Abstract
Chicken litter is produced in large quantities from all types of poultry raising activities. It is primarily used for land application, thus it is essential to analyze its properties before it is released to the environment. The objective of this study is to compare the microbiological and chemical properties of litter generated from layer and broiler chickens reared under intensive and free-range production systems. The microbiological analysis consisted of the enumeration of total bacteria, total coliforms,
Staphylococcus species,
Salmonella species and
Clostridium perfringens. Chicken litter from layers reared under intensive and free range systems showed lower mean total bacterial count than the litter collected from chicken broilers reared under either of the two systems (
P
=
0.0291). The litter from intensive layers had the lowest mean total coliform counts (
P
=
0.0222) while the lowest
Staphylococcus species count was observed in the litter from free-range layers (
P
=
0.0077). The
C. perfringens count was the lowest in chicken litter from intensively raised broilers and layers (
P
=
0.0001).
The chemical properties of litter from the different chicken types and production systems were compared based on determination of pH, electrical conductivity, carbon, nitrogen, phosphorus, potassium, cadmium and zinc. Litter from free-range broilers showed the highest pH value (
P
=
0.0005); however, the electrical conductivity was higher in the litter from both intensive and free-range layers compared to the litter from both broiler production systems (
P
=
0.0117).
Chicken litter from intensive systems had higher nitrogen content than litter from free-range systems (
P
=
0.0000). The total phosphorus was the lowest in free-range broiler litter (
P
=
0.0001), while the total potassium was the lowest in litter from intensively managed broilers (
P
=
0.0000). Zinc appeared higher in litter from layers compared to that from broilers (
P
=
0.0101). The cadmium content was higher in the litter from free-range broilers and layers compared to that in the litter from intensively managed systems (
P
=
0.0439).
Staphylococcus species in the litter as well as cadmium concentrations seem to be the most critical parameters presenting risks on the environment and on human health. Based on the lowest coliform counts (an indication of water pollution), the high nutrient levels and the low cadmium values, litter from intensively managed layers appears as the most suitable for application on agricultural soils.