A study of methods for handling and composting cattle and swine manure and urine from the point of view of hygiene

Abstract

The aim of this study was to increase the knowledge of basic facts important for the hygienic aspects of different types of manure handling. The investigations were on urine separation in animal housing, storage of solid or liquid manure (slurry) outside animal housing, a new method for solid manure handling (the so-called ‘mole hill’ dung system), composting of solid manure in the field and the viability of Salmonella in the liquid separated from the manure slurry. The studies showed the following results. It was possible to effectively separate urine from manure if it were done in the gutter immediately behind each tied animal in cowhouses or in the entire length of the dunging passage in swine houses. In houses with urine separation indoors, the animals were generally somewhat cleaner than in houses without urine separation. The pH value of the urine was then about 9 even when the dry matter content was over 10%. It was not possible to separate urine from manure, except to a very small degree, once the two were mixed by, for instance, using scrapers in the gutter. In the urine separated in this way the pH was about 7, i.e. the same as in the liquid separated from slurry. The viability of two Salmonella types was tested in the liquid and both types were found even after 13 weeks. The addition of a large amount of rain water via the dung yard, as well as seepage to the urine tank, lowered the pH considerably. In order to maintain a high pH in cases where there is an effective urine drainage indoors it is, therefore, important to have a separate tank for seepage and precipitation. The ‘mole hill’ dung system lowered the outdoor odour considerably, reduced the fly problem and seemed to cause quicker composting. It was found possible to use the ‘mole hill’ dung system even with manure mixed with considerable amounts of straw. A general appraisal of different manure handling methods, based on the results obtained from these studies, shows that solid manure handling with an effective urine separation gives the best conditions generally for animal health and hygiene inside and outside the animal houses. It also gives a better barrier against contamination via manure and urine from the animal houses than other types of manure handling.