Effects of encapsulated algae oil supplements on the production of DHA-enriched milk in mid-lactating dairy cows

This study was conducted to assess the effects of encapsulated algae oil (EAO) supplementation on the production of DHAenriched milk in mid-lactating dairy cows.A total of 60 mid-lactation dairy cows were randomly assigned to 4 treatment groups, comprising the addition of EAO (DHA >17%) at 0, 60, 120, 180 g/d per head (equivalent to 0, 10, 20, 30 g/d DHA).The experiment lasted for 8 weeks with an additional 10 d' pre-feeding period.Compared with the control group, the ECM and fat content were increased in 10 g/d DHA group, while decreased in 20 g/d and 30 g/d DHA levels.No significant treatment effect was observed on DMI and milk composition.The content of milk DHA exceeded 100 ppm (10 mg/100 mL) by the fifth week when 30 g/d DHA was administered.The conversion rate for all groups exceeded 10%, while the group supplemented with 10 g/d DHA exhibited the highest level.No significance was found in saturated and monounsaturated fatty acids.In contrast, polyunsaturated fatty acids, including DHA, significantly increased with the EAO supplementation.Besides, compared with raw milk, the DHA content of pasteurized milk decreased by 8.39%, and UHT milk decreased by 25.64%.In summary, EAO supplements significantly increased the milk DHA content without influencing the overall milk performance of dairy cows.