Jeremiah D. Davis

THERMAL ENVIRONMENT IN A FOUR-HORSE SLANT LOAD TRAILER

Little information has been published describing thermal conditions in horse trailers while in transit. Dry bulb temperature (Tdb), globe temperature (Tg), and relative humidity (RH) were measured in ten locations within a fully enclosed four-horse slant-load trailer with and without animals to assess the thermal environment during transport as influenced by vehicle speed and vent configuration. Wet bulb globe temperature (WBGT) was calculated to assess thermal comfort. Interior-exterior temperature differences were analyzed to account for effects of changing weather conditions. Temperature differences between the interior of the trailer and ambient conditions for Tdb ranged from 5.1°C to 9.5°C, dew point (Tdp) ranged from 4.4°C to 13°C, and WBGT ranged from 2.9°C to 7.9°C. Temperature differences decreased with increasing vehicle speed and open vent area and increased with animals present. Heat stress conditions are likely to occur in horse trailers of similar design given their limited ventilation and the temperature increases measured in this study, and warrant improvements in trailer design to increase ventilation.

Development of a GPS Herd Activity and Well-Being Kit (GPS HAWK) to Monitor Cattle Behavior and the Effect of Sample Interval on Travel Distance

As an alternative to commercial GPS tracking collars, a low-cost GPS Herd Activity and Well-being Kit (GPS HAWK) was developed to monitor locomotion behavior of cattle at a high sampling frequency (20 s). The operational goal of the GPS HAWK was to collect GPS location data at a user-specified frequency and store the data in a secure format (compact flash media) for retrieval and optimize power consumption to extend the sampling period. The GPS HAWK uses a Garmin 12-channel low-power GPS receiver powered by a sealed-lead acid battery housed in an aluminum enclosure on a shoulder-mounted harness. Data gathered by the GPS HAWKs were used to determine individual daily travel distance (DTD) and the effect of sample interval (SI) on this measurement. Differences (P < 0.0001) were shown in DTD across four days using animals with available data. The Angus cows (Bos Tarus L.) averaged 4.05 ± 0.14 km/d (2.52 ± 0.09 mi/d) during the four days. Sample interval (SI) had an effect on DTD. Differences in DTD were detected for all SIs (P < 0.0001) except between the 60- and 120-s intervals. By changing the SI from 20 s to 20 min, the mean DTD decreased by 1.68 km or 44%. Significant errors in estimates of cattle energetics from GPS monitoring can be introduced by increasing sampling interval. Therefore, researchers must account for increasing error in DTD due to undersampling as SI is increased to save battery power and to increase the interval between animal handling periods. Holding the GPS system in place consistently with a shoulder mounted harness proved to be somewhat challenging.

Methods of Remote, Continuous Temperature Detection in Beef Cattle

Beef cattle core body temperature (CBT) was remotely and continuously measured over three ambient conditions (Period 1 at 30 °C, Period 2 at 20 °C, and Period 3 at 15 °C) at three sites: rectum, near the tympanic membrane, and peritoneal cavity. Ear surface measurements were taken under the same conditions with a temperature sensor placed on the ventral ear surface and were compared to the CBT measurements. Visual observation of the temperature measurements illustrated similar trends in the ear surface temperature and CBT measurements over time. A differencing method was used create a Temperature Index to detect the onset of fever in cattle. The use of the Index as a threshold showed promise. The animals’ baseline temperatures (Periods 1, 2 and 3) did not intersect this threshold until fever was present. A different threshold value was determined for rectal vs. ear surface temperatures. While promising, this system of detection needs improvements in hardware reliability and convenience before it can be implemented into a production setting.

Spatial variability of heating profiles in windrowed poultry litter

SUMMARY In-house windrow composting of broiler litter has been suggested as a means to reduce microbial populations between flocks. Published time-temperature goals are used to determine the success of the composting process for microbial reductions. Spatial and temporal density of temperature measurement can influence the accuracy in determining what portion of a windrow section has achieved specified time-temperature goals. In this study, windrow section temperature was recorded every 2 min for 7 d on a 10 × 10-cm grid in 183 (width) × 91 cm (height) windrow sections. In 5 windrow sections, ordinary kriging was used to predict the mean portion of the windrow cross-sectional area reaching time-temperature goals of 40°C for 120 h, 50°C for 24 h, and 55°C for 4 h. Based on these results, 88.5 ± 2.0%, 80.8 ± 3.9%, and 38.4 ± 11.7% of the windrow cross-sectional area can be expected to reach published microbial reduction time-temperature goals of 40°C for 120 h, 50°C for 24 h, and 55°C for 4 h, respectively. This study illustrates the need to monitor temperature at multiple locations within windrowed litter to characterize heating profiles. Temporal and spatial sampling densities must be standardized to properly characterize temperature profiles in windrowed broiler litter. Additional research should be conducted to determine the degree of pathogen destruction achieved in the various time-temperature regions of the windrow pile. This study was useful in illustrating the efficacy (proportion of windrow cross-section) of windrow composting as a treatment method for reducing microbial populations as measured by time-temperature goals in used broiler litter.

Moisture Determination in Windrowed Switchgrass Using Electrical Resistance Probes

Determining moisture content (MC) levels in windrowed biomass is important for both forage producers and researchers. Energy crops such as switchgrass have been troublesome when using standard methods set for electrical resistance meters. The objectives of this study were to i) develop the methodologies needed to measure MC in switchgrass using electrical resistance meters, ii) to determine the effects of pressure and probe orientation on MC measurement and iii) to generate MC calibration equations for electrical resistance meters using switchgrass in the senescence growth stage. Two meters (Meter 1, Farmex HT-PRO; Meter 2, Delmhorst F-2000) were selected based on commercial availability. A forage compression apparatus was designed and constructed with on-farm materials and methods to provide a simple system of applying pressure achievable by any forage producer or researcher in the field. A study was performed to test four levels of moisture contents (10%, 20%, 30%, and 40%), five pressures (0, 1.68, 3.11, 4.55,

Infrared Thermographic Evaluation of Commercially Available Incandescent Heat Lamps

Infrared thermography is a useful tool in visualizing and quantifying spatial distribution in radiant heat of incandescent heat lamps. Radial temperature profiles of six commercially available heat lamps (100W to 250W) were comparatively characterized. Heat lamps with the same power output do not necessarily produce the same temperature profiles on the heated surface because the shape of the temperature profiles was shown to be greatly affected by the lamp lens prescription. At a lamp height of 45.7 cm (18 in.), the net usable area (NUA) for the piglets was 0.102, 0.155, 0.146, 0.275, 0.139 and 0.113 m2 (1.10, 1.67, 1.57, 2.96, 1.50, and 1.22 ft2), respectively, for 100W Retrolite (100CZ20), 125W Hogslat (125HOG), 125W SLI Lighting (125SLI), 175W Retrolite (175CZ20), 175W Phillips (175PLP), and 250W SLI Lighting (250SLI). The 175CZ20 had the largest NUA and was the most efficient lamp on the basis of NUA per rated Watt. Although the 250SLI had the largest lamp heated area, it and the 175PLP were the least efficient lamps due to the large hotspots they produced. Lamp height affects the size of heated area, hotspot area and NUA for most of the lamps tested. These results suggest that in a commercial swine farrowing system, the 175CZ20 has the most potential among the incandescent heat lamps tested for meeting the thermal needs of the piglets and improving energy efficiency of the localized supplemental heating.

Development of a Mechanical Undercutting System to Minimize Sweetpotato Skinning during Harvest

Abstract. Sweetpotatoes have been an important high-value crop in Mississippi and future growth is expected. Industry growth has created the need for a continuous supply of sweetpotatoes throughout the year. Therefore, managing the harvest process and postharvest storage environment is critical to maintaining a year-round supply of quality sweetpotato roots. This has been a challenge in Mississippi and growers have been experiencing post-harvest losses due to excessive root shrinkage (weight loss) and bacterial and fungal rots. Studies indicate that 20% to 25% of sweetpotatoes are lost to moisture loss and decay during postharvest storage. This is directly related to skinning at harvest procedures that cause cuts and abrasions (skinning) to the delicate skin of the sweetpotato root is. These wounds provide a way-of-entry for diseases to infect the root, as well as moisture loss that results in root shrinkage. De-vining sweetpotatoes prior to harvest is a commonly used method to halt root growth and to begin toughening the skin. This method is viable for producers using manually-assisted harvesting for the fresh market. Producers using bulk harvesting prefer to leave vines on to reduce the amount of foreign material going into storage. A new method of halting plant growth and allowing the root to cure in the ground prior to harvest is needed. The objective of this study was to design and test a mechanical root pruning blade to halt plant growth and initiate skin set prior to harvest of sweetpotatoes and to quantify the effects of undercutting sweetpotatoes on skin strength relative to de-vining. It was hypothesized that cutting the deep root of the sweetpotato plant would allow this process to begin. Therefore, two different undercutting implements were designed and fabricated. One was assembled from currently available off-the-shelf components and the other was a modified commercially available sweetpotato digger. These implements were tested in experimental plots and the skin strength was directly measured. Root skin strength was measured at three days and six days after treatment. There was a significant rainfall event on the fifth day after treatment, meaning that no comparison between the time periods can be made. One of the tested varieties responded to undercutting. Results indicated that at three days after treatment, undercutting had no significant effect on skin strength for both vine conditions (vine-on and de-vined). At six days after treatment, undercutting with the newly developed implement significantly increased skin strength for roots in which the vine had been left on. There was no difference between using the modified digger and no treatment. Additionally, there was no treatment effect on roots which were de-vined. These results indicate that in a bulk harvesting system, undercutting with the new implement will increase skin strength after the roots have cured in the ground.

Assessing Cross-Sectional Air Velocity Uniformity in Commercial Broiler Houses via the Traverse Method

Abstract. Air velocity is a contributing factor to maintaining a production environment that promotes production efficiency, thermal comfort, and animal well-being. Variations in size, design, and equipment of production facilities contribute greatly to the air velocity generated. This study assessed mean cross-sectional air velocities and total air flow of two broiler production facilities. Test facility 1 was an 18.3 A— 170.7 m smooth sidewall broiler production facility and test facility 2 was a 12.19 A— 121.9 m curtain sidewall broiler production facility. Air velocity was characterized down each house with a Scalable Environment Assessment System (SEAS). Cross-sections were measured at 2.44 m and 3.05 m intervals in the axial direction for test facility 1 and 2 respectively. Total air flow was measured with Fan Assessment and Numeration System (FANS) units. Normalized cross-sectional air velocity was plotted against proportion of total house length to compare the cross-sectional air velocity of the two facilities. Test facility 1 showed 26.5% of the total house length below superficial velocity while test facility 2 only had 17.5% below superficial velocity. Test facility 1 demonstrated 11.4% of the facility length below normalized superficial velocity for temperature control at the exhaust fan end of the facility. Physical arrangement of the feed hoppers, heating systems, and tunnel fans are important for improving uniformity of air velocity in commercial broiler houses.

Improving Commercial Broiler Attic Inlet Ventilation through CFD Analysis

The use of solar heated attic air is an area of increasing interest in commercial poultry production. Attic inlets satisfy the demand for alternative heating while being simple to implement in an existing poultry house. A number of demonstration projects have suggested that attic inlets may decrease the amount of fuel required to raise minimum ventilation air to set point temperature by tempering the inlet air. However, little attention has been given to the configuration of the attic space and its influence on thermal energy extraction. The objectives of this study were as follows: 1) Collect data for the operation of attic inlets in a commercial broiler house, 2) develop a two-dimensional computational fluid dynamic (CFD) simulation model using experimental data, and 3) Use the simulation to investigate the efficiency of attic inlet system configurations. Field data collected during the operation of attic inlets in an east-west oriented broiler house illustrated the asymmetric heating and stratification of air temperature. A two dimensional CFD simulation model was developed for attic inlet system operation using field data to develop boundary conditions. The simulation demonstrated that the strategic placement of a simple 2.44 m ridge cap diverter and a central inlet riser (1.3 m high) may increase thermal energy extraction by 55% and 68% (30 s and 60 s fan runtimes, respectively) over the measured attic inlet system.

Cooling cows: the udder way

The objective of this study was to explore an alternative way to cool cows in time of heat stress. The procedure followed was to compare wetting the udder only to wetting the whole body. Twelve pregnant lactating Holstein cows were used in the study. The cows were exposed to four treatments each day over 4 days. The treatments were: (1) wetting the whole body without blowing air (n = 24), (2) wetting the whole body and blowing air (n = 12), (3) wetting the udder only without blowing air (n = 24), and (4) wetting the udder and blowing air directly towards the udder (n = 12). Water was sprayed until it dripped from the cow body. Identical fans were used to blow air onto the wet area, and were on until measurements of rectal temperature, respiration rate, and skin surface temperature both at the udder and body (chest to rear rib area) were taken. Respiration rates and skin temperatures were significantly higher (p> 0.05) when wetting the udder versus wetting the whole body. There was no statistical difference in rectal temperature between udder and whole-body wetting with or without air blowing onto the skin. Since rectal temperature is a measure of internal body temperature, it can be concluded that udder wetting alone is as effective as wetting the whole body in abating thermal stress of dairy cows. Blowing air onto the wet udder further decreased udder surface temperature. The rectal and vaginal temperatures were highly correlated (R = 0.93).