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The pig, one of the most important livestock species, is a meaningful source of global meat production. It is necessary, however, to prove whether a food product that a discerning customer selects in a store is actually made from pork or venison, or does not contain it at all. The problem of food authenticity is widespread worldwide, and cases of meat adulteration have accelerated the development of food and the identification methods of feed species. It is worth noting that several different molecular biology techniques can identify a porcine component. However, the precise differentiation between wild boar and a domestic pig in meat products is still challenging. This paper presents the current state of knowledge concerning the species identification of the domestic pig and wild boar DNA in meat and its products.

Background These days the number of potential food allergens is very large, but chicken is one of the most common allergens in dogs. Elimination diet is one of the clinical tools for the diagnosis of allergies and allergy tests are not very reliable. The restriction diet is most commonly carried out by feeding pet foods, relying on the ingredients on the label to select an elimination diet not containing previously eaten foods. Unfortunately, mislabeling of pet food is quite common. The purpose of this study was to determine the absence or presence of chicken DNA using both qualitative and quantitative polymerase chain reaction (PCR) analysis methods in dry and wet maintenance complete pet foods for adult dogs. Results were used to verify the declared composition on the labels. Results Eleven out of fifteen (73%) dog foods were produced as declared by the manufacturer, two of which showed the presence of chicken protein as stated on the label. The remaining nine foods contained amounts of chicken DNA below 1%, consistent with declarations that no chicken was added in the composition. Four of tested dog foods (27%) were not produced consistently with the declaration on the packaging. Two dog foods (one dry and one wet) did not contain the claimed chicken protein. In two foods the addition of chicken DNA was detected at the level of over 2% and almost 6%, respectively. Conclusions In this study, we focused on one of the most commonly undeclared animal species on the label—chicken protein—and performed DNA analyzes to investigate possible contamination and mislabeling. The results showed some inaccuracies. However, most of them are trace amounts below 1%, which proves compliance with the label. Our results showed that undeclared animal species can be as common as missing an animal protein declared on the label. The conducted research indicates that both dry and wet analyzed foods should not be recommended as a diagnostic tool in elimination tests, because it may result in false negative results. Over-the-counter maintenance foods for dogs should not be recommended for the diagnosis and treatment of food hypersensitivity.

Species identification of the components of various duck breeds has revealed that the lowest identifiable number of components depends on the breed. The results (shown on the agarose gel) of a species-specific PCR reaction for Rouen ducks were less intense than the results for the same amount of components from other popular duck breeds, suggesting differences in the Rouen duck genome. Therefore, the present study aimed to identify part of the Rouen duck’s gene sequences and to develop two new primer pairs. The first pair enables breed-independent identification of duck DNA, and the second distinguishes Rouen ducks from Chinese and Indian Runner ducks. The sequencing reaction yielded sequences of 1386 bp in length, and the identified sequence differs by around 7% from the sequences of Chinese duck species. The detected sequence contributes to improving species identification methods for duck DNA. On its basis, two primers for the identification of duck DNA were designed. The first allows for DNA amplification with the same sensitivity regardless of duck breed. The second primer’s pair is breed specific, and it distinguishes Rouen ducks from Chinese and Indian Runner ducks. Both methods are very sensitive (0.05%).

This study developed a method to identify the species of duck and goose DNA extracted from various matrices. The research material included meat, down, whole feathers, and blood. The analysis was performed with real-time PCR using minor groove binder probes and primers that bind to cytochrome b (duck) and 12S ribosomal RNA (goose) sequences. For all matrices, the reactions were species-specific. Cross-reactions either did not occur or occurred after 36 cycles, corresponding to an amplification for the species content of 10− 5 %, i.e., several times below the limit of detection (LOD = 0.01%) and limit of quantification (LOQ = 0.1%). The standard curves obtained by consecutive dilutions were linear (R2 > 0.99), the slopes ranged from 3.2 to − 3.6, and the retardation factors were 23–26. The amplitude threshold analysis demonstrated that significant differences between successive matrices make it impossible to select one reference material to produce a standard curve effective for analyzing each type of matrix. A comparison between the reference material and the test material reveals that the accuracy of the developed method (the match between the actual and the measured value) is above 78%. Validation methods indicate that this method can be used to identify duck and goose DNA in the analyzed matrices.

The aim of this study was to determine a match between DNA recovered from evidence material, such as knocked down red deer, and from comparative material in form of two brown traces on the bonnet of a car driven by a person suspected of knocking down the animal. The spots coming from the car provided no DNA profile, which questioned that they originated from a red deer and ruled out performance of a comparative DNA analysis. For this reason, the material obtained from the blood smear was analyzed for species identification. The method applied can discriminate between cattle, red deer and roe deer based on restriction analysis (Tsp509I) of PCR product (195bp), obtained by amplifying a fragment of the cytochrome b coding gene. Because the obtained restriction profile confirmed the match with red deer DNA for one trace, and in the second case ruled out that the biological traces originated from the species mentioned above, the PCR products were subjected to sequencing. In both cases, 195bp PCR products that were 98% homologous with red deer DNA sequence-NC_007704.2-trace1 and with the gene coding for the human ryanodine receptor-NC_008799.2-trace2. The quantity and quality of DNA obtained from the traces collected from the car bonnet did not allow confirmation of the involvement of a specific animal in the event, but the applied method made it possible to determine the species from which the obtained traces originated. Furthermore, the applied method, which was used earlier to determine cervine DNA, was successfully used to detect human DNA.

The objective of the study was to demonstrate how mitochondrial DNA (mtDNA) can be used to determine the species origin of animal microtraces. The study included pieces of cat and dog hair without the root, a fragment of cooked chicken bone (0.1g), three goose down samples (0.028 g), a pork swab, a pork scratching (5×5×5 mm), and pork lard (0.22 g). DNA was isolated from all of these samples using the method appropriate for the particular source material. The extracts had DNA concentration exceeding 5.4 ng/µl with A260/280 purity range of 1.14-1.88. Next, the samples were subjected to PCR and real-time PCR with species-specific primers and primers complementary to mitochondrial DNA (mtDNA). Control reactions based on the amplification of eukaryotic-specific fragment (18S rRNA) were additionally performed. PCR and real-time PCR products for detection of species-specific mtDNA were obtained for all templates, whereas during the detection of eukaryote DNA no product was obtained for dog and cat hair only. The poor quality of the obtained DNA did not prevent the analysis. The results showed that mitochondrial DNA is suitable for identification of small or highly processed samples, in which genomic DNA often cannot be analyzed.

Chicken is a common protein source in pet foods and is concurrently listed among food allergens. Commercial over-the-counter (OTC) diets with an alternative animal protein source are considered suitable for dietary elimination trials by pet owners. The potential presence of undeclared chicken-derived ingredients in these diets can compromise the outcome of the trial during the diagnosis of adverse food reactions. The aim of this study was to selectively verify the absence or presence of chicken DNA in 10 OTC dry canine foods, using qualitative and quantitative approaches. The method of identification of chicken-derived protein was elaborated with the polymerase chain reaction (PCR) technology, whereas quantitative real-time PCR was used for the quantitative assessment. In most of the analysed samples, the chicken DNA was detectable; however, the quantified amounts were predominantly low, although differences between batches were observed.

The objective of the study was to develop a universal method for the species identification of bovine, porcine, ovine and chicken components using PCR. The proposed primers generate short amplicons of 90, 85, 67 and 66 bp for cattle, pigs, sheep and chickens respectively within the gene encoding COX1 in the case of ovine and porcine tissues, 12SrRNA for cattle, and 16SrRNA for chickens. The proposed primers only amplify the DNA of the species for which they were designed, and do not cross-react with the DNA of other species of animals and plants, the tissues of which could be the ingredients of feed mixtures or products used for food production. The use of short amplification products for the indicators allows for the highly effective species identification of animal components, both in raw samples and in samples processed at high temperature and pressure. The method developed is effective for a broad range of animal products such as lard, animal meals, pet foods, plasma, whey, milk substitute, and others. The PCR products obtained are species specific for both components in amounts of 0.1% and for 100% animal samples. Limit of quantification (LOD) for the meal contained in plant feeds and in animal feeds from other species is 0.08% for poultry meal and 0.09% for bovine, porcine and ovine meal. The specificity and high sensitivity of the indicators, as well as the universality and usefulness of the method regardless of the degree of processing, type and form of the source material are its greatest advantages.

The objective of this study was species identification of the following biological trace material: skin, blood stains, meat samples and jawbone with a tooth, which were the subject of expert opinion ordered by a court. The expert appraisement was conducted by an analysis of a cytochrome b fragment. The choice of mtDNA fragment for analysis was based on its conservation in mammals which enabled several farm and wild species to be identified with one pair of primers. The PCR product was differentiated by Tsp509I and Alulenzymes. Due to problems with amplification of roe deer DNA, primers specific to this species only, flanking a cytochrome b fragment (Y1495 1.1), were designed. On the basis of this analysis, it was concluded that the skin sample was derived from a goat, dried blood from a roe deer, the jawbone from cattle, and two meat samples from a roe deer and red deer. This method allowed rapid and efficient identification of several species of mammals using diverse biological material.