Poultry litter: Is it safe enough to be used as soil fertilizer?

• bacteria,
• fungi,
• viruses,
• parasites,
• antibiotics,
• pathogens with antibiotic-resistant genes,
• heavy metals,
• growth and sex hormones,
• pesticide, etc.

Therefore, a review from Kyakuwaire et al. (2019) consolidated information from different sources about the contaminants in chicken litter with potential negative effects on human, animal, and environmental health.

This research group hypothesized that “Chicken litter in its current form does not meet the minimum standards for land application and general release into the environment.”

Bacteria and antibiotic-resistant genes

Regarding bacteria and antibiotic-resistant genes, the most prevalent microorganism found in poultry litter in Australia was Actinobacillus, with a 100% presence; Salmonella resulted in 83% in reused broiler litter which is 15% less than those found in non-reused broiler litter.

In the United States, the samples were taken from broiler fecal matter, in which were detected a high prevalence of Actinobacillus and Campylobacter in around 80 to 100 percent.

Moreover, in all samples taken either from chicken litter or compost from Australia, the U.S., Canada, and Nigeria, several microorganisms were detected exceeding the recommended levels for soil improvement. Those microorganisms included E. coli, Salmonella, Staphylococcus, Campylobacter, Clostridium, Listeria, Bordetella, Corynebacterium, Globicatella, Mycobacterium, Streptococcus, and Actinobacillus.

“These are highly pathogenic bacteria with health devastating effects in humans and livestock and the potential to widely spread in the environment both vertically and horizontally, implying that they can have devastating human and environment health as well as economic problems.” Said the authors.

For example, Clostridium perfringes causes food poisoning and wound infection in humans, and hemorrhagic enteritis and Campylobacter can affect the nervous system with neurological disorders in very young, elderly, or immune-compromised human patients.

Fungi, Helminthes, Parasitic Protozoa, and Viruses

The study indicated that the older the litter, the greatest the amount of pathogenic fungi. In research on broiler litter from Portugal, the following fungi were detected:

• Penicillin spp. was the most frequently found (59.9%),
• followed by Alternaria (17.8%),
• Cladosporium (7.1%), and
• Aspergillus (5.7%) in fresh litter.

Also, Penicillin spp. was the most commonly isolated (42.3%), followed by Scopulariopsis spp (38.3%), Trichospporon spp. (8.8%), and Aspergillus spp. (5.5%) in an aged litter.

On the other hand, talking about helminth parasites, one of the most commonly excreted from poultry is Ascaridia galli. This parasite has been mainly seen in layers and is pathogenic in young birds. Another common is Davainea and Rallietina sp. which are the most common in chicken litter.

Those can lead to nutrient malabsorption in chickens, reduced egg production, and deaths. However, the helminths found in the chicken litter have been reported not to cause parasitic infection in humans and other mammals.

Antibiotics and Pesticides

The authors indicated that there are few studies showing antibiotics and pesticides residues in the chicken litter, but most detected have been:

• Fluoroquinolones, which include ciprofloxacin, danofloxacin, difloxacin, enrofloxacin, fleroxacin, lomefloxacin, and norfloxacin.
• Sulfonamides that entail sulfachloropyradazine, sulfadiazine, sulfadimidine, sulfaguanidine, sulfamerazine, sulfomethoxazole, sulfamonomethoxine, and sulfanilamide.
• Tetracyclines, which encompass chlortetracycline, doxycycline, methacycline, oxytetracycline, fluoroquinolones, sulfonamides, and tetracyclines.

Conclusions

“Chicken litter is also contaminated with a vast array of antibiotics and heavy metals. There are no standards set specifically for chicken litter for most of its known contaminants. Even where standards exist for related products such as compost, there is wide variation across countries and bodies mandated to set standards for safe disposal of organic wastes.”

Source: Kyakuwaire, M.; Olupot, G.; Amoding, A.; Nkedi-Kizza, P.; Ateenyi Basamba, T. How Safe is Chicken Litter for Land Application as an Organic Fertilizer?: A Review. Int. J. Environ. Res. Public Health 2019, 16, 3521. https://doi.org/10.3390/ijerph16193521