[en] Determining accurately the ventilation rates from rabbits houses, using non-expensive and non-invasive methods, is needed. The main aim of this work was to test the carbon dioxide balance as a method to determine the ventilation rate in fattening rabbit farms. In addition, the CO2 release rate from rabbit manure was measured, and the effect of CO2 concentration gradient between the inlet and outlet air of the building, on the method accuracy was characterized. To these aims, a fattening rabbit farm was evaluated during two periods and CO2 concentrations were simultaneously monitored in the inlet and outlet air by using a photoacoustic monitor. Ventilation rates were also directly determined by calibration of the exhaust fans and monitoring their operation times. CO2 emissions from manure were measured during two whole fattening periods, using a flux chamber and a photoacoustic monitor. The effect of CO2 concentrations gradient between the inlet and outlet of the farm on the accuracy of the balance was studied through statistical regressions. The CO2 emission from manure resulted in 13% of total CO2 emissions (considering both manure and animals). No statistically significant differences were found between measured and calculated ventilation rates. The effect of the CO2 gradient on the balance accuracy was statistically significant only in one of the trials. According to these results, the CO2 balance can be recommended for the determination of ventilation rates in fattening rabbit buildings.

[es] El desarrollo de t&eacute;cnicas de bajo coste y poco invasivas es necesario para la determinaci&oacute;n de la tasa de ventilaci&oacute;n en granjas de conejos. El objetivo principal de este trabajo fue evaluar el balance de CO2 como m&eacute;todo para determinar la tasa de ventilaci&oacute;n en granjas de conejos de cebo. Adem&aacute;s, se midi&oacute; la tasa de producci&oacute;n de CO2 procedente del esti&eacute;rcol, y se estudi&oacute; el efecto del gradiente de concentraciones de dicho gas, entre el interior y exterior de la instalaci&oacute;n, sobre la precisi&oacute;n del m&eacute;todo. Para ello, se evalu&oacute; una granja de conejos de cebo durante dos periodos y utilizando un medidor fotoac&uacute;stico se midieron simult&aacute;neamente las concentraciones de CO2 en el interior y exterior de la nave. La tasa de ventilaci&oacute;n se determin&oacute; tras calibrar los ventiladores de la nave y monitorizar su tiempo de funcionamiento. Las emisiones de CO2 del esti&eacute;rcol se midieron durante dos ciclos de cebo, utilizando un medidor fotoac&uacute;stico y una c&aacute;mara din&aacute;mica. El efecto del gradiente de las concentraciones de CO2 sobre la precisi&oacute;n del m&eacute;todo se evalu&oacute; mediante an&aacute;lisis de regresi&oacute;n. La producci&oacute;n de CO2 del esti&eacute;rcol fue el equivalente al 13% de la producci&oacute;n total en la nave. No se encontraron diferencias estad&iacute;sticamente significativas entre los flujos de ventilaci&oacute;n medidos y calculados. El efecto del gradiente de CO2 sobre la precisi&oacute;n del m&eacute;todo fue significativo s&oacute;lo en uno de los periodos. As&iacute; pues, se puede recomendar el uso de balances de CO2 para determinar las tasas de ventilaci&oacute;n en granjas de conejos de cebo.