Abstract: The objective of this study was to observe the effects of propylene glycol on energy balance, blood parameter, concentration of glucose and adipose in the liver during peripartum period in dairy cows. Multiparous Holstein dairy cows with similar body weight ((683.1±14.9)kg), lactation number (2.5±0.2), corrected milk yield in last lactation ((7 339±18)kg) and expected calving date ((24.5±0.2)d ) were allocated into four treatments at random. Graded levels (0, 150, 300 and 450 mL·d-1) of propylene glycol were supplemented in the four treatments from day 19 prepartum. The results showed that body condition score at 7, 21 and 35 d postpartum increased, body weight loss from 7 to 35 d postpartum reduced, energy balance at 14 d prepartum and 7, 21 and 35 d postpartum was improved significantly by the 300 and 450 mL·d-1 treatment compared with 0 mL·d-1 treatment (P<0.05). Cows receiving 300 and 450 mL·d-1 propylene glycol had a higher plasma glucose and insulin at 14 d prepartum and 7, 21 and 35 d postpartum, lower plasma NEFA, βhydroxybutyrate and triacylglycerol at 7, 21 and 35 d postpartum than that of 0 mL·d-1 treatment (P<0.05). 300 and 450 mL·d-1 propylene glycol supplementation decreased the contents of triacylglycerol in the liver and increased the contents of glycogen in the liver compared to 0 mL·d-1 propylene glycol treatment (P<0.05). The results indicated that propylene glycol supplementation was beneficial to peripartum cows in reducing the lipolysis, enhancing the gluconeogenesis and improving energy balance status, the optimum dose was about 300 mL·d-1.

Key words: propylene glycol, energy balance, peripartum period, Holstein dairy cows