The age of cows as a factor shaping the antioxidant level during a nutritional experiment with fish oil and linseed supplementation for increasing the antioxidant value of milk.

BACKGROUND: So far, in research studies, the age of cows has not been considered as a factor that may influence the changes in the content of milk ingredients with antioxidant properties modified by the feed supplementation. The aim of this study was to determine the influence of supplementation on the content of ingredients having antioxidant properties and to determine the influence of the age of cows taking part in the experiment on these changes. The experiment was conducted using 20 Polish Holstein Friesian cows, 10 primiparous and 10 multiparous. The combined supplementation of fish oil and linseed constituted the experimental factor.
RESULTS: The milk of primiparous cows after 21 days of supplementation was characterised by a higher content of C18:1 trans-11, C18:2 cis-9, trans-11, α-retinol, α-tocopherol and β-lactoglobulin compared to the milk of multiparous cows, in which a higher level of lactoferrin, C20:5 and β-carotene was recorded. In both groups an increase in the total antioxidant status was noted (a higher level in the milk of primiparous cows).
CONCLUSIONS: Modification of the diet of cows with fish oil and linseed significantly influenced antioxidant properties of their milk; however, the response of multiparous and primaparous cows was noticeably different to the supplement introduced.