Influence of thermal heat load accumulation on daily rumination time of lactating Holstein cows in a zone with temperate climate.

In the future, conflicts between animal welfare and climate change will gradually intensify. In the present study, we investigated the daily rumination time (RT) of lactating Holstein-Friesian cows in a zone with temperate climate and the effects of heat load duration and heat load intensity. Responses of individual cows to heat load were assessed, adjusting for milk yield, lactation number, days in milk as well as reproductive status and season. A total of 27,149 data points from 183 cows in a naturally ventilated barn in Brandenburg, Germany, were collected from June 2015 to May 2017. Ambient temperature and relative humidity were recorded at eight positions inside the barn every 5 min, and the temperature-humidity index (THI) was calculated. Based on THI, the degree of heat load was determined, using critical thresholds of THI = 68, 72, and 80. Daily RT was measured with a microphone-based sensor system (collar) on the cow's neck. The analysis models included autocorrelations in time series as well as individual cow-related effects. With each 5 min exposure to contemporaneous heat load, a decrease of approximately 1.17 min d-1 in RT per cow from non-heat stress to heat stress conditions by exceeding THI ≥68 (p < 0.01). This effect was intensified by exceeding the critical THI thresholds of 68 and 72. As heat load duration and intensity increased, daily RT decreased in comparison to daily RT under non-stress conditions. High-yielding (>38.4 kg milk/day) cows were more influenced in rumination time than low-yielding (≤28.8 kg milk/day) cows. With moderate contemporaneous heat load, RT decreased by 0.14 min d-1 per 5 min in high-yielding cows compared to low-yielding cows under moderate heat load. A decrease of 0.1 min d-1 was found in daily RT of mid-yielding cows. However, the delayed effects of heat load (one to three days after the heat stress event) were associated with days in milk and reproduction status. When the heat load duration lasted for several days, the responses were less pronounced than the impacts of contemporaneous heat load (when the heat stress event lasted for one day). Delayed mild heat load resulted in an increase in RT by 0.13 min d-1 in lactating cows ≤60 DIM. This was also found with delayed moderate heat load. Lactating cows ≤60 DIM showed a rise of 0.09 min d-1 in RT. RT also showed interactions with reproduction status of cows under delayed moderate heat stress. Lactating cows with ≤180 days of pregnancy showed an increase of 0.61 min d-1 in RT. Similarly, cows with >180 days of pregnancy had 0.64 min d-1 more RT compared to non-pregnant cows. Further analysis with higher temporal resolution of RT than data accumulation in 24-h blocks as well as the assessment of the correlation between feed composition, intake and rumination will elucidate the influence of heat load on daily RT.

Improvements of weaned pigs barn hygiene to reduce the spread of antimicrobial resistance.

The spread of antimicrobial resistance (AMR) in animal husbandry is usually attributed to the use of antibiotics and poor hygiene and biosecurity. We therefore conducted experimental trials to improve hygiene management in weaned pig houses and assessed the impact on the spread. For each of the two groups examined, the experimental group (EG) and the control group (CG), three replicate batches of piglets from the same pig breeder, kept in pre-cleaned flat decks, were analyzed. In the flat decks of the experimental groups, the hygiene conditions (cleaning, disinfection, dust removal and fly control) were improved, while regular hygiene measures were carried out in the control groups. The occurrence and spread of AMR were determined in Escherichia coli (E. coli; resistance indicator) using cultivation-dependent (CFU) and -independent (qPCR) methods as well as whole genome sequencing of isolates in samples of various origins, including feces, flies, feed, dust and swabs. Surprisingly, there were no significant differences (p > 0.05) in the prevalence of resistant E. coli between the flat decks managed with conventional techniques and those managed with improved techniques. Selective cultivation delivered ampicillin- and sulfonamide-resistant E. coli proportions of up to 100% and 1.2%, respectively. While 0.5% E. coli resistant to cefotaxime and no ciprofloxacin resistance were detected. There was a significant difference (p < 0.01) in the abundance of the blaTEM-1 gene in fecal samples between EG and CG groups. The colonization of piglets with resistant pathogens before arrival, the movement of flies in the barn and the treatment of bacterial infections with antibiotics obscured the effects of hygiene improvement. Biocide tolerance tests showed no development of resistance to the farm regular disinfectant. Managing hygiene alone was insufficient for reducing antimicrobial resistances in piglet rearing. We conclude that the complex factors contributing to the presence and distribution of AMR in piglet barns underscore the necessity for a comprehensive management strategy.

Effects of tasipimidine premedication with and without methadone and dexmedetomidine on cardiovascular variables during propofol-isoflurane anaesthesia in Beagle dogs.

OBJECTIVE: To evaluate cardiovascular effects of oral tasipimidine on propofol-isoflurane anaesthesia with or without methadone and dexmedetomidine at equianaesthetic levels. STUDY DESIGN: Prospective, placebo-controlled, blinded, experimental trial. ANIMALS: A group of seven adult Beagle dogs weighing (mean ± standard deviation) 12.4 ± 2.6 kg and a mean age of 20.6 ± 1 months. METHODS: The dogs underwent four treatments 60 minutes before induction of anaesthesia with propofol. PP: placebo orally and placebo (NaCl 0.9%) intravenously (IV); TP: tasipimidine 30 µg kg-1 orally and placebo IV; TMP: tasipimidine 30 µg kg-1 orally and methadone 0.2 mg kg-1 IV; and TMPD: tasipimidine 30 µg kg-1 orally with methadone 0.2 mg kg-1 and dexmedetomidine 1 µg kg-1 IV followed by 1 µg kg-1 hour-1. Isoflurane in oxygen was maintained for 120 minutes at 1.2 individual minimum alveolar concentration preventing motor movement. Cardiac output (CO), tissue blood flow (tbf), tissue oxygen saturation (stO2) and relative haemoglobin content were determined. Arterial and mixed venous blood gases, arterial and pulmonary artery pressures and heart rate (HR) were measured at baseline; 60 minutes after oral premedication; 5 minutes after IV premedication; 15, 30, 60, 90 and 120 minutes after propofol injection; and 30 minutes after switching the vaporiser off. Data were analysed by two-way anova for repeated measures; p < 0.05. RESULTS: Tasipimidine induced a significant 20-30% reduction in HR and CO with decreases in MAP (10-15%), tbf (40%) and stO2 (43%). Blood pressure and oxygenation variables were mainly influenced by propofol-isoflurane-oxygen anaesthesia, preceded by short-lived alterations related to IV methadone and dexmedetomidine. CONCLUSIONS AND CLINICAL RELEVANCE: Tasipimidine induced mild to moderate cardiovascular depression. It can be incorporated into a common anaesthetic protocol without detrimental effects in healthy dogs, when anaesthetics are administered to effect and cardiorespiratory function is monitored.

Anaesthetic-sparing effect of the anxiolytic drug tasipimidine in Beagle dogs.

OBJECTIVE: To evaluate the effect of oral tasipimidine on dog handling, ease of catheter placement and propofol and isoflurane requirements for anaesthesia. STUDY DESIGN: Placebo-controlled, randomized, blinded, experimental trial. ANIMALS: A group of seven adult Beagle dogs weighing (mean ± standard deviation) 13.1 ± 2.7 kg with a mean age of 18.6 ± 1 months. METHODS: The dogs underwent four treatments before induction of anaesthesia with propofol. PP: placebo orally (PO) 60 minutes before induction of anaesthesia followed by placebo (NaCl 0.9%) intravenously (IV). TP: tasipimidine 30 µg kg-1 (PO) 60 minutes before induction of anaesthesia followed by placebo (NaCl 0.9%) IV. TMP: tasipimidine 30 µg kg-1 PO 60 minutes before induction of anaesthesia followed by methadone 0.2 mg kg-1 IV. TMPD: tasipimidine 30 µg kg-1 PO 60 minutes before induction of anaesthesia followed by methadone 0.2 mg kg-1 and dexmedetomidine 1 µg kg-1 IV followed by a dexmedetomidine constant rate infusion of 1 µg kg-1 hour-1. Sedation, response to catheter placement, intubation quality, time to loss of consciousness, time to intubation, required dose of propofol and minimum alveolar isoflurane concentration preventing motor movement (MACNM) were determined. A mixed-model analysis or the Friedman and Mann-Whitney test were used; p-value < 0.05. RESULTS: Response to catheter placement did not differ between treatments. Tasipimidine alone reduced the propofol dose by 30%. Addition of methadone or methadone and dexmedetomidine reduced the propofol dose by 48% and 50%, respectively. Isoflurane MACNM was reduced by 19% in tasipimidine-medicated dogs, whereas in combination with methadone or methadone and dexmedetomidine, isoflurane MACNM was reduced by 35%. CONCLUSIONS AND CLINICAL RELEVANCE: An anxiolytic dose of tasipimidine induced mild signs of sedation in dogs and reduced propofol and isoflurane requirements to induce and maintain anaesthesia, which needs to be considered in an anaesthetic plan.

Evaluation of a Respiration Rate Sensor for Recording Tidal Volume in Calves under Field Conditions.

In the assessment of pulmonary function in health and disease, both respiration rate (RR) and tidal volume (Vt) are fundamental parameters of spontaneous breathing. The aim of this study was to evaluate whether an RR sensor, which was previously developed for cattle, is suitable for additional measurements of Vt in calves. This new method would offer the opportunity to measure Vt continuously in freely moving animals. To measure Vt noninvasively, the application of a Lilly-type pneumotachograph implanted in the impulse oscillometry system (IOS) was used as the gold standard method. For this purpose, we applied both measuring devices in different orders successively, for 2 days on 10 healthy calves. However, the Vt equivalent (RR sensor) could not be converted into a true volume in mL or L. For a reliable recording of the Vt equivalent, a technical revision of the RR sensor excluding artifacts is required. In conclusion, converting the pressure signal of the RR sensor into a flow equivalent, and subsequently into a volume equivalent, by a comprehensive analysis, provides the basis for further improvement of the measuring system.

Assessment of the biochemical methane potential of in-house and outdoor stored pig and dairy cow manure by evaluating chemical composition and storage conditions.

Biogas production is a suitable option for producing energy from dairy and pig manure types. During manure storage, organic matter degradation results in methane emissions decreasing the potential biogas yield. The present research advances the understanding of the biochemical methane potential (BMP) and the chemical characteristics of manure collected year-round from sequential stages of the liquid manure management chain of commercial dairy cow and pig farms. To this end, manure samples from six livestock farms in Germany were analyzed. The results showed that changes in chemical composition during storage led to a 20.5% decrease in the BMP of dairy manure from the barn to outdoor storage. For fattening pig manure samples, there was a 39.5% decrease in the BMP from intermediate to outdoor storage. An analysis of BMP according to manure age showed that pig manure degrades faster than dairy manure; the importance of promptly feeding manure to the biogas plant in order to avoid significant CH4 emission losses and reduction in energy producing capacity was highlighted. The best BMP predictors for dairy manure were the contents of dry matter, volatile solids and lignin, whereas best BMP predictors for pig manure were dry matter and volatile fatty acid (VFA) content. Prediction models performed well for samples from outdoor storages; refinements for predicting BMP of less aged samples presenting lower chemical variability would be necessary.

Bacterial genome sequencing tracks the housefly-associated dispersal of fluoroquinolone- and cephalosporin-resistant Escherichia coli from a pig farm.

The regular use of antimicrobials in livestock production selects for antimicrobial resistance. The potential impact of this practice on human health needs to be studied in more detail, including the role of the environment for the persistence and transmission of antimicrobial-resistant bacteria. During an investigation of a pig farm and its surroundings in Brandenburg, Germany, we detected abundant cephalosporin- and fluoroquinolone-resistant Escherichia coli in pig faeces, sedimented dust, and house flies (Musca domestica). Genome sequencing of E. coli isolates revealed large phylogenetic diversity and plasmid-borne extended-spectrum beta lactamase (ESBL) genes CTX-M-1 in multiple strains. [Correction added on 28 February 2023, after first online publication: In the preceding sentence, 'and TEM-1' was previously included but has been deleted in this version.] Close genomic relationships indicated frequent transmission of antimicrobial-resistant E. coli between pigs from different herds and across buildings of the farm and suggested dust and flies as vectors for dissemination of faecal pathogens. Strikingly, we repeatedly recovered E. coli from flies collected up to 2 km away from the source, whose genome sequences were identical or closely related to those from pig faeces isolates, indicating the fly-associated transport of diverse ESBL-producing E. coli from the pig farm into urban habitation areas. The observed proximity of contaminated flies to human households poses a risk of transmission of antimicrobial-resistant enteric pathogens from livestock to man.

Thermodynamic assessment of heat stress in dairy cattle: lessons from human biometeorology.

A versatile meteorological index for predicting heat stress in dairy cattle remains elusive. Despite numerous attempts at developing such indices and widespread use of some, there is growing skepticism about the accuracy and adequacy of the existing indices as well as the general statistical approach used to develop them. At the same time, precision farming of high-yielding animals in a drastically changing climate calls for more effective prediction and alleviation of heat stress. The present paper revisits classical work on human biometeorology, particularly the apparent temperature scale, to draw inspiration for advancing research on heat stress in dairy cattle. The importance of a detailed, mechanistic understanding of heat transfer and thermoregulation is demonstrated and reiterated. A model from the literature is used to construct a framework for identifying and characterizing conditions of potential heat stress. New parameters are proposed to translate the heat flux calculations based on heat-balance models into more tangible and more useful meteorological indices, including an apparent temperature for cattle and a thermoregulatory exhaustion index. A validation gap in the literature is identified as the main hindrance to the further development and deployment of heat-balance models. Recommendations are presented for systematically addressing this gap in particular and continuing research within the proposed framework in general.

The Role of Streptococcus spp. in Bovine Mastitis.

The Streptococcus genus belongs to one of the major pathogen groups inducing bovine mastitis. In the dairy industry, mastitis is the most common and costly disease. It not only negatively impacts economic profit due to milk losses and therapy costs, but it is an important animal health and welfare issue as well. This review describes a classification, reservoirs, and frequencies of the most relevant Streptococcus species inducing bovine mastitis (S. agalactiae, S. dysgalactiae and S. uberis). Host and environmental factors influencing mastitis susceptibility and infection rates will be discussed, because it has been indicated that Streptococcus herd prevalence is much higher than mastitis rates. After infection, we report the sequence of cow immune reactions and differences in virulence factors of the main Streptococcus species. Different mastitis detection techniques together with possible conventional and alternative therapies are described. The standard approach treating streptococcal mastitis is the application of ß-lactam antibiotics. In streptococci, increased antimicrobial resistance rates were identified against enrofloxacin, tetracycline, and erythromycin. At the end, control and prevention measures will be considered, including vaccination, hygiene plan, and further interventions. It is the aim of this review to estimate the contribution and to provide detailed knowledge about the role of the Streptococcus genus in bovine mastitis.

Particulate matter emissions during field application of poultry manure - The influence of moisture content and treatment.

Along with industry and transportation, agriculture is one of the main sources of primary particulate matter (PM) emissions worldwide. Bioaerosol formation and PM release during livestock manure field application and the associated threats to environmental and human health are rarely investigated. In the temperate climate zone, field fertilization with manure seasonally contributes to local PM air pollution regularly twice per year (spring and autumn). Measurements in a wind tunnel, in the field and computational fluid dynamics (CFD) simulations were performed to analyze PM aerosolization during poultry manure application and the influence of manure moisture content and treatment. A positive correlation between manure dry matter content (DM) and PM release was observed. Therefore, treatments strongly increasing the DM of poultry manure should be avoided. However, high manure DM led to reduced microbial abundance and, therefore, to a lower risk of environmental pathogen dispersion. Considering the findings of PM and microbial measurements, the optimal poultry manure DM range for field fertilization was identified as 50-70%. Maximum PM10 concentrations of approx. 10 mg per m3 of air were measured during the spreading of dried manure (DM 80%), a concentration that is classified as strongly harmful. The modeling of PM aerosolization processes indicated a low health risk beyond a distance of 400 m from the manure application source. The detailed knowledge about PM aerosolization during manure field application was improved with this study, enabling manure management optimization for lower PM aerosolization and pathogenic release into the environment.

Agricultural fertilization with poultry manure results in persistent environmental contamination with the pathogen Clostridioides difficile.

During a field experiment applying broiler manure for fertilization of agricultural land, we detected viable Clostridioides (also known as Clostridium) difficile in broiler faeces, manure, dust and fertilized soil. A large diversity of toxigenic C. difficile isolates was recovered, including PCR ribotypes common from human disease. Genomic relatedness of C. difficile isolates from dust and from soil, recovered more than 2 years after fertilization, traced their origins to the specific chicken farm that had delivered the manure. We present evidence of long-term contamination of agricultural soil with manure-derived C. difficile and demonstrate the potential for airborne dispersal of C. difficile through dust emissions during manure application. Clostridioides genome sequences virtually identical to those from manure had been recovered from chicken meat and from human infections in previous studies, suggesting broiler-associated C. difficile are capable of zoonotic transmission.

Low airborne tenacity and spread of ESBL-/AmpC-producing Escherichia coli from fertilized soil by wind erosion.

ESBL-/AmpC-producing Escherichia coli from organic fertilizers were previously detected on soil surfaces of arable land and might be emitted by wind erosion. To investigate this potential environmental transmission path, we exposed ESBL-/AmpC-positive chicken litter, incorporated in agricultural soils, to different wind velocities in a wind tunnel and took air samples for microbiological analysis. No data exist concerning the airborne tenacity of ESBL-/AmpC-producing E. coli. Therefore, we explored the tenacity of two ESBL/AmpC E. coli strains and E. coli K12 in aerosol chamber experiments at different environmental conditions. In the wind tunnel, ESBL/AmpC-producing E. coli were detected in none of the air samples (n = 66). Non-resistant E. coli were qualitatively detected in 40.7% of air samples taken at wind velocities exceeding 7.3 m s-1 . Significantly increased emission of total viable bacteria with increasing wind velocity was observed. In the aerosol chamber trials, recovery rates of airborne E. coli ranged from 0.003% to 2.8%, indicating a low airborne tenacity. Concluding, an emission of ESBL/AmpC E. coli by wind erosion in relevant concentrations appears unlikely because of the low concentration in chicken litter compared with non-resistant E. coli and their low airborne tenacity, proven in the aerosol chamber trials.

Methane emissions from the storage of liquid dairy manure: Influences of season, temperature and storage duration.

Methane emissions from livestock manure are primary contributors to GHG emissions from agriculture and options for their mitigation must be found. This paper presents the results of a study on methane emissions from stored liquid dairy cow manure during summer and winter storage periods. Manure from the summer and winter season was stored under controlled conditions in barrels at ambient temperature to simulate manure storage conditions. Methane emissions from the manure samples from the winter season were measured in two time periods: 0 to 69 and 0 to 139 days. For the summer storage period, the experiments covered four time periods: from 0 to 70, 0 to 138, 0 to 209, and 0 to 279 continuous days, with probing every 10 weeks. Additionally, at the end of all storage experiments, samples were placed into eudiometer batch digesters, and their methane emissions were measured at 20 °C for another 60 days to investigate the potential effect of the aging of the liquid manure on its methane emissions. The experiment showed that the methane emissions from manure stored in summer were considerably higher than those from manure stored in winter. CH4 production started after approximately one month, reaching values of 0.061 kg CH4 kg-1 Volatile Solid (VS) and achieving high total emissions of 0.148 kg CH4 kg-1 VS (40 weeks). In winter, the highest emissions level was 0.0011 kg CH4 kg-1 VS (20 weeks). The outcomes of these experimental measurements can be used to suggest strategies for mitigating methane emissions from manure storage.

Direct Measurements of the Volume Flow Rate and Emissions in a Large Naturally Ventilated Building.

The direct measurement of emissions from naturally ventilated dairy barns is challenging due to their large openings and the turbulent and unsteady airflow at the inlets and outlets. The aim of this study was to quantify the impacts of the number and positions of sensors on the estimation of volume flow rate and emissions. High resolution measurements of a naturally ventilated scaled building model in an atmospheric boundary layer wind tunnel were done. Tracer gas was released inside the model and measured at the outlet area, using a fast flame ionization detector (FFID). Additionally, the normal velocity on the area was measured using laser Doppler anemometry (LDA). In total, for a matrix of 65 × 4 sensor positions, the mean normal velocities and the mean concentrations were measured and used to calculate the volume flow rate and the emissions. This dataset was used as a reference to assess the accuracy while systematically reducing the number of sensors and varying the positions of them. The results showed systematic errors in the emission estimation up to +97%, when measurements of concentration and velocity were done at one constant height. This error could be lowered under 5%, when the concentrations were measured as a vertical composite sample.

Airborne bacterial emission fluxes from manure-fertilized agricultural soil.

This is the first study to quantify the dependence on wind velocity of airborne bacterial emission fluxes from soil. It demonstrates that manure bacteria get aerosolized from fertilized soil more easily than soil bacteria, and it applies bacterial genomic sequencing for the first time to trace environmental faecal contamination back to its source in the chicken barn. We report quantitative, airborne emission fluxes of bacteria during and following the fertilization of agricultural soil with manure from broiler chickens. During the fertilization process, the concentration of airborne bacteria culturable on blood agar medium increased more than 600 000-fold, and 1 m3 of air carried 2.9 × 105 viable enterococci, i.e. indicators of faecal contamination which had been undetectable in background air samples. Trajectory modelling suggested that atmospheric residence times and dispersion pathways were dependent on the time of day at which fertilization was performed. Measurements in a wind tunnel indicated that airborne bacterial emission fluxes from freshly fertilized soil under local climatic conditions on average were 100-fold higher than a previous estimate of average emissions from land. Faecal bacteria collected from soil and dust up to seven weeks after fertilization could be traced to their origins in the poultry barn by genomic sequencing. Comparative analyses of 16S rRNA gene sequences from manure, soil and dust showed that manure bacteria got aerosolized preferably, likely due to their attachment to low-density manure particles. Our data show that fertilization with manure may cause substantial increases of bacterial emissions from agricultural land. After mechanical incorporation of manure into soil, however, the associated risk of airborne infection is low.

Functional relationship of particulate matter (PM) emissions, animal species, and moisture content during manure application.

Livestock manure is recycled to agricultural land as organic fertilizer. Due to the extensive usage of antibiotics in conventional animal farming, antibiotic-resistant bacteria are highly prevalent in feces and manure. The spread of wind-driven particulate matter (PM) with potentially associated harmful bacteria through manure application may pose a threat to environmental and human health. We studied whether PM was aerosolized during the application of solid and dried livestock manure and the functional relationship between PM release, manure dry matter content (DM), treatment and animal species. In parallel, manure and resulting PM were investigated for the survival of pathogenic and antibiotic-resistant bacterial species. The results showed that from manure with a higher DM smaller particles were generated and more PM was emitted. A positive correlation between manure DM and PM aerosolization rate was observed. There was a species-dependent critical dryness level (poultry: 60% DM, pig: 80% DM) where manure began to release PM into the environment. The maximum PM emission potentials were 1 and 3 kg t-1 of applied poultry and pig manure, respectively. Dried manure and resulting PM contained strongly reduced amounts of investigated pathogenic and antibiotic-resistant microorganisms compared to fresh samples. An optimal manure DM regarding low PM emissions and reduced pathogen viability was defined from our results, which was 55-70% DM for poultry manure and 75-85% DM for pig manure. The novel findings of this study increase our detailed understanding and basic knowledge on manure PM emissions and enable optimization of manure management, aiming a manure DM that reduces PM emissions and pathogenic release into the environment.

Daily rumination time of lactating dairy cows under heat stress conditions.

The dairy industry in regions with moderate climates, such as Central Europe, will be increasingly challenged in the future by climate change. The problem of heat stress will especially affect dairy husbandry in naturally ventilated barns (NVB). The approach of the study was to determine a heat stress threshold of the average daily temperature-humidity index (THI) that results in changes in the daily rumination time (RT) of lactating, high-yielding cows. The data set was composed of a high sample size of 183 cows and long-duration measurements of 21240 daily observations over two years from June 2015 to May 2017, which were collected in an NVB in Groß Kreutz, Germany. The THI was calculated in 5-min intervals by data from several sensors in different positions inside the barn. Additionally, every cow from the herd of an average of 53 cows in the experimental procedure was wearing a neck collar with a Lely Qwes HR system that provided the RT 24 h a day (12 2-h recordings were summarized). The study showed that heat stress also negatively influenced RT in moderate climates. The heat stress threshold of 52 THI was determined by broken-stick regression and indicated changes of RT of lactating dairy cows in Germany. During the experimental period, the heat stress threshold for RT was reached from April to September for up to 720 h per month. The changes in RT to the heat stress threshold will be affected by cows' characteristics. Therefore, we considered several cow-related factors, such as milk yield (MY), lactation number (LN), lactation stage (days in milk, or DIM) and pregnancy stage (P) to better understand cows' individual reactions to heat stress. Multiparous, high-yielding cows in later lactation stages are potentially more strongly affected than other cows.

Critical THI thresholds based on the physiological parameters of lactating dairy cows.

The severity of heat stress conditions in high-yielding dairy cows is currently underestimated. The present study aimed to determine the heat load threshold of the temperature-humidity index (THI) on physiological parameters of lactating Holstein-Friesian cows under a continental climatic zone in Germany. Physiological parameter measurements, such as respiration rate (RR), measured hourly, and heart rate (HR) and rectal temperature (RT), both measured twice daily, were performed in a total of 139 multiparous cows on three randomly chosen measurement days per week. In addition, the ambient temperature and relative humidity of the barn were recorded every 5 min to calculate the current THI. The physiological parameter data were linked to the THI, and the heat load thresholds were determined using the broken-stick model. The heat load duration effect of each physiological parameter was obtained by regression analysis. Considering the increases in the physiological parameters, our study provided reliable data to determine heat load thresholds for lactating high-yielding dairy cows in a moderate climatic zone. The heat load threshold could be determined for RR in standing cows (THI = 70) and lying cows (THI = 65) and for HR (THI = 72) and RT (THI = 70) in standing cows. The heat load duration also demonstrated a significant effect on the increases in physiological parameters among dairy cows. In particular, the present study enabled a strategy to be devised to initiate heat mitigation in high-yielding dairy cows when they are exposed to THIs above 65.

Effects of the C/N ratio and moisture content on the survival of ESBL-producing Escherichia coli during chicken manure composting.

Antibiotic-resistant bacteria are a threat to human and animal health. In recent years, the presence of extended-spectrum-ß-lactamase (ESBL)-producing Escherichia (E.) coli in chicken manure, which is used as organic fertilizer, is a concern. The aim of the present study was to determine the effects of the carbon/nitrogen (C/N) ratio and moisture content (MC) on the survival of ESBL-producing E. coli during laboratory-scale composting of chicken manure. Nine different compost mixtures were enriched with an ESBL-producing E. coli strain to an initial concentration of 7 log10 CFU/g, and the number of E. coli, temperature, and chemical conditions during composting were determined. The fastest decrease in E. coli occurred for all mixtures with a C/N ratio of 10:1. Additionally, dry mixtures with an MC of 20% and a C/N ratio of either 10:1 or 40:1 exhibited faster reductions in E. coli than the moist mixtures did, despite having lower maximum temperatures within the bioreactors. The decimal reduction times ranged from 0.27 days in a mixture with a C/N ratio of 10:1 and 40% MC to 4.82 days in a mixture with a C/N ratio of 40:1 and 40% MC. Both the C/N ratio and MC had a significant effect on the number of ESBL-producing E. coli and on temperature development; the C/N ratio additionally affected the pH value and content of ammoniacal nitrogen during chicken manure composting. The results of this study demonstrate a considerable range of mechanisms involved in the inactivation of E. coli during chicken manure composting.

Cow individual activity response to the accumulation of heat load duration.

In the course of predicted climate change, the welfare of dairy cows and heat load to which they are exposed have become increasingly important even under moderate climate conditions. The objective of this study was to investigate the cow individual activity response to heat load in terms of the heat load duration and intensity in lactating, high-yielding Holstein-Friesian cows in a moderate climate zone. The study was conducted from June 2015 to April 2017 in a naturally ventilated barn in Brandenburg, Germany. The determined temperature-humidity index (THI) inside the barn was used to define the heat load. The heat load was characterized by the average daily THI as well as the duration and intensity of the defined THI levels. In addition to the heat load on the measurement day, we studied the cow individual activity response to the heat load accumulated over the three days preceding the measurement day. The activity of the cows (n = 196) was measured by accelerometers and described the resting behavior and the number of steps per cow and day. The analysis models included autocorrelations in time series as well as individual cow factors. An increase in the duration and intensity of heat load on the measurement day led to a decrease in the lying time and an increase in the number of steps. The cows showed a reduced activity response to heat load when there was additional heat load accumulation over the three days preceding the measurement day. The cows in an advanced stage of lactation were more sensitive to heat load than cows in the early lactation stage. Multiparous cows showed less pronounced activity responses than primiparous cows. Heat load accumulation and individual cow-related factors should be considered in prediction models for the sensitive animal-specific recognition of heat load on the basis of activity responses.