Comparative analysis of electrolytes, IL-6, SAA, and protein profiles in milk from different animal species

Milk composition varies among species under uniform farm conditions and can influence its physicochemical, biochemical, and functional properties. Phosphorus levels were highest in sheep milk. Potassium and chloride levels were highest in goat milk. Numerically higher SAA concentrations were observed in goat and cow milk, though differences among species were not statistically significant. IL-6 levels showed numerical variation among species without statistical significance. 70 kDa protein band was uniquely detected in goat milk with SDS-PAGE. Compositional differences provide a basis for future hypothesis-driven research on species-specific dairy applications. Milk composition varies among species and can influence its physicochemical, biochemical, and functional properties. This study comparatively evaluated electrolyte concentrations, inflammatory markers, and milk serum protein profiles in raw milk obtained from cows (n = 11), buffaloes (n = 11), sheep (n = 17), and goats (n = 11) raised under the same farm conditions in Samsun, Türkiye. Phosphorus concentrations were measured spectrophotometrically, while chloride, sodium, and potassium levels were determined using an ion-selective electrode method. Interleukin-6 (IL-6) and serum amyloid A (SAA) levels were determined by ELISA, total protein content by bicinchoninic acid assay, and protein profiles by Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE). Phosphorus levels were highest in sheep milk and lowest in goat milk (p < 0.05), whereas sodium concentrations did not differ significantly among species (p > 0.05). Potassium and chloride levels were highest in goat milk and lowest in buffalo milk (p < 0.05). SAA concentrations were highest in goat and cow milk, while IL-6 levels were highest in buffalo milk. SDS-PAGE revealed 18 protein bands ranging from 11 to 379 kDa, with buffalo and goat milk exhibiting the greatest protein diversity and cow milk the lowest. A 70 kDa protein band was uniquely detected in goat milk. These preliminary results indicate species-specific patterns observed under uniform management conditions in milk electrolyte composition, inflammatory markers, and protein profiles, providing a compositional basis for future hypothesis-driven research on species-specific milk characteristics and potential dairy applications.