Microplastics contamination in commercial fish meal and feed: a major concern in the cultured organisms

Microplastic contamination in commercial fish feeds: A major concern for sustainable aquaculture from a developing country

Due to the widespread presence in food stuff like chicken, fish, meat, milk, sugar, salt, honey, microplastics (MPs) are an emerging environmental health concern nowadays. This study aimed to investigate the presence of MP particles in commercial poultry feed and edible tissues of chickens around Rajshahi City of Bangladesh. A total of 10 feed samples and 30 chicken meat samples (breast, liver, gizzard) from five different poultry farms were analysed. MPs were detected in all sample types and the detected particles were less than 1 mm and greater than 1 µm in size. A total of 758 MP particles were collected from 10 feed samples and 30 chicken samples (breast, liver and gizzard of 10 chickens of 3 different variant) belonging to 5 different poultry farms. A total of 187 MP particles were collected from 10 feed samples, with a mean of 18.7 ± 2.40 MPs / g of feed. A total of 571 MP particles were collected from 30 chicken samples (breast, liver and gizzard of 10 chickens of 3 different variant), with a mean of 0.95±0.03 MPs / g of chicken meat sample. Four different types of shapes of MP particles (fibres, fragments, pellets and sheets) were identified from the feed samples and the chicken meat samples. Among these, fibres were the dominant type of shapes in both sample types (feed and chicken meat). Six different colors (red, blue, green, yellow, violet, transparent) were observed in the MP particles collected from the feed and chicken meat samples. The predominant colors of particles collected from feed and chicken flesh samples were red and transparent, respectively. Detected polymers included polyethylene Terephthalate (PET), polyethylene (PE) , and polypropylene (PP). The study results reveal that poultry feed is a primary route of MP exposure and that edible parts of chickens are highly contaminated with MPs at levels comparable to global trends. This suggests potential human exposure through poultry consumption and highlights the need for regulatory monitoring and feed quality control.

Microplastic (MP) contamination in aquaculture feed presents an increasing threat to both the aquaculture industry and global public health. This study examines the occurrence, abundance, characteristics, and risk assessment of MPs in commercial tilapia (Oreochromis niloticus) feeds. MP contamination was found in all feed samples, with the highest levels observed in grower feeds (2150 ± 70.71 MPs/kg), followed by starter feeds (1650 ± 70.71 MPs/kg) and finisher feeds (1300 ± 141.42 MPs/kg). Fibers were the dominant morphotype (85%), and polymer analysis using FTIR identified polypropylene (38.74%) and polyethylene (33.61%) as the most common polymers. Additionally, 84.64% of the extracted MPs were in the 100–1500 µm size range, posing significant health risks to tilapia and potential exposure to consumers. The estimated polymer hazard index (PHI) value for the three feed categories was very high, signaling alarming health risks. The mean polymer load index (PLI) values across the feed categories ranged from 4.23 to 8.03, indicating minor contamination. The study attributes the sources of MPs to feed ingredients, packaging materials, and processing machinery. The high PHI value underscores the need for urgent action to mitigate MP pollution in tilapia farming.Graphical

The purpose of the work is a veterinary and sanitary examination of the quality and safety of feed for sturgeon fish, including the analysis of changes in the microflora of feed during storage in terms of organoleptic, physicochemical and microbiological indicators. Samples of fish meal, reworked loose fish meal, readymade fish food were taken for the study. It has been established that 6 % of feed does not meet the regulatory requirements for organoleptic indicators, 3 % – for physicochemical indicators in excess of the mass fraction of crude ash by 57 % and the content of mass fraction of crude fat by 10 %. The content of MRL of heavy metals and toxicological indicators correspond to the regulatory requirements for all types of studied feed. Microbiological indicators did not meet the regulatory requirements in 6 % of samples for the presence of sulfide-reducing anaerobes, microscopic molds in one sample of fish meal and the content of Alternaria ssp, Penicillium patulum, Aspergillus ssp and yeast Zygosaccaromyces ssp and Xeromyces ssp in one sample of ready-made fish. At storing until the end of the shelf life, 94 % samples of fish meal from two manufacturers were benign in all respects, they could withstand storage for 6 months without signs of spoilage, 90 % of the samples of the finished fish food microbiological stability until the end of the shelf life and another 14 days after the expiration date declared by the manufacturer. At all stages of the study pathogenic bacteria: Salmonella ssp., enter pathogenic E. coli, L. monocytogenes, S aureus and other coagulase-positive staphylococci were absent in all studied feeds. The species composition of fishmeal microflora changed during storage, the amount of mesophilic microflora decreased, the microflora of the feed was represented by saprophytic spore-forming microorganisms of the genera Bacillus ssp, including Bac. сereus 0,5×105 UFC/G and Clostridium ssp, psychrophilic bacteria of the genera Pseudomonas and Enterococcus. The greatest accumulation of microflora was observed on the 35th day of storage.

Microplastics in fish meals: An exposure route for aquaculture animals

In order to improve feed safety, we investigated the feasibility of using fluorescence spectral imaging (FSI) technique to qualitatively detect meat and bone meal (MBM) mixed with fish meal (FM). Using the FSI system, the spectra of 90 FM and MBM samples from different regions were collected with denoising and binary processing to obtain images. The spectral data curves over the wavelength range of 400–680 nm were used for identification and were pre-treated with various methods. Next, the curves were plotted based on stereo spectrograms; then, partial least squares discriminant analysis (PLS-DA) was applied to determine the FM and MBM samples. One FM sample and one MBM sample were randomly selected and mixed together (v/v, 1:1), and the mixture’s pseudo-color (PC) image was generated by mapping the best grayscale values using a spectrogram method. The resulting PC image was then used for spatial identification of the mixture. The PLS-DA results indicated that the identification effect was best after the multiplicative scatter correction where the sensitivity, specificity, and accuracy all equaled to 1. The PC image demonstrate that the FM (green) and MBM (red) accounted for 52.6 and 47.4 % of the total volume, respectively, corresponding with the actual 1:1 ratio. Additionally, the experimental test of three low concentration-mixed powder samples (c[MBM] = 1.5 %, c[MBM] = 3 %, and c[MBM] = 5 %) determined that the lower limit of application (LLA) of the proposed method is c[MBM] = 1.5 %. Theoretical limit of detection (LOD) of the method was calculated about c[MBM] = 0.75 % through linear regression. These experiments show that the spectral and spatial information provided by FSI can rapidly and nondestructively determine whether FM is mixed with MBM.

Determination of Gizzerosine Activity in Fish Meal with a Homologous Radioimmunoassay

Microplastic (MP) contamination of freshwater ecosystems is still in the focus of research and public attention, as aquatic environments have a high ecological, economic, and recreational value. We now know that rivers do not only function as pathways of MPs into oceans but may also act as temporary MP sinks. However, due to methodological differences, the comparability of studies on MP contamination of rivers is still limited. To compare MP contamination between different river systems, to analyze if there is a constant increase in MP contamination from the upper to the lower course of the river, and to investigate if there are distinct MP distribution patterns, we set up a large-scale survey. We chose two large river systems, the Rhine and Danube catchments with their tributaries and sampled 23 rivers of different sizes at 53 sampling locations in southwest Germany. Surface water sampling, sample processing, and analysis were performed with the same methodology to obtain comparable results on MP number, polymer type, and particle’s size and shape. Fully quantitative data were generated down to 300 µm by using a manta trawl net with a 300-µm mesh size for sampling. Nevertheless, we also included the non-quantitative sampled fraction of particles down to a size of 20 µm in our FTIR analysis after plastic-friendly sample purification by enzymatic oxidative treatment. Plastic concentrations recorded in surface water at the sampling locations ranged from 0.7 to 354.9 particles/m³. Concerning all samples, the number of particles increased toward lower size classes (61.0 ± 34.2% below 300 µm), and fragments were the prevailing shape (90.7 ± 13.6%). Polyethylene (49.2 ± 25.9%) and polypropylene (33.2 ± 22.6%) were the most frequent polymer types. Our survey did not reveal distinct MP distribution patterns or a constant increase of MP abundance within river courses in the investigated river systems. Next, to provide a large-scale dataset of microplastic contamination in surface waters of southwest Germany, our study shows that a representative sampling of MPs in rivers is challenging. MP particles are not homogeneously distributed in rivers, and this indicates that spatial and temporal changes in MP abundance should always be considered in MP monitoring approaches.

Sixteen laboratories from different countries undertook chemical tests to determine the lysine content of 8 samples of fish meal. The chemical tests were total lysine (gas liquid chromatography or ion exchange chromatography), dye binding capacity (DBC), dye binding lysine (DBL), and reactive lysine (FDNB). The same samples of fish meal were analysed for biologically‐available lysine in four laboratories by chick feeding experiments. Estimates of lysine by all methods except DBC differed significantly between laboratories, but generally meals were ranked similarly by each laboratory. The largest estimate of between laboratory variance, and also the poorest concordance of ranking of the meals by the different laboratories was shown by DBL. The chemical methods for measuring lysine gave means which were significantly different from the bioassay results. However, all the chemical methods gave values which correlated with the bioassay values. The DBC, DBL and FDNB methods gave similarly high correlation coefficients while total lysine was less well correlated. Use of the chemical methods to predict values for biologically‐available lysine gave wide confidence limits which are likely to encompass the variability in the majority of commercial fish meal samples. Consequently none of the chemical methods can be regarded as satisfactory for the purpose of distinguishing between normal commercial samples of fish meals in terms of an absolute content of biologically‐available lysine. The chemical methods may, however, be used in a more limited sense to detect differences in quality between meals of known history without indicating any absolute values for biologically‐available lysine. The dye binding methods appear suitable for process control within a fish meal factory where the analyses are carried out in a single laboratory and the nature of the raw material is known.

Variation in menhaden fish meal characteristics and their effects on ruminal protein degradation as assessed by various techniques

Microplastics contamination through a mighty estuarine island: Distribution, influencing factors, and risk assessment

Wetlands provide numerous ecosystem services including freshwater purification. Nonetheless, their functionality is continuously impacted by many pollutants. Plastics are considered as an emerging threat for these ecosystems, but only recently have studies began to focus on plastic and microplastic (MP) contamination in wetlands, especially in biota. This study aims to investigate the abundance of MPs in two ubiquitous aquatic insect taxa (i.e. Corixidae (Hemiptera) and Chironomidae (Diptera)) collected in twelve zones within Mediterranean wetlands belonging to three basins located in Andalusia (south-west Spain). We compared MP contamination across basins and tested the proximity to landfills and presence of colonial waterbirds [i.e. white storks (Ciconia ciconia) and gulls (Larus michahellis and L. fuscus)] on MP abundance in aquatic insects. We also performed stable isotope analyses of nitrogen and carbon (δ15N and δ13C) to evaluate the potential association between MP abundance and isotopic values. We detected 571 suspected MPs (mostly blue fibers) in insects of different developmental stages (i.e., larvae, pupae, nymphs and adults). Polyesters and polypropylene were the most frequent polymers detected. The generalized linear mixed models indicated that MP abundance decreased with increasing distance from landfills; but it also increased in sites with birds that fed on landfills and roost in wetlands. When controlling for landfill effects, sites in the smallest basin (Guadalete) had lower MP contamination than those in Odiel-Tinto and the much larger (>15×) Guadalquivir. Moreover, we found a negative association between MPs items/g (or mean MPs) and 15N isotopes in adult corixids. Our findings showed that MP pollution is present in all the study areas, including strictly protected wetlands. The use of aquatic insects for biomonitoring of MP pollution can help identify priority areas for management actions to mitigate plastic pollution.

The transmission of aflatoxins from fish products to consumers primarily occurs through the contamination of fish flesh and feed by aflatoxigenic fungi. This study comprehensively examined the prevalence and extent of fungal contamination in the flesh of Oreochromis niloticus and Mugil cephalus, as well as in fish feed. Furthermore, it assessed the aflatoxin-producing potential of Aspergillus flavus through fluorometric and molecular assays, providing critical insights into the risks associated with mycotoxin contamination in aquaculture products. O. niloticus and M. cephalus (n = 20 for each species) and fish feed (n = 30) were collected from fish farms and feed markets in Ismailia Governorate, Egypt. The total mold counts exceeded the permissible limit in 25% of the examined O. niloticus samples and 53.3% of the examined feed samples. A. flavus was the predominant species recovered from O. niloticus (48%), M. cephalus (75%), and feed samples (32.4%). All samples tested positive for total aflatoxins using afla fluorometry. Additionally, 60% of O. niloticus and 80% of fish feed samples exceeded global mycotoxin regulatory limits. Among the 33 Aspergillus flavus isolates, only 10 were toxigenic, testing positive for the aflatoxin regulatory (aflR) gene. Sequence analysis of the aflR gene revealed a high genetic similarity between the examined strain and A. flavus strains from Italy, Egypt, and Saudi Arabia. These findings highlight fish feed as a major source of mycotic infections and aflatoxin contamination in fish flesh. Fish feed represents a primary source of mycotic infections and aflatoxin contamination of fish flesh. This source could constitute a health hazard for consumers. Therefore, implementing strict quality control measures for feed storage and processing, along with regular monitoring of aflatoxin levels in aquaculture products, is essential to mitigate health risks and ensure food safety. The combination of morphological and molecular assays is recommended for truthfully monitoring aflatoxogenic A. flavus.

Twenty-two samples of commercial fish meals from Norway, Chile and Peru were analysed for cholesterol and oxysterols using gas chromatography. Cholesterol content ranged from 25.2 to 64.8 g kg−1 total lipids. Detectable levels of the oxysterols 7β-hydroxycholesterol and 7-ketocholesterol were found and their identity was confirmed by gas chromatography-mass spectrometry. Samples of fish meal exhibited wide variability in oxysterols content, 7β-hydroxycholesterol ranging from 3.9 to 105.6 mg kg−1 total lipids (0.4–9.4 mg kg−1 dry matter) and 7-ketocholesterol from 2.0 to 56.2 mg kg−1 total lipids (0.2–5.0 mg kg−1 dry matter). The formation of 7β-hydroxycholesterol and 7-ketocholesterol in one sample of Norse LT94 fish meal stored at room temperature was also studied. Oxysterol content increased during the first 42 days of storage by about 350% and then decreased with further storage. The low amount of oxysterols measured indicates a limited degree of cholesterol oxidation in commercially available fish meals.

Intestinal digestibility of amino acids in rumen-undegraded protein estimated using a precision-fed cecectomized rooster bioassay: II. Distillers dried grains with solubles and fish meal