Heavy metal toxicity in poultry: a comprehensive review

Heavy metal pollution in poultry feeds and broiler chickens in Bangladesh

The poultry industry poses a significant threat of heavy metal poisoning for the people of Bangladesh. The research was performed to assess the levels of heavy metals in chicken feed as well as other consumable sections of poultry fowl, and to determine the possible health hazards implicated. The levels of seven metals were evaluated in sixteen commercially available poultry feeds and in three edible portions of chicken obtained from several local markets in Rajshahi city. The metal concentrations were investigated via an atomic absorption spectrophotometer following the wet digestion method. The amount of Cr, Cd, Pb, Cu, Mn, Ni, and Fe in poultry feeds were observed from 0.03 to 12.85 mg/kg, 0.01-1.64 mg/kg, 0.15-4.21 mg/kg, 2.65-45.83 mg/kg, 22.63-188.85 mg/kg, 0.09-2.64 mg/kg, and 0.54-41.01 mg/kg, respectively. In broiler chickens, the concentrations were determined from 0.87 to 3.15 mg/kg, 0.01-0.05 mg/kg, 0.19-1.09 mg/kg, 0.96-3.78 mg/kg, 4.45-23.53 mg/kg, 0.07-0.56 mg/kg, and 2.70-92.32 mg/kg, respectively. With the exception of Cu, Mn, and Fe, most heavy metal concentrations in chickens exceeded the highest allowed concentration set by FAO/WHO. The estimated EDI, THQ and TTHQ numbers for all metals examined were found to be below MTDI, indicating that consumption of chicken meat poses noncarcinogenic risk to individuals. Comparatively, ILCR associated with Cd and Pb are around the safety threshold, but Cr exceeds the permissible range and poses a significant risk.

Mercury Level in Worldwide Poultry Food Products: a Systematic Review

Mercury is a metal known for its toxic effects on environmental, animal and human health. The presence of Hg in poultry and its potential impact on food safety still need to be explored, especially considering that poultry is the most consumed source of protein in the global population. This study aimed to systematically review mercury and methylmercury levels in poultry meat and eggs worldwide. The searches were conducted in the Web of Science, PubMed, and Scopus databases, resulting in 123 studies, of which only 30 were deemed suitable. Studies were found across sixteen countries: India, Thailand, Malaysia, China, Poland, Egypt, Ghana, Nigeria, Bangladesh, Iran, USA, Italy, Colombia, Romania, Tanzania, Algeria, and Saudi Arabia. Five poultry species were reported, with chicken being the most recorded species in 16 countries. Among biological samples, eggs and liver were the most used for measuring mercury and methylmercury levels. Levels above those permitted by regulatory organizations such as the United States Department of Agriculture (USDA), China's National Health Commission (NHC), and Thailand's Ministry of Public Health - set at 0.05, 0.05, and 0.02 mg.kg-1 respectively - were observed in 12 of the 17 countries, with the highest concentrations detected in chicken eggs from Colombia. Therefore, poultry production is not Hg-free and contamination by this metal must be monitored.

Ecological prevalence and genomic characterization of Salmonella isolated from selected poultry farms in Jiangxi province, China

Non-typhoidal Salmonella (NTS), particularly antimicrobial-resistant serovars, remains the major source of foodborne bacterial illnesses. Raw chicken is the leading cause of human salmonellosis. In this study, we evaluated the prevalence, antimicrobial resistance profiles, and genomic features of 143/1,800 (7.94%) Salmonella strains isolated from poultry farms in five major regions of Jiangxi province, China, between 2022 and 2023 using Whole genome sequencing (WGS). Among Salmonella isolates, the most common serovars were Infantis (ST32) and Enteritidis (ST11). Resistance to amoxicillin and tetracycline was the most prevalent, with 60.84% of Salmonella isolates exhibiting a multi-drug resistance (MDR) pattern. The detection of antimicrobial-resistant genes (ARGs) examined was aligned with the resistant phenotypes found. A total of 61 ARGs were identified, with aph(3')-Ia, qnrS1, aph(3'')-Ib, and tetA being the prominent ARGs. Furthermore, 24 beta-lactam genes were also identified, including blaTEM, blaSHV, and blaCTX-M. The number of ARGs and the distribution of serovars varied according to the year, farms, and cities. Salmonella isolates carried 13 heavy metal resistance genes (HMRGs) and two biocide resistance genes, with pcoS being the most prevalent. A total of 145 virulence genes and 19 plasmids were found, with serovars Infantis and Enteritidis having the most virulence genes. The high occurrence of MDR Salmonella in this study, particularly carrying numerous mobile genetic elements (MGEs), posed a serious threat to food safety and public health, emphasizing the need to improve poultry farm hygiene to decrease contamination and transmission.

Chlorogenic acid alleviates cadmium-induced neuronal injury in chicken cerebral cortex by inhibiting incomplete autophagy mediated by AMPK-ULK1 pathway

Cadmium (Cd) is an environmental pollutant that has neurotoxic properties, which poses serious threats to human health and the development of poultry farming. Chlorogenic acid (CGA) is a dietary polyphenol exhibit various biological activities such as antioxidant, anti-inflammatory, and autophagy regulation. In addition, CGA can penetrate the blood-brain barrier and exert neuroprotective effects. This study explored the mechanism of CGA in alleviating Cd-induced cerebral cortical neuron injury in chickens. The results showed that in vivo, CGA reduced the Cd level and alleviated Cd-induced histopathological and ultrastructural damages in the chicken cerebral cortex. Further research has found that CGA alleviated Cd-induced incomplete autophagy and activation of the AMPK-ULK1 pathway. In vitro, AMPK inhibitors (Compound C) could alleviate Cd-induced incomplete autophagy in chicken cerebral cortical neurons. In addition, CGA alleviated the decreased viability, incomplete autophagy, and activation of the AMPK-ULK1 pathway induced by Cd in chicken cerebral cortical neurons. In summary, CGA can alleviate Cd-induced cerebral cortical neuron injury in chickens, which is related to CGA alleviating Cd-induced incomplete autophagy by inhibiting the AMPK-ULK1 pathway.

Guardians of the Gut: Harnessing the Power of Probiotic Microbiota and Their Exopolysaccharides to Mitigate Heavy Metal Toxicity in Human for Better Health

Heavy metal pollution is a significant global health concern, posing risks to both the environment and human health. Exposure to heavy metals happens through various channels like contaminated water, food, air, and workplaces, resulting in severe health implications. Heavy metals also disrupt the gut's microbial balance, leading to dysbiosis characterized by a decrease in beneficial microorganisms and proliferation in harmful ones, ultimately exacerbating health problems. Probiotic microorganisms have demonstrated their ability to adsorb and sequester heavy metals, while their exopolysaccharides (EPS) exhibit chelating properties, aiding in mitigating heavy metal toxicity. These beneficial microorganisms aid in restoring gut integrity through processes like biosorption, bioaccumulation, and biotransformation of heavy metals. Incorporating probiotic strains with high affinity for heavy metals into functional foods and supplements presents a practical approach to mitigating heavy metal toxicity while enhancing gut health. Utilizing probiotic microbiota and their exopolysaccharides to address heavy metal toxicity offers a novel method for improving human health through modulation of the gut microbiome. By combining probiotics and exopolysaccharides, a distinctive strategy emerges for mitigating heavy metal toxicity, highlighting promising avenues for therapeutic interventions and health improvements. Further exploration in this domain could lead to groundbreaking therapies and preventive measures, underscoring probiotic microbiota and exopolysaccharides as natural and environmentally friendly solutions to heavy metal toxicity. This, in turn, could enhance public health by safeguarding the gut from environmental contaminants.

Macro, Trace and Toxic Element Composition in Liver and Meat of Broiler Chicken Associated with Cecal Microbiome Community

The current study presents a meta-analysis of the detailed relationship between the composition of 25 essential and toxic elements in chicken tissues examined by ICP-MS and the gut microbial community analyzed using NGS techniques. The examination of chicken liver and meat revealed typical elemental compositions, called the "elementomes". The α-elementomes showed high contents of macro elements (Na, K, Mg, Ca, P), majority trace elements (Sr, Se, Mn, Fe, Co, Cu, Zn) and some toxic elements (B, Pb, Ni, Cd); β-elementomes indicated accumulation of Si, V and Cr; γ-elementomes indicated accumulation of Al, As and Hg. Characterization of the microbiomes' structure showed two distinct enterotypes, designated "microbiome patterns"; the first was enriched in the phylum Bacteroidota, and the second was dominated by Bacillota and coupled with members of the phyla Actinomycetota, Cyanobacteriota and Thermodesulfobacteriota. A comparison of elementomes and microbiomes demonstrated a clear correspondence between the α- and γ-elementomes belonging to the Bacteroidota-enriched pattern, while the β-elementome was predominantly found in chicken groups belonging to the Bacillota + ACT pattern. This insight proposes a novel strategy to improve deficiency or excess of certain elements in the host by gut microbiome modulation, which needs to be verified with further in vivo experiments.

Potential Teratogenicity Effects of Metals on Avian Embryos

Agricultural areas can provide sources of food and hiding and nesting places for wild birds. Thus, the chemical load of potentially toxic elements (Cd, Cu, Pb) due to industrial and agricultural activities can affect not only the adult birds but also the embryos developing in the egg. The toxic effects of heavy metals applied alone were investigated on chicken embryos in the early and late stages of embryonic development using injection and immersion treatment methods. On day 3 of incubation, permanent preparations were made from the embryos to study the early development stage. There were no significant differences observed in embryo deaths and developmental abnormalities in this stage. On day 19 of incubation, the number of embryonic deaths, the body weight of the embryos, and the type of developmental abnormalities were examined. The embryonic mortality was statistically higher in the groups treated with cadmium and lead in the case of the injection treatment. A significant increase in developmental disorders was observed in the copper-treated group using the immersion application. The body weight significantly decreased in the cadmium- and lead-treated group using both treatment methods. However, a significant change in the body weight in the copper-treated group was only realized due to the injection method.

Concentrations, Sources, and Health Risk of Heavy Metals in Edible Parts of Broilers from Northeast of Algeria

Heavy metals contamination of poultry products is a major concern for public health. This study aimed to determine the concentration of mercury (Hg), lead (Pb), and iron (Fe) in the edible parts of broilers, as well as in feed, drinking water, and litter as sources of contamination and to assess their possible human health risk in the province of Jijel (Northeast Algeria). The range of Hg, Pb, and Fe in edible parts were 0.004-0.007, 0.185-0.480, and 28.536-88.306 mg/kg, respectively, and the difference in content was only significant (p < 0.05) for lead. Breast and thigh samples had Pb concentrations above the maximum limit. Spearman coefficient analysis revealed that most correlations were positive between metals detected in feed, water, and litter and those in the edible parts of broilers. But most of them were insignificant (p > 0.05). The estimated daily intake (EDI) values of examined metal exceeded the tolerable daily intake (PTDI). The target hazard quotients (THQ) and hazard index (HI) of all metals were lower than 1, suggesting no significant carcinogenic risks. The calculated incremental lifetime cancer risk (ILCR) of Pb was higher than 10-4 for men, women, and children, indicating the presence of carcinogenic risk. Considering the wide consumption of broiler meat, regular national monitoring of heavy metals in the broiler production chain is recommended to protect population health.

Protective effect of naringenin on cadmium chloride-induced renal injury via alleviating oxidative stress, endoplasmic reticulum stress, and autophagy in chickens

Cadmium (Cd) is a highly hazardous toxic substance that can cause serious harm to animals. Previous studies have indicated that cadmium chloride (CdCl2) can damage organs, such as the liver, ovaries, and testicles. Naringenin (Nar) represents a flavonoid with various properties that promote the alleviation of Cd-induced damage. In this experiment, 60 chickens were divided into the control group, 150 mg/kg CdCl2 treatment group, 250 mg/kg Nar treatment group, and 150 mg/kg CdCl2 + 250 mg/kg Nar co-treatment group, which were treated for 8 weeks. Kidney tissues samples were collected to investigate kidney function, including oxidative stress (OS), endoplasmic reticulum (ER) stress, and autophagy activity. Experimental results showed the decreased weight of chickens and increased relative weight of their kidneys after CdCl2 treatment. The increase in NAG, BUN, Cr, and UA activities, as well as the increase in MDA and GSH contents, and the decrease activities of T-AOC, SOD, and CAT in the kidney, manifested renal injury by OS in the chickens. TUNEL staining revealed that CdCl2 induced apoptosis in renal cells. CdCl2 upregulates the mRNA and protein expression levels of GRP78, PERK, eIF2α, ATF4, ATF6, CHOP, and LC3, and inhibited the mRNA and protein expression levels of P62 proteins, which leads to ER stress and autophagy. The CdCl2 + Nar co-treatment group exhibited alleviated CdCl2-induced kidney injury, OS, ER stress, and autophagy. Research has demonstrated that Nar reduces CdCl2-induced kidney injury through alleviation of OS, ER stress, and autophagy.

Transcriptomic and metabolomic profiles of Pirata subpiraticus in response to copper exposure

Copper (Cu) contamination represents a persistent and significant form of heavy metal pollution in agricultural ecosystems, posing serious threats to organisms in current society. Spiders serve as crucial biological indicators for assessing the impact of heavy metals-induced toxicity. However, the specific molecular responses of spiders to Cu exposure and the mechanisms involved are not well understood. In our study, the wolf pond spiders, Pirata subpiraticus, were exposed to Cu for 21 d, resulting in a notable decline in survival rates compared with the control (n = 50, p < 0.05). We observed an increased expression of enzymes like glutathione peroxidase and superoxide dismutase (p < 0.05), signaling a strong oxidative stress response crucial for counteracting the harmful effects of reactive oxygen species. This response was corroborated by a rise in malondialdehyde levels (p < 0.05), a marker of lipid peroxidation and oxidative damage. Transcriptomic and metabolomic analyses revealed 2004 differentially expressed genes (DEGs) and 220 metabolites (DEMs). A significant number of these DEGs were involved in the glutathione biosynthetic process and antioxidant activity. A conjoint analysis revealed that under the Cu stress, several important enzymes and metabolites were altered (e.g., cathepsin A, legumain, and lysosomal acid lipase), affecting the activities of key biological processes and components, such as lysosome and insect hormone biosynthesis. Additionally, the protein interaction network analysis showed an up-regulation of processes like the apoptotic process, glutamate synthase activity, and peroxisome, suggesting that spiders activate cellular protective strategies to cope with stress and maintain homeostasis. This study not only deepens our understanding of spider biology in the context of environmental stress but also makes a significant contribution to the field of environmental stress biology.

Enhancing trimethoprim pollutant removal from wastewater using magnetic metal-organic framework encapsulated with poly (itaconic acid)-grafted crosslinked chitosan composite sponge: Optimization through Box-Behnken design and thermodynamics of adsorption parameters

Trimethoprim (TMP), an antibiotic contaminant, can be effectively removed from water by using the innovative magnetic metal-organic framework (MOF) composite sponge Fe3O4@Rh-MOF@PIC, which is shown in this study. The composite is made up of magnetite (Fe3O4) nanoparticles and a rhodium MOF embedded in a poly(itaconic acid) grafted chitosan matrix. The structure and characteristics of the synthesized material were confirmed by thorough characterization employing SEM, FTIR, XPS, XRD, and BET techniques. Notably, the composite shows a high magnetic saturation of 64 emu g-1, which makes magnetic separation easier, according to vibrating sample magnetometry. Moreover, BET analysis revealed that the Fe3O4@Rh-MOF@PIC sponge had an incredibly high surface area of 1236.48 m2/g. Its outstanding efficacy was confirmed by batch adsorption tests, which produced a maximum adsorption capacity of 391.9 mg/g for the elimination of TMP. Due to its high porosity, magnetic characteristics, and superior trimethoprim uptake, this magnetic MOF composite sponge is a promising adsorbent for effective removal of antibiotics from contaminated water sources. An adsorption energy of 24.5 kJ/mol was found by batch investigations on the Fe3O4@Rh-MOF@PIC composite sponge for trimethoprim (TMP) adsorption. The fact that this value was up 8 kJ/mol suggests that the main mechanism controlling TMP absorption onto the sponge adsorbent is chemisorption. Chemisorption requires creating strong chemical interactions between adsorbate and adsorbent surface groups, unlike weaker physisorption. The magnetic composite sponge exhibited strong removal capabilities and high adsorption capacities for the antibiotic pollutant. The Fe3O4@Rh-MOF@PIC composite sponge also showed magnetism, which allowed for easy magnetic separation after adsorption. Over the course of 6 cycles, it showed outstanding reusability, and XRD confirmed that its composition was stable. The high surface area MOF's pore filling, hydrogen bonding, π-π stacking, and electrostatic interactions were the main trimethoprim adsorption mechanisms. This magnetic composite is feasible and effective for removing antibiotics from water because of its separability, reusability, and synergistic adsorption mechanisms via electrostatics, H-bonding, and π-interactions. The adsorption results were optimized using Box Behnken-design (BBD).

Species Differences and Tissue Distribution of Heavy Metal Residues in Wild Birds

Birds are useful as bioindicators of metal pollution, but the variety of species and tissue distribution may influence the study of heavy metal burdens in birds. The objective of this study was to determine the levels of heavy metals in wild birds' carcasses to acquire information on species differences and the tissue distribution of metals in wild birds in Thailand. Species differences in metal buildup were observed in the livers and kidneys, but not in the feathers. A significantly higher accumulation of Cd was found in the livers and kidneys of the granivorous birds compared to those in the water birds. In all the groups of birds, the Pb level in the livers (>15 ppm) and feathers (>4 ppm) exceeded the threshold limits, causing potential lead poisoning and disturbing the reproductive success. The Cd accumulation in the kidneys was above 2-8 ppm, indicating increased environmental exposure to Cd in these birds. The Cd, Pb, Ni, Zn, and Fe concentrations in the livers could be estimated using the kidneys, while the Pb level in the liver may be predicted using feathers. Furthermore, water birds' feathers may be potentially appropriate bioindicators for long-term exposure. Research on the origin of metal contamination is needed to reduce the threat of heavy metals to the health of both birds and other wildlife species.

Spirulina supplementation to alleviate negative effects of lead in layer chicken

Objectives

Lead (Pb), a toxic heavy metal, is a serious concern for poultry that negatively affects their productivity and health. To combat those issues efficiently, it is necessary to include feed supplements that have rich antioxidant properties for satisfactory health and productivity. Spirulina platensis (Sp), a microalgae, is a compound that provides several health benefits for humans and animals. This study explores that supplementation of Sp in diet as well as in water reduces the burden of Pb in different tissues, improves hematology, and improves the productive performance of advanced-age laying hens.

Materials and methods

Forty birds were separated into four groups: the control (C), Spirulina (Sp), Pb, and (Pb + Sp) groups. The Pb group was given Pb acetate at a dose of 2 gm/l in water ad libitum for 4 weeks. Sp group was fed Sp at a dose of 4 gm/kg feed. The Pb + Sp group was given Pb and Sp as in the previous groups.

Results

Productive performance and hematology such as hemoglobin (Hb), packed cell volume, red blood cell, mean corpuscular volume, mean corpuscular Hb (MCH) concentration, and MCH were significantly (p < 0.05) decreased in Pb-treated groups compared to controls. The distribution of Pb concentration was highest in the bones and lowest in the gizzard. However, Sp treatment significantly (p < 0.05) increased the productive performance and the hematological parameters. Moreover, Pb concentration in different organs significantly decreased in the group treated with Sp.

Conclusion

This study indicates that Sp can possibly be used as a natural and powerful dietary additive to mitigate heavy metal intoxication in chickens, thereby being efficient and effective for production.