Changes in Arsenic, Copper, Iron, Manganese, and Zinc Levels Resulting from the Application of Poultry Litter to Agricultural Soils

Phytase Improves Zinc Utilization by Broiler Chickens

The study aimed to evaluate phytase effects on the availability of zinc (Zn) from corn and soybean meal feeds for broiler chickens, whereas, in parallel, Zn requirements were investigated. A total of 640 Cobb × Cobb 500 male chicks were fed a Zn-deficient diet (18.87 ± 0.87 mg/kg Zn) until 7 days of age. The experiment was a 2 × 5 factorial with 10 treatments (feeds with or without phytase × 5 increasing dietary Zn levels) with 8 replications of 8 birds each. Supplemental Zn sulfate heptahydrate was used (measurements of the Zn analyzed in the feeds were 30.1 ± 0.73, 61.6 ± 0.13, 90.4 ± 1.60, 123.6 ± 1.99, and 151.9 ± 1.84 mg/kg, respectively). There were no interactions between phytase and Zn for any evaluated response. Phytase improved broiler performance and increased plasma myo-inositol, Zn content in the liver and tibia, Zn retention, and digestible energy (p < 0.05). No significant impact of dietary Zn was found on broiler performance (p > 0.05) except for Zn excretion and tibia Zn content. Adding phytase at 4000 FYT increased the apparent ileal Zn digestibility by 98% and Zn retention by 13.7%, whereas Zn supplementation of up to 151.9 mg/kg did not impact broiler performance.

Latent Benefits and Toxicity Risks Transmission Chain of High Dietary Copper along the Livestock-Environment-Plant-Human Health Axis and Microbial Homeostasis: A Review

The extensive use of high-concentration copper (Cu) in feed additives, fertilizers, pesticides, and nanoparticles (NPs) inevitably causes significant pollution in the ecological environment. This type of chain pollution begins with animal husbandry: first, Cu accumulation in animals poisons them; second, high Cu enters the soil and water sources with the feces and urine to cause toxicity, which may further lead to crop and plant pollution; third, this process ultimately endangers human health through consumption of livestock products, aquatic foods, plants, and even drinking water. High Cu potentially alters the antibiotic resistance of soil and water sources and further aggravates human disease risks. Thus, it is necessary to formulate reasonable Cu emission regulations because the benefits of Cu for livestock and plants cannot be ignored. The present review evaluates the potential hazards and benefits of high Cu in livestock, the environment, the plant industry, and human health. We also discuss aspects related to bacterial and fungal resistance and homeostasis and perspectives on the application of Cu-NPs and microbial high-Cu removal technology to reduce the spread of toxicity risks to humans.

Combined effect of growth promoter roxarsone and copper on the earthworm Eisenia fetida

Roxarsone (ROX) and copper (Cu) are growth promoters in livestock to promote growth and prevent disease. These chemicals and their metabolites are released to the soil through manure application and have a potential adverse effect on soil-dwelling organisms. The objective of this study was to investigate the combined subacute effect of ROX exposure (0, 80, 240, 720 mg kg^-1) and Cu exposure (0, 80, 160 mg kg^-1) in earthworms (Eisenia fetida). Growth, reproduction, spermatogenesis under light microscope, and heavy metal residue were investigated during 56-day exposure period. Results showed that Cu exposure of 80 or 160 mg kg^-1 alleviated the effect of ROX on cocoon production or hatching. The cocoon number exhibited an increase (P < 0.05) at 80 mg kg^-1 ROX on day 28, compared with the 0 mg kg^-1 ROX, in the presence of 80 mg kg^-1 Cu, whereas there was no effect (P > 0.05) in the presence of 160 mg kg^-1 Cu. The hatching success at 80 or 240 mg kg^-1 ROX exhibited a decrease (P < 0.05) on day 28, in the absence of Cu, whereas no effect (P > 0.05) was observed in the presence of 80 or 160 mg kg^-1 Cu. The other reproductive parameters (cocoon weight, juvenile number, and biomass) demonstrated a decrease (P < 0.05) only at 720 mg kg^-1 ROX in the presence or absence of Cu. However, with increasing exposure time, the above reproductive parameters were not affected (P > 0.05) in all groups on day 56. On the other hand, sperm deformity (%) increased (P < 0.05) at 240 or 720 mg kg^-1 ROX on day 28, in the presence or absence of Cu; however, the microstructural alteration in seminal vesicles occurred only at 720 mg kg^-1 ROX, exhibiting disordered distribution and decreased mature sperm bundles. In addition, ROX or Cu residues in earthworms demonstrated an increase with increasing ROX or Cu exposure concentration. Our present results may provide important insight on combined toxicity of chemicals in soils.