Abstract: [Objective] To understand the effect of propylene glycol on the contents of glucose and ketone bodies in plasma of postpartum dairy cows and the residual situation of propylene glycol in milk.[Method]Eighteen multiparous cows with expected date of delivery within 5~20 d were randomly divided into 3 groups.The control group was not fed with propylene glycol,and the experimental group was fed with propylene glycol 500 g/ head within 2 hours after delivery,and the experimental group was fed with propylene glycol 300 g/head within 2 hours after delivery. The cattle feeding management was carried out according to the field procedures. After oral administration,milk samples were taken three times a day,and tail vein blood was collected on an empty stomach the next morning. The contents of propylene glycol in milk,glucose and ketone bodies in plasma were determined. [Result] The content of propylene glycol in milk reached the highest within 8 h after oral administration,and decreased gradually at 16 h and 24 h. No propylene glycol was detected at 32 h.At each time point,the content of propylene glycol in milk of experimental group 1 was higher than that of experimental group 2.The plasma glucose content in the experimental group was higher than that in the control group. The plasma glucose content in the experimental group was 3.49 μmol/mL,that in the experimental group was 3.28 μmol/mL,and that in the control group was 2.07 μmol/mL. Propylene glycol had a significant effect on the plasma glucose content（P<0.05）,but the plasma glucose content in the experimental group was higher than that in the experimental group,but the difference was not significant（P>0.05）.The plasma ketone body content in the experimental group was lower than that in the control group. The plasma ketone body content in the experimental group was 1.14 μmol/mL,the plasma ketone body content in the experimental group was 1.47 μmol/mL,and the plasma ketone body content in the control group was 3.20 μmol/mL.Propylene glycol significantly reduced the plasma ketone body level（P<0.05）.The plasma ketone bodies in test group 1 were lower than those in test group 2,and the difference was not significant（P>0.05）.[Conclusion] After drinking propylene glycol,the residual amount of propylene glycol in milk is extremely low,which has no influence on the quality and safety of milk. Propylene glycol can significantly increase plasma glucose content,reduce ketone body level and improve the negative energy balance of dairy cows.The dosage of 500 g group/head is better than that of 300 g group/head.

Key words: propylene glycol, postpartum cows, plasma, glucose, ketone body