Effect of Diet on the Stable Isotopes of Carbon and Nitrogen in Cow-Sheep-Goat Milk -Abstract ParaskeviChantzi pchantzi@geo.auth.gr Faculty of Veterinary Medicine Laboratory of Nutrition Aristotle University of Thessaloniki
54124 Thessaloniki Greece
Union of Agricultural Cooperatives of Naxos
84300 Cyclades Greece
NivesOgrinc nives.ogrinc@ijs.si Department of Environmental Sciences Jožef Stefan Institute
Jamova 39 1000 Ljubljana Slovenia
DorisPotočnik doris.potocnik@ijs.si Department of Environmental Sciences Jožef Stefan Institute
Jamova 39 1000 Ljubljana Slovenia
StellaDokou Faculty of Veterinary Medicine Laboratory of Nutrition Aristotle University of Thessaloniki
54124 Thessaloniki Greece
IliasGiannenas igiannenas@vet.auth.gr Faculty of Veterinary Medicine Laboratory of Nutrition Aristotle University of Thessaloniki
54124 Thessaloniki Greece
MichalisVernikos m.vernikos@easnaxos.com Union of Agricultural Cooperatives of Naxos
84300 Cyclades Greece
NektariosDGiadinis ngiadini@vet.auth.gr Clinic of Farm Animals School of Veterinary Medicine Faculty of Health Sciences Aristotle University of Thessaloniki
54124 Thessaloniki Greece
Effect of Diet on the Stable Isotopes of Carbon and Nitrogen in Cow-Sheep-Goat Milk -Abstract 6B35AEFFAB1A71E90BCB7E391BBA0FBD GROBID - A machine learning software for extracting information from scholarly documents

1 Twelve (12) bulk samples of Holstein cow's milk, fifteen (15) bulk samples of sheep and goat's milk, and forty-three (43) feed samples were collected in August 2020 from livestock farms in Naxos Island, South Aegean, Greece. Three milk samples were taken from milk coolers in 25ml falcon bottles from each station and subjected to isotopic analysis to determine their carbon ( 13 C/ 12 C) and nitrogen ( 15 N/ 14 N) isotopic ratios. The isotopic values of the feed ranged from -26.1 ‰ to -16.8 ‰ for δ 13 C (mean value -21.4‰) and from 1.5‰ to 6.5‰ for δ 15 N (mean value 3.9‰). When plotted again each other (fig. 1), the samples could be discriminated into three groups. The first group corresponded mainly to cow feed with lower δ 15 N values (1.3‰ to 2.8‰), while the second group is represented by cow feed with higher δ 15 N values (3.5‰ to 6.5‰ and lower δ 13 C values (-26.1‰ to -23.9‰). The third group is made up predominantly of sheep/goat feed with higher δ 15 N values (3.8‰ and 6.5‰) and δ 13 C values (-21.7‰ to -16.8‰). From the carbon and nitrogen values of soya [δ 13 C: -26.6‰, δ 15 N: 0.7‰] and maize [δ 13 C: -11.8‰, δ 15 N: 4.3‰] used in the sampled feed, it can be concluded that both feed components determine the isotopic record of feed rations. Milk casein isotopic values ranged from -24.4‰ to -18.1‰ for δ 13 C (mean value -20.7‰) and from 3.9‰ to 8.4‰ for δ 15 N (mean value 5.7‰). The δ 13 Ccasein values in cow milk were also higher than in feed for -3.14‰ and 2.96‰ agreeing with the δ 13 Cfeed-casein values reported in the literature. In addition, a 1-4 ‰ increase in the δ 13 C ‰ values are reported during the metabolism of feed into milk protein, while feeding maize results in a -4‰ reduction. The data from this study shows that animal proteins were naturally 15 N-enriched relative to their diet (δ 15 Νfeed-milk = -4.3 to -1.1‰), a trophic shift consistent with reported values for dairy cows (2.4‰ and 3.2‰) and in growing cattle (3.6‰ and 3.8‰). The δ 13 Cfeed-casein (-5.5‰ to 4.4‰) and δ 15 Νfeed-milk (-4.1‰ to 0.6‰) for sheep/goat samples were higher, reflecting a semi-extensive type of farming and those environmental parameters that affect the isotopic record.
Figure 1 :Figure 1: Carbon and nitrogen isotope values for feed samples from livestock farms in Naxos Island, South Aegean, Greece Keywords Isotopes, carbon, nitrogen, milk, feed, traceability, authenticity Acknowledgements This research was funded by the European Regional Development Fund of the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship, and Innovation, under the call RESEARCH -CREATE -INNOVATE (project code: Τ2EDK-02988 entitled "Monitoring of the environmental fingerprint in Graviera Naxou PDO product for certification of authenticity and geographical origin")
Acknowledgements