20–26 or 31–20°C, 26 or 31°C for 6 h d–1 at 10:00–16:00) moderate Ta (experiment 1) and effect of RH (35, 60 or 85%) on growth performance and droppings' corticosterone metabolites at chronic (step-wisely increasing temperature by 3°C every 3 d from 20 to 32°C within 15 d: 20–23–26–29–32°C) moderate Ta (experiment 2). Droppings were collected at the 2, 4, 6, 8, and 22 h after Ta-RH controlled in experiment 1 and at the 2, 4, 6, and 22 h after Ta controlled to 32°C in experiment 2. The results showed that: 1) In experiment 1, 85% RH increased (P<0.05) the droppings' corticosterone metabolites at the 2, 6, 8, and 22 h and 35% RH increased (P<0.05) it at the 2 and 22 h compared to the 60% RH. Moreover, 85% RH further increased (P<0.05) it compared to the 35% RH, however, no difference (P>0.05) was found in ADFI among the three RH groups at acute moderate 26°C; 35 and 85% RH increased (P<0.05) droppings' corticosterone metabolites at the 2, 6, 8 and 22 h and decreased (P<0.05) ADFI compared to the 60% RH, moreover, 85% RH further increased (P<0.05) droppings' corticosterone metabolites and further decreased (P<0.05) ADFI compared to the 35% RH at acute moderate 31°C; and the average of droppings' corticosterone metabolites in the whole period had a negative correlation (P<0.02) with the ADFI. 2) In experiment 2, 85% RH increased (P<0.01) droppings' corticosterone metabolites only at the 2 h and decreased (P<0.02) ADFI and average daily gain (ADG) compared to the 60% RH, no difference (P>0.05) in droppings' corticosterone metabolites was found between the 35 and 60% RH, however, 35% RH decreased (P<0.01) ADG compared to the 60% RH, and the average of droppings' corticosterone metabolites in the whole period also had a negative correlation (P<0.02) with ADFI and ADG. In conclusion, droppings' corticosterone metabolites could be used as a RH stress index and low and high RH, especially high RH, reduced growth performance possibly through inducing RH stress at moderate temperature.

Assessment of ergot (Claviceps purpurea) exposure in pregnant and postpartum beef cows

Cows were fed ration for 9 wk containing 5, 48, 201, and 822 μg kg−1 ergot alkaloids. The objective was to evaluate the impact of ergot consumption in beef cow–calf operations. Ergot alkaloids up to 822 μg kg−1 did not alter the weight of peripartum and postpartum beef cows (P = 0.93) or nursing calves (P = 0.08), rectal temperature (P = 0.16), or plasma prolactin concentrations (P = 0.30) at moderate ambient temperatures. Ergot did not influence the time (&gt;1 ng mL−1; P = 0.79) or the progesterone concentration (P = 0.38) at the time of first postpartum rise or the size of the first (14 ± 0.6 mm; P = 0.40) and second (13 ± 0.5 mm; P = 0.41) follicles to ovulate. The maximum size of the first postpartum corpus luteum (CL) was 4 mm larger in the 822 μg kg−1 ergot group compared with the control (P = 0.03) for the first ovulation post partum, but not for the second (P = 0.11). There was no effect of ergot exposure on the number of days until the appearance of the first (43 ± 4 d; P = 0.95) or second (52 ± 4 d; P = 0.98) CL post partum. Ergot alkaloid concentrations up to 822 μg kg−1 did not affect pregnancy rates (X2 = 0.36). In conclusion, ergot alkaloid exposure for 9 wk to concentrations as high as 822 μg kg−1 did not alter performance in pregnant and postpartum beef cattle at moderate ambient temperatures.