New developments in the detection and identification of processed animal proteins in feeds

Inorganic Characterization of Feeds Based on Processed Animal Protein Feeds

The potential of utilizing inorganic constituents in processed animal proteins (PAPs) for species identification in animal feeds was investigated, with the aim of using these constituents to ensure the quality and authenticity of the products. This study aimed to quantify the inorganic content across various PAP species and assess whether inorganic analysis could effectively differentiate between PAP species, ultimately aiding in the identification of PAP fractions in animal feeds. Four types of PAPs, namely bovine, swine, poultry, and fish-based, were analyzed and compared to others made up of feathers of vegetal-based feed. Also, three insect-based PAPs (Cricket, Silkworm, Flour Moth) were considered in this study to evaluate the differences in terms of the nutrients present in this type of feed. Ionic chromatography (IC) was used to reveal the concentrations of NO3-, NO2, Cl-, and SO42-, and inductively coupled plasma optical emission spectroscopy (ICP-OES) to detect Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, Si, Sr, Ti, and Zn. The application of multivariate chemometric techniques to the experimental results allowed us to determine the identification capability of the inorganic composition to identify correlations among the variables and to reveal similarities and differences among the different species. The results show the possibility of using this component for discriminating between different PAPS; in particular, fish PAPs are high in Cd, Sr, Na, and Mg content; swine PAPs have lower metal content due to high fat; feathers and vegetal feed have similar Al, Si, and Ni, but feathers are higher in Fe and Zn; and insect PATs have nutrient levels comparable to PAPs of other origins but are very high in Zn, Cu, and K.

An Overview of Near Infrared Spectroscopy and Its Applications in the Detection of Genetically Modified Organisms

Near-infrared spectroscopy (NIRS) has become a more popular approach for quantitative and qualitative analysis of feeds, foods and medicine in conjunction with an arsenal of chemometric tools. This was the foundation for the increased importance of NIRS in other fields, like genetics and transgenic monitoring. A considerable number of studies have utilized NIRS for the effective identification and discrimination of plants and foods, especially for the identification of genetically modified crops. Few previous reviews have elaborated on the applications of NIRS in agriculture and food, but there is no comprehensive review that compares the use of NIRS in the detection of genetically modified organisms (GMOs). This is particularly important because, in comparison to previous technologies such as PCR and ELISA, NIRS offers several advantages, such as speed (eliminating time-consuming procedures), non-destructive/non-invasive analysis, and is inexpensive in terms of cost and maintenance. More importantly, this technique has the potential to measure multiple quality components in GMOs with reliable accuracy. In this review, we brief about the fundamentals and versatile applications of NIRS for the effective identification of GMOs in the agricultural and food systems.

Official Feed Control Linked to the Detection of Animal Byproducts: Past, Present, and Future

In the context of the expansion of the human population, availability of food, and in extension of animal feed, is a big issue. Favoring a circular economy by the valorization of byproducts is a sustainable way to be more efficient. Animal byproducts are an interesting source of feed materials due to their richness in proteins of high nutritional value. Prevention and control efforts have allowed a gradual lifting of the feed ban regarding the use of animal byproducts. Nevertheless, the challenge remains the development of analytical methods enabling a distinction between authorized and unauthorized feed materials. This Review focuses on the historical and epidemiological context of the official control, the evaluation of current and foreseen legislation, and the available methods of analysis for the detection of constituents of animal origin in feedingstuffs. It also underlines the analytical limitations of the approach and discusses some prospects of novel methods to ensure food and feed safety.

Bridging legal requirements and analytical methods: a review of monitoring opportunities of animal proteins in feed

Availability and safety of food ranks among the basic requirements for human beings. The importance of the food producing sector, inclusive of feed manufacturing, demands a high level of regulation and control. This paper will present and discuss the relationships in the triangle of legislation, the background of hazards with a biological nature, and opportunities for monitoring methods, most notable for prion-based diseases as primary issue. The European Union legislation for prevention of prion-based diseases since 2000 is presented and discussed. The definitions and circumscriptions of groups of species will be analysed in the view biological classification and evolutionary relationships. The state of the art of monitoring methods is presented and discussed. Methods based on visual markers (microscopy), DNA-based methods (PCR), protein-based methods (ELISA, mass spectroscopy, proteomics), near infrared oriented methods and combinations thereof are being evaluated. It is argued that the use in legislation of non-homogeneous groups of species in a biological sense will hamper the optimal design of monitoring methods. Proper definitions are considered to act as bridges between legal demands and suitable analytical methods for effective monitoring. Definitions including specified groups of species instead of single species are more effective for monitoring in a range of cases. Besides the desire of precise circumscription of animal groups targeted by legislation, processed products need well defined definitions as well. Most notable examples are blood versus blood products, and hydrolysis of several types of material. The WISE principle for harmonising the design of legislation and of analytical methods is discussed. This principle includes the elements Witful (reasonable legal principles), Indicative (clear limits between prohibition and authorisation), Societal demands (public health, environment, economy), and Enforceable (presence of suited monitoring methods) in order to promote a balanced effort for reaching the desired level of safety in the food production chain.

New feed ingredients: the insect opportunity

In the framework of sustainability and a circular economy, new ingredients for feed are desired and, to this end, initiatives for implementing such novel ingredients have been started. The initiatives include a range of different sources, of which insects are of particular interest. Within the European Union, generally, a new feed ingredient should comply with legal constraints in terms of 'yes, provided that' its safety commits to a range of legal limits for heavy metals, mycotoxins, pesticides, contaminants, pathogens etc. In the case of animal proteins, however, a second legal framework applies which is based on the principle 'no, unless'. This legislation for eradicating transmissible spongiform encephalopathy consists of prohibitions with a set of derogations applying to specific situations. Insects are currently considered animal proteins. The use of insect proteins is a good case to illustrate this difference between a positive, although restricted, modus and a negative modus for allowing animal proteins. This overview presents aspects in the areas of legislation, feed safety, environmental issues, efficiency and detection of the identity of insects. Use of insects as an extra step in the feed production chain costs extra energy and this results in a higher footprint. A measure for energy conversion should be used to facilitate the comparison between production systems based on cold- versus warm-blooded animals. Added value can be found by applying new commodities for rearing, including but not limited to category 2 animal by-products, catering and household waste including meat, and manure. Furthermore, monitoring of a correct use of insects is one possible approach for label control, traceability and prevention of fraud. The link between legislation and enforcement is strong. A principle called WISE (Witful, Indicative, Societal demands, Enforceable) is launched for governing the relationship between the above-mentioned aspects.

Peptidomic Approach to Developing ELISAs for the Determination of Bovine and Porcine Processed Animal Proteins in Feed for Farmed Animals

The European Commission (EC) wants to reintroduce nonruminant processed animal proteins (PAPs) safely into the feed chain. This would involve replacing the current ban in feed with a species-to-species ban which, in the case of nonruminants, would only prohibit feeding them with proteins from the same species. To enforce such a provision, there is an urgent need for species-specific methods for detecting PAPs from several species in animal feed and in PAPs from other species. Currently, optical microscopy and the polymerase chain reaction are the officially accepted methods, but they have limitations, and alternative methods are needed. We have developed immunoassays using antibodies raised against targets which are not influenced by high temperature and pressure. These targets were identified in a previous study based on an experimental approach. One optimized competitive ELISA detects bovine PAPs at 2% in plant-derived feed. The detection capability demonstrated on blind samples shows a good correlation with mass spectrometry results.

Species Identification of Bovine, Ovine and Porcine Type 1 Collagen; Comparing Peptide Mass Fingerprinting and LC-Based Proteomics Methods

Collagen is one of the most ubiquitous proteins in the animal kingdom and the dominant protein in extracellular tissues such as bone, skin and other connective tissues in which it acts primarily as a supporting scaffold. It has been widely investigated scientifically, not only as a biomedical material for regenerative medicine, but also for its role as a food source for both humans and livestock. Due to the long-term stability of collagen, as well as its abundance in bone, it has been proposed as a source of biomarkers for species identification not only for heat- and pressure-rendered animal feed but also in ancient archaeological and palaeontological specimens, typically carried out by peptide mass fingerprinting (PMF) as well as in-depth liquid chromatography (LC)-based tandem mass spectrometric methods. Through the analysis of the three most common domesticates species, cow, sheep, and pig, this research investigates the advantages of each approach over the other, investigating sites of sequence variation with known functional properties of the collagen molecule. Results indicate that the previously identified species biomarkers through PMF analysis are not among the most variable type 1 collagen peptides present in these tissues, the latter of which can be detected by LC-based methods. However, it is clear that the highly repetitive sequence motif of collagen throughout the molecule, combined with the variability of the sites and relative abundance levels of hydroxylation, can result in high scoring false positive peptide matches using these LC-based methods. Additionally, the greater alpha 2(I) chain sequence variation, in comparison to the alpha 1(I) chain, did not appear to be specific to any particular functional properties, implying that intra-chain functional constraints on sequence variation are not as great as inter-chain constraints. However, although some of the most variable peptides were only observed in LC-based methods, until the range of publicly available collagen sequences improves, the simplicity of the PMF approach and suitable range of peptide sequence variation observed makes it the ideal method for initial taxonomic identification prior to further analysis by LC-based methods only when required.

Identification of Proteins and Peptide Biomarkers for Detecting Banned Processed Animal Proteins (PAPs) in Meat and Bone Meal by Mass Spectrometry

The outbreak of bovine spongiform encephalopathy (BSE) in the United Kingdom in 1986, with processed animal proteins (PAPs) as the main vector of the disease, has led to their prohibition in feed. The progressive release of the feed ban required the development of new analytical methods to determine the exact origin of PAPs from meat and bone meal. We set up a promising MS-based method to determine the species and the source (legal or not) present in PAPs: a TCA-acetone protein extraction followed by a cleanup step, an in-solution tryptic digestion of 5 h (with a 1:20 protein/trypsin ratio), and mass spectrometry analyses, first without any a priori, with a Q-TOF, followed by a targeted triple-quadrupole analysis. Using this procedure, we were able to overcome some of the major limitations of the official methods to analyze PAPs, detecting and identifying prohibited animal products in feedstuffs by the monitoring of peptides specific for cows, pigs, and sheep in PAPs.

Safety, specificity and immunogenicity of a PrP(Sc)-specific prion vaccine based on the YYR disease specific epitope

Prions are a novel form of infectivity based on the misfolding of a self-protein (PrP(C)) into a pathological, infectious isomer (PrP(Sc)). The current uncontrolled spread of chronic wasting disease in cervids, coupled with the demonstrated zoonotic nature of select livestock prion diseases, highlights the urgent need for disease management tools. While there is proof-of-principle evidence for a prion vaccine, these efforts are complicated by the challenges and risks associated with induction of immune responses to a self-protein. Our priority is to develop a PrP(Sc)-specific prion vaccine based on epitopes that are uniquely exposed upon misfolding. These disease specific epitopes (DSEs) have the potential to enable specific targeting of the pathological species through immunotherapy. Here we review outcomes of the translation of a prion DSE into a PrP(Sc)-specific vaccine based on the criteria of immunogenicity, safety and specificity.

Automatic and rapid discrimination of cotton genotypes by near infrared spectroscopy and chemometrics

This paper reports the application of near infrared (NIR) spectroscopy and pattern recognition methods to rapid and automatic discrimination of the genotypes (parent, transgenic, and parent-transgenic hybrid) of cotton plants. Diffuse reflectance NIR spectra of representative cotton seeds (n = 120) and leaves (n = 123) were measured in the range of 4000-12000 cm(-1). A practical problem when developing classification models is the degradation and even breakdown of models caused by outliers. Considering the high-dimensional nature and uncertainty of potential spectral outliers, robust principal component analysis (rPCA) was applied to each separate sample group to detect and exclude outliers. The influence of different data preprocessing methods on model prediction performance was also investigated. The results demonstrate that rPCA can effectively detect outliers and maintain the efficiency of discriminant analysis. Moreover, the classification accuracy can be significantly improved by second-order derivative and standard normal variate (SNV). The best partial least squares discriminant analysis (PLSDA) models obtained total classification accuracy of 100% and 97.6% for seeds and leaves, respectively.

Identification of cattle, llama and horse meat by near infrared reflectance or transflectance spectroscopy

Visible and near infrared reflectance spectroscopy (VIS-NIRS) was used to discriminate meat and meat juices from three livestock species. In a first trial, samples of Longissimus lumborum muscle, corresponding to beef (31) llamas (21) and horses (27), were homogenised and their spectra collected in reflectance (NIRSystems 6500 scanning monochromator, in the range of 400-2500 nm). In the second trial, samples of meat juice (same muscle) from the same species (20 beef, 19 llama and 19 horse) were scanned in folded transmission (transflectance). Discriminating models (PLS regression) were developed against "dummy" variables, testing different mathematical treatments of the spectra. Best models indentified the species of almost all samples by their meat (reflectance) or meat juice (transflectance) spectra. A few (three of beef and one of llama, for meat samples; one of beef and one of horse, for juice samples) were classified as uncertain. It is concluded that NIRS is an effective tool to recognise meat and meat juice from beef, llama and horses.

Detection of banned ruminant-derived material in industrial feedstuffs by TaqMan real-time PCR Assay

A ruminant-specific real-time PCR system was designed and applied for the detection of processed animal protein from ruminants in industrial feedstuffs. The assay includes a primer pair and a TaqMan probe selectively targeting mitochondrial 16S rRNA gene sequences from the ruminant group and another primer-probe set based on the eukaryotic nuclear 18S rRNA gene (positive amplification control). Both ruminant and eukaryotic PCR systems generated short PCR amplicons of 79 and 77 bp, respectively. To evaluate the suitability of the real-time PCR assay for the detection of banned by-products of ruminant origin, 126 feed samples subjected to rendering under current European legislation regulations were analyzed. The assay achieved 100% success in classifying the samples as positive or negative in terms of qualitative ruminant composition, with a detection limit of 0.1%. The quantitative ability of the assay is however restricted by variations in the composition and treatment of the feeds, which affect the amount and quality of amplifiable DNA.

An overview of the legislation and light microscopy for detection of processed animal proteins in feeds

From the first cases of bovine spongiform encephalopathy (BSE) among cattle in the United Kingdom in 1986, the route of infection of BSE is generally believed by means of feeds containing low level of processed animal proteins (PAPs). Therefore, many feed bans and alternative and complementary techniques were resulted for the BSE safeguards in the world. Now the feed bans are expected to develop into a "species to species" ban, which requires the corresponding species-specific identification methods. Currently, banned PAPs can be detected by various methods as light microscopy, polymerase chain reaction, enzyme-linked immunosorbent assay, near infrared spectroscopy, and near infrared microscopy. Light microscopy as described in the recent Commission Regulation EC/152/2009 is the only official method for the detection and characterization of PAPs in feed in the European Union. It is able to detect the presence of constituents of animal origin in feed at the level of 1 g/kg with hardly any false negative. Nevertheless, light microscopy has the limitation of lack of species specificity. This article presents a review of legislations on the use of PAPs in feedstuff, the detection details of animal proteins by light microscopy, and also presents and discusses the analysis procedure and expected development of the technique.

Identification of transgenic foods using NIR spectroscopy: a review

The utilization of chemometric methods in the quantitative and qualitative analysis of feeds, foods, medicine and so on has been accompanied with the great evolution in the progress and in the near infrared spectroscopy (NIRS). Hence, recently the application of NIR spectroscopy has extended on the context of genetics and transgenic products. The aim of this review was to investigate the application of NIR spectroscopy to identificate transgenic products and to compare it with the traditional methods. The results of copious researches showed that the application of NIRS technology was successful to distinguish transgenic foods and it has advantages such as fast, avoiding time-consuming, non-destructive and low cost in relation to the antecedent methods such as PCR and ELISA.

Improving the discriminatory power of a near-infrared microscopy spectral library with a support vector machine classifier

A multi-group classifier based on the support vector machine (SVM) has been developed for use with a library of 48,456 spectra measured by near-infrared reflection microscopy (NIRM) on 227 samples representing 26 animal feed ingredients and 4 possible contaminants of animal origin. The performance of the classifier was assessed by a five-fold cross-validation, dividing at the sample level. Although the overall proportion of misclassifications was 27%, almost all of these involved the confusion of pairs of similar ingredients of vegetable origin. Such confusions are unimportant in the context of the intended use of the library, which is the detection of banned ingredients in animal feed. The error rate in discrimination between permitted and banned ingredients was just 0.17%. The performance of the SVM classifier was substantially better than that of the K-nearest-neighbors method employed in previous work with the same library, for which the comparable error rates are 36% overall and 0.39% for permitted versus banned ingredients.

Quantitative determination of soybean meal content in compound feeds: comparison of near-infrared spectroscopy and real-time PCR

Standard methods for determining the raw material content of compound feed are little exploited, except for the identification of meat and bone meal in feeds. In this work, near-infrared (NIR) spectroscopy and real-time polymerase chain reaction (PCR) were applied in order to establish new and fast methods for quantification of soybean meal content in compound feeds. The best prediction quality was achieved by using a model based on NIR spectroscopy (R2 = 0.9857, standard error of cross-validation 1.1065). Furthermore, a sensitive qualitative detection method by using the real-time PCR was developed (R2 = 0.976, slope -3.7599). Finally, the differences between the real-time PCR result and the NIR spectroscopy result for a given sample were also treated, and we found that the NIR spectroscopy method provided quite accurate results which approach closely those of the real-time PCR method.