A model for ribosome translocation based on the alternated displacement of its subunits.

A meaningful dilemma in ribosome translocation arising from experimental facts is that, although the ribosome-mRNA interaction force always has a significant magnitude, the ribosome still moves to the next codon on the mRNA. How does the ribosome move to the next codon in the sequence while holding the mRNA tightly? The hypothesis proposed here is that ribosome subunits alternate the grip of the ribosome on the mRNA, freeing the other subunit of such interaction for a while, thus allowing its motion to the following codon. Based on this assumption, a single-loop cycle of ribosome configurations involving the relative position of its subunits is elaborated. When its dynamic is modeled as a Markov network, it gives expressions for the average ribosome translocation speed and stall force as functions of the equilibrium constants among the proposed ribosome configurations. The calculations have a reasonable agreement with experimental results, and the succession of molecular events considered here is consistent with current biomolecular concepts of the ribosome translocation process. Thus, the alternative displacements hypothesis developed in the present work suggests a feasible explanation of ribosome translocation.

Sensor validation to record rumination and analysis of behavioral parameters of dairy Gyr heifers in feedlot systems.

The use of sensors for livestock monitoring has grown in the last decade, motivated not only by the search for improvements in animal production and health, but also by the better use of physical, financial, and human resources in the management of livestock. Since precision livestock farming depends on technological innovation, including the use of sensors, it is essential to validate their applicability in confined animals. Therefore, the objective was to evaluate the functioning of the SCR Heatime® HR System sensor in heifers and analyze the behavioral differences of these animals in two feedlot systems (tie-stall and loose-housing). Eleven Gyr heifers of 10 months of age and an average body weight of 179 ± 26 kg were used. Animals were equipped with the SCR Heatime® HR System 7 days before the evaluations for adaptation, with the behavioral and system studies carried out during two periods each of 5 days, for 8 h a day. Five heifers were housed in tie-stall bedding and six were housed in loose-housing. After the evaluations for a period, animals have been switched systems in the following period. While the animals had the sensors attached to their bodies, behavioral evaluations were also performed visually, every 3 min by two evaluators per system. Behavior activities were characterized as standing, lying, idle standing, idle lying, ruminating standing, ruminating lying, feed, and water intake. The regression for the rumination activity recorded between the sensor and the visual assessment was significant only for loose-housing (P = 0.0002), but the Pearson correlation between both was negative and low (r = - 0.25; P = 0.0002). The sensor overestimated rumination by 27.3% in loose-housing (28 vs. 22 min/2 h) and 38.5% in tie-stall (36 vs. 26 min/2 h). Thus, when considering the different feedlot systems, validation was not possible due to the overestimation of time spent on rumination activity determined by the sensor. In the behavioral comparison between the systems by visual assessment, there was a significant difference (P < 0.05) for the behaviors of motor activity, idle lying, total idle time, and feed intake between the animals in the two housing systems. As for idle standing, ruminating standing, total rumination time, and water intake, there was no difference (P > 0.05). However, the time spent ruminating lying was greater from 10:00 to 12:00 h (43 ± 3 min/2 h) in the tie-stall, whereas in the loose-housing the animals distribute more uniformly their rumination from 08:00 to 16:00 h (26 min/2 h on average). Therefore, the use of the SCR Heatime® HR System sensor is not recommended for Gyr heifers housed in tie-stall and loose-housing systems. Regarding the daytime range of rumination and the accuracy improvements of similar sensors, it is recommended to develop them in both feedlot systems using the periods of less rumination in early morning in tie-stall and late afternoon in loose-housing.

Individual and environmental factors associated with defecation while lying down in dairy cows.

Cows typically defecate while standing. Freestalls are designed to position standing cows such that their feces fall into the alley. Cows sometimes defecate while lying down, increasing the risk that feces contaminate the stall surface. We conducted 2 studies investigating cow-level and environmental factors associated with defecating while recumbent. In experiment 1, we hypothesized that conditions making it more difficult for cows to stand up (including greater age, high body weight, pregnancy, and lameness) would increase the risk of this behavior. We followed 92 cows for 12 d, scanning stalls 5 times/d using live observation. Almost half (48%) of all cows defecated while recumbent at least once; cows that spent more time lying down and that were earlier in gestation were at highest risk. Weight, parity, age, and lameness were not associated with this behavior. In experiment 2, we tested how overstocking influenced the occurrence of defecating while recumbent. We predicted overstocking would increase the occurrence of this behavior, especially when cows were in stalls at more preferred locations. We recorded stall occupancy, displacement attempts, and defecating while recumbent in 4 groups of 36 cows tested at both 100% and 150% lying stall stocking densities for 2 nights each using a crossover design. Overstocking resulted in higher stall use and more displacements, but less lying and fewer perching events. We did not detect any relationship between use of specific stalls or competition and defecating while recumbent. Most recorded displacements were associated with perching. Increased time perching increased the likelihood of defecating while recumbent, perhaps because perching cows were less dominant or more reluctant to stand up once lying down in the stall. Overstocking did not increase defecating while recumbent, likely because cows spent less time lying down. Together, these results indicate that defecating while recumbent can be common, and points to some of the cow-level factors associated with this behavior.

Effects of small milking stalls on stress responses in dairy cows during milking in group milking parlors.

Milking stall dimensions have not been adapted to the increase in cow body size caused by selection for better milking performance over the past decades. Improper milking stall dimensions might limit cow comfort, could lead to stress responses during milking and thus could negatively affect cow welfare. A crossover study was conducted in an experimental milking parlor that was converted from a herringbone (HB) to a side-by-side (SBS) parlor. The milking stall dimensions were modified in length and width and for HB also in depth (perpendicular distance between rump rail and breast rail). The stall dimensions applied during the experiments ranged from much smaller than common in European dairy farming to much larger. Treatments were applied for 2 wk per milking parlor type. In each milking parlor type, a total of 30 cows, kept in 2 groups were observed during milking for behavioral and physiological stress responses and for milking performance. In addition, milk cortisol levels and somatic cell counts were measured at the end of the 2-wk period. Outcome variables were selected based on a principal component analysis and analyzed using mixed effects models reflecting the experimental design. The results showed that the first cow per milking batch required more time (on average >40 s) to enter very small HB stalls than to enter small, large and very large stalls (<30 s). Also, cows yielded more milk per milking in very small and very large HB stalls than in the small and large milking stall dimensions [very small: 15.8 kg; 95% confidence interval (CI), 14.2-17.4 kg); small: 14.3 kg (95% CI, 12.8-15.9 kg); large: 14.6 kg (95% CI, 13.1-16.1 kg); very large: 16.1 kg (95% CI, 14.6-17.6 kg)]. The other behavioral, physiological and milk flow parameters as well as udder health were not affected by stall dimensions. For the SBS parlor, effects of milking stall dimensions were not detectable in any of the parameters. Despite the strong avoidance behavior to enter the milking parlor (measured as latency), no acute stress responses were found during milking. However, the study cannot exclude long-term effects of narrow stall dimensions on stress levels and possibly udder health, which should be investigated in future studies.

Graduate Student Literature Review: The effect of chain length and stall width on common outcome measures of dairy cow welfare in stall-based housing systems.

Given increased societal concern for the welfare of dairy cattle and the heightened concern of consumers about the ability of cows to fulfill their needs for rest and for movement, an understanding of the effect of stall-based housing systems on such needs becomes of prime scientific importance. In tie-stall systems, the ability of the cow to express her need for movement is largely affected by tethering; increasing chain length increased the cow's ease of movement in the space allowed to her. Regarding the ability of the cow to rest, the size of the stall bed (including its width) has been linked with measures of lying time. For the most part, current industry recommendations are not being followed on commercial farms, although improvements in terms of compliance seem to have been made in the last decade. Following the recommendations for chain length appears to aid in reducing the prevalence of injuries and may even aid in maintaining the cleanliness of the cows, although the few studies available are inconsistent. Wider stalls were associated with increased lying time and reduced prevalence of injuries, although in the latter case, data from different studies show inconsistent results. The link between stall width and common welfare outcome measures appears more clearly in tiestall systems, although improving the lateral space allowance for cows reduces collisions with equipment in freestall systems as well. Overall, the width of the stall and the length of the chain play roles in modulating the cows' ability to rest and to move comfortably in the confines of the stall, and should be carefully considered when designing stall-based housing systems that enhance the welfare of dairy cows.

Making tiestalls more comfortable: III. Providing additional lateral space to improve the resting capacity and comfort of dairy cows.

Dairy cows housed in tiestalls are restricted to one space; therefore, this space should be designed to accommodate all the activities cows need to perform. Lying is a very important behavior for dairy cows as well as a critical measure in the assessment of stall designs, to ensure that the cows' needs for resting space are met. The objective of this study was to determine if increasing tiestall width alters the lying behavior of lactating dairy cows. Two treatments were compared: the current recommendation (139 cm) and a double stall (284 cm). Sixteen cows were blocked by parity and lactation stage, then randomly allocated to a treatment and a stall within 1 of 2 rows in the research barn, for 6 wk. The average stall length was 188 cm. Leg-mounted accelerometers were used to record lying behaviors. Cows were video-recorded 24 h/wk using surveillance cameras positioned above the stalls. Video data from wk 1, 3, and 6 were extracted at a rate of 1 image/min and analyzed by a trained observer to assess the position and the location of the cow's body, head, and limbs during the lying hours. Lying behaviors and frequency of each position and location were analyzed in SAS (SAS Institute Inc., Cary, NC) using a mixed model in which treatment, block, and week were included as fixed factors, and cow and row as random factors. Multiple comparisons were adjusted using the Scheffé method. Results indicate that cows in double stalls fully extended their hindlimbs more often than single stall cows (21.7 vs. 7.6% of lying time). Cows in double stalls also intruded in the neighboring stalls with their hindlimbs less often (1.3 vs. 14.7% of lying time), instead positioning them inside their own stall more often (92.7 vs. 84.6% of lying time). Use of the second stall in the double stall group totaled 11.6, 5.1, 33.8, and 18.0% of lying time, respectively, for the head, front legs, hind legs, and body. Total lying time was not statistically different between double (716 min/d) and single stall (671 min/d) groups. Contacts with stall hardware during lying-down movements were also less frequent in double stalls (43.1 vs. 77.1% of lying events) compared with single stalls. These results suggest that dairy cows housed in double stalls modified their resting habits and used the extra space made available to them. Increasing stall width beyond the current recommendation is likely to benefit the cows by improving their ability to rest.

Making tiestalls more comfortable: IV. Increasing stall bed length and decreasing manger wall height to heal injuries and increase lying time in dairy cows housed in deep-bedded tiestalls.

Poor stall configuration can negatively affect cow welfare by impairing lying behavior and leading to injuries in dairy cows. The comfort of the stall bed in tiestalls is affected by the material components of the stall bed (stall base and bedding), but also by the amount of space provided. The amount of space cows are able to access lengthwise in a tiestall is determined by the stall bed length and the height of the manger wall (the front limit of the stall bed), which can limit access into the space available at the front of the stall. This project aimed to maximize cow comfort in deep-bedded tiestalls by investigating the combined effect of increased bed length and decreased manger wall height in a crossover experiment (2 periods with 1 wk habituation + 6 wk data collection). Two rows of 12 tiestalls were modified (n = 24 cows). Each row was a different length, short (178 cm; length commonly found in Quebec) or long (188 cm), and cows remained on the same row (same stall bed length) for the entire experiment. In each row, there were 6 stalls of each manger wall height treatment: high (20 cm, upper limit recommended) or low (5 cm). During period 2, cows switched manger wall height treatments. A 7.6-cm-deep straw bedding layer was added to all stalls by adding a bedding keeper to the ends of stalls. All initially injured locations healed over the 14-wk study, and 2 patterns of healing emerged. Improvement in hock injury (lateral tarsal and calcanei) was observed from wk 1 to 6 for all treatments. A plateau in injury severity score reduction was observed in period 2 for the hock (lateral, dorsal, and medial calcanei), anatomical knee, carpal joints (front knees), and proximal and medial neck, which was likely the result of the insensitivity of the injury scoring scheme rather than healing not occurring. Cows in long stalls were found to spend more time lying (14.1 vs. 13.3 h/d) and had longer lying bouts than cows in short stalls (74.1 vs. 52.9 min/bout). Manger wall height did not affect injury or lying time, but may affect how cows position themselves while lying. Higher lying times in our study were comparable to those reported in deep-bedded loose pens, indicating that cows with more bedding, especially those in long stalls, were more comfortable. Our results suggest that deep-bedded straw stalls with bedding keepers have the potential to be beneficial to cow comfort on tiestall farms.

Short communication: Use of the Clegg hammer measure as an indicator of stall-surface compressibility in tie-stall housing and its relationship with stall comfort.

Stall base and stall surface (i.e., with or without bedding) are key risk factors in cow comfort in dairy herds. In Canada, rubber mats, concrete floors, and mattresses are the most common stall bases used in tie-stall systems. Straw, wood shavings, and sand, at variable depths, are the most commonly used type of bedding. The Clegg hammer (Clegg Impact Soil Tester Hammer; Lafayette Instrument Company, Lafayette, IN) is a tool used by engineers to test the compressibility of pavement or golf course surfaces. Recently, this tool has also been used to measure the compressibility of the stall surface on freestall dairy farms. A total of 32 tie-stall dairy herds were selected in Québec to test the usefulness of the Clegg hammer as a tool to assess stall surface compressibility in tie-stall housing. This study had 2 main objectives: (1) identify the location and the number of measurements needed to obtain a stable indicator of compressibility, and (2) identify differences in the compressibility of the stall surface depending on the stall base and bedding depth. On each farm, we tested the compressibility of 10 stalls. No significant differences were found between the front and the back of the stall for the location of the Clegg hammer measures. The differences in readings of the Clegg hammer were nonsignificant after the third measure taken at the same location, meaning that 3 measures are sufficient at one location to obtain a compressibility measure. Significant differences were found among the different stall base and surface combinations tested. Rubber mats were less compressible than mattresses. When a large quantity of bedding (>7.5 cm) was added on top of rubber mats, the compressibility results were equal to those of mattresses ≥10 yr old without bedding. To appropriately test the compressibility of stall surface in tie-stall farms, we recommend measuring the compressibility of the stall base on its own and with the usual amount of bedding used on the farm. Our study establishes that both stall base and surface affect compressibility, and that a large quantity of bedding helps increase the compressibility of the bed, especially on a harder stall base.

Graduate Student Literature Review: The effects of bedding, stall length, and manger wall height on common outcome measures of dairy cow welfare in stall-based housing systems.

Understanding and improving dairy cow welfare in stall-based housing systems is an important issue for the dairy industry, and one area of the stall that has a large impact on cow welfare is the stall bed. The stall bed is defined both by its size and by the material components of the stall bed (bedding depth, bedding type, and stall base type). This review examines the current literature to determine how the material components of the stall bed, as well as bed length and manger wall/brisket board height (which together define the length of the stall bed) can affect cow welfare through lying time, injuries, lameness, and cow and stall cleanliness. Of the material components of the stall bed, bedding depth appears to have the largest potential positive impact on dairy cow welfare, as deeper levels of bedding in stalls, regardless of the bedding type, can improve compressibility to the extent that the stall base type is negligible. As such, deeper levels of bedding have been associated with increased lying time and a reduced likelihood of a cow developing injuries or becoming lame. Longer stall bed lengths have been shown to increase lying time and decrease the prevalence of injury and lameness. The effect of manger wall or brisket board height on cow welfare has not been studied extensively, but they may work in conjunction with other stall components to define the resting space available to the cow. Overall, the material components of the stall bed, stall length, and manger wall/brisket board height, as well as their combination, all influence cow welfare and need to be taken in consideration to improve the overall welfare of cows in stall-based housing systems.

Properties of conventional and alternative bedding materials for dairy cattle.

The bedding material used in barns for dairy cows has a significant effect on animal welfare and performance. Bedding influences the duration in which animals remain lying down and, consequently, the processes of rumination and milk production. It is crucial to have a complete understanding of the properties of bedding materials and the effects of alternative bedding materials on dairy cattle. This paper aims to evaluate the physical, chemical, and biological properties of various alternative and conventional bedding materials for dairy cattle for use in compost bedded pack or freestall barn systems. We analyzed 50 samples of 17 bedding materials produced in 3 European countries. We analyzed physical properties including the water holding capacity, porosity, moisture content, bulk density, dry bulk density, and particle size. Chemical analyses were performed to determine the total N, total organic C, and C:N ratio. In the biological analyses, the Escherichia coli count, total bacteria count, coliform count, and Klebsiella spp. count were assessed. The results demonstrated how the physical properties of the bedding materials may influence the chemical and biological properties. All of the materials presented adequate chemical properties to be used as bedding material. The physical properties of the bedding materials differed widely among the materials except for the dry bulk density, which presented no difference. Moreover, the contamination of each studied microorganism was observed for each bedding material to determine which material had the lowest level of contamination. Posidonia oceanica, Miscanthus grass, and spelt husks could be considered as a potential alternative material for use as bedding material for dairy cows in both systems (i.e., composted bedded pack and freestall). This experiment illustrated the importance of performing thorough physical, chemical, and biological analyses before implementing a material as bedding for dairy cattle.

Effect of evaporative cooling and altitude on dairy cows milk efficiency in lowlands.

The objective of this current work was to determinate the effect of high temperatures on milk production of dairy cows in southern Slovakia in the year 2015. The hypotheses that milk production is influenced by the altitude and cooling were tested. Production data included 227,500 test-day records belonging to 34 Holstein breed herds situated in lowlands, 115 to 150 m above sea level (ASL) and kept in free-stall housing. Dairy farms were classified into groups based on cooling system. The first group of cows (19 herds) was cooled evaporative (foggers) and forced ventilation, and the second group (15 herds) was using cooled only forced ventilation (automatically controlled fans in housing and feeding areas). During the period from May to September, 36 summer and 22 tropical days were recorded, 37 days had a mean thermal humidity index value above 72.0, and on 34 days we recorded mean values above 78.0. The highest milk yields were recorded at the altitude 1 (115 m ASL) (9219.0 kg year-1; 10327.0 kg year-1) and the lowest at the altitude 2 (126 m ASL) (7598.7 kg year-1; 8470.21 kg year-1) (P < 0.001). Dairy cows cooled evaporative milked significantly more milk than cows cooled only with forced air flow (9650.4 kg vs. 8528.0 kg; P < 0.001). Fat and protein production differed also significantly (364.0 kg vs. 329.5 kg, P < 0.001; 312.2 kg vs. 279.7 kg, P < 0.001). It can be concluded that not only heat stress but also location farm above sea level can affect milk production. Evaporative cooling associated with increased air velocity is the appropriate protection against high temperatures.

Development of a Linear Acoustic Array for Aero-Acoustic Quantification of Camber-Bladed Vertical Axis Wind Turbine.

Vertical axis wind turbines (VAWT) are a source of renewable energy and are used for both industrial and domestic purposes. The study of noise characteristics of a VAWT is an important performance parameter for the turbine. This study focuses on the development of a linear microphone array and measuring acoustic signals on a cambered five-bladed 45 W VAWT in an anechoic chamber at different tip speed ratios. The sound pressure level spectrum of VAWT shows that tonal noises such as blade passing frequencies dominate at lower frequencies whereas broadband noise corresponds to all audible ranges of frequencies. This study shows that the major portion of noise from the source is dominated by aerodynamic noises generated due to vortex generation and trailing edge serrations. The research also predicts that dynamic stall is evident in the lower Tip speed ratio (TSR) region making smaller TSR values unsuitable for a quiet VAWT. This paper compares the results of linear aeroacoustic array with a 128-MEMS acoustic camera with higher resolution. The study depicts a 3 dB margin between two systems at lower TSR values. The research approves the usage of the 8 mic linear array for small radius rotary machinery considering the results comparison with a NORSONIC camera and its resolution. These observations serve as a basis for noise reduction and blade optimization techniques.

Automated detection of estrous behavior in tie-stall housing using a barometer and accelerometer.

Tie-stall housing inhibits movement in cows, thereby restricting the behavioral indicators used by farmers for detecting estrous. In this study, we investigated the changes in patterns of lying and standing times at estrous, and evaluated the potential for automated detection of estrous within tie-stalls using a barometer and accelerometer. On estrous days, total daily standing time was significantly longer than that during non-estrous days (P < 0.05). A practical method was developed for detecting slight altitude changes using a novel device, which consisted of a barometer and accelerometer, and was attached to the neckband. Total daily standing time predicted using this new device was found to be highly correlative with the observed measured data (r = 0.95, P < 0.01), indicating the accuracy of the device in measuring daily standing time in tie-stall housed cows. In addition, the device detected an overall increase in total daily standing time during estrous days.

Rotating Stall Induced Non-Synchronous Blade Vibration Analysis for an Unshrouded Industrial Centrifugal Compressor.

Rotating stall limits the operating range and stability of the centrifugal compressor and has a significant impact on the lifetime of the impeller blade. This paper investigates the relationship between stall pressure wave and its induced non-synchronous blade vibration, which will be meaningful for stall resonance avoidance at the early design phase. A rotating disc under a time-space varying load condition is first modeled to understand the physics behind stall-induced vibration. Then, experimental work is conducted to verify the model and reveal the mechanism of stall cells evolution process within flow passage and how blade vibrates when suffering such aerodynamic load. The casing mounted pressure sensors are used to capture the low-frequency pressure wave. Strain gauges and tip timing sensors are utilized to monitor the blade vibration. Based on circumferentially distributed pressure sensors and stall parameters identification method, a five stall cells mode is found in this compressor test rig and successfully correlates with the blade non-synchronous vibration. Furthermore, with the help of tip timing measurement, all blades vibration is also evaluated under different operating mass flow rate. Analysis results verify that the proposed model can show the blade forced vibration under stall flow condition. The overall approach presented in this paper is also important for stall vibration and resonance free design with effective experimental verification.

Non-Contact Measurement of Blade Vibration in an Axial Compressor.

Complex blade responses such as a rotating stall or simultaneous resonances are common in modern engines and their observation can be a challenge even for state-of-the-art tip-timing systems and trained operators. This paper analyses forced vibrations of axial compressor blades, measured during the bench tests of the SO-3 turbojet. In relation to earlier studies conducted in Poland with a small number of sensors, a multichannel tip-timing system let us observe simultaneous responses or higher-order modes. To find possible symptoms of a failure, blade responses in a healthy and unhealthy engine configuration with an inlet blocker were studied. The used analysis methods covered all-blade spectrum and the circumferential fitting of blade deflections to the harmonic oscillator model. The Pearson coefficient of correlation between the measured and predicted tip deflection is calculated to evaluate fitting results. It helps to avoid common operator mistakes and misinterpreting the results. The proposed modal solver can track the vibration frequency and adjust the engine order on the fly. That way, synchronous and asynchronous vibrations are observed and analysed together with an extended variant of least squares. This approach saves a lot of work related to configuring the conventional tip-timing solver.

Using a shell as a wing: pairing of dissimilar appendages in atlantiid heteropod swimming.

Atlantiid heteropods are zooplanktonic marine snails which have a calcium carbonate shell and single swimming fin. They actively swim to hunt prey and vertically migrate. Previous accounts of atlantiid heteropod swimming described these animals sculling with the swimming fin while the shell passively hung beneath the body. Here, we show, via high-speed stereophotogrammetric measurements of body, fin and shell kinematics, that the atlantiid heteropod Atlanta selvagensis actively flaps both the swimming fin and shell in a highly coordinated wing-like manner in order to swim in the intermediate Reynolds number regime (Re=10-100). The fin and shell kinematics indicate that atlantiid heteropods use unsteady hydrodynamic mechanisms such as clap-and-fling and delayed stall. Unique features of atlantiid heteropod swimming include the coordinated pairing of dissimilar appendages, use of the clap and fling mechanism twice during each stroke cycle, and the fin's extremely large stroke amplitude, which exceeds 180 deg.

Effect of stall design on dairy calf transition to voluntary feeding on an automatic milk feeder after introduction to group housing.

Automatic milk feeders (AMF) for young dairy calves are widely used in the dairy industry. These feeders are thought to have benefits for calf health and welfare and may reduce labor required for feeding; however, little is known about how calves adapt to feeding with AMF. The objective of this study was to observe the effects of feeding stall design on calves learning to use the AMF. The hypothesis was that solid side stalls, compared with steel bar stalls, would result in a longer latency to approach and feed from the AMF without assistance. A total of 147 Holstein calves (80 male and 67 female) were enrolled at 4 d of age, introduced to a group pen, and, at the same time, trained on an AMF. For training, calves were allowed to suck on the trainer's fingers and guided to the teat. Calves were allocated to 1 of 2 stall designs at the pen level, depending on which treatment cohort they were born into, either with steel bar stall walls (n = 46 male, 34 female calves) or with solid side stall walls (n = 34 male, 33 female calves). For 72 h after introductory training on the AMF, data from the feeders were collected and calf behavior was monitored by video. Outcomes measured included latency to first voluntary visit to the feeder and to first feeding, time spent in the feeder, amount of milk consumed over 72 h, number of retraining sessions required (retrained if <2 L was consumed every 12 h), and exploratory behavior, such as sniffing and licking of the feeder. Data were analyzed using mixed effects linear regression models or a Poisson model for the outcome of retraining. For certain outcomes the effects of stall design interacted with difficulty of training (willingness to enter feeder and drink); for the 38% of calves that were scored as moderately difficult to train on a scale of easy, moderate, or difficult, treatment (stall design) differences were detected. These calves took 2× longer to lick or bite toward the nipple, 2× longer to first voluntarily feeding, and consumed less milk over 72 h following training when trained on the steel bar stall design. These results suggest simple features of a stall may influence how quickly calves learn to use an AMF, but that the influence of stall wall design was affected by how easy calves were to train on the feeder upon initial introduction, which may depend in part on certain aspects of calf temperament. For many calves, solid side stalls at an AMF resulted faster in adaption than the steel bar stalls.

Static Characterization of the Driving, Normal and Stall Forces of a Double-Sided Moving-Permanent Magnet-Type Planar Actuator Based on Orthogonal Planar Windings.

This work presents a study of the traction, normal and stall forces in a two-sided planar actuator with orthogonal planar windings and a mover that comprises two cars magnetically coupled to each other through two pairs of permanent magnets (PMs). There is no ferromagnetic armature core because of the permanent magnets array in the mover and orthogonal traction forces can be generated in order to move both cars jointly in any direction on a plane. The stall force is the minimal force necessary to break up the magnetic coupling between the two cars. When one of the cars is subjected to an external force through the x- or y-axis, the cars can become out of alignment with respect to each other and the planar actuator cannot work properly. The behavior of the forces was modelled by numerical and analytical methods and experimental results were obtained from tests carried out on a prototype. The average sensitivity of the measured static propulsion planar force along either axis is 4.48 N/A. With a 20-mm displacement between the cars along the direction of the x-axis and no armature current, a magnetic stall force of 17.26 N is produced through the same axis in order to restore the alignment of the two cars.

Microbiological quality of air in free-range and box-stall stable horse keeping systems.

The aim of this study was to assess the microbiological quality of air in three horse riding centers differing in the horse keeping systems. The air samples were collected in one facility with free-range horse keeping system and two with box stalls of different sizes. The samples were collected over a period of 3 years (2015-2017), four times per year (spring, summer, autumn, winter) to assess the effect of seasonal changes. The prevalence of aerobic mesophilic bacteria, mold fungi, actinomycetes, Staphylococcus spp., and Escherichia coli was determined by the air collision method on Petri dishes with appropriate microbiological media. At the same time, air temperature, relative humidity, and particulate matter concentration (PM10, PM2.5) were measured. It was found that the horse keeping system affects the occurrence of the examined airborne microorganisms. Over the 3-year period of study, higher temperature and humidity, as well as particulate matter concentration-which notoriously exceeded limit values-were observed in the facilities with the box-stall system. The air sampled from the largest horse riding center, with the largest number of horses and the box-stall system of horse keeping, was also characterized by the heaviest microbiological contamination. Among others, bacteria from the following genera: Staphylococcus spp., Streptococcus spp., Bacillus spp., and E. coli and fungi from the genera Aspergillus, Fusarium, Mucor, Rhizopus, Penicillium, Trichothecium, Cladosporium, and Alternaria were identified in the analyzed samples.

The effect of alphacypermethrin-treated mesh protection against African horse sickness virus vectors on jet stall microclimate, clinical variables and faecal glucocorticoid metabolites of horses.

BACKGROUND: African horse sickness (AHS) is of importance to health and international trade in horses worldwide. During export from and transit through AHS endemic countries or zones, physical and chemical measures to protect horses from the vectors of AHS virus (AHSV) are recommended by the World Organization for Animal Health. Protection of containerized air transport systems for horses (jet stalls) with alphacypermethrin insecticide-treated high density polyethylene mesh is effective in reducing the Culicoides midge vector attack rate. In order to determine the effect of this mesh on jet stall ventilation and horse welfare under temperate climatic conditions, jet stall microclimate, clinical variables and faecal glucocorticoid metabolite (FGM) levels of 12 horses were monitored during overnight housing in either a treated or untreated stall in two blocks of a 2 × 3 randomized crossover design. RESULTS: Temperature difference between the treated stall and outside was significantly higher than the difference between the untreated stall and outside at 1/15 time points only (P = 0.045, r = 0.70). Relative humidity (RH) difference between the treated stall and outside did not differ from the untreated stall and outside. Temperature and RH in the treated stall were highly and significantly correlated with outside temperature (r = 0.96, P < 0.001) and RH (r = 0.95, P < 0.001), respectively. No significant differences were detected between rectal temperatures, pulse and respiratory rates of horses in the treated stall compared to the untreated stall. Mean FGM concentrations for horses housed in the treated stall peaked earlier (24 h) and at a higher concentration than horses housed in the untreated stall (48 h), but were not significantly different from baseline. No significant difference was detected in FGM concentrations when the treated and untreated stall groups were compared at individual time points up to 72 h after exiting the jet stall. CONCLUSIONS: Alphacypermethrin-treated HDPE mesh could be used under temperate climatic conditions to protect horses in jet stalls against AHSV vectors, without compromising jet stall microclimate and horse welfare.