Treatment of animal carcasses in poultry farms using sealed ditches

Several hen carcass elimination experiments were conducted by isolating corpses in a sealed ditch and adding different doses of lime. The aim was to evaluate the viability of this method as an alternative to other elimination techniques, as required in the European regulation CE 1774/2002 [Reglamento CE 1774/2002, de 3 de octubre por el que se establecen las normas sanitarias aplicables a los subproductos animales no destinados a consumo humano]. The experiments were carried out at a natural scale, in a 200m3 ditch located in a livestock enterprise, using a proportion of 200g of lime/kg of carcass. We observed a high degradation of carcasses after six months, the method being also safe from a microbiological point of view. The material extracted from the ditch had a high calcium content (330.7gkg(-1)), which makes it an ideal product for soil lacking this element, or as an acidity corrector in acid soils due to its basic (pH 8.48) nature. It also contains a significant amount of mineral nutrients (17.0gkg(-1) N, 2.4gkg(-1) P and 4.9gkg(-1) K) and organic matter (101.5gkg(-1)). We also analysed the material extracted from the ditch prior to its renovation for the experiments and followed the processes taking place in the ditch during the first six months, when lime doses of 100, 200 and 300 gkg(-1) of treated carcass were applied. Simultaneously, we carried out laboratory experiments in cylindrical 25L deposits to evaluate the gas release of the three (100, 200 and 300g of lime/kg carcass) doses of lime used. After the tenth week, we observed CO2 concentrations ranging from 5% for the lower lime doses to very low levels for the 300g lime/kg carcass dose. As regards methane, in the three series of experiments, the release was highest during the first weeks, began to decrease in the eighth week and reached its lower value during the fourteenth week. Emissions of NO2 were not observed, and the levels of NH3 and SH2 were usually so high that they exceeded the detection level of the apparatus used to register them.