Emisiones de gases procedentes de purines obtenidos a partir de cerdos de cebo alimentados con pulpas cítricas

Abstract

[ES] El cerdo se consume de forma amplia en todo el mundo, y en su cría se producen cantidades relevantes de gases como el CH4 (metano) y el NH3 (amoniaco), los cuales tienen un efecto negativo sobre el medio ambiente. El objetivo de este trabajo es conocer cuál es el efecto sobre estas emisiones al incluir pulpas de cítricos en la dieta de cerdos de engorde. El estudio tendrá dos fases. En una primera fase, se recogerán purines correspondientes a una prueba de valor nutricional incorporando pulpas cítricas y se determinarán las emisiones potenciales de CH4 mediante el método del ¿potencial bioquímico de metano¿ (de sus siglas en inglés, BMP). En una segunda fase, se alimentarán 160 cerdos a partir de los 60 kg de peso vivo del cerdo y 4 tratamientos diferentes (40 animales por tratamiento) consistentes en dosis crecientes de pulpa cítrica (0%, 8%, 16% y 24%) y se recogerán los purines derivados de los mismos. Una vez retirados los purines se determinarán las emisiones de los gases (NH3 y CH4) semanalmente. Se empleará un medidor de gases fotoacústico para medir las concentraciones de los gases al finalizar el ensayo, paralelamente a una línea de impingers (borboteadores ácidos) que permitirán verificar las mediciones de NH3 por parte del medidor fotoacústico. Este TFM desarrollará competencias de investigación en materia de producción animal y medio ambiente. Igualmente, aborda un caso práctico relacionado con la economía circular, uniendo sectores como la industria agroalimentaria (a través de los subproductos de industrias cítricas), la alimentación animal (productores de piensos) y la producción animal (granjas).

[EN] Pig meat is the most consumed meat in a worldwide level and its consumption is expected to continue growing in the following years. However, this can also have negative consequences for the environment due to the increase of greenhouse gases and other gases such as ammonia (NH3) that can be emitted to the atmosphere. There are studies that report introducing modifications in the diet in order to reduce the gases that slurries emit. In this work the inclusion of citrus pulp (orange) in the diets of finishing pigs is studied, in order to quantify and analyze how such inclusion affects the gases that slurries emit. Specifically, two tests were performed: the first one had the aim of studying the effect of including a high level of citrus pulp on the methane production potential. Three different diets were used (two of them with a 50% inclusion of citrus pulp), and methane (CH4) from the slurry was quantified. The second test studied the effect on the emission of CH4 and NH3 in similar conditions to commercial conditions, by adding moderated quantities of citrus pulp to the feed. In this second study four diets were used, with different levels of inclusion citrus pulp inclusion: 0%, 8%, 16% and 24%. The emitted NH3 was measured with the open chamber method and the capture of the gas with an acid trap, while CH4 was measured with the closed chamber method and a photoacoustic gas analyzer. The results of the first study indicated that including citrus pulp affects the final composition of NH3 and TKN (Total Kjeldahl Nitrogen) of the slurry, as well as its pH, while the potential emission of CH4 was reduced. On the other hand, the inclusion of moderated quantities of citrus pulp of the second study did not significantly affect any of the parameters, but a great variability of the results was observed. This was due to the behavior of the animals in water use, affecting the dilution of the slurries, which lead to hidden effects on gas emissions. Therefore, it was not possible to detect any effect on emissions adding citrus pulp in pig feeding in commercial conditions.