Blood hormones, metabolic parameters and fatty acid proportion in dairy cows fed condensed tannins and oils blend

The aim of this study was to track the changes in blood parameters of mid-lactation multiparous Polish Holstein-Friesian cows in response to a diet supplemented with a mixture of fish-soybean oils blend and tannin-containing lingonberry shrub (Vaccinium vitis idaea; VVI) extract. Twelve lactating cows were randomly assigned to a crossover design of two treatments (6 cows per treatment) which consisted of a control diet containing no supplement (CON) and CON supplemented with a mixture of 99 g of VVI leaves extract and 660 g of blended fish-soybean oils (MIX) daily. The obtained results showed a significant increase in plasma glucose level, as well as C18:1t11 and n-3 fatty acids proportion. A significant decrease was also observed in insulin concentration, triglyceride and C18:0 proportion. Generally, the saturated fatty acid proportion decreased while the unsaturated fatty acid significantly increased with the MIX diet. In conclusion, using supplements of a mixture of VVI extract and fish-soybean oils blend modulated the unsaturated fatty acid proportion in blood, without affecting the dairy cows’ blood parameters which were all within the normal ranges.