-Heat production by fattening pigs in deep-litter or conventional slatted floor systems. The insulation and ventilation requirements for livestock buildings depend on the amount of heat and water vapour produced by the animals. Our knowledge of heat production in slatted floor buildings must be adapted to the deep-litter system, in which there is early composting of the slurry. We isolated the effect of the husbandry system on heat and water vapour production using the same building, animals and external temperature. We compared the amount of heat and water vapour produced with the deep-litter system to that predicted by models, and to that of a conventional slatted floor system, used as a reference. Twelve

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This work evaluated N dynamics that occurs over time within swine slurry composting piles. Real-time quantitative PCR (qPCR) analyzes were conducted to estimate concentrations of bacteria community harboring specific catabolic nitrifying-ammonium monooxygenase (amoA), and denitrifying nitrate- (narG), nitrite- (nirS and nirG), nitric oxide- (norB) and nitrous oxide reductases (nosZ) genes. NH3-N, N2O-N, N2-N emissions represented 15.4 ± 1.9%, 5.4 ± 0.9%, and 79.1 ± 2.0% of the total nitrogen losses, respectively. Among the genes tested, temporal distribution of narG, nirS, and nosZ concentration correlated significantly (p<0.05) with the estimated N2 emissions. Denitrifying catabolic gene ratio (cnorB+qnorB)/nosZ ≥ 100 was indicative of N2O emission potential from the compost pile. Considering our current empirical limitations to accurately measure N2 emissions from swine slurry composting at field scale the use of these catabolic genes could represent a promising monitoring tool to aid minimize our uncertainties on biological N mass balances in these systems.

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RESUMO:A demanda por fontes alternativas de energia tem crescido nos últimos anos em função das variações do preço do petróleo aliadas à recente crise energética. Por meio da digestão anaeróbia é possível transformar os dejetos de suínos em biogás. No presente trabalho, estudou-se a viabilidade econômica do uso do biogás como fonte alternativa para a geração de energia elétrica para diferentes períodos de geração. O método utilizado para a avaliação econômica foi o Valor Presente Líquido. O tempo de retorno do capital investido também foi calculado levando em consideração o desconto da taxa de juros nos fluxos de caixa. O estudo demonstrou ser economicamente viável a utilização do biogás da suinocultura, como fonte para geração de energia elétrica. O aumento da demanda de energia elétrica na propriedade aumenta o Valor Presente Líquido e diminui o tempo de retorno do investimento. PALAVRAS-CHAVE:biogás, suínos, energia elétrica, análise econômica. ECONOMIC ANALYSIS OF THE GENERATION OF ELECTRIC ENERGY FROM BIOGAS IN PIG PRODUCTION ABSTRACT:The demand for alternative sources of energy has grown in recent years in line with the variation of petroleum prices coupled with the recent energy crisis. Through anaerobic digestion swine manure can be converted into biogas. In the present study it was evaluated the economic viability of using biogas as an alternative source for the production of electricity, for different periods of generation. The method used for the economic evaluation was the Net Present Value (NPV). The time of return on invested capital was also calculated taking into account the discount interest rate on cash flows. The study proved to be economically viable use of biogas from swine manure as a source for generating electricity. The increased demand for electricity in the property increases the Net Present Value and decreases the time required for return of the investment.