Periods Of High Ambient Temperature Research Articles

Compound bioengineering protein improves growth performance and intestinal health in broiler chickens under high-temperature conditions.

In recent years, more frequent and prolonged periods of high ambient temperature in summer compromised poultry production worldwide. This study was conducted to investigate the effects of compound bioengineering protein (CBP) on the growth performance and intestinal health of broilers under high ambient temperatures. A total of 400 one-day-old Arbor Acres birds were randomly distributed into five treatment groups: control group (CON) with basal diet, or a basal diet supplemented with CBP 250, 500, 750, and 1,000 mg/kg, respectively. The trial lasted 42 d, all birds were raised at normal ambient temperature for the first 21 d and then subjected to the artificial hyperthermal condition with the temperature at 32 ± 2 °C and relative humidity at 60 ± 5% during 22 to 42 d. Dietary CBP supplementation improved the growth performance and serum antioxidant capacity (total antioxidant capacity and total superoxide dismutase), and decreased serum cortisol, aminotransferase, and alkaline phosphatase of broilers. Dietary CBP inclusion enhanced intestinal barrier function by promoting intestinal morphology and reducing intestinal permeability (diamine oxidase), increased the intestinal antioxidant capacity by elevating glutathione peroxidase activity in the duodenum, reducing malondialdehyde content in the jejunum. Dietary CBP supplementation also alleviated intestinal inflammation by decreasing interleukin (IL)-6 content in the jejunum and ileum, promoting IL-10 levels in the ileum, down-regulating the mRNA abundance of intestinal inflammatory-related genes interferon-gamma (IFN-γ) in the duodenum and up-regulating IL-10 in the jejunum. Additionally, CBP increased the population of total bacteria and Lactobacillus in cecal chyme. Collectively, dietary CBP inclusion exerts beneficial effects on the broilers, which are reflected by enhancing antioxidant capacity, promoting intestinal barrier function, ameliorating intestinal immune response, and regulating intestinal bacteria, thus improving the growth performance of broilers under high-temperature conditions. In general, 750 mg/kg CBP supplementation is more effective.

ADAPTATION OF SPORTS AND LEISURE COMPLEXES NETWORK IN UKRAINIAN CITIES TO CLIMATE CHANGE

The climate change that is taking place all around the world today presents challenges for all inhabitants of the planet, including the citizens of Ukraine. Taking all of these circumstances into consideration, it is necessary to introduce new methods of forming the environment that meet the new conditions. The article examines the influence of climate change on the recreational spaces of Ukrainian cities focusing on the location of sports and leisure complexes and their facilities. The article explores the influence of the temperature and humidity of the recreational environment on the athletes' performance and health. The work identifies and systematizes the positive and negative effects of the climate change on a network of sports and leisure complexes and their athletes. The main implication is that outdoor activities can cause heat stress during periods of high ambient temperature. This indicates that the existing sports and leisure complexes are not adapted to climate change. The paper studies the world's practical ways of adapting the urban environment to climate change paying particular attention to a system for alerting the population about the heat waves and informing the citizens about ways to strengthen their immunity; the creation of green and water infrastructure in cities and suburban areas; systems for objective monitoring of diseases and infectious agents affected by climate change, as well as planning for the prevention of these diseases; ensuring the population's access to clean drinking water and monitoring compliance with the technology of disinfection and purification. The study, premised on this analysis, has provided several proposals for adaptive measures implemented while designing a network of sports and leisure complexes in the architectural and urban planning aspects. It is predicted that such measures will help visitors adapt to climate change. It enables us to develop approaches for forming a future network of sports and leisure, taking into consideration cities' changing climatic conditions.

Effects of Heat-Stress on Oocyte Number and Quality and In Vitro Embryo Production in Holstein Heifers

Background: This study aimed to determine the effects of environmental temperature on the number and quality of oocytes and embryo production rates obtained by performing ovum pick up (OPU). Heat stress leads to long-term, short-term, visible, and invisible effects in dairy cows. Its effects on reproduction are evident in all stages, from oocyte development to birth. Disturbance in ovarian follicle development, follicular dominance deficiency, anoestrus, polyspermia, embryoniclosses, decreased fetal growth, and abortion are some examples of responses to these effects. The aim of the present study was aimed to determine the effects of ambient temperature on oocyte quality and number and embryo production rates.Materials, Methods & Results: The animal material used in this study comprised 10 Holstein heifers. At the beginning of the study, the heifers were 13-15 months old. OPU was performed at different times of the year, and weather conditions were recorded. Grouping according to ambient temperature was done as < 10°C (group 1), 10-25°C (group 2), and > 25°C (group 3). The veterinary ultrasonography device and a set of compatible intravaginal OPU probe, catheter, and aspiration device were used for OPU application. All antral follicles with diameters of 2-8 mm in the ovaries were aspirated. The aspirated follicle fluids were examined under a stereo microscope, and the cumulus-oocyte complexes (COC) were collected and classified according to their structure. A, B, and C-quality oocytes were included in the in vitro embryo production process. After performing 69 OPUs on random days of the cycle, the number of oocytes per OPU was found to be 8.72, 6.32, and 6.85 in groups 1, 2, and 3, respectively (P < 0.05). The number of viable oocytes per OPU was 6.83, 4.64, and 4.65 in groups 1, 2, and 3, respectively (P < 0.05). The statistical difference between the first group and the other groups was significant for cleavage and blastocyst counts (P < 0.05).Discussion: All the negative effects of heat stress on animals resulted from the increased body temperature. Reproductive performance is adversely affected by high temperatures and humidity during periods of high ambient temperatures. Metabolic heat is released, and the heat load increases due to the metabolism of nutrients in cattle. Internal body temperature is regulated via the dissipation of metabolic heat to the environment. The amount of heat dissipated via conduction andconvection depends on the unit body weight, surface area, skin and coat color, difference in temperature gradient of the animal and ambient temperature, and humidity. In the present study, it was determined that the blastocyst development rates of the oocytes obtained in the warm season (>25°C [group 3]) were lower than those of the other groups. It was concluded that this may be because the oocytes developed under chronic heat stress in the animals, and several cycles were required to enhance oocyte quality and developmental potential. Additional studies are needed to investigate the response of oocytes obtained with OPU to heat stress during embryonic developmental stages and to determine the sensitivity and effects of embryonic tissue damage according to developmental stages. Based on the results of the present study, it was concludedthat performing OPU and in vitro embryo production (IVEP) when the ambient temperature is close to the thermoneutral limits may increase the blastocyst development rates. Keywords: blastocyst, heat stress, heifer, in vitro embryo production, oocyte quality, ovum pick-up.

Off-design operation of the dry-cooled supercritical CO2 power cycle

The supercritical CO2 recompression cycle (the ‘sCO2 cycle’) is highly efficient, scalable, simple, and compatible with dry cooling. Two scenarios where dry-cooled sCO2 cycles may operate off design are (1) during periods of high ambient temperature, and (2) when operating at part-load output (in load-following roles). Understanding sCO2 cycle off-design performance is essential for financial feasibility assessment, detailed design, and providing control system setpoints. Off-design performance can be maximised by exploiting the cycle’s pressure, temperature, and turbomachinery speed degrees of freedom. Several previous studies arbitrarily constrain these degrees of freedom, giving sub-optimal performance predictions. Other studies fail to consider CO2’s steep and non-linear property variations, leading to inaccurate results. To address these limitations, this work presents a detailed sCO2 cycle model, which captures property changes and component off-design behaviour. The model is used to systematically explore the off-design operating space, thus showing novel off-design performance trends and best operating strategies. Elevated ambient temperatures reduce power output more than efficiency, but this effect can be mitigated with appropriate operating strategies. At an ambient temperature of 40 °C (10 °C above design), design-point power output can be maintained with an 8.7% minimum turbine pressure increase, alongside compressor speed control. Alternatively, at this same temperature, design-point power output can be maintained with only a 4.4% (2 percentage point) efficiency reduction and a slightly higher (13.7%) turbine pressure increase. During turn-down, design-point efficiency can be maintained at 44% of design-point power output by using pressure and compressor speed control. Main compressor speed control alone is effective for above-design ambient temperatures, while dual compressor speed control provides significant benefits during turn-down. Compared to past sCO2 cycle studies, this work reports better off-design performance, which demonstrates the importance of off-design operating strategies and highlights the flexibility and potential of the cycle.

Thermal Mechanisms Preventing or Favoring Multiple Ovulations in Dairy Cattle.

Simple SummaryWhile cows are usually monovular, the incidence of dizygous twin births has recently increased considerably alongside increasing milk production. Genetic progress and improvements in nutrition and management practices have led to a continuous increase in milk yield and thus also to multiple ovulations and twin pregnancies. Twin pregnancies are undesirable as they seriously compromise the welfare of the cow and herd economy. A better understanding of the processes associated with multiple ovulations should help to reduce rates of twinning. During the stages of the sexual cycle, temperature gradients are established within the ovary and throughout the genital tract. Pre-ovulatory local cooling of the reproductive system favors male and female gamete maturation and subsequent fertilization. In fact, thermal mechanisms may prevent or favor multiple ovulations and thus twinning. The purpose of this review was to update this topic.While cows are predominantly monovular, over the past 30 years the incidence of multiple ovulations and thus twinning has increased considerably alongside milk production. Multiple pregnancies are not desirable as they negatively affect the health of cows and the herd economy. Although causal mechanisms associated with multiple ovulations have been extensively revised, the process of multiple ovulations is not well understood. Recent studies on the thermal biology of the reproductive system have shown how thermal mechanisms may prevent or favor multiple ovulations. This review focuses on this relationship between thermal dynamics and multiple pregnancies. Cooling of the pre-ovulatory follicle is able to regulate ovulation. In effect, pre-ovulatory local cooling of the female reproductive system favors male and female gamete maturation and promotes fertilization. Thermal stress is proposed here as a model of stress. Periods of high ambient temperature affect the processes of pre-ovulatory follicular cooling and multiple ovulations. While the ratio between unilateral and bilateral multiple pregnancies is normally close to one, under heat stress conditions, this ratio may be 1.4 favoring unilateral multiple pregnancies. A ratio approaching unity is here proposed as an indicator of cow wellbeing.

Potential Role of Amino Acids in the Adaptation of Chicks and Market-Age Broilers to Heat Stress.

Increased average air temperatures and more frequent and prolonged periods of high ambient temperature (HT) associated with global warming will increasingly affect worldwide poultry production. It is thus important to understand how HT impacts poultry physiology and to identify novel approaches to facilitate improved adaptation and thereby maximize poultry growth, health and welfare. Amino acids play a role in many physiological functions, including stress responses, and their relative demand and metabolism are altered tissue-specifically during exposure to HT. For instance, HT decreases plasma citrulline (Cit) in chicks and leucine (Leu) in the embryonic brain and liver. The physiological significance of these changes in amino acids may involve protection of the body from heat stress. Thus, numerous studies have focused on evaluating the effects of dietary administration of amino acids. It was found that oral l-Cit lowered body temperature and increased thermotolerance in layer chicks. When l-Leu was injected into fertile broiler eggs to examine the cause of reduction of Leu in embryos exposed to HT, in ovo feeding of l-Leu improved thermotolerance in broiler chicks. In ovo injection of l-Leu was also found to inhibit weight loss in market-age broilers exposed to chronic HT, giving rise to the possibility of developing a novel biotechnology aimed at minimizing the economic losses to poultry producers during summer heat stress. These findings and the significance of amino acid metabolism in chicks and market-age broilers under HT are summarized and discussed in this review.

Prospects of HSP70 as a genetic marker for thermo-tolerance and immuno-modulation in animals under climate change scenario.

Heat stress induced by long periods of high ambient temperature decreases animal productivity, leading to heavy economic losses. This devastating situation for livestock production is even becoming worse under the present climate change scenario. Strategies focused to breed animals with better thermo-tolerance and climatic resilience are keenly sought these days to mitigate impacts of heat stress especially in high input livestock production systems. The 70-kDa heat shock proteins (HSP70) are a protein family known for its potential role in thermo-tolerance and widely considered as cellular thermometers. HSP70 function as molecular chaperons and have major roles in cellular thermotolerance, apoptosis, immune-modulation and heat stress. Expression of HSP70 is controlled by various factors such as, intracellular pH, cyclic adenosine monophosphate (cyclic AMP), protein kinase C and intracellular free calcium, etc. Over expression of HSP70 has been observed under oxidative stress leading to scavenging of mitochondrial reactive oxygen species and protection of pulmonary endothelial barrier against bacterial toxins. Polymorphisms in flanking and promoter regions in HSP70 gene have shown association with heat tolerance, weaning weight, milk production, fertility and disease susceptibility in livestock. This review provides insight into pivotal roles of HSP70 which make it an ideal candidate genetic marker for selection of animals with better climate resilience, immune response and superior performance.

Coping with climate change: limited behavioral responses to hot weather in a tropical carnivore

Climate change is widely accepted to be one of the greatest threats to species globally. Identifying the species most at risk is, therefore, a conservation priority. Some species have the capacity to adapt to rising temperatures through changing their phenology, behavior, distribution, or physiology, and, therefore, may be more likely to persist under rising temperatures. Recent findings suggest that the African wild dog Lycaon pictus may be impacted by climate change, since reproductive success is consistently lower when pup-rearing coincides with periods of high ambient temperature. We used GPS collars, combined with generalized linear mixed-effects models, to assess wild dogs’ potential to adapt to high ambient temperatures through flexible timing of hunting behavior. On days with higher maximum temperatures, wild dogs showed lower daytime activity and greater nocturnal activity, although nocturnal activity did not fully balance the decrease in daytime activity, particularly during the denning period. Increases in nocturnal activity were confined mainly to moonlit nights, and were seldom observed when packs were raising pups. Our findings suggest that nocturnal activity helps this cursorial hunter to cope with high daytime temperatures. However, wild dogs appear not to use this coping strategy when they are raising pups, suggesting that their resource needs may not be fulfilled during the pup-rearing period. Given that moonlight availability—which will not change as the climate changes—constrains wild dogs’ nocturnal activity, the species may have insufficient behavioral plasticity to mitigate increasing diurnal temperatures. These findings raise concerns about climate change impacts on this endangered species, and highlight the need for behavior to be considered when assessing species’ vulnerability to climate change.

Design and Manual to Construct Rainout-Shelters for Climate Change Experiments in Agroecosystems

Climate change models predict reduced summer precipitations for most European countries, including more frequent and extreme summer droughts. Rainout-shelters which intercept part of the natural precipitation provide an effective tool to investigate effects of different precipitation levels on biodiversity and ecosystem functioning. In this study, we evaluate and describe in detail a fixed-location rainout shelter (2.5×2.5m) with partial interception of natural rainfall. We provide a complete parts list, a construction manual and detailed CAD drawings allowing to rebuild and use these shelters for rainfall manipulation studies. In addition, we describe a rainout-shelter control treatment giving the possibility to quantify and account for potential shelter artifacts. To test the rainout-shelters, we established the following three treatments each in eight winter wheat plots of the agricultural long-term farming system comparison trial DOK in Therwil (Switzerland): (1) A rainout-shelter with 65% interception of rainfall, (2) a rainout-shelter control without interception of rainfall, and (3) an ambient control. The rainout-shelter effectively excluded 64.9% of the ambient rainfall, which is very close to the a priori calculated exclusion of 65.1%. In comparison to the ambient control plots, gravimetric soil moisture decreased under the rainout-shelter by a maximum of 11.1 percentage points. Air temperature under the rainout-shelter differed little from the ambient control (−0.55◦C in 1.2m height and +0.19◦C in 0.1m height), whereas soil temperatures were slightly higher in periods of high ambient temperature (+1.02◦C), but remained basically unaffected in periods of low ambient temperature (+0.14◦C). A maximum edge effect of 0.75m defined a sampling area of 1 × 1m under the rainout-shelter. The rainout-shelters presented here, proved to sustain under heavy weather and they were well-suited to be used in agricultural fields where management operations require the removal of the rainout-shelters for management operations. Overall, the results confirmed the good performance of the presented rainout-shelters regarding rainout-shelter artifacts, predictable rain exclusion, and feasibility for experimental studies in agricultural fields.

Influence of dietary cation–anion difference in finishing diets fed to Holstein steers during periods of high ambient temperature on feedlot performance and digestive function

ABSTRACTOne hundred twenty-six Holstein steers (457.1 ± 27.5 kg BW) were used in a 127-d experiment to evaluate the influence of dietary cation–anion difference (DCAD) on growth performance and carcass characteristics. Treatments consisted of steam-flaked corn-based diets supplemented to provide DCAD of 34, 84 or 134 mEq/kg diet DM. There was no treatment effect (P > .20) on ADG, DMI, gain efficiency or dietary NE. Six Holstein steers (196 ± 3 kg) with cannulas in rumen and proximal duodenum were used in a replicated 3 × 3 Latin Square design to evaluated treatment effects on digestion characteristics. The DCAD did not affect (P > .20) ruminal or total digestion of OM, NDF, starch and N, or ruminal pH and VFA molar proportions. It is concluded that increasing DCAD of Holstein steers fed a conventional steam-flaked corn-based diet under conditions of high ambient temperature will not enhance growth performance.

Fecal Immunochemical Test (FIT) for Colon Cancer Screening: Variable Performance with Ambient Temperature.

Fecal immunochemical tests (FITs) are widely used in colorectal cancer (CRC) screening, but hemoglobin degradation, due to exposure of the collected sample to high temperatures, could reduce test sensitivity. We examined the relation of ambient temperature exposure with FIT positivity rate and sensitivity. This was a retrospective cohort study of patients 50 to 75 years in Kaiser Permanente Northern California's CRC screening program, which began mailing FIT kits annually to screen-eligible members in 2007. Primary outcomes were FIT positivity rate and sensitivity to detect CRC. Predictors were month, season, and daily ambient temperatures of test result dates based on US National Oceanic and Atmospheric Administration data. Patients (n = 472,542) completed 1,141,162 FITs. Weekly test positivity rate ranged from 2.6% to 8.0% (median, 4.4%) and varied significantly by month (June/July vs December/January rate ratio [RR] = 0.79, 95% confidence interval [CI], 0.76 to 0.83) and season. FIT sensitivity was lower in June/July (74.5%; 95% CI, 72.5 to 76.6) than January/December (78.9%; 95% CI, 77.0 to 80.7). FITs completed during high ambient temperatures had lower positivity rates and lower sensitivity. Changing kit design, specimen transportation practices, or avoiding periods of high ambient temperatures may help optimize FIT performance, but may also increase testing complexity and reduce patient adherence, requiring careful study.

Bowel Ischemia in Heat Stroke: A Rare Complication

Introduction: Exertional Heat Stroke (EHS) is one of the leading causes of death in young athletes. This is commonly seen in youngsters who engage in heavy exercise during periods of high ambient temperature. We report a case of a young female who developed bowel ischemia and shock liver after a marathon run on a warm summer afternoon. Case: A 27 y/o female was brought to the ER after she collapsed an hour into a marathon. At presentation she was hyperthermic with T of 40.2 °C, encephalopathic and hypotensive. She was rapidly cooled with IV cold normal saline and cooling blankets. Initial evaluation showed evidence of SIRS, lactic acidosis and rhabdomyolysis with acute kidney injury. Her mental status improved within a few hours of cooling and resuscitation. By the next day she developed bloody diarrhea and labs showed acute liver failure with elevated transaminases (ALT: 1484 AST:1217), and elevated PT & PTT, along with worsening of rhabdomyolysis with further elevation of creatine kinases (CK: 2213, CK-MB: 47.38). This was complicated by development of Disseminated Intravascular Coagulation (DIC) with acute thrombocytopenia, elevated D-Dimer and reduced Fibrinogen, and hemolysis. Gastroenterology and Hematology concluded that this was bowel ischemia, shock liver and DIC from Heat stroke. She was managed with aggressive IV fluid resuscitation and her symptoms resolved over the next two days. Following up in clinic two weeks after discharge, she was asymptomatic and her labs showed return of liver function, renal function and hemogram to baseline. Discussion: Exertional Heat illness is a continuum of illnesses arising from the body's inability to cope with heat during exertion, which range from heat cramps to life threatening Exertional Heat Stroke (EHS). Athletes performing intense exercise in high ambient temperature and humidity are at risk for EHS. Despite increased awareness in athletes and coaches, deaths related to EHS appear to be on the rise. EHS is a multisystem, life-threatening syndrome characterized by CNS dysfunction and end organ damage with high body temperatures. The complications of EHS are as a direct result of ischemia and oxidative & nitrosative stress which commonly include kidney injury, liver injury or rhabdomyolysis and CNS dysfunction (which ranges from disorientation and headache to seizure and coma). DIC has been reported in some severe cases but Intestinal complications are rare in EHS. Our patient had a global hypoperfusion state from EHS resulting in bowel ischemia that manifested as intestinal bleeding. Literature reveals one case where EHS lead to Colon perforation from bowel ischemia due to lack of timely intervention. Early recognition and timely management of EHS is crucial to prevent serious complications like bowel ischemia and colon perforation.

Effects of zinc sulfate pretreatment on heat tolerance of Bama miniature pig under high ambient temperature.

The aim of this study was to evaluate the heat tolerance of Bama miniature pigs under high ambient temperature (40°C) and Zn interactive functions during heat treatment (HT). Bama miniature pigs (male; n = 24; 6-mo old; BW = 10.79 ± 0.06 kg) were randomly allotted to 4 groups and were fed a basal diet or the basal diet supplemented with 1,500 mg of Zn (ZnSO4·H2O)/kg diet for 38 d. At 7 mo of age (d 30), the thermal neutral (TN) groups remained at 25°C, whereas the HT groups were exposed to ambient temperature at 40°C for 5 h daily for 8 consecutive days. Pigs in 4 groups were sacrificed on d 38. Individual rectal temperatures, skin temperatures, and breathing rates were recorded at 3 h after the onset of HT and the blood samples were collected immediately after HT on d 30, 34, and 38. Pigs fed diets with or without Zn doubled their breathing rates (P < 0.05) and increased body surface, scrotal, and rectal temperatures during HT on d 30, 34, and 38, respectively. Zinc supplementation increased BW gain (BWG; P < 0.05) during 38-d experiment period, and HT decreased BWG only from d 30 to 34 (P < 0.05). Heat treatment increased serum testosterone on d 30 (P < 0.05). Zinc supplementation decreased the heat-induced increase of testosterone in HT on d 30 and 34 (P < 0.05). The relative weight of liver increased in HT groups (P < 0.05). Zinc supplementation decreased the relative weights of spleen (P < 0.05) and testis (P < 0.01). The values of abnormal lymphocyte count and large unstained cell count declined approximately 5 times in groups of Zn supplementation, whereas Zn supplementation increased the values of red blood cell count, hemoglobin, hematocrit, mean corpuscular volume, and mean corpuscular hemoglobin. Zinc concentrations increased in serum, liver, kidney, epididymis, longissimus, hair, and feces in groups fed with Zn (P < 0.01). However, additional Zn decreased Zn concentrations in lung, spleen, and testis (P < 0.01). Moreover, HT decreased serum Zn concentrations (P < 0.01). In conclusion, Zn supplementation could be used to alleviate the decline of serum Zn during periods of high ambient temperatures. However, pretreated supplementation with pharmacological Zn did not promote heat tolerance but impacted the erythropoiesis, immunity, and reproductive organ development in Bama miniature pigs.

Influence of Feeding Enzymatically Hydrolyzed Yeast Cell Wall on Growth Performance and Digestive Function of Feedlot Cattle during Periods of Elevated Ambient Temperature.

In experiment 1, eighty crossbred steers (239±15 kg) were used in a 229-d experiment to evaluate the effects of increasing levels of enzymatically hydrolyzed yeast (EHY) cell wall in diets on growth performance feedlot cattle during periods of elevated ambient temperature. Treatments consisted of steam-flaked corn-based diets supplemented to provide 0, 1, 2, or 3 g EHY/hd/d. There were no effects on growth performance during the initial 139-d period. However, from d 139 to harvest, when 24-h temperature humidity index averaged 80, EHY increased dry matter intake (DMI) (linear effect, p<0.01) and average daily gain (ADG) (linear effect, p = 0.01). There were no treatment effects (p>0.10) on carcass characteristics. In experiment 2, four Holstein steers (292±5 kg) with cannulas in the rumen and proximal duodenum were used in a 4×4 Latin Square design experiment to evaluate treatments effects on characteristics of ruminal and total tract digestion in steers. There were no treatment effects (p>0.10) on ruminal pH, total volatile fatty acid, molar proportions of acetate, butyrate, or estimated methane production. Supplemental EHY decreased ruminal molar proportion of acetate (p = 0.08), increased molar proportion of propionate (p = 0.09), and decreased acetate:propionate molar ratio (p = 0.07) and estimated ruminal methane production (p = 0.09). It is concluded that supplemental EHY may enhance DMI and ADG of feedlot steers during periods of high ambient temperature. Supplemental EHY may also enhance ruminal fiber digestion and decrease ruminal acetate:propionate molar ratios in feedlot steers fed steam-flaked corn-based finishing diets.

Influence of feeding chromium-enriched enzymatically hydrolyzed yeast on growth performance, dietary energetics and carcass characteristics in feedlot cattle under conditions of high ambient temperature

Forty crossbred steers (245 ± 0.95 kg) were used in a 222-day feeding trial to assess the effects of a supplementation of chelated chromium-enhanced extract of enzymatically hydrolyzed yeast (Cr-EHY) on growth performance, dietary energetics and carcass characteristics in feedlot cattle finishing during high ambient temperatures. Treatments consisted of a steam-flaked corn-based diets supplemented with 0 or 0.4 g/kg of diet with Cr-EHY (0.3 g/kg of TruMax plus 0.1 g/kg of chelated Cr). Both dry matter intake (DMI) and climatic variables were measured weekly and the temperature humidity index (THI) was estimated. Daily maximal THI that exceeding a THI value of 72 was reached in 213 of the 222-day study (avg. THI = 75.24). During the initial 112-day period (including the receiving and diet transition phases), Cr-EHY increased average daily gain (ADG) (7%, P = 0.03). This effect was due to a tendency (P = 0.07) for increased DMI. There were no treatment effects on gain efficiency and dietary net energy (NE). Overall, however, there were no treatment effects on growth performance or dietary NE. Nevertheless, Cr-EHY supplementation had a modulating effect on carcass quality, decreasing carcass fat thickness (10%, P = 0.09, and increasing longissimus muscle area (7%, P < 0.01) and retail yield of boneless closely trimmed primal cuts (2%, P = 0.07). Results indicate that supplementation with a chelated chromium-enhanced extract of enzymatically hydrolyzed yeast can have beneficial effects on feed intake and daily weight gain, particularly during the initial receiving growing phase. It also appears to have a modulating effect on carcass quality, enhancing muscularity and reducing external fat. These results indicate that Cr supplementation has a modulating effect on carcass quality and may enhance DMI and corresponding ADG of feedlot cattle during periods of high ambient temperature.

Effect of lactation stage, its number, current milk performance and barn air temperature on laterality of Holstein dairy cows laying behaviour

The aim of this study was to determine effect of lactation stage and number, current milk performance and ambient temperature on laterality of dairy cows laying behaviour (i.e. preference of either left or right body side). The monitoring was performed at the University Training Farm in Žabčice, Czech Republic, (geographical coordinates 49° 0’4’’ N and 16° 36’ E, the altitude 179 m) within the six warmest months of the year 2010 (i.e. from 1 April 2010 to 30 September 2010). Observed were altogether 70 Holstein dairy cows with the average daily milk production of 34.48 kg of milk, which were kept in loose housing boxes with bedding (size of boxes: 2500 mm x 1250 mm). Animals were directly observed once a week (always at 9.00 a.m.). In the course of observation, the position of dairy cows in the barn was exactly recorded. In case of laying animals, it was recorded on which body side they were resting. Altogether 1,239 records of laying position of individual dairy cows were analysed and it was found out that the experimental animals preferred the left body side of their body (left and right laterality was observed in 671 and 568 animals, respectively). This left-side laterality was more frequent among animals in later stages of lactation (more than 200 days) and also in dairy cows with a higher number of lactations (4th and more). Dairy cows with a below-average milk performance rested on their left body side more frequently than those with a high level of milk production. As compared with average and/or low air temperatures, the left laterality was more frequent in periods of high ambient temperatures.

Interactions of shade and feeding management on feedlot performance of crossbred steers during seasonal periods of high ambient temperature

Three experiments were conducted to evaluate the influence of shade and feeding management on performance of crossbred steers during periods of high ambient temperature. Exp. 1 evaluated the influence of shade (0 vs. 3.3 m2/steer) on growth performance and dietary NE. Air temperature and humidity averaged 29.7 °C and 44%, respectively. Shade improved DMI (6%, P 0.20) ADG but increased (4%, P < 0.10) dietary NE. It is concluded that both provision of shade and management of feeding schedule are effective tools for improving growth-performance and efficiency of energy use in feedlot cattle.

Evaporative Cooling of Gas Turbine Engines

There are numerous gas turbine applications in power generation and mechanical drive service where power drop during the periods of high ambient temperature has a very detrimental effect on the production of power or process throughput. Several geographical locations experience very high temperatures with low coincident relative humidities. In such cases media evaporative cooling can be effectively applied as a low cost power augmentation technique. Several misconceptions exist regarding their applicability to evaporative cooling, the most prevalent being that they can only be applied in extremely dry regions. This paper provides a detailed treatment of media evaporative cooling, discussing aspects that would be of value to an end user, including selection of climatic design points, constructional features of evaporative coolers, thermodynamic aspects of its effect on gas turbines, and approaches to improve reliability. It is hoped that this paper will be of value to plant designers, engineering companies, and operating companies that are considering the use of media evaporative cooling.

Effects of adjustable and stationary fans with misters on core body temperature and lying behavior of lactating dairy cows in a semiarid climate

Cows readily seek shade to reduce solar heat load during periods of high ambient temperature. Typically, auxiliary cooling systems are oriented to maximize cooling for shaded cows. However, when a shade structure is oriented north-south, stationary fan and mister cooling systems are unable to track shade as the sun’s angle shifts throughout the day, and thus can become ineffective. The FlipFan Dairy Cooling System (Schaefer Ventilation Equipment, Sauk Rapids, MN) employs fans and misters that follow shade and compensate for wind speed by rotating on a horizontal axis. Multiparous, lactating Holstein cows (n=144) on a commercial dairy in Arizona were cooled by a fixed system comprised of stationary fans and misters acting as control or the adjustable FlipFan operated for 16.5 h/d (0830 to 0100 h). Core body temperatures (CBT) of 64 cows (4 pens/treatment; 8 cows/pen; 6d) and lying behavior of 144 cows (4 pens/treatment; 18 cows/pen; 5d) were collected by intravaginal and leg data loggers, respectively. Cows were balanced by milk production, blocked by days in milk, and randomly assigned to pen within block. Pen was the experimental unit. In a second experiment, isothermal maps were developed using a fixed system of thermal data loggers arranged in the shaded areas of the pens at different times of day and were analyzed for differences in the temperature-humidity index (THI) achieved by each cooling treatment. Ambient conditions consisted of a mean temperature of 33.0°C, mean relative humidity of 40.3%, and mean THI of 80.2. Mean 24-h CBT for FlipFan was lower than control (38.9 vs. 39.1±0.04°C). A treatment × time interaction was observed in which CBT of FlipFan was 0.4°C lower than control from 0600 to 0800h and 1500 to 1600h. Cows cooled by FlipFan spent more time lying down compared with those cooled by control (9.5 vs. 8.6 h/d). Cows under FlipFan had more frequent lying bouts than did those under control (12.8 vs. 10.7 bouts/d). Lower CBT and decreased standing time are consistent with the findings of other studies when ambient heat load was reduced. In the second experiment, the FlipFan system achieved a lower THI in the morning and evening (5.9 and 1.7%, respectively), and the THI also tended to be 0.8% lower in the afternoon compared with that of control. Results indicate that FlipFan is more effective than a stationary fan and mister system at decreasing CBT, increasing lying time and bouts, and providing a more desirable microenvironment for cows throughout the day in a semiarid environment.

Effect of transportation during periods of high ambient temperature on physiologic and behavioral indices of beef heifers

To determine the effect of transportation during periods of high ambient temperature on physiologic and behavioral indices of beef heifers. 20 heifers (mean body weight, 217.8 kg). Ten heifers were transported 518 km when the maximum ambient temperature was ≥ 32.2°C while the other 10 heifers served as untransported controls. Blood samples were collected from transported heifers at predetermined intervals during the transportation period. For all heifers, body weights, nasal and rectal temperatures, and behavioral indices were measured at predetermined intervals for 3 days after transportation. A week later, the entire process was repeated such that each group was transported twice and served as the control twice. Transported heifers spent more time near the hay feeder on the day of transportation, had lower nasal and rectal temperatures for 24 hours after transportation, and spent more time lying down for 2 days after transportation, compared with those indices for control heifers. Eight hours after transportation, the weight of transported heifers decreased 6%, whereas that of control heifers increased 0.6%. At 48 hours after initiation of transportation, weight, rectal temperature, and time spent at various pen locations did not differ between transported and control heifers. Cortisol concentrations were higher 4 hours after initiation of transportation, compared with those determined just prior to transportation. Results indicated transportation during periods of high ambient temperatures caused transient changes in physiologic and behavioral indices of beef heifers.