Abstract:

【Objective】 The objective of this study was to observe effects of propanediol supplementation on feed intake, lactation performance, changes in body weight, energy balance, concentrations of blood metabolites and urine ketones in early lactation Holstein dairy cows. 【Method】 Thirty-two multiparous Holstein dairy cows, blocked by lactation number, corrected milk yield in last lactation, and expected calving date, were allocated into four treatments in a randomized block experiment. Graded levels (0, 150, 300, and 450 ml?d-1) of 1,2-propanediol were supplemented in the four treatments. 【Result】 The results showed that average feed intake, milk yield, milk protein percentage, milk lactose percentage, milk dry matter percentage and feed efficiencies were not affected significantly by propanediol supplementation (P＞0.05). Milk fat percentage was significantly depressed by the 450 ml?d-1 treatment compared to the control (P＜0.05). Cows receiving 300 and 450 ml?d-1 propanediol had a higher plasma glucose and serum insulin, lower plasma NEFA and β-hydroxybutyrate than control (P＜0.05). 300 and 450 ml?d-1 propanediol supplementation decreased the contents of ketones in excreted urine compared to 150 ml?d-1 and control (P＜0.05). The energy balance was improved in cows receiving the 300 and 450 ml?d-1 propanediol treatments as reflected energy balance calculations, and a lower body weight loss compared to cows in control (P＜0.05). 【Conclusion】 Results of the present study indicated that propanediol supplementation is beneficial to early lactating cows in improving their energy balance status, the optimum dose is about 300 ml per cow per day.

Key words: 2-propanediol, lactation performance, energy balance, metabolites, early lactation, Holstein dairy cows