丙二醇对泌乳早期奶牛泌乳性能和血液代谢产物的影响

 【目的】研究丙二醇对泌乳早期奶牛采食量、泌乳性能、体重变化、能量平衡、血液代谢产物和尿酮浓度的影响。【方法】选取32头经产奶牛，根据泌乳期、上一泌乳期305 d产奶量和预产期，采用随机区组设计分为4组，分别在基础日粮中添加1,2-丙二醇0、150、300和450 ml?d-1，测定采食量、产奶量、乳成分、体重、血糖和尿酮等浓度的变化。【结果】日粮添加丙二醇对奶牛的采食量、产奶量、乳蛋白率、乳糖率、乳干物质率和饲料转化效率无显著影响，450 ml?d-1组乳脂率显著低于0和150 ml?d-1组（P＜0.05）。添加丙二醇后，300、450 ml?d-1组血浆葡萄糖和胰岛素浓度显著高于0组（P＜0.05），而血浆游离脂肪酸和β-羟丁酸浓度显著低于0组（P＜0.05）;300、450 ml?d-1组尿酮浓度显著低于0和150 ml?d-1组（P＜0.05）。添加丙二醇300、450 ml?d-1显著改善泌乳早期奶牛能量负平衡，减少了体重下降。【结论】日粮添加丙二醇有益于改善泌乳早期奶牛能量平衡状况，适宜添加量为300 ml?d-1。

Effects of Propanediol Supplementation on Lactation Performance and Blood Metabolites in Early Lactation Holstein Dairy Cows

【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.