In this study, we aimed to assess the spatial variability of microclimate inside a closed compost-bedded pack barn (CBP) with a negative ventilation system during summer and winter. The research was carried out in a CBP located in the Zona da Mata region, Minas Gerais, Brazil. For each of the stations analyzed, the following environmental mean variables observed inside a CBP were measured: air dry-bulb temperature (t db ), air relative humidity (RH), and windspeed, Temperature-Humidity index, and specific enthalpy. The kriging maps showed that the most critical housing conditions in the thermal environment were found, mainly, from the central part of the CBP, close to the exhaust fans. The analyses also pointed out that the system presented temperature gradients along the length, up to 3°C. During the summer afternoon, the entire region of the CBP was in a discomfort situation (t db >26°C; RH>75%). During the winter, the measured environmental data remained within the comfort zone throughout the facility. However, probably due to the lack of thermal insulation of the material used to close the sides of the CBP, it did not allow spatial thermal uniformity for both seasons.It was also inefficient to keep the animals within the comfort zone for lactating cattle during the critical summer period.

For drip irrigation design and management, it is necessary to know the relation between flow and pressure acting on emitters. In the case of subsurface drip irrigation, the backpressure phenomenon may change the hydraulic characteristics of emitters. Thus, this study aimed at determining such relationship between flow and pressure of different driplines in surface and subsurface conditions; aiming to find possible differences in hydraulic behavior. We tested four emitter types; two pressure compensating (D5000 and Hydro PCND) and two non-pressure compensating (TalDrip and Jardiline). Emitter flow rates were attained in atmospheric conditions and submerged in water, in which submergence levels represented backpressure. Assays were performed using inlet pressures of 80, 100, 120, and 150 kPa for the Hydro PCND dripline and 25, 50, 100, and 150 kPa for the other ones; the backpressures were of 0.49, 1.47, 2.45, 4.41 and 6.37 kPa with four replications. The emitters had their proportionality constants and discharge exponents changed in submerged applications, representing backpressure effect. Non-pressure compensating emitters had their discharge exponent decreased, while in pressure compensating ones, it was increased. Backpressure reduced emitter flow rates at all evaluated pressures.KEYWORDS: discharge exponent, proportionality constant, trickle irrigation. EFEITOS DA CONTRAPRESSÃO SOBRE A RELAÇÃO VAZÃO-PRESSÃO DE TUBOGOTEJADORESRESUMO: Para o projeto e o manejo da irrigação por gotejamento, é necessário o conhecimento da relação entre vazão e pressão atuante sobre os emissores. Porém, o fenômeno da contrapressão, no caso do gotejamento subsuperficial, pode alterar as características hidráulicas dos emissores. Assim, o objetivo deste trabalho foi determinar a relação entre a vazão e a pressão de diferentes tubogotejadores em condições superficiais e subsuperficiais, e as possíveis diferenças no comportamento hidráulico dos emissores nessas duas condições. Foram utilizados nos ensaios quatro emissores: dois autocompensantes (D5000 e Hydro PCND) e dois não autocompensantes (TalDrip e Jardiline). A vazão destes foi obtida em condição atmosférica e submersa em água, em que os níveis de submersão representaram a contrapressão. Os ensaios foram realizados utilizando as pressões de entrada de 80; 100; 120 e 150 kPa para o tubo gotejador Hydro PCND e 25; 50; 100 e 150 kPa, para os demais, e contrapressões de 0,49; 1,47; 2,45; 4,41 e 6,37 kPa, com quatro repetições. Os emissores tiveram suas constantes de proporcionalidade e expoentes de descarga alterados em aplicação submersa. Emissores não autocompe nsantes tiveram seu expoente de descarga diminuído, enquanto nos autocompensantes, este aumentou. A vazão de emissores foi reduzida pelo efeito da contrapressão, em todas as pressões avaliadas.

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The aim of this research was to evaluate the spatial distribution of bedding variables in a climate-controlled compost bedded pack barn (CBP) equipped with an evaporative cooling system associated with a tunnel ventilation mode. The study was conducted on a farm in the West Mesoregion of Minas, MG, Brazil. The interior of the animal facility was divided into a mesh of 120 equidistant points, where the bedding surface temperature (t b-sur ), the bedding temperature at 0.20 m depth (t b-20 ) and the bedding penetration resistance (PR b ) of layer 0 to 0.20 m depth were measured. Bedding samples were collected to obtain the moisture (M b ) and pH in the surface and at 0.20 m depth. Geostatistics technique was used to evaluate the dependence and spatial distribution. Through the bedding area, the t b-sur presented low variability, with 6 ºC of amplitude, and t b-20 presented highest values (up to 55 °C). The spatial distribution of M b-20 was similar to that observed on the surface and its highest levels occurred in the region near the feed alley (> 40%). The distribution of pH was similar in both layers. The tendency of high PR b occurred in the layer between 0.15 and 0.20 m (0 and 1500 kPa).

The objective of this study was to evaluate and characterize the dependence and the spatial and temporal distribution of variables and indices of the thermal environment in an open compost-bedded pack barn system with positive-pressure ventilation (CBPPV) during the winter period. The study was conducted in a CBPPV system located in the Zona da Mata region, Minas Gerais, Brazil. The indoor environment was divided into a mesh composed of 55 equidistant points, where data on dry-bulb air temperature (tdb) and relative humidity (RH) were collected. The collected data were divided into four periods—dawn, morning, afternoon, and night—and mean values were obtained. To evaluate the thermal microenvironment, the temperature and humidity index (THI) and the specific enthalpy of air (h) were used. For spatial dependence analysis, geostatistical techniques were applied. Through the results, a strong spatial dependence was verified for all variables evaluated. Through THI and h maps, conditions of thermal comfort were found for dairy cattle. The highest values of tdb, THI, and h were recorded in the afternoon period in the northwest region of the facility (tdb = 23.2 °C, THI = 69.7, and h = 50.9 kJ∙kg of dry air−1).

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The objective of this study was to evaluate the thermal comfort of growing and finishing pigs affected by the different constructive typologies of the installations regarding the floor and lateral partitions. Were evaluated the following pen types: pen with water pit, pen with partially slotted floor on the sides, and pen with partially slotted floor on the sides and in the center of the facilities. The following thermal variables were measured: dry bulb temperature, black globe temperature, relative humidity, and air velocity. Based on these data, the temperature and humidity index, the temperature index of the globe and humidity, and the specific enthalpy were calculated. The pen with a water pit showed higher average relative air humidity and lower black globe temperature compared to the other pens. In the hottest period of the day, the temperature index of the globe and humidity presented mean values above that recommended for adult pigs, although there were no differences between pens. This indicates that animals, irrespective of the type of pen used, have suffered from thermal stress, which most likely affected their performance.

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