Genetic traceability: a tool for the promotion of local alpine products
Mountain agriculture is traditionally based on the breeding of autochthonous breeds well-adapted to live and graze in high mountain pastures.
According to the FAO report The State of the World’s Animal Genetic Resources (2007), since 2000 an animal species per month on average has faced extinction. Moreover about 20% of the autochthonous cattle, sheep, pig and avian breed is now endangered.
Among these cattle breeds there are Alpine Grey and Burlina. They are local alpine breeds reared in Northern Italy; their population has decreased since the past decades due to their substitution with more productive and highly selected breeds such as the cosmopolitan Holstein Friesian and Brown Swiss.
Anyway such autochthonous breeds still have some chances of survival. In fact, they are often used to produce local traditional food that are gaining increasing importance for the consumers. It is then important to enhance the strong link among territory, breed and local productions.
A group of researchers from the Istituto Zooprofilattico Sperimentale delle Venezie, lead by the laboratories of Trento, has studied a genetic traceability system to value local products obtained from Alpine Grey and Burlina (RC IZSVe 18/2011). The system enables to protect both small farmers and consumers from frauds and to guarantee the truthfulness of label information.
The proposed traceability system is set up on DNA analysis. In fact DNA features permit to overcome limits of conventional authentication systems of food products based on paper documentation. DNA analysis allows the identification of animals and their derived products and, in some instances, for product breed identification.
As it is impossible to counterfeit, DNA can be a tool for the promotion of local traditional products and for the safeguard of food security. DNA nucleotide differences are as an indelible label that follow the animal from its birth until consumer plate; analyzing the DNA obtained from a steak enables to identify the animal species, the breed and even the individual animal from which it has been obtained.
The FAO and the International Society for Animal Genetics (ISAG) draw up a list of 30 microsatellite markers for each of the most relevant farm animal species. Microsatellites are highly polymorphic (multiallelic), non coding regions very frequent in genomic DNA that can be utilized to set up genetic traceability system.
The genetic traceability
Genetic traceability allows for different identification level: individual, breed and species. In this research we focused on the first two.
- Individual traceability allows the identification of the animal from which a product has been obtained. To reach this goal, DNA purified from food is analyzed using microsatellites or SNPs (Single Nucleotide Polymorphism) molecular markers. Microsatellites analysis enables to have a unique genetic profile for each animal, the so called DNA fingerprinting. Clearly, the most microsatellites are studied, the most is difficult finding two individuals sharing the same genetic profile. For this kind of studies in cattle the list of 30 microsatellites proposed by FAO and ISAG is suitable.
- Breed traceability aims to guarantee the origin of mono-breed food products. Some examples of these traditional Italian productions are the Spressa cheese from milk of Rendena cattle breed, the Parmigiano Reggiano obtained only by Reggiana cattle breed milk, the Pecorino cheese from Massese sheep breed milk and the Fiorentina steak from Chianina cattle breed. In this case, the ideal molecular marker should be “breed specific”, that is to say that it must have an allelic variant always present in one breed and always absent in all the others. These markers are rather difficult to find, some examples are genes coding for coat colour, for pied coat or for horn presence. As an alternative, one can use microsatellite markers but the obtained genetic profiles must be submitted to statistical analysis to assign them to a specific breed.
The study used the 30 microsatellites suggested by FAO and ISAG due to their high polymorphism. We analyzed more than 100 samples of either blood or muscle collected from Alpine Grey and Burlina cattle. All animals were enrolled in the herd book and farms were well distributed in Trentino Alto-Adige region.
The sampling was set up to collect the most of the breed variability and to be representative of the entire population. In this way we had a database with DNA fragments of each analyzed animal. To test the efficacy of the breed traceability system, 9 samples belonging to other cattle breeds were collected and analyzed at the same loci. After the appropriate statistical analysis all of them (100%) were classified as not Alpine Grey.
The same molecular markers have been used also to set up an individual traceability system for Alpine Grey and Burlina meat. Several microsatellites sets, composed by different number of markers, were tested and finally it was possible to achieve very satisfactory results even with less than 30 microsatellites.
Regarding Alpine Grey, our study evidenced that the probability to find two individuals sharing the same genetic profile for an “unlikely coincidence” was 1 over 12 million. This result was achieved analyzing only 11 markers instead of 30.
A field trial was also realized to verify the efficacy of the traceability system. Blood sample were collected from Burlina animals during their life in the farm before being slaughter. Later muscle samples were collected from the same animals, in the slaughter-houses. Both samples were submitted to DNA analysis with microsatellites markers. A comparison between genetic profiles of samples collected in farms and at the slaughter-houses confirmed that the two samples came from the same individual.
The trial enabled to verify the genetic investigation efficacy on samples collected in the slaughter-houses, where it is easier to have DNA contamination due to the presence of blood and biological fluids from many different animals. This kind of genetic identification could be then useful to find out frauds due to animal exchange.
This study showed that even if microsatellite technology is dated, they still are a good and efficient instrument for individual identification. After all nowadays microsatellites are used as well in human forensic and paternity testing for both humans and animals.
The development of a method which can link breeds to their products could contribute to improve autochthonous breed profitability and, as consequence, the sustainability of animal production. This should have a benefic impact on breeders income. The setting up of traceability system could be important to guarantee product origin and to promote food products. This is even more outstanding for local traditional foods strictly link to a territory and to a unique breed.