[The use of flocculation sludge in poultry feed. Chemical and microbiological composition]

For the purpose of making inventories, the chemical and microbiological composition of samples of flocculated sludge of poultry, pig and cattle-stock slaughter-houses were examined. This was required to study the possibilities of using flocculated sludge as raw material in animal feed. Chemical studies showed that the dry matter (dm) levels of the various specimens of sludge varied markedly. (Broiler sludge 7.1% of dm, pig sludge 7.5%, cattle-stock sludge 5.5% and laying-hen sludge 13.3%). Broiler- and laying-hen sludge contained more crude fat than did the other samples of sludge. Measured by the concentrations of lysine, methionine and cystine, the sludge product was most similar to the protein of meal-and-bone meal and soy-bean meal. The iron content of almost all samples examined was very high. In view of the current standards for concentrations of metal in complete animal feeds, the concentrations of iron and lead will have to be taken into account in using this sludge product. The proportion of total polymers in the fat fractions of samples of sludge varied from 2.4% to 39.2%, less than 10% only being observed in two samples. The microbiological composition of broiler and pig sludge did not differ. Both the total aerobic bacterial count and the number of Enterobacteriaceae, Escherichia coli and Salmonella were found to be high. Species of Campylobacter were not isolated; however, a number of samples were found to be positive for adenovirus. Prior to deciding to use flocculated sludge in livestock feeding, the product will have to undergo thorough decontamination.