Brazilian poultry production has reached unprecedented levels in recent years, especially regarding to the broiler chickens production activity. This increasing productivity is due to progressive implementation of technology in this sector of the animal production in Brazil, which is being mainly focused on improving the animal environment and also, the diets offered to the birds combined with genetic advances. One consequence of high productivity of broiler chickens is the exacerbated production of waste, especially used litter, which has high levels of nutrients, among which is the nitrogen (N), that makes the poultry litter a material with high biological potential to be used as fertilizer. One way of depleting the quality of the litter is through volatilization of N as gaseous ammonia (NH3). The cycling of N for a whole broiler barn has been poorly treated in the current Brazilian scientific literature, which is the reason why this literature review was developed. The aim was to depict all possible sources and sinks and the mechanisms transformation of N inside the barn. Special focus was given to the processes of formation and models of NH3 volatilization. As main conclusion, we observed that the increase in feed conversion ratio with age is one of the factors that contributed to non-utilization of N offered to broilers, implying in a higher concentration of this nutrient in the litter with increasing age and consequently potential of its loss through volatilized NH3.

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The objective of this study was to adapt and validate a computer model using the Computational Fluid Dinamics (CFD), in the prediction of temperature and air speed in a duct distribution system coupled to a heating furnace that is used in typical poultry houses in tropical and subtropical countries. The validation of the model with experimental data was satisfactory, presenting normalized mean square error NMSE values of 0.25 and 0.02 for air temperature and air speed, respectively. The results evidenced that the proposed model is adequate for predicting the air speed and temperature for this type of system, and could be used to improve the efficiency of the distribution of heat inside and around air ducts using different air speeds, types of materials and dimensions.

The aim of this study was to evaluate two types of poultry bedding litter (wood shavings and coffee husks) with increasing use cycles, the best time to proceed with composting based on the carbon/nitrogen ratio and the ability to generate ammonia. The results obtained with the present experiment conditions indicated that the litter with wood shavings in the first cycle and the litter with coffee husks in the first and second cycles presented the best behavior in terms of the C/N ratio needed for later use as compost. In regards to the contamination potential, it was found that increasing the number of reutilizations for both the wood-shaving and coffee-husk litters resulted in a greater ammonia emission.

Brazil is the largest broiler meat exporter in the world. This important economic activity generates income in different branches of the production chain. However, the decomposition of residues incorporated in the poultry litter generates several gases, among them ammonia. When emitted from the litter to the air, ammonia can cause several damages to animals and man, in addition to being able to convert into a greenhouse gas. Thus, the aim of this article was to carry out a review of the ammonia emission factors in the production of broilers, the methodologies for measuring, and the inventories of emissions already carried out in several countries. The main chemical processes for generating ammonia in poultry litter have been introduced and some practices that can contribute to the reduction of ammonia emissions have been provided. The PMU, Portable Monitoring Unit, and the SMDAE, Saraz Method for Determination of Ammonia Emissions, with the required adaptations, are methodologies that can be used to quantify the ammonia emissions in hybrid facilities with a natural and artificial ventilation system. An ammonia emission inventory can contribute to the control and monitoring of pollutant emissions and is an important step towards adopting emission reductions. However, quantifying the uncertainties about ammonia emission inventories is still a challenge to be overcome.

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This study aimed to analyze the effect of the area size and location of openings for natural ventilation on the temperature and relative humidity inside a typological facility for coffee wet processing that have been using in Colombia and some South America Countries as well, with mechanical drying inside, using modeling with computational fluid dynamics modeling, in order to find the best suitable condition for preserve the quality of the coffee parchment. A significant effect was found regarding the area and location of the openings for natural ventilation on the internal hygrothermal environment, but no significant effect was found on the temperature. It was also found that the chimney effect plays a decisive role in the mass transfer of water vapor and heat to the outside of the building, and helping to maintain a suitable internal environment for the preservation of coffee.