Assessment of bacterial diversity in the chicken litter: A potent risk to environmental health

Abstract

Using chicken litter as an organic fertilizer on land is the most common, cheapest and environmentally safest way to manage the latter generated swiftly from the poultry industry.  Raw chicken litter has been applied to field soils where various vegetables are cropped to increase yield or productivity. However, the chicken litter frequently come in contact with different environments, such as water, soil, microbes and vegetation. When chickens defecate, their litters, in a few countries, are particularly reused for the next flock, potentially causing cross-contamination. Due to various contact points in the environment, a high probability of bacterial transmission is predicted, which could lead to infection spread in animals and humans. Consumption of contaminated water, food, and meat could lead to the transmission of deadly infections. Microbes in the chicken litter also affect the grazing animals while feeding on fields duly applied with chicken litter as manure. The maximum permissible limits (MPLs) in the chicken litter for land application should not exceed 106-108 CFU/g for Coliform bacteria. Antibiotics are regularly mixed in the diet or drinking water of chicken grown in marketable poultry farms for treating bacterial diseases. Rampant usage of antimicrobials also results in resistant bacteria's survival in animal excreta. Herein, we surveyed the literature to identify the major bacterial genus harboured in the fields applied with chicken manure to increase soil fertility. Our detailed survey identified different bacterial pathogens from chicken litter samples from different investigations. Most studies showed the prevalence of Campylobacter, Salmonella, Enterococcus, E. coli, Bacillus, Comamonas, Proteus and Citrobacter, including many other bacterial species in the chicken litter samples. This article suggested that chicken litter does not meet the standard parameters for direct application as organic fertilizer in the fields. Before being applied to the ground, chicken litter should be treated to lessen the danger of polluting crops or water supplies by reducing the prevalence of harmful bacteria carrying antibiotic-resistance genes.