奶牛瘤胃及肝脏内乳前体物代谢规律的研究

姜发彬 庄苏

摘 要：选择6只安装门静脉、肝静脉和股动脉慢性血管瘘的健康泌乳中期荷斯坦奶牛作为试验动物，采用2×2交叉试验设计，每组3只，试验日粮分为高精料（High Concentrate，HC）和低精料（Low Concentrate，LC），两组饲料的精粗比分别为6∶4和4∶6，研究不同精粗比日粮对泌乳奶牛瘤胃发酵类型以及内脏VFA、葡萄糖、β-羟丁酸吸收和代谢的影响。结果表明：奶牛采食后，瘤胃液pH值迅速降低，HC组和LC组瘤胃液pH值最小值分别出现在采食后1 h（pH=5.94）和2 h（pH=6.04）。与LC日粮相比，HC日粮组显著瘤胃液中丙酸浓度（P<0.05），乙酸、丁酸和TVFA浓度差异不显著，但是在数值上的平均浓度均有所增加；高精料日粮组降低乙酸/丙酸比例（P=0.06）。HC日粮与LC日粮瘤胃中产生的最大TVFA浓度分别在采食后1 h和2 h。HC日粮能够显著提高乙酸、丙酸、丁酸和TVFA（P<0.05）门静脉血浆中浓度以及门静脉-动脉血浆浓度差（difference of portal-artery，PA）（P<0.05）。VFA肝静脉-门静脉血浆浓度差（difference of hepatic-portal vein，HP）均为负值，并且HC组HP值小于LC组。除丙酸和丁酸的HP值（P<0.05）外，其余VFA的HP值在两种日粮条件下没有显著性差异。丁酸的肝静脉-动脉血浆浓度差（difference of hepatic-artery，HA）为负值且接近零，其余VFA的HA值都是正值。并且HC日粮显著增加乙酸和TVFA的HA值（P<0.05），而丙酸HA值显著降低（P<0.05）。HC日粮显著提高门静脉、肝静脉和动脉血浆中葡萄糖（P<0.05）、非酯化脂肪酸（P<0.05）和β-羟丁酸浓度（P<0.05）。结论：饲喂HC日粮奶牛瘤胃形成丙酸型发酵，并且HC日粮能够提供更多的能量物质供机体利用。

关键词：精粗比 瘤胃 肝脏 挥发性脂肪酸

Metabolic Rule of Milk Precursor in the Rumen and Liver of Dairy Cows

Jiang Fabin Zhuang Su

（Nanjing Agricultural University）

Abstract：Six healthy mid-lactating Holstein dairy cows with chronic indwelling catheters in the portal， hepatic vein and femoral artery were used in randomized crossover trial designed to evaluate the effect of concentrate to forage ratio on the rumen fermentation patterns and splanchnic absorption and metabolism of VFA， glucose and β-Hydroxybutyrate. The experimental diets consisted of concentrate and forage which were high concentrate diet （HC，40% forage，60% concentrate） or low concentrate diet （LC，40% concentrate，60% forage）， respectively. The results showed that the concentration value of acetate， propionate， butyrate and total VFA in rumen fluid were higher， and concentration of propionate wassignificant （P<0.05） when cows fed HC diets compared with LC diets. The ratio of acetate to propionate was tended to decreased （P=0.06） in HC diet compared with LC diet. The concentration of acetate， propionate， butyrate and TVFA in the portal vein in HC diets were markedly higher（P<0.05） than in LC diets. Compared with LC diet， HC diet markedly increased the portal-arterial（PA） concentration differences of acetate， propionate， butyrate and TVFA. While， the value of hepatic-portal（HP） difference is negative and the propionate and butyrate concentration difference in HP was significant （P<0.05） in cows fed HC diet than LC diet. Except propionate， the hepatic-arterial（HA） concentration differences of acetate and TVFA increased significantly（P<0.05）. Glucose， Nonesterified fatty acid and β-Hydroxybutyrate concentrations of portal， hepatic vein and arterial were markedly higher（P<0.05） for cows fed HC diet than that fed LC diet. In conclusion， the high concentrates diet may provide more energy to the whole body in lactating cows.

Key Words： Concentrate to forage ratio； Rumen； liver； Volatile fatty acids

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