奶牛瘤胃及肝臟內乳前體物代謝規律的研究

姜發彬 莊蘇

摘 要：選擇6只安裝門靜脈、肝靜脈和股動脈慢性血管瘺的健康泌乳中期荷斯坦奶牛作為試驗動物，采用2×2交叉試驗設計，每組3只，試驗日糧分為高精料（High Concentrate，HC）和低精料（Low Concentrate，LC），兩組飼料的精粗比分別為6∶4和4∶6，研究不同精粗比日糧對泌乳奶牛瘤胃發酵類型以及內臟VFA、葡萄糖、β-羥丁酸吸收和代謝的影響。結果表明：奶牛采食后，瘤胃液pH值迅速降低，HC組和LC組瘤胃液pH值最小值分別出現在采食后1 h（pH=5.94）和2 h（pH=6.04）。與LC日糧相比，HC日糧組顯著瘤胃液中丙酸濃度（P<0.05），乙酸、丁酸和TVFA濃度差異不顯著，但是在數值上的平均濃度均有所增加；高精料日糧組降低乙酸/丙酸比例（P=0.06）。HC日糧與LC日糧瘤胃中產生的最大TVFA濃度分別在采食后1 h和2 h。HC日糧能夠顯著提高乙酸、丙酸、丁酸和TVFA（P<0.05）門靜脈血漿中濃度以及門靜脈-動脈血漿濃度差（difference of portal-artery，PA）（P<0.05）。VFA肝靜脈-門靜脈血漿濃度差（difference of hepatic-portal vein，HP）均為負值，并且HC組HP值小于LC組。除丙酸和丁酸的HP值（P<0.05）外，其余VFA的HP值在兩種日糧條件下沒有顯著性差異。丁酸的肝靜脈-動脈血漿濃度差（difference of hepatic-artery，HA）為負值且接近零，其余VFA的HA值都是正值。并且HC日糧顯著增加乙酸和TVFA的HA值（P<0.05），而丙酸HA值顯著降低（P<0.05）。HC日糧顯著提高門靜脈、肝靜脈和動脈血漿中葡萄糖（P<0.05）、非酯化脂肪酸（P<0.05）和β-羥丁酸濃度（P<0.05）。結論：飼喂HC日糧奶牛瘤胃形成丙酸型發酵，并且HC日糧能夠提供更多的能量物質供機體利用。

關鍵詞：精粗比 瘤胃 肝臟 揮發性脂肪酸

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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