Comprehensive Characterization of Acorns from Selected Quercus Species: Nutritional Composition, Phytochemical Profile and Potential Relevance to Swine Nutrition

Acorns represent a traditional seasonal feed resource for pigs in Mediterranean production systems; however, comparative information on the nutritional composition and safety of acorns from Central European oak species remains scarce. The present study comprehensively characterized acorns of Quercus robur, Q. petraea, and Q. rubra to assess their potential relevance to pig nutrition based on their chemical composition. Proximate composition, mineral content, fatty acid and amino acid profiles, phenolic compounds, tannins, triterpenoid acids, and heavy metal concentrations were determined using analytical methods. Differences among the analyzed acorn samples were observed in nutritional composition and phytochemical profile. Acorns from all three species were characterized by a high proportion of unsaturated fatty acids, particularly oleic acid, a favourable amino acid profile, and the presence of phenolic compounds, tannins, and triterpenoid acids. Heavy metal concentrations remained below the maximum levels established by European legislation for feed materials, indicating that the analyzed acorns showed no heavy-metal-related exceedances of the applicable European limits for feed materials. The results indicate that acorns from Central European oak species represent a locally available feed resource of potential relevance to pig nutrition. This comprehensive chemical characterization provides a scientific basis for future nutritional studies and further evaluation of acorns as sustainable feed materials.