I. L. Berry

Minimum Ventilation Requirement and Associated Energy Cost for Aerial Ammonia Control in Broiler Houses

Minimum ventilation rate (MVR) and bird performance of four commercial-scale broiler houses were monitored for 16 consecutive growouts. A complete house clean-out was conducted after the 7th growout and again after the 13th growout. Between the clean-outs, only caked litter was removed, and new bedding was added to the old litter.

Temperature and humidity profiles of broiler houses with experimental conventional and tunnel ventilation systems

This article describes the spatial and diurnal patterns of air temperature and relative humidity (RH) in commercial-scale broiler houses (12 ¥ 122 m, 40 ¥ 400 ft) using experimental conventional and tunnel heating, cooling, and ventilation systems. The experimental broiler houses used 76-cm (2.5-ft) side curtains and combined mechanical and natural ventilation. Heating was provided by propane brooders and space furnaces. Cooling was accomplished with side-mounted cooling fans and misting nozzles in the conventional houses, but with fans and evaporative cooling pads in the tunnel houses. Interior mixing fans, arranged to circulate air in a “racetrack” fashion, were used in the tunnel houses.

A computerized measurement and data acquisition system for field poultry research

A comprehensive computerized measurement and data acquisition system was developed to collect dynamic data relating to thermal environment profiles, energy use, operational characteristics, and animal performance of four field research broiler houses (12 × 121 m each). Although the basic components of the system consisted of available industrial electronic and mechanical products, certain design and application features involved were noteworthy and could be of reference value to those who wish to conduct similar field measurements. The 85–90 response variables in each broiler house were measured every two minutes and stored every 10 minutes into a battery-powered data logger. Outside climatic data were collected similarly with a local weather station. A central PC was linked to the data loggers via a 75 Ωoaxial transmission cable and communication software. Unattended data acquisition was implemented by automatically retrieving data from the data loggers, storing the data on the PC hard drive, and backing them up on floppy disks. Daily body weight of the broilers was monitored with a stand-alone weighing unit in each house. Each weighing unit consisted of two platform electronic load-cell scales. The unit could display up to 10 days of weight readings. Having operated for three years, the system allowed for collection of an enormous amount of valuable data for various investigations that could not have been obtained otherwise from such commercial-scale broiler facilities. The data enabled the researchers to analyze dynamic environmental profiles; dynamic patterns of energy use; projected energy shavings with alternative building structures and ventilation strategies; feeding and drinking behavior of the broilers, and daily growth performance. General maintenance of the measurement system included periodically refilling water reservoirs (once every 3–5 days) of the fan-actuated psychrometers designed to operate in dusty environment; cleaning (and sometimes adjusting) the psychrometers after each flock; occasionally repairing thermocouples broken by the chickens; and replacing data logger batteries about once every four months. Lightning proved to be the major challenge to the reliability of the system, particularly to the analog outputs of the feed weigh bin scales.

Energy Use Analysis of Open-Curtain vs. Totally Enclosed Broiler Houses in Northwest Arkansas

Seventeen years of electricity and propane fuel use data collected from broiler production houses at the University of Arkansas Applied Broiler Research Farm (ABRF) in Northwest Arkansas were analyzed to quantify the relative effect of open-curtain versus totally enclosed housing systems on energy use. The ABRF consists of four commercial-scale 12- × 121-m (40-× 400-ft) houses and raises broilers under standard production contracts. After the first 15 years of production with open-curtain system, all houses were converted to the solid-wall enclosed system with drop ceiling, tunnel ventilation, and cooling pads in early 2006. The renovations led to reduction of the overall building heat loss factor (W·K-1) from 1389 to 586 for the two steel-frame houses and from 1022 to 428 for the two wooden-truss houses. Mean outside temperature (ranging from 14.7°C to 17.5°C or 58.5°F to 63.5°F in annual mean temperature during the 17-year period) and bird age were found to be the major factors affecting propane fuel usage and ventilation fan electricity usage. Electricity for ventilation and lighting comprised about 87% of the total electricity usage. Annual electricity usage was 27% higher with the enclosed system than with the open-curtain system (102 vs. 80 kWh per 1000-kg market bird weight or 46.4 vs. 36.4 kWh/1000 lb), due to loss of natural daylight and increased mechanical ventilation in the enclosed system. Propane use was comparable between curtain-sided and solid-wall housing schemes, averaging 76- and 65-L/1000 kg market bird weight (9.1 vs. 7.8 gal/1000 lb) before and after renovation, respectively. Higher fuel cost resulted in higher fuel expenditure for winter heating than electricity expenditure for summer cooling in this region. With increasing energy costs, analysis of energy use, as conducted in this study, will assist the decision making of growers to improve energy efficiency or explore alternative energy application.

A Fan-Actuated Mechanism for Controlled Exposure of a Psychrometer Wet Bulb Sensor to a Dusty Environment

An aspirated psychrometer which uses a unique mechanism for raising the wet bulb sensor from a reservoir and into the airstream during aspiration was designed and tested. The device uses thermocouples and an electronic datalogger to measure the wet bulb and dry bulb temperatures during aspiration. In laboratory tests over a wide range of vapor pressures, the root-mean-squared-difference (RMSD) between relative humidity from the psychrometer and a chilled mirror hygrometer was 0.3%. In tests in a commercial broiler house, differences between three psychrometers (RMSD=2.0%) could be traced to experimental uncertainty in temperature measurement. Tests in broiler houses have shown the psychrometer mechanisms to be reliable with minor maintenance required every five to ten days.

Heat and moisture production of commercial broilers under pad cooling or surface wetting in summer.

Evaporative cooling of ventilation air to ameliorate heat-stress of livestock and poultry in summer has been widely adopted in the Southern broiler production area in the U. S. However, water usage can be high, and cooling effect may not be satisfactory under humid condition. Intermittent surface wetting system in tunnel ventilated (TV) broiler houses were evaluated side-by-side with evaporative cooling system in commercial production settings during five flocks in summer months over three years. Data collected in the evaluation were calculated for house-level sensible and latent heat loads. Despite the total specific heat production rates of houses using two types of cooling system were equivalent under the testing conditions, the partitioning of sensible and latent heat loads were different. Sensible heat load dominated during day time in houses using evaporative cooling pads and TV, while latent heat load were the primary pathway of heat loss in houses using surface wetting and TV.

Field Evaluation of Controlled Surface Wetting System to Cool Broiler Chickens

Two overhead, low-pressure sprinkling systems were tested for their efficacy of cooling broiler chickens in two houses (treatment) during two summer flocks, and compared to the evaporative cooling systems in two other houses (control) on a commercial broiler farm. The bird live weight, feed conversion, livability were not significantly different between the treatment houses and the control houses. The sprinkler houses had substantially higher air temperature but lower relative humidity than that in the control houses during day time in the test periods. Litter moisture conditions at the end of grow-outs were not significantly different. Cooling water in treatment houses averaged about 1/3 of those used in control houses during first summer flock, and averaged about 1/10 of those of control houses during second summer flock. Electricity for ventilation in treatment houses were higher than that in control houses during second summer flock, due to the relatively cooler ambient temperature during the second test period and tunnel fans in control houses operated slightly less than those in treatment houses.

Heat and Moisture Production of Broiler Chickens in Commercial Housing

Heat and moisture production rates (HP, MP) of modern broiler chickens (Cobb strain) raised on litter in commercial production settings were determined from environmental and production data collected over 16 consecutive flocks during a three-year period. The flock size averaged 18,800 birds per house, with an average growth period of 56 days. Specific total HP rate (W/kg body mass) obtained from this study is slightly greater than that reported by Reece and Lott (1982) for birds of the same body mass at 21.1°C. However, MP is reduced in modern broiler houses with nipple drinkers. Regression equations were established that predict total, sensible and latent HP in modern broiler houses over common ranges of body mass, air temperature, relative humidity, and lighting conditions.

Control Algorithms for an Aspirated Psychrometer

Relative humidity in agricultural buildings can be computed with readings from an aspirated psychrometer by utilizing an algorithm for selecting the appropriate values of wet and dry bulb temperature observed during each aspiration period. A dataset consisting of observations of wet and dry bulb temperature from four psychrometers during 10-min aspiration periods was analyzed to determine the effect of four different algorithms on the computed relative humidity. Algorithms designed to reduce aspiration time by sensing steady or increasing wet bulb temperature gave inconsistent results. The recommended algorithm uses wet and dry bulb temperature readings corresponding to the occurrence of the maximum wet bulb depression during aspiration, with an aspiration period of 4-6 min being adequate for most purposes using the psychrometer tested.