甘油对围产期奶牛能量平衡和肝脏糖原合成的影响

为了研究甘油对围产期奶牛能量平衡和肝脏糖原合成的影响,选用24头体重(674.6±13.8) kg、胎次(2.5±0.5)、上一泌乳期305 d产奶量(7 412±15) kg和预产期(23.8±0.3) d的经产奶牛,随机分为4组,从分娩前19 d开始分别在基础日粮中添加甘油0,100,200和300 g/d。结果表明,与对照组相比,添加甘油200和300 g/d,显著提高了奶牛分娩后7,21和35 d体况评分,显著改善了奶牛分娩前14 d和分娩后7,21和35 d的能量平衡。200和300 g/d组奶牛分娩前14 d胰岛素浓度和分娩后7,21和35 d奶牛血糖和胰岛素浓度显著高于对照组(P<0.05)。200和300 g/d组奶牛分娩后7,21和35 d血浆游离脂肪酸和β-羟丁酸浓度显著低于对照组和100 g/d组(P<0.05)。200和300 g/d组奶牛分娩后7,21和35 d肝脏糖原含量和糖异生途径限速酶活性显著高于对照组(P<0.05)。结果显示在日粮中添加甘油能够加强肝脏葡萄糖异生作用,改善奶牛能量平衡,适宜添加量为200 g/d。

Effects of glycerol on energy balance and concentration of glucose in the liver during the peripartum period in dairy cows

To observe the effects of glycerol on energy balance, blood parameter, glucose and adipose concentrations in the liver during the peripartum period in dairy cows, multiparous Holstein dairy cows with similar body weights (674.6±13.8 kg), lactation numbers (2.5±0.5), corrected milk yields in the last lactation (7 412±15 kg) and expected calving dates (23.8±0.3 d) were allocated into four treatments at random. Graded levels (0, 100, 200, and 300 g/d) of glycerol were supplemented in the four treatments from day 19 peripartum. Body condition score at 7, 21 and 35 d postpartum was increased, body weight loss from 7 to 35 d postpartum was reduced, energy balance at 14 d peripartum and 7, 21 and 35 d postpartum was improved significantly (P<0.05) by the 200 g/d and 300 g/d treatment compared with the 0 g/d treatment. Cows receiving 200 g/d and 300 g/d glycerol had a higher insulin concentration at 14 d peripartum and higher plasma glucose and insulin concentrations at 7, 21 and 35 d postpartum than the 0 g/d treatment (P<0.05). They had lower plasma NEFA and β-hydroxybutyrate at 7, 21 and 35 d postpartum than the 0 g/d and 100 g/d treatment (P<0.05) while 200 g/d and 300 g/d glycerol supplementation increased the contents of glycogen and key regulatory enzymes of gluconeogenesis in the liver compared with the 0 g/d glycerol treatment (P<0.05). Glycerol supplementation was beneficial to peripartum cows in enhancing the gluconeogenesis and improving energy balance status. The optimum dose was about 200 g per cow per day.