The study was designed to test the effect of including fish oil and canola oil from transition period to early lactation on milk yield and metabolic responses in Holstein dairy cows. Holstein cows were randomly assigned in 1 of 2 treatments: 1) 0% oil (control, n=9) and 2) 2% oil (supplemented, 1% fish oil-1% canola oil, n=9) from -2 to 7 weeks relative to calving. Cows were blocked by parity, previous 305-2x milk production and expected calving time. Dry matter intake (DMI) was recorded daily and feed sample was collected weekly. Cows were milked 3 times per day and daily yields were recorded. Using vacutainer tubes, blood samples were collected weekly before the morning feeding, kept on ice and centrifuged within 30 min at 3000 x g for 20 min. Aliquots of serum were stored at –20°C until analysis for glucose, triglyceride, cholesterol, and serum urea nitrogen (SUN). The data repeated in time were analyzed by using a mixed model (PROC MIXED, SAS Inst. Inc., Cary, NC) for a completely randomized design with repeated measures. Inclusion of fish oil and canola oil in diet increase milk production significantly (p=0.042), in compare with control diet. Dry Matter Intake in prepartum (p=0.17; 13.78 and 14.47 ± 0.33), and postpartum (p=0.72; 21.16 and 20.19 ± 0.50) were not different between control and supplemented diets. The blood glucose (p=0.92; 57.79 ± 1.46 and 57.61 ± 1.39 mg/dl, respectively), cholesterol (p=0.37; 113.86 ± 3.63 and 118.28 ± 3.42 mg/dl, respectively), SUN (p=0.45; 18.21 ± 0.45 and 18.68 ± 0.43 mg/dl, respectively), and triglyceride (p=0.45; 23.61 ± 1.22 and 24.86 ± 1.09 mg/dl, respectively) were similar between control and supplemented diets in seven weeks after calving. The results of this experiment show that including fish oil and canola oil had no apparent effects on metabolic responses, but milk yield was significantly increase in supplemented diet.

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