基础日粮下关中奶山羊乳腺对营养物质摄取和利用的研究

Study on Nutrient Uptake and Utilization in the Mammary Gland of Guanzhong Dairy Goats Fed Basal Diet

本试验旨在研究基础日粮条件下关中奶山羊乳腺对营养物质摄取和利用的规律。试验选用4只处于泌乳中期且安装有阴外动脉血插管的关中奶山羊测定乳腺血流量和动静脉营养物质浓度差。结果表明,在基础日粮条件下,每天平均产奶量为1.50 kg的关中奶山羊,每天乳中产出乳蛋白50.18 g、乳脂52.54 g和乳糖69.75 g;每天乳腺摄取乙酸60.65 g、丙酸3.07 g、丁酸6.23 g、葡萄糖126.76 g和甘油三酯26.71 g。奶山羊每天乳腺摄取氨基酸总量50.76 g,乳腺氨基酸摄取率为35.74%,其中必需氨基酸(essential amino acid,EAA)摄取量38.37 g/d,乳腺摄取率45.80%,各氨基酸摄取率由大到小的顺序为:Met>Phe>Leu>Ile>Lys>Thr>Val>His>Arg;非必需氨基酸(nonessential amino acid,NEAA)摄取量12.40 g/d,乳腺摄取率21 28%,各氨基酸摄取率由大到小的顺序为:Glu>Asp>Ala>Tyr>Pro>Ser>Gly。乳腺动脉总氨基酸浓度为282.38 mg/L,静脉氨基酸浓度为181.46 mg/L,动静脉浓度差为100.92 mg/L。在基础日粮条件下,关中奶山羊EAA的乳腺摄取率显著高于NEAA(P<0.05)。乳腺摄取的氨基酸中99%用于合成乳蛋白;乳腺摄取的乳脂前体中98%用于合成乳脂;乳腺摄取的葡萄糖中59%用于合成乳糖,41%葡萄糖用于氧化供能或转化成其他营养物质。

The aim of the paper was to study the nutrient uptake and utilization in the mammary gland of Guanzhong dairy goats fed basal diet. Four Guanzhong dairy goats were fixed with vessel catheters at the external pudic artery to determine blood flow and artery-vein concentration difference across the mammary gland. The results were as follows： under the condition of feeding a basic diet, the average milk yield of the four goats was 1.50 kg and milk protein, milk fat and lactose out- put were 50.18, 52.54 and 69.75 g/d. Acetic acid, propionic acid, butyric acid, glucose and triglycerides uptake quantity were 60.65, 3.07, 6.23, 126.76 and 26.71 g/d, respectively. The uptake quantity of total amino acids in the mammary gland was 50.76 g/d and the uptake rate in the mammary gland was 35.74%. The uptake quantity of EAA was 38.87 g/d and the uptake rate in the mammary gland was 45.80%. The order of uptake quantity of individual amino acid was Met〉 Phe〉Leu〉Ile〉Lys〉Thr〉Val〉His〉Arg. NEAA uptake quantity was 12.40 g/d and uptake rate was 21.28%. The order of uptake of individual amino acid was Glu〉Asp〉Ala〉Tyr〉Pro〉Ser〉Gly. The concentration of total amino acids in the external pudic artery was 282.38 mg/L; the concentration of total amino acids in the mammary vein was 181.46 mg/L; the concentration difference between the mammary artery and the vein was 100.92 mg/L. The uptake rate of EAA was significantly higher than that of NEAA under the condition of feeding basal diet （P〈0.05）. About 99% amino acids uptaken by the mammary gland was used for synthesis of milk protein; 98% milk fat precursors was used for synthesis of milk fat; 59% glucose was used for synthesis of lactose and 41% was oxidized to provide energy or transferred to other nutrients.