H. Grodzki

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.

Influence of linseed variety on fatty acid profile in cow's milk

BACKGROUND The aim of this study was to examine the influence of linseed variety on the concentration of cows milk constituents, particularly fatty acids. The experiment was conducted on 30 Polish Holstein Friesian cows whose diet was supplemented with two varieties of crude linseed, Opal and Szafir. RESULTS After 21 days of linseed supplementation, the Szafir variety proved to be a better supplement than the Opal variety, particularly in relation to the concentration of saturated fatty acids, C20:5 (69.2% higher) and C22:6 (147.1% higher) and also because of improved chemical composition of the milk (19.7% higher fat, 2.9% higher protein and 39.9% higher casein content). CONCLUSION Linseed variety significantly influenced the lipid fraction level and the basic chemical composition of cows milk. Linseed variety should therefore be taken into consideration in subsequent experiments in addition to the quantity and physical form of linseed. The results showed that the use of a diet supplemented with linseed, especially the Szafir variety, was effective in reducing saturation, atherogenic and thrombogenic indices, yielding benefits for consumers by improving the nutritional quality of cows milk.

Effect of fish oil and linseed supplementation on the protein composition of milk from cows with different β-lactoglobulin phenotypes.

BACKGROUND The objective of this study was to determine the impact of fish oil and linseed (FOL) supplements on the protein fraction levels of milk from cows with different phenotypes of β-lactoglobulin. RESULTS After 21 days of supplementation the study showed significantly higher concentrations of whey proteins, especially lysozyme (144% increase) and lactoferrin (45.5% increase), compared with milk from control cows (total mixed ration with no supplemented FOL). A reverse trend was demonstrated for casein, casein index and casein number (lower level). The most favourable change (higher level), in terms of lactoferrin, α-lactalbumin and bovine serum albumin contents in milk, was recorded in cows with the BB variant of β-lactoglobulin. The highest level of lysozyme was recorded in the milk of cows with the AB variant of β-lactoglobulin. CONCLUSION The combined supplementation of fish oil and linseed had a positive impact on whey proteins in cows milk. In addition, the phenotype of β-lactoglobulin also played a role in milk protein composition. There is therefore a clear indication that nutritional experiments should take into account not only food supplements but also the genetic variants of β-lactoglobulin.