Abstract

ESPINOZA, Yusmary; HERNANDEZ Z, Marcos J; BARRERA CH, Teresa V  and  OBISPO, Néstor E. Effect of animal feeding on the microbiological quality of manures used as fertilizers. Zootecnia Trop. [online]. 2009, vol.27, n.2, pp.151-161. ISSN 0798-7269.

To evaluate the relationship between type of diet and microbiology quality of cow, hen, and pig manure used as fertilizers, we collected samples of each manure (M) from farms located in Aragua, Carabobo, and Yaracuy states, Venezuela. On the basis of a completely randomized experimental design with four repetitions, the following treatments were compared: bovine (B), poultry (G), and pork (C) manures, in combination with two different types of diets (D1 and D2) provided to the animals, for six treatments. Samples were processed and analyzed for total bacteria and fungi contents, and total and fecal coliform bacteria. There was not a specific effect of the type of diet on the number of bacteria and fungi among the manures. The higher content of bacteria and fungi was observed in bovine and poultry manures, respectively. In general, the amount of fecal coliforms found in the manures ranked between 2 x 106 to 7 x 107 MPN/g. These values exceed those values internationally allowed for these pathogens in the manures used as fertilizers. Manures were grouped on the basis of their similarities of microbial loads, pathogens or fertilizer conditions, in three well defined groups: I: BD1 and BD2, II: GD1, GD2 and CD1, and III: CD2. Group I, with less stable conditions, was associated to the mineralization and higher number of bacteria. The second was more stable as organic fertilizer with lesser capacity to immobilize the N, but with a high risk for the public health due to its high load of pathogens. The third group had the highest risk for public health that compromises its use as organic fertilizer.

Keywords : manure; diet; feeding; quality; fertilizer.

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